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Search for "Horner–Wadsworth–Emmons reaction" in Full Text gives 32 result(s) in Beilstein Journal of Organic Chemistry.
(Bio)isosteres of ortho- and meta-substituted benzenes
- H. Erik Diepers and
- Johannes C. L. Walker
Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78
- homologation and hydrolysis led to aldehyde (±)-46 which could then be oxidised to acid (±)-47 using a Pinnick oxidation. BCH 42b also led to ester (±)-48 via a Horner–Wadsworth–Emmons reaction followed by hydrogenation of the formed alkene. 1,2-BCH 44 could be turned into amine (±)-49 by oxime formation and
Graphical Abstract
Figure 1: Scaffolds commonly reported as bioisosteric replacements of para-substituted benzene and examples p...
Figure 2: 1,2-BCPs as isosteres for ortho-and meta-substituted benzenes: comparison of reported exit vector p...
Scheme 1: 1,2-Disubstituted bicyclo[1.1.1]pentanes as isosteres of ortho-substituted benzenes. A: Baran, Coll...
Scheme 2: Synthesis of 1,2-BCPs from BCP 15 by bridge C–H bromination as reported by MacMillan and co-workers ...
Figure 3: Comparative physicochemical data of telmisartan, lomitapide and their BCP isosteres [26,33]. Shake flask d...
Figure 4: 1,2-Disubstituted bicyclo[2.1.1]hexanes as isosteres of ortho-benzenes: Exit vector parameters of t...
Scheme 3: Synthesis of 1,2-disubstituted bicyclo[2.1.1]hexanes via alkene insertion into bicyclo[1.1.0]butane...
Scheme 4: Synthesis of 1,2-disubstituted bicyclo[2.1.1]hexanes via intramolecular crossed [2 + 2] cycloadditi...
Figure 5: Comparison of physicochemical data of fluxapyroxad and boscalid and their 1,2-BCH bioisosteres [36]. Sh...
Figure 6: Antifungal activity of fluxapyroxad, its 1,5-BCH bioisostere (±)-55, boscalid and its bioisostere 1...
Figure 7: 1,5-Disubstituted bicyclo[2.1.1]hexanes as isosteres of ortho-substituted benzenes. Comparison of e...
Scheme 5: Synthesis of 1,5-disubstituted bicyclo[2.1.1]hexanes as isosteres of ortho-benzenes via intramolecu...
Figure 8: Comparison of physicochemical data of fluxapyroxad and boscalid and their 1,5-BCH bioisosteres [45]. Sh...
Figure 9: Antifungal activity of fluxapyroxad, its 1,5-BCH bioisostere (±)-64, boscalid and its bioisostere 1...
Figure 10: 1,5-Disubstituted 3-oxabicylco[2.1.1]hexanes as isosteres for ortho-benzenes: Comparison of exit ve...
Scheme 6: Synthesis of 1,5-disubstituted 3-oxabicyclo[2.1.1]hexanes as isosteres for ortho-benzenes via intra...
Figure 11: Comparison of physicochemical data of fluxapyroxad and boscalid and their 3-oxa-1,5-BCH bioisostere...
Figure 12: Antifungal activity of fluxapyroxad and boscalid and their 3-oxa-1,5-BCH bioisosteres (±)-75 and (±...
Figure 13: 1,2-Disubstituted bicyclo[3.1.1]heptanes as isosteres of ortho-benzenes. Schematic representation o...
Scheme 7: Synthesis of 1,2-disubstituted bicyclo[3.1.1]heptanes as isosteres for ortho-benzenes via alkene in...
Figure 14: 1,2-Disubstituted stellanes as ortho-benzene isosteres: Comparison of selected exit vector paramete...
Scheme 8: Synthesis of 1,2-disubstituted stellanes as isosteres for ortho-benzenes reported by Ryabukhin, Vol...
Figure 15: 1,2-Disubstituted cubanes as ortho-benzene isosteres: Comparison of substituent distances and angle...
Scheme 9: Synthesis of 1,2-disubsituted cubanes as isosteres for ortho-benzenes. A: Synthesis of 1,2-cubane d...
Figure 16: 1,3-Disubstituted bicyclo[2.1.1]hexanes as isosteres of meta-benzenes: comparative exit vector para...
Scheme 10: Synthesis of 1,3-disubstituted bicyclo[2.1.1]hexanes as isosteres for meta-benzenes reported by Wal...
Figure 17: 1,4-Disubstituted bicyclo[2.1.1]hexanes as isosteres of meta-benzenes: comparative exit vector para...
Scheme 11: Synthesis of 1,4-disubstituted bicyclo[2.1.1}hexanes as isosteres for ortho-benzenes via intramolec...
Figure 18: 1,4-Disubstituted-2-oxabicyclo[2.1.1]hexanes as meta-benzene isosteres: comparison of selected exit...
Scheme 12: Synthesis of 1,4-disubstituted 2-oxabicyclo[2.1.1]hexanes as isosteres for meta-benzenes. A: Mykhai...
Figure 19: Comparative physicochemical data for 2- and 3-oxa-1,4-BCHs and para-substituted benzene equivalents...
Figure 20: 1,5-Disubstituted bicyclo[3.1.1]heptanes as isosteres of meta-benzenes: comparison of exit vector p...
Scheme 13: Synthesis of [3.1.1]propellane as a precursor for 1,5-disubsituted bicyclo[3.1.1]heptanes. A: aGass...
Scheme 14: Synthesis of iodine-substituted 1,5-disubstituted bicyclo[3.1.1]heptanes as isosteres for meta-benz...
Scheme 15: Synthesis of nitrogen-, chalcogen- and tin-substituted 1,5-disubstituted bicyclo[3.1.1]heptanes as ...
Figure 21: Comparative physicochemical data of URB597 and 1,5-BCHep isostere 146 [27]. Kinetic aqueous solubility ...
Figure 22: [2]-Ladderanes as isosteres of meta-benzenes: comparison of reported exit vector parameters [63].
Scheme 16: Synthesis of cis-2,6-disubstituted bicyclo[2.2.0]hexanes as isosteres for meta-benzenes. A: Brown a...
Figure 23: Comparative physicochemical data of meta-benzene 158 and [2]-ladderane isostere 159 [63]. Partition coe...
Figure 24: 1,3-Disubstituted cubanes as isosteres of meta-benzenes: comparison of selected exit vector paramet...
Scheme 17: Synthesis of 1,3-disubsituted cubanes as isosteres for meta-benzenes. A: MacMillan and co-workers’ ...
Figure 25: Comparative physicochemical data of lumacaftor and its 1,3-cubane bioisostere 183 [51]. Distribution co...
Figure 26: 1,3-Disubstituted cuneanes as isosteres of meta-benzenes: comparison of selected exit vector parame...
Scheme 18: Synthesis of 1,3-cuneanes as isosteres of meta-benzene. A: Synthesis of 1,3-cuneanes reported by La...
Figure 27: Comparative physicochemical data of sonidegib and its 1,3-cuneane isostere 190 [71]. aSolubility was to...
Figure 28: Exemplary polysubstituted scaffolds related to disubstituted scaffolds suggested as isosteres of or...
Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities
- Jorge de Lima Neto and
- Paulo Henrique Menezes
Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31
- synthesis of combretastatin D-1 (1) using the flash vacuum pyrolysis (FVP) technique, which consisted on the contraction of 16-membered sulfone derivatives, by extrusion of sulfur dioxide [58]. The synthesis of the required sulfone was initiated by a Horner–Wadsworth–Emmons reaction between the aldehyde 52
Graphical Abstract
Figure 1: Structures of some members of the combretastatin D series, corniculatolides, and isocorniculatolide...
Scheme 1: Biosynthetic pathway proposed by Pettit and co-workers.
Scheme 2: Biosynthetic pathway towards corniculatolides or isocorniculatolides proposed by Ponnapalli and co-...
Scheme 3: Retrosynthetic approaches.
Scheme 4: Attempt of total synthesis of 2 by Boger and co-workers employing the Mitsunobu approach [27].
Scheme 5: Total synthesis of combretastatin D-2 (2) reported by Boger and co-workers employing an intramolecu...
Scheme 6: Formal synthesis of combretastatin D-2 (2) by Deshpande and co-workers using the Mitsunobu conditio...
Scheme 7: Total synthesis of combretastatin D-2 (2) by Rychnovsky and Hwang [36].
Scheme 8: Divergent synthesis of (±)-1 form combretastatin D-2 (2) by Rychnovsky and Hwang [36].
Scheme 9: Enantioselective synthesis of 1 by Rychnovsky and Hwang employing Jacobsen catalyst [41].
Scheme 10: Synthesis of fragment 57 by Couladouros and co-workers [43,45].
Scheme 11: Formal synthesis of compound 2 by Couladouros and co-workers [43,45].
Scheme 12: Synthesis of fragment 66 by Couladouros and co-workers [44,45].
Scheme 13: Synthesis of fragment 70 by Couladouros and co-workers [44,45].
Scheme 14: Synthesis of fragment 77 by Couladouros and co-workers [44,45].
Scheme 15: Synthesis of combretastatins 1 and 2 by Couladouros and co-workers [44,45].
Scheme 16: Formal synthesis of compound 2 by Gangakhedkar and co-workers [48].
Scheme 17: Synthesis of fragment 14 by Cousin and co-workers [50].
Scheme 18: Synthesis of fragment 91 by Cousin and co-workers [50].
Scheme 19: Formal synthesis of compound 2 by Cousin and co-workers [50].
Scheme 20: Synthesis of 2 diolide by Cousin and co-workers [50].
Scheme 21: Synthesis of combretastatin D-4 (4) by Nishiyama and co-workers [54].
Scheme 22: Synthesis of fragment 112 by Pettit and co-workers [55].
Scheme 23: Synthesis of fragment 114 by Pettit and co-workers [55].
Scheme 24: Attempt to the synthesis of compound 2 by Pettit and co-workers [55].
Scheme 25: Synthesis of combretastatin-D2 (2) starting from isovanilin (80) by Pettit and co-workers [55].
Scheme 26: Attempted synthesis of combretastatin-D2 (2) derivatives through an SNAr approach [55].
Scheme 27: Synthesis of combretastatin D-4 (4) by Pettit and co-workers [55].
Scheme 28: Synthesis of combretastatin D-2 (2) by Harras and co-workers [57].
Scheme 29: Synthesis of combretastatin D-4 (4) by Harras and co-workers [57].
Scheme 30: Formal synthesis of combretastatin D-1 (1) by Harras and co-workers [57].
Scheme 31: Synthesis of 11-O-methylcorniculatolide A (5) by Raut and co-workers [69].
Scheme 32: Synthesis of isocorniculatolide A (7) and O-methylated isocorniculatolide A 8 by Raut and co-worker...
Scheme 33: Synthesis of isocorniculatolide B (10) and hydroxyisocorniculatolide B 175 by Kim and co-workers [71].
Scheme 34: Synthesis of compound 9, 178, and 11 by Kim and co-workers [71].
Scheme 35: Synthesis of combretastatin D-2 prodrug salts [55].
Figure 2: ED50 values of the combretastatin D family against murine P388 lymphocytic leukemia cell line (appr...
Figure 3: IC50 of compounds against α-glucosidase [19].
Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones
- Benedikt Kolb,
- Daniela Silva dos Santos,
- Sanja Krause,
- Anna Zens and
- Sabine Laschat
Beilstein J. Org. Chem. 2023, 19, 176–185, doi:10.3762/bjoc.19.17
- condensation of enals 6 with aldehydes 7a or ketones 7b [6][7][8][9][10][11], isomerization of alkynones 8 [12][13][14][15], Horner–Wadsworth–Emmons reaction of unsaturated phosphonates 9 and aldehydes 10 [16][17], and dehydrogenation of enones 11 [18]. Further, Claisen rearrangement of vinyl propargylic
Graphical Abstract
Scheme 1: Examples of biologically active compounds with (2Ε,4E)-unsaturated ketone units.
Scheme 2: Selected examples for the synthesis of conjugated dienones from the literature [6-21].
Scheme 3: Previous work of hydrozirconations with Schwartz's reagent and our work [54,55,57,58,61,62].
Scheme 4: Synthesis of substituted enynes 25f–o via Corey–Fuchs reaction and Hunsdiecker reaction.
Scheme 5: Synthesis of non-natural (a) and natural (b) dienone-containing terpenes: synthesis of β-ionone (3)....
Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris
- Angelique Ladwig,
- Markus Kroll and
- Stefan Schulz
Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16
- in a Michael addition with methyl acrylate, affording aldehyde 4 (Scheme 1). Instead of the original Wittig reaction [13], a Horner–Wadsworth–Emmons reaction using diethyl (2-methylallyl)phosphonate and BuLi led to a higher yield and formation of the pure (E)-isomer 5. The required phosphonate was
Graphical Abstract
Figure 1: Calling male Hyperolius cinnamomeoventris with exposed vocal sac carrying the yellow gular gland. Figure 1 ...
Figure 2: Macrolides identified in gular glands of male Hyperolius cinnamomeoventris.
Figure 3: Total ion chromatogram (TIC) of a gular gland extract of Hyperolius cinnamomeoventris on a polar DB...
Figure 4: Mass spectrum of sesquiterpene A (I = 1596) from the gular gland extract of male Hyperolius cinnamo...
Scheme 1: Racemic synthesis of cadinols modified from Taber and Gunn [13]. Conditions a) i) K2CO3 (0.35 equiv), 0...
Scheme 2: Enantioselective synthesis with (S)-Jørgensen’s organocatalyst S-16. Conditions: a) S-16 (5 mol %),...
Figure 5: TIC and gas chromatographic Kovats retention indices RI [24] values determined on a Hydrodex β-6TBDM ph...
Figure 6: Coinjection of R-14 and S-14 with a gular gland extract of Hyperolius cinnamomeoventris performed w...
Figure 7: Mass spectra of each cadinol-type diastereomer. The box colors refer to the peaks and compounds in Figure 5....
Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles
- Bilge Banu Yagci,
- Selin Ezgi Donmez,
- Onur Şahin and
- Yunus Emre Türkmen
Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6
- starting from the commercially available triethyl phosphonoacetate (14, Scheme 2a). The deprotonation of 14 with NaH followed by alkylation using (iodomethyl)trimethylsilane afforded phosphonate 15 in 60% yield (7.0 g). Its subsequent Horner–Wadsworth–Emmons reaction with isovaleraldehyde resulted in the
Graphical Abstract
Scheme 1: Examples of aza-Nazarov reactions.
Scheme 2: Aza-Nazarov cyclization on gram scale.
Scheme 3: Scope of the aza-Nazarov cyclization with acyclic imines. aThe syntheses of aza-Nazarov products 19b...
Figure 1: X-ray crystal structure of compound 19l.
Scheme 4: Proposed mechanism for the formation of diastereomers 19 and 22.
Scheme 5: Preparation of acyl chloride 23.
Scheme 6: Aza-Nazarov reaction tested using β-TMS-substituted acyl chloride 23.
Scheme 7: Hydrolysis of N-acyliminium intermediates.
Scheme 8: (a) Two possible pathways for the formation of 7 and (b) investigation of the reaction between imin...
Scheme 9: (a) Preparation of acyl chlorides 6ba and 6bb in diastereomerically pure forms, (b) aza-Nazarov cyc...
Total synthesis of grayanane natural products
- Nicolas Fay,
- Rémi Blieck,
- Cyrille Kouklovsky and
- Aurélien de la Torre
Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181
- group on C6 was introduced after cyclopropane ring-opening, ketone protection, epoxidation and reductive ring-opening of the resulting epoxide. A one-pot β-keto phosphonate formation/Horner–Wadsworth–Emmons reaction with formaldehyde afforded 38, a precursor for the key oxidative dearomatization-induced
Graphical Abstract
Figure 1: General structure of grayanane natural products.
Scheme 1: Grayanane biosynthesis.
Scheme 2: Matsumoto’s relay approach.
Scheme 3: Shirahama’s total synthesis of (–)-grayanotoxin III.
Scheme 4: Newhouse’s syntheses of fragments 25 and 29.
Scheme 5: Newhouse’s total synthesis of principinol D.
Scheme 6: Ding’s total synthesis of rhodomolleins XX and XXII.
Scheme 7: First key step of Luo’s strategy.
Scheme 8: Luo’s total synthesis of grayanotoxin III.
Scheme 9: Synthesis of principinol E and rhodomollein XX.
Scheme 10: William’s synthetic effort towards pierisformaside C.
Scheme 11: Hong’s synthetic effort towards rhodojaponin III.
Scheme 12: Recent strategies for grayanane synthesis.
Vicinal ketoesters – key intermediates in the total synthesis of natural products
- Marc Paul Beller and
- Ulrich Koert
Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129
- ]. The α-ketoester 41 was accessible from amide 38, which in turn was obtained from allylic alcohol 37. Oxidation and Horner–Wadsworth–Emmons reaction with phosphonate 39 delivered the silyl enol ether 40, which was deprotected and cyclized via a Grubbs metathesis to α-ketoester 41. Subsequent
- was synthesized by a Horner–Wadsworth–Emmons reaction of phosphonate 48 with aldehyde 47. Enantiopure aldehyde 47 was easily accessible from oxazolidinone 46 via Evans-aldol chemistry [23]. Heating of the α-ketoester 49 led to the highly substituted cyclopentanol 50 in a good dr of ≈5:1 (minor
Graphical Abstract
Scheme 1: Structures of vicinal ketoesters and examples for their typical reactivity.
Scheme 2: Doyle’s diastereoselective intramolecular aldol addition of α,β-diketoester.
Scheme 3: Synthesis of euphorikanin A (16) by intramolecular, nucleophilic addition [6].
Scheme 4: Ketoester cycloisomerization for the synthesis of preussochromone A (24) [10].
Scheme 5: Diastereoselective, intramolecular aldol reaction of an α-ketoester 28 in the synthesis of (−)-preu...
Scheme 6: Synthesis of an α-ketoester through Riley oxidation and its use in an α-ketol rearrangement in the ...
Scheme 7: Azomethine imine cycloaddition towards the synthesis of the proposed structure of palau’amine (44) [19]....
Scheme 8: Intramolecular diastereoselective carbonyl-ene reaction of an α-ketoester in the synthesis of jatro...
Scheme 9: Grignard addition to an α-ketoester and subsequent Friedel–Crafts cyclization in the synthesis of (...
Scheme 10: Diastereoselective addition to an auxiliary modified α-ketoester in the formal synthesis of (+)-cam...
Scheme 11: Intramolecular photoreduction of an α-ketoester in the synthesis of (rac)-isoretronecanol (69) [26].
Scheme 12: α-Ketoester as nucleophile in a Tsuji–Trost reaction in the synthesis of (rac)-corynoxine (76) [27].
Scheme 13: Mannich reaction of an α-ketoester in the synthesis of (+)-gracilamine (83) [28].
Scheme 14: Enantioselective aldol reaction using an α-ketoester in the synthesis of (−)-irofulven (87) [29].
Scheme 15: Allylboration of a mesoxalic acid ester in the synthesis of (+)-awajanomycin (92) [30,31].
Scheme 16: Condensation of a diamine with mesoxolate in the synthesis of (−)-aplaminal (96) [32].
Scheme 17: Synthesis of mesoxalic ester amide 102 and its use in the synthesis of (rac)-cladoniamide G (103) [33].
Scheme 18: The thermodynamically controlled, intramolecular aldol addition of a vic-tricarbonyl compound in th...
The stereochemical course of 2-methylisoborneol biosynthesis
- Binbin Gu,
- Anwei Hou and
- Jeroen S. Dickschat
Beilstein J. Org. Chem. 2022, 18, 818–824, doi:10.3762/bjoc.18.82
- . Results and Discussion Enantioselective synthesis of 2-methyllinalyl diphosphate The synthesis of (R)- and (S)-2-Me-LPP started with the Horner–Wadsworth–Emmons reaction [34][35] of sulcatone (2) with triethyl 2-phosphonopropionate to obtain ethyl 2-methylgeranate (3) as a mixture of the E and Z
Graphical Abstract
Scheme 1: Biosynthesis of 2-MIB (1). A) Naturally observed pathway through methylation of GPP to 2-Me-GPP by ...
Figure 1: A) Active site of 2MIBS with the bound substrate surrogate 2FGPP (generated with Pymol from the cry...
Scheme 2: Synthesis of (R)- and (S)-2-Me-LPP.
Figure 2: Structures of 2MIBS side products and spontaneous degradation products of 2-Me-LPP. The enantiomers...
Figure 3: Total ion chromatograms of extracts from an incubation of A) enantiomerically pure (R)-2-Me-LPP wit...
Scheme 3: Hypothetical mechanism for the isomerization of (S)-2-Me-LPP through 2-Me-GPP to (R)-2-Me-LPP.
A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries
- Guido Gambacorta,
- James S. Sharley and
- Ian R. Baxendale
Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90
Graphical Abstract
Figure 1: Representative shares of the global F&F market (2018) segmented on their applications [1].
Figure 2: General structure of an international fragrance company [2].
Figure 3: The Michael Edwards fragrance wheel.
Figure 4: Examples of oriental (1–3), woody (4–7), fresh (8–10), and floral (11 and 12) notes.
Figure 5: A basic depiction of batch vs flow.
Scheme 1: Examples of reactions for which flow processing outperforms batch.
Scheme 2: Some industrially important aldol-based transformations.
Scheme 3: Biphasic continuous aldol reactions of acetone and various aldehydes.
Scheme 4: Aldol synthesis of 43 in flow using LiHMDS as the base.
Scheme 5: A semi-continuous synthesis of doravirine (49) involving a key aldol reaction.
Scheme 6: Enantioselective aldol reaction using 5-(pyrrolidin-2-yl)tetrazole (51) as catalyst in a microreact...
Scheme 7: Gröger's example of asymmetric aldol reaction in aqueous media.
Figure 6: Immobilised reagent column reactor types.
Scheme 8: Photoinduced thiol–ene coupling preparation of silica-supported 5-(pyrrolidin-2-yl)tetrazole 63 and...
Scheme 9: Continuous-flow approach for enantioselective aldol reactions using the supported catalyst 67.
Scheme 10: Ötvös’ employment of a solid-supported peptide aldol catalyst in flow.
Scheme 11: The use of proline tetrazole packed in a column for aldol reaction between cyclohexanone (65) and 2...
Scheme 12: Schematic diagram of an aminosilane-grafted Si-Zr-Ti/PAI-HF reactor for continuous-flow aldol and n...
Scheme 13: Continuous-flow condensation for the synthesis of the intermediate 76 to nabumetone (77) and Microi...
Scheme 14: Synthesis of ψ-Ionone (80) in continuous-flow via aldol condensation between citral (79) and aceton...
Scheme 15: Synthesis of β-methyl-ionones (83) from citral (79) in flow. The steps are separately described, an...
Scheme 16: Continuous-flow synthesis of 85 from 84 described by Gavriilidis et al.
Scheme 17: Continuous-flow scCO2 apparatus for the synthesis of 2-methylpentanal (87) and the self-condensed u...
Scheme 18: Chen’s two-step flow synthesis of coumarin (90).
Scheme 19: Pechmann condensation for the synthesis of 7-hydroxyxcoumarin (93) in flow. The setup extended to c...
Scheme 20: Synthesis of the dihydrojasmonate 35 exploiting nitro derivative proposed by Ballini et al.
Scheme 21: Silica-supported amines as heterogeneous catalyst for nitroaldol condensation in flow.
Scheme 22: Flow apparatus for the nitroaldol condensation of p-hydroxybenzaldehyde (102) to nitrostyrene 103 a...
Scheme 23: Nitroaldol reaction of 64 to 105 employing a quaternary ammonium functionalised PANF.
Scheme 24: Enantioselective nitroaldol condensation for the synthesis of 108 under flow conditions.
Scheme 25: Enatioselective synthesis of 1,2-aminoalcohol 110 via a copper-catalysed nitroaldol condensation.
Scheme 26: Examples of Knoevenagel condensations applied for fragrance components.
Scheme 27: Flow apparatus for Knoevenagel condensation described in 1989 by Venturello et al.
Scheme 28: Knoevenagel reaction using a coated multichannel membrane microreactor.
Scheme 29: Continuous-flow apparatus for Knoevenagel condensation employing sugar cane bagasse as support deve...
Scheme 30: Knoevenagel reaction for the synthesis of 131–135 in flow using an amine-functionalised silica gel. ...
Scheme 31: Continuous-flow synthesis of compound 137, a key intermediate for the synthesis of pregabalin (138)...
Scheme 32: Continuous solvent-free apparatus applied for the synthesis of compounds 140–143 using a TSE. Throu...
Scheme 33: Lewis et al. developed a spinning disc reactor for Darzens condensation of 144 and a ketone to furn...
Scheme 34: Some key industrial applications of conjugate additions in the F&F industry.
Scheme 35: Continuous-flow synthesis of 4-(2-hydroxyethyl)thiomorpholine 1,1-dioxide (156) via double conjugat...
Scheme 36: Continuous-flow system for Michael addition using CsF on alumina as the catalyst.
Scheme 37: Calcium chloride-catalysed asymmetric Michael addition using an immobilised chiral ligand.
Scheme 38: Continuous multistep synthesis for the preparation of (R)-rolipram (173). Si-NH2: primary amine-fun...
Scheme 39: Continuous-flow Michael addition using ion exchange resin Amberlyst® A26.
Scheme 40: Preparation of the heterogeneous catalyst 181 developed by Paixão et al. exploiting Ugi multicompon...
Scheme 41: Continuous-flow system developed by the Paixão’s group for the preparation of Michael asymmetric ad...
Scheme 42: Continuous-flow synthesis of nitroaldols catalysed by supported catalyst 184 developed by Wennemers...
Scheme 43: Heterogenous polystyrene-supported catalysts developed by Pericàs and co-workers.
Scheme 44: PANF-supported pyrrolidine catalyst for the conjugate addition of cyclohexanone (65) and trans-β-ni...
Scheme 45: Synthesis of (−)-paroxetine precursor 195 developed by Ötvös, Pericàs, and Kappe.
Scheme 46: Continuous-flow approach for the 5-step synthesis of (−)-oseltamivir (201) as devised by Hayashi an...
Scheme 47: Continuous-flow enzyme-catalysed Michael addition.
Scheme 48: Continuous-flow copper-catalysed 1,4 conjugate addition of Grignard reagents to enones. Reprinted w...
Scheme 49: A collection of commonly encountered hydrogenation reactions.
Figure 7: The ThalesNano H-Cube® continuous-flow hydrogenator.
Scheme 50: Chemoselective reduction of an α,β-unsaturated ketone using the H-Cube® reactor.
Scheme 51: Incorporation of Lindlar’s catalyst into the H-Cube® reactor for the reduction of an alkyne.
Scheme 52: Continuous-flow semi-hydrogenation of alkyne 208 to 209 using SACs with H-Cube® system.
Figure 8: The standard setups for tube-in-tube gas–liquid reactor units.
Scheme 53: Homogeneous hydrogenation of olefins using a tube-in-tube reactor setup.
Scheme 54: Recyclable heterogeneous flow hydrogenation system.
Scheme 55: Leadbeater’s reverse tube-in-tube hydrogenation system for olefin reductions.
Scheme 56: a) Hydrogenation using a Pd-immobilised microchannel reactor (MCR) and b) a representation of the i...
Scheme 57: Hydrogenation of alkyne 238 exploiting segmented flow in a Pd-immobilised capillary reactor.
Scheme 58: Continuous hydrogenation system for the preparation of cyrene (241) from (−)-levoglucosenone (240).
Scheme 59: Continuous hydrogenation system based on CSMs developed by Hornung et al.
Scheme 60: Chemoselective reduction of carbonyls (ketones over aldehydes) in flow.
Scheme 61: Continuous system for the semi-hydrogenation of 256 and 258, developed by Galarneau et al.
Scheme 62: Continuous synthesis of biodiesel fuel 261 from lignin-derived furfural acetone (260).
Scheme 63: Continuous synthesis of γ-valerolacetone (263) via CTH developed by Pineda et al.
Scheme 64: Continuous hydrogenation of lignin-derived biomass (products 265, 266, and 267) using a sustainable...
Scheme 65: Ru/C or Rh/C-catalysed hydrogenation of arene in flow as developed by Sajiki et al.
Scheme 66: Polysilane-immobilized Rh–Pt-catalysed hydrogenation of arenes in flow by Kobayashi et al.
Scheme 67: High-pressure in-line mixing of H2 for the asymmetric reduction of 278 at pilot scale with a 73 L p...
Figure 9: Picture of the PFR employed at Eli Lilly & Co. for the continuous hydrogenation of 278 [287]. Reprinted ...
Scheme 68: Continuous-flow asymmetric hydrogenation using Oppolzer's sultam 280 as chiral auxiliary.
Scheme 69: Some examples of industrially important oxidation reactions in the F&F industry. CFL: compact fluor...
Scheme 70: Gold-catalysed heterogeneous oxidation of alcohols in flow.
Scheme 71: Uozumi’s ARP-Pt flow oxidation protocol.
Scheme 72: High-throughput screening of aldehyde oxidation in flow using an in-line GC.
Scheme 73: Permanganate-mediated Nef oxidation of nitroalkanes in flow with the use of in-line sonication to p...
Scheme 74: Continuous-flow aerobic anti-Markovnikov Wacker oxidation.
Scheme 75: Continuous-flow oxidation of 2-benzylpyridine (312) using air as the oxidant.
Scheme 76: Continuous-flow photo-oxygenation of monoterpenes.
Scheme 77: A tubular reactor design for flow photo-oxygenation.
Scheme 78: Glucose oxidase (GOx)-mediated continuous oxidation of glucose using compressed air and the FFMR re...
Scheme 79: Schematic continuous-flow sodium hypochlorite/TEMPO oxidation of alcohols.
Scheme 80: Oxidation using immobilised TEMPO (344) was developed by McQuade et al.
Scheme 81: General protocol for the bleach/catalytic TBAB oxidation of aldehydes and alcohols.
Scheme 82: Continuous-flow PTC-assisted oxidation using hydrogen peroxide. The process was easily scaled up by...
Scheme 83: Continuous-flow epoxidation of cyclohexene (348) and in situ preparation of m-CPBA.
Scheme 84: Continuous-flow epoxidation using DMDO as oxidant.
Scheme 85: Mukayama aerobic epoxidation optimised in flow mode by the Favre-Réguillon group.
Scheme 86: Continuous-flow asymmetric epoxidation of derivatives of 359 exploiting a biomimetic iron catalyst.
Scheme 87: Continuous-flow enzymatic epoxidation of alkenes developed by Watts et al.
Scheme 88: Engineered multichannel microreactor for continuous-flow ozonolysis of 366.
Scheme 89: Continuous-flow synthesis of the vitamin D precursor 368 using multichannel microreactors. MFC: mas...
Scheme 90: Continuous ozonolysis setup used by Kappe et al. for the synthesis of various substrates employing ...
Scheme 91: Continuous-flow apparatus for ozonolysis as developed by Ley et al.
Scheme 92: Continuous-flow ozonolysis for synthesis of vanillin (2) using a film-shear flow reactor.
Scheme 93: Examples of preparative methods for ajoene (386) and allicin (388).
Scheme 94: Continuous-flow oxidation of thioanisole (389) using styrene-based polymer-supported peroxytungstat...
Scheme 95: Continuous oxidation of thiosulfinates using Oxone®-packed reactor.
Scheme 96: Continuous-flow electrochemical oxidation of thioethers.
Scheme 97: Continuous-flow oxidation of 400 to cinnamophenone (235).
Scheme 98: Continuous-flow synthesis of dehydrated material 401 via oxidation of methyl dihydrojasmonate (33).
Scheme 99: Some industrially important transformations involving Grignard reagents.
Scheme 100: Grachev et al. apparatus for continuous preparation of Grignard reagents.
Scheme 101: Example of fluidized Mg bed reactor with NMR spectrometer as on-line monitoring system.
Scheme 102: Continuous-flow synthesis of Grignard reagents and subsequent quenching reaction.
Figure 10: Membrane-based, liquid–liquid separator with integrated pressure control [52]. Adapted with permission ...
Scheme 103: Continuous-flow synthesis of 458, an intermediate to fluconazole (459).
Scheme 104: Continuous-flow synthesis of ketones starting from benzoyl chlorides.
Scheme 105: A Grignard alkylation combining CSTR and PFR technologies with in-line infrared reaction monitoring....
Scheme 106: Continuous-flow preparation of 469 from Grignard addition of methylmagnesium bromide.
Scheme 107: Continuous-flow synthesis of Grignard reagents 471.
Scheme 108: Preparation of the Grignard reagent 471 using CSTR and the continuous process for synthesis of the ...
Scheme 109: Continuous process for carboxylation of Grignard reagents in flow using tube-in-tube technology.
Scheme 110: Continuous synthesis of propargylic alcohols via ethynyl-Grignard reagent.
Scheme 111: Silica-supported catalysed enantioselective arylation of aldehydes using Grignard reagents in flow ...
Scheme 112: Acid-catalysed rearrangement of citral and dehydrolinalool derivatives.
Scheme 113: Continuous stilbene isomerisation with continuous recycling of photoredox catalyst.
Scheme 114: Continuous-flow synthesis of compound 494 as developed by Ley et al.
Scheme 115: Selected industrial applications of DA reaction.
Scheme 116: Multistep flow synthesis of the spirocyclic structure 505 via employing DA cycloaddition.
Scheme 117: Continuous-flow DA reaction developed in a plater flow reactor for the preparation of the adduct 508...
Scheme 118: Continuous-flow DA reaction using a silica-supported imidazolidinone organocatalyst.
Scheme 119: Batch vs flow for the DA reaction of (cyclohexa-1,5-dien-1-yloxy)trimethylsilane (513) with acrylon...
Scheme 120: Continuous-flow DA reaction between 510 and 515 using a shell-core droplet system.
Scheme 121: Continuous-flow synthesis of bicyclic systems from benzyne precursors.
Scheme 122: Continuous-flow synthesis of bicyclic scaffolds 527 and 528 for further development of potential ph...
Scheme 123: Continuous-flow inverse-electron hetero-DA reaction to pyridine derivatives such as 531.
Scheme 124: Comparison between batch and flow for the synthesis of pyrimidinones 532–536 via retro-DA reaction ...
Scheme 125: Continuous-flow coupled with ultrasonic system for preparation of ʟ-ascorbic acid derivatives 539 d...
Scheme 126: Two-step continuous-flow synthesis of triazole 543.
Scheme 127: Continuous-flow preparation of triazoles via CuAAC employing 546-based heterogeneous catalyst.
Scheme 128: Continuous-flow synthesis of compounds 558 through A3-coupling and 560 via AgAAC both employing the...
Scheme 129: Continuous-flow photoinduced [2 + 2] cycloaddition for the preparation of bicyclic derivatives of 5...
Scheme 130: Continuous-flow [2 + 2] and [5 + 2] cycloaddition on large scale employing a flow reactor developed...
Scheme 131: Continuous-flow preparation of the tricyclic structures 573 and 574 starting from pyrrole 570 via [...
Scheme 132: Continuous-flow [2 + 2] photocyclization of cinnamates.
Scheme 133: Continuous-flow preparation of cyclobutane 580 on a 5-plates photoreactor.
Scheme 134: Continuous-flow [2 + 2] photocycloaddition under white LED lamp using heterogeneous PCN as photocat...
Figure 11: Picture of the parallel tube flow reactor (PTFR) "The Firefly" developed by Booker-Milburn et al. a...
Scheme 135: Continuous-flow acid-catalysed [2 + 2] cycloaddition between silyl enol ethers and acrylic esters.
Scheme 136: Continuous synthesis of lactam 602 using glass column reactors.
Scheme 137: In situ generation of ketenes for the Staudinger lactam synthesis developed by Ley and Hafner.
Scheme 138: Application of [2 + 2 + 2] cycloadditions in flow employed by Ley et al.
Scheme 139: Examples of FC reactions applied in F&F industry.
Scheme 140: Continuous-flow synthesis of ibuprofen developed by McQuade et al.
Scheme 141: The FC acylation step of Jamison’s three-step ibuprofen synthesis.
Scheme 142: Synthesis of naphthalene derivative 629 via FC acylation in microreactors.
Scheme 143: Flow system for rapid screening of catalysts and reaction conditions developed by Weber et al.
Scheme 144: Continuous-flow system developed by Buorne, Muller et al. for DSD optimisation of the FC acylation ...
Scheme 145: Continuous-flow FC acylation of alkynes to yield β-chlorovinyl ketones such as 638.
Scheme 146: Continuous-flow synthesis of tonalide (619) developed by Wang et al.
Scheme 147: Continuous-flow preparation of acylated arene such as 290 employing Zr4+-β-zeolite developed by Kob...
Scheme 148: Flow system applied on an Aza-FC reaction catalysed by the thiourea catalyst 648.
Scheme 149: Continuous hydroformylation in scCO2.
Scheme 150: Two-step flow synthesis of aldehyde 655 through a sequential Heck reaction and subsequent hydroform...
Scheme 151: Single-droplet (above) and continuous (below) flow reactors developed by Abolhasani et al. for the ...
Scheme 152: Continuous hydroformylation of 1-dodecene (655) using a PFR-CSTR system developed by Sundmacher et ...
Scheme 153: Continuous-flow synthesis of the aldehyde 660 developed by Eli Lilly & Co. [32]. Adapted with permissio...
Scheme 154: Continuous asymmetric hydroformylation employing heterogenous catalst supported on carbon-based sup...
Scheme 155: Examples of acetylation in F&F industry: synthesis of bornyl (S,R,S-664) and isobornyl (S,S,S-664) ...
Scheme 156: Continuous-flow preparation of bornyl acetate (S,R,S-664) employing the oscillating flow reactor.
Scheme 157: Continuous-flow synthesis of geranyl acetate (666) from acetylation of geraniol (343) developed by ...
Scheme 158: 12-Ttungstosilicic acid-supported silica monolith-catalysed acetylation in flow.
Scheme 159: Continuous-flow preparation of cyclopentenone 676.
Scheme 160: Two-stage synthesis of coumarin (90) via acetylation of salicylaldehyde (88).
Scheme 161: Intensification process for acetylation of 5-methoxytryptamine (677) to melatonin (678) developed b...
Scheme 162: Examples of macrocyclic musky odorants both natural (679–681) and synthetic (682 and 683).
Scheme 163: Flow setup combined with microwave for the synthesis of macrocycle 686 via RCM.
Scheme 164: Continuous synthesis of 2,5-dihydro-1H-pyrroles via ring-closing metathesis.
Scheme 165: Continuous-flow metathesis of 485 developed by Leadbeater et al.
Figure 12: Comparison between RCM performed using different routes for the preparation of 696. On the left the...
Scheme 166: Continuous-flow RCM of 697 employed the solid-supported catalyst 698 developed by Grela, Kirschning...
Scheme 167: Continuous-flow RORCM of cyclooctene employing the silica-absorbed catalyst 700.
Scheme 168: Continuous-flow self-metathesis of methyl oleate (703) employing SILP catalyst 704.
Scheme 169: Flow apparatus for the RCM of 697 using a nanofiltration membrane for the recovery and reuse of the...
Scheme 170: Comparison of loadings between RCMs performed with different routes for the synthesis of 709.
Facile synthesis of 7-alkyl-1,2,3,4-tetrahydro-1,8-naphthyridines as arginine mimetics using a Horner–Wadsworth–Emmons-based approach
- Rhys A. Lippa,
- John A. Murphy and
- Tim N. Barrett
Beilstein J. Org. Chem. 2020, 16, 1617–1626, doi:10.3762/bjoc.16.134
- the Wittig step presented complications on both gram and kilogram scales. Herein, we report a novel synthetic sequence to tetrahydro-1,8-naphthyridines using a Horner–Wadsworth–Emmons reaction using diphosphorylated compound 7, proceeding in high yields and high purities without the need for
- would afford phosphonate 12 upon quenching with diethyl chlorophosphate via formation of the dianion. This could then be used in a subsequent Horner–Wadsworth–Emmons reaction to construct the carbon skeleton of amine 6. Upon the addition of a single equivalent of diethyl chlorophosphate, phosphoramidate
- integrin inhibitors. Commonly used synthetic routes to tetrahydro-1,8-naphthyridine moieties by hydrogenation of saturated naphthyridines 3. Previous synthetic route to fluoropyrrolidine 6 utilising a Wittig reaction and the novel, higher yielding route using a Horner–Wadsworth–Emmons reaction. Synthesis
Graphical Abstract
Figure 1: The Arg–Gly–Asp tripeptide sequence and examples of tetrahydro-1,8-naphthyridine-containing integri...
Scheme 1: Commonly used synthetic routes to tetrahydro-1,8-naphthyridine moieties by hydrogenation of saturat...
Scheme 2: Previous synthetic route to fluoropyrrolidine 6 utilising a Wittig reaction and the novel, higher y...
Scheme 3: Synthesis of phosphoramidate 9 from tetrahydro-1,8-naphthyridine 8. Conditions: s-BuLi (3 equiv), d...
Scheme 4: Mono- and diphosphorylation of tetrahydro-1,8-naphthyridine 11. Conditions: (i) s-BuLi (2 equiv), d...
Scheme 5: Synthesis of amine 6 from phosphonate 7 and aldehyde 5. Conditions: (i) T3P® (50% w/w in DCM, 3 equ...
Scheme 6: Monodeuteration of 13 as observed by 1H and 13C NMR. Conditions: s-BuLi (3 equiv), THF, −42 °C, 20 ...
Scheme 7: Sequential diphosphorylation of tetrahydronaphthyridine 11. Conditions: (i) iPrMgCl (1.5 equiv), TH...
Scheme 8: Possible mechanistic pathways for the formation of dimer 28. Conditions: KOt-Bu, THF, 1 h, 68% yiel...
Scheme 9: Alkylation of phosphoramidate 13 by iodide 29 to afford compound 30 and byproducts alcohol 31 and d...
Volatiles from the tropical ascomycete Daldinia clavata (Hypoxylaceae, Xylariales)
- Tao Wang,
- Kathrin I. Mohr,
- Marc Stadler and
- Jeroen S. Dickschat
Beilstein J. Org. Chem. 2018, 14, 135–147, doi:10.3762/bjoc.14.9
- –Wadsworth–Emmons reaction with triethyl 2-phosphonopropionate (19) yielded ethyl (E)-2,4-dimethylhex-2-enoate (20) as a separable mixture of E and Z stereoisomers (E/Z = 10:1). The purified E diastereomer was reduced with DIBAl-H to the corresponding alcohol 21. A PCC oxidation and addition of
- (Figure 2A) that was similar to a data base spectrum of manicone ((E)-4,6-dimethyloct-4-en-3-one, 10), but no retention index for this compound was available from the literature. For unambiguous structural verification compound 10 was synthesised starting from 2-methylbutanal (18, Scheme 3). A Horner
Graphical Abstract
Scheme 1: A selection of widespread fungal volatiles.
Figure 1: Total ion chromatogram of a representative headspace extract from Daldinia clavata MUCL 47436. Peak...
Scheme 2: Identified volatiles from Daldinia clavata MUCL 47436.
Figure 2: Mass spectra of volatiles from D. clavata that were identified by synthesis.
Scheme 3: Synthesis of manicone (10).
Scheme 4: Synthesis of a racemic mixture of all four diastereomers of 11.
Figure 3: Gas chromatographic analysis of 11 on a homochiral stationary phase. a) Synthetic mixture of all ei...
Scheme 5: Enantioselective synthesis of (4R,5S,6S)-11c and (4S,5R,6S)-11d.
Scheme 6: Epimerisations of (4R,5S,6S)-11c and (4S,5R,6S)-11d under basic conditions.
Figure 4: Gas chromatographic analysis of 11 on a homochiral stationary phase. a) Synthetic mixture of all ei...
Scheme 7: Proposed biosynthesis for (4R,5R,6S)-11a.
Figure 5: Mass spectra of a) 6-methyl-5,6-dihydro-2H-pyran-2-one (9), b) 6-propyl-5,6-dihydro-2H-pyran-2-one,...
Scheme 8: Synthesis of 6-methyl-5,6-dihydro-2H-pyran-2-one (9) and 6-nonyl-2H-pyran-2-one (17).
The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones
- Ommid Anamimoghadam,
- Saira Mumtaz,
- Anke Nietsch,
- Gaetano Saya,
- Cherie A. Motti,
- Jun Wang,
- Peter C. Junk,
- Ashfaq Mahmood Qureshi and
- Michael Oelgemöller
Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275
- and co-workers and incorporated an intramolecular Horner–Wadsworth–Emmons reaction as a crucial step [10]. Due to their diverse biological activities, a variety of synthetic pathways to 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones has been developed over the past two decades [10][11][12][13][14
Graphical Abstract
Figure 1: Molecular structures of AL-12, AL-12B and AL-5.
Scheme 1: Retrosynthetic analysis of AL-12, AL-12B and AL-5 (in their neutral forms) and their derivatives.
Scheme 2: Optimization study using phenylacetate 2a.
Scheme 3: Photodecarboxylative additions to N-(bromoalkyl)phthalimides.
Figure 2: Crystal structures of photoaddition products 3a (left) and 3b (right).
Scheme 4: Formation of 5 by photodecarboxylative additions.
Scheme 5: Acid-catalyzed dehydration of 3a–q.
Figure 3: Crystal structure of (E)-7a. Side view and front view.
Scheme 6: Amination of dehydrated products 7a–q.
Figure 4: Crystal structure of (Z)-8a. Side view and front view.
Scheme 7: Mechanistic scenario for the photodecarboxylative addition.
Scheme 8: Possible scenarios for nucleophilic cyclization to 4.
Scheme 9: Possible E/Z isomerization for compounds 8a–y.
Total syntheses of the archazolids: an emerging class of novel anticancer drugs
- Stephan Scheeff and
- Dirk Menche
Beilstein J. Org. Chem. 2017, 13, 1085–1098, doi:10.3762/bjoc.13.108
- alcohol 49 in 76% over 2 steps [83]. Before TBS protection the Weinreb amide was generated and then conversed into the phosphonate 50 as a precursor for a Horner–Wadsworth–Emmons reaction. The olefination led to unsaturated ketone 52 in 79% yield. For the final fragment synthesis the ketone was reduced
Graphical Abstract
Scheme 1: Molecular structures of the archazolids.
Scheme 2: Retrosynthetic analysis of archazolid A by the Menche group.
Scheme 3: Synthesis of north-eastern fragment 5 through a Paterson anti-aldol addition and multiple Still–Gen...
Scheme 4: Synthesis of 4 through an Abiko–Masamune anti-aldol addition.
Scheme 5: Thiazol construction and synthesis of the southern fragment 6.
Scheme 6: Completion of the total synthesis of archazolid A.
Scheme 7: Synthesis of archazolid B (2) by a ring closing Heck reaction of 38.
Scheme 8: Retrosynthetic analysis of archazolid B by the Trauner group.
Scheme 9: Synthesis of acid 40 from Roche ester 41 involving a highly efficient Trost–Alder ene reaction.
Scheme 10: Synthesis of precursor 39 for the projected relay RCM reaction.
Scheme 11: Final steps of Trauner’s total synthesis of archazolid B.
Scheme 12: Overview of the different retrosynthetic approaches for the synthesis of dihydroarchazolid B (3) re...
Scheme 13: Fragment synthesis of 69 towards the total synthesis of 3.
Scheme 14: Organometallic addition of the side chain to access free alcohol 75.
Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates
- Mohammad Haji
Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121
- dephosphorylated by treatment with lithium aluminum hydride to give isoindolin-1-ones 61 (Scheme 15). Also the Kabachnik–Fields reaction of formylbenzoic acid (55), dimethyl phosphonate and amines 62 or 66 followed by subsequent Horner–Wadsworth–Emmons reaction of the resulting cycloadducts 63 and 67 with
- isoindolin-1-one-3-phosphonates. A microwave-assisted Kabachnik–Fields reaction toward isoindolin-1-ones. The synthesis of 3-arylmethyleneisoindolin-1-ones through a Horner–Wadsworth–Emmons reaction of Kabachnik–Fields reaction products. An efficient one-pot method for the synthesis of ethyl (2-alkyl- and 2
Graphical Abstract
Scheme 1: The Biginelli condensation.
Scheme 2: The Biginelli reaction of β-ketophosphonates catalyzed by ytterbium triflate.
Scheme 3: Trimethylchlorosilane-mediated Biginelli reaction of diethyl (3,3,3-trifluoropropyl-2-oxo)phosphona...
Scheme 4: Biginelli reaction of dialkyl (3,3,3-trifluoropropyl-2-oxo)phosphonate with trialkyl orthoformates ...
Scheme 5: p-Toluenesulfonic acid-promoted Biginelli reaction of β-ketophosphonates, aryl aldehydes and urea.
Scheme 6: General Kabachnik–Fields reaction for the synthesis of α-aminophosphonates.
Scheme 7: Phthalocyanine–AlCl catalyzed Kabachnik–Fields reaction of N-Boc-piperidin-4-one with diethyl phosp...
Scheme 8: Kabachnik–Fields reaction of isatin with diethyl phosphite and benzylamine.
Scheme 9: Magnetic Fe3O4 nanoparticle-supported phosphotungstic acid-catalyzed Kabachnik–Fields reaction of i...
Scheme 10: The Mg(ClO4)2-catalyzed Kabachnik–Fields reaction of 1-tosylpiperidine-4-one.
Scheme 11: An asymmetric version of the Kabachnik–Fields reaction for the synthesis of α-amino-3-piperidinylph...
Scheme 12: A classical Kabachnik–Fields reaction followed by an intramolecular ring-closing reaction for the s...
Scheme 13: Synthesis of (S)-piperidin-2-phosphonic acid through an asymmetric Kabachnik–Fields reaction.
Scheme 14: A modified diastereoselective Kabachnik–Fields reaction for the synthesis of isoindolin-1-one-3-pho...
Scheme 15: A microwave-assisted Kabachnik–Fields reaction toward isoindolin-1-ones.
Scheme 16: The synthesis of 3-arylmethyleneisoindolin-1-ones through a Horner–Wadsworth–Emmons reaction of Kab...
Scheme 17: An efficient one-pot method for the synthesis of ethyl (2-alkyl- and 2-aryl-3-oxoisoindolin-1-yl)ph...
Scheme 18: FeCl3 and PdCl2 co-catalyzed three-component reaction of 2-alkynylbenzaldehydes, anilines, and diet...
Scheme 19: Three-component reaction of 6-methyl-3-formylchromone (75) with hydrazine derivatives or hydroxylam...
Scheme 20: Three-component reaction of 6-methyl-3-formylchromone (75) with thiourea, guanidinium carbonate or ...
Scheme 21: Three-component reaction of 6-methyl-3-formylchromone (75) with 1,4-bi-nucleophiles in the presence...
Scheme 22: One-pot three-component reaction of 2-alkynylbenzaldehydes, amines, and diethyl phosphonate.
Scheme 23: Lewis acid–surfactant combined catalysts for the one-pot three-component reaction of 2-alkynylbenza...
Scheme 24: Lewis acid catalyzed cyclization of different Kabachnik–Fields adducts.
Scheme 25: Three-component synthesis of N-arylisoquinolone-1-phosphonates 119.
Scheme 26: CuI-catalyzed three-component tandem reaction of 2-(2-formylphenyl)ethanones with aromatic amines a...
Scheme 27: Synthesis of 1,5-benzodiazepin-2-ylphosphonates via ytterbium chloride-catalyzed three-component re...
Scheme 28: FeCl3-catalyzed four-component reaction for the synthesis of 1,5-benzodiazepin-2-ylphosphonates.
Scheme 29: Synthesis of indole bisphosphonates through a modified Kabachnik–Fields reaction.
Scheme 30: Synthesis of heterocyclic bisphosphonates via Kabachnik–Fields reaction of triethyl orthoformate.
Scheme 31: A domino Knoevenagel/phospha-Michael process for the synthesis of 2-oxoindolin-3-ylphosphonates.
Scheme 32: Intramolecular cyclization of phospha-Michael adducts to give dihydropyridinylphosphonates.
Scheme 33: Synthesis of fused phosphonylpyrans via intramolecular cyclization of phospha-Michael adducts.
Scheme 34: InCl3-catalyzed three-component synthesis of (2-amino-3-cyano-4H-chromen-4-yl)phosphonates.
Scheme 35: Synthesis of phosphonodihydropyrans via a domino Knoevenagel/hetero-Diels–Alder process.
Scheme 36: Multicomponent synthesis of phosphonodihydrothiopyrans via a domino Knoevenagel/hetero-Diels–Alder ...
Scheme 37: One-pot four-component synthesis of 1,2-dihydroisoquinolin-1-ylphosphonates under multicatalytic co...
Scheme 38: CuI-catalyzed four-component reactions of methyleneaziridines towards alkylphosphonates.
Scheme 39: Ruthenium–porphyrin complex-catalyzed three-component synthesis of aziridinylphosphonates and its p...
Scheme 40: Copper(I)-catalyzed three-component reaction towards 1,2,3-triazolyl-5-phosphonates.
Scheme 41: Three-component reaction of acylphosphonates, isocyanides and dialkyl acetylenedicarboxylate to aff...
Scheme 42: Synthesis of (4-imino-3,4-dihydroquinazolin-2-yl)phosphonates via an isocyanide-based three-compone...
Scheme 43: Silver-catalyzed three-component synthesis of (2-imidazolin-4-yl)phosphonates.
Scheme 44: Three-component synthesis of phosphonylpyrazoles.
Scheme 45: One-pot three-component synthesis of 3-carbo-5-phosphonylpyrazoles.
Scheme 46: A one-pot two-step method for the synthesis of phosphonylpyrazoles.
Scheme 47: A one-pot method for the synthesis of (5-vinylpyrazolyl)phosphonates.
Scheme 48: Synthesis of 1H-pyrrol-2-ylphosphonates via the [3 + 2] cycloaddition of phosphonate azomethine yli...
Scheme 49: Three-component synthesis of 1H-pyrrol-2-ylphosphonates.
Scheme 50: The classical Reissert reaction.
Scheme 51: One-pot three-component synthesis of N-phosphorylated isoquinolines.
Scheme 52: One-pot three-component synthesis of 1-acyl-1,2-dihydroquinoline-2-phosphonates and 2-acyl-1,2-dihy...
Scheme 53: Three-component reaction of pyridine derivatives with ethyl propiolate and dialkyl phosphonates.
Scheme 54: Three-component reactions for the phosphorylation of benzothiazole and isoquinoline.
Scheme 55: Three-component synthesis of diphenyl [2-(aminocarbonyl)- or [2-(aminothioxomethyl)-1,2-dihydroisoq...
Scheme 56: Three-component stereoselective synthesis of 1,2-dihydroquinolin-2-ylphosphonates and 1,2-dihydrois...
Scheme 57: Diphosphorylation of diazaheterocyclic compounds via a tandem 1,4–1,2 addition of dimethyl trimethy...
Scheme 58: Multicomponent reaction of alkanedials, acetamide and acetyl chloride in the presence of PCl3 and a...
Scheme 59: An oxidative domino three-component synthesis of polyfunctionalized pyridines.
Scheme 60: A sequential one-pot three-component synthesis of polysubstituted pyrroles.
Scheme 61: Three-component decarboxylative coupling of proline with aldehydes and dialkyl phosphites for the s...
Scheme 62: Three-component domino aza-Wittig/phospha-Mannich sequence for the phosphorylation of isatin deriva...
Scheme 63: Stereoselective synthesis of phosphorylated trans-1,5-benzodiazepines via a one-pot three-component...
Scheme 64: One-pot three-component synthesis of phosphorylated 2,6-dioxohexahydropyrimidines.
Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate
- Sean P. Bew,
- Glyn D. Hiatt-Gipson,
- Graham P. Mills and
- Claire E. Reeves
Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103
- ester via a Horner–Wadsworth–Emmons reaction caught our attention [47]. Changing tack and in a slightly modified procedure to that originally reported by Fujiwara et al. triethyl phosphonoacetate was deprotonated (NaH) and the resulting stabilised ylide (not shown) reacted by slow addition of
Graphical Abstract
Scheme 1: Simplified overview outlining how a small number of different IPNs are synthesised and are able to ...
Scheme 2: Protocols for the synthesis of O-nitrated alcohols using (±)-isoprene epoxide and 2° alcohols as st...
Scheme 3: Attempted synthesis of O-nitrate ester rac-19 and rac-20 synthesis.
Scheme 4: Olah et al. O-nitrated alcohol syntheses of 23–33 using N-nitro-2,4-6-trimethylpyridinium tetrafluo...
Scheme 5: O-nitration study using 22 and the alcohols 34–37.
Scheme 6: Silver nitrate mediated synthesis of 2-oxopropyl nitrate 43.
Scheme 7: Application of isoprene for the synthesis of precursors to IPNs and synthesis via ‘halide for nitra...
Scheme 8: Synthesis of (E)-3-methyl-4-chlorobut-2-en-1-ol ((E)-60) and (Z)-3-methyl-4-chlorobut-2-en-1-ol ((Z...
Scheme 9: Using NOESY interactions to establish the conformations of the C=C bonds within (E)-10 and (Z)-9.
Scheme 10: Synthesis of isoprene nitrates (E)-11 and (Z)-12 from ketone 63.
Scheme 11: Attempted synthesis of rac-8 from O-mesylate rac-71.
Scheme 12: Synthesis of O-nitrate 73 from O-mesylate 72.
Scheme 13: Attempted synthesis of 2° alcohol containing 1° nitrate ester rac-19 and the unexpected synthesis o...
Scheme 14: Synthesis of monoterpene derived (1R,5S)-(−)-myrtenol nitrate 86.
Regiodefined synthesis of brominated hydroxyanthraquinones related to proisocrinins
- Joyeeta Roy,
- Tanushree Mal,
- Supriti Jana and
- Dipakranjan Mal
Beilstein J. Org. Chem. 2016, 12, 531–536, doi:10.3762/bjoc.12.52
- signals corresponding to two protons of the epoxide at δ 4.18 and 3.54 [44]. Since the yield of 32 was low, we considered a Horner–Wadsworth–Emmons reaction of aldehyde 31 with triethyl phosphonoacetate as an alternative. Unfortunately, it was not successful, probably due to the interference of the
Graphical Abstract
Figure 1: Halogenated anthraquinones.
Scheme 1: Initially proposed synthetic scheme for proisocrinins 6–11.
Scheme 2: Synthesis of cyanophthalide 12.
Scheme 3: Synthesis of cyclohexenone 13.
Scheme 4: Darzens condensation route to proisocrinins.
Scheme 5: Synthesis of cyclohexenone 36.
Scheme 6: Synthesis of the proisocrinin core structure.
New tris- and pentakis-fused donors containing extended tetrathiafulvalenes: New positive electrode materials for rechargeable batteries
- Shintaro Iwamoto,
- Yuu Inatomi,
- Daisuke Ogi,
- Satoshi Shibayama,
- Yukiko Murakami,
- Minami Kato,
- Kazuyuki Takahashi,
- Kazuyoshi Tanaka,
- Nobuhiko Hojo and
- Yohji Misaki
Beilstein J. Org. Chem. 2015, 11, 1136–1147, doi:10.3762/bjoc.11.128
- undesired byproducts. The homo-coupling reaction using 11 might give 12 in a good yield, however, toxic and expensive mercury(II) acetate has to be used for the synthesis of 11. Thus, the cross-coupling reaction is useful for saving 11. The Horner–Wadsworth–Emmons reaction of 12 with 2 equiv of aldehydes
Graphical Abstract
Figure 1: Chemical structures of 1–9 and TTP.
Scheme 1: Synthesis of 5–9.
Figure 2: Molecular orbitals of 5a (trans isomer).
Figure 3: Molecular orbitals of 6a (trans isomer).
Figure 4: Molecular orbitals of 8a (trans isomer).
Figure 5: Deconvoluted cyclic voltammograms of (a) 5d, (b) 7d and (c) 9d.
Scheme 2: Plausible redox processes of 5d and 7d.
Scheme 3: Plausible redox process of 9d.
Figure 6: (a) Galvanostatic charge-discharge curves of (a) 5c/Li and (b) 6b/Li cells.
Figure 7: Cycle-life performances for 5b/Li, 5c/Li and 6b/Li cells.
Figure 8: (a) Galvanostatic charge–discharge curves, and (b) cycle-life performances for a 8c/Li cell.
Figure 9: Molecular structures of 20 and 21.
Synthesis of the furo[2,3-b]chromene ring system of hyperaspindols A and B
- Danielle L. Paterson and
- David Barker
Beilstein J. Org. Chem. 2015, 11, 265–270, doi:10.3762/bjoc.11.29
- methylenedioxyphenyl groups in ketone 8 would be added by sequential addition of aryllithiates to both the carbonyl and aldehyde groups, derived from the terminal alkene, of a homoallylic carboxylic acid derivative 9. Our route to ketone 8 began from salicylaldehyde (10) which underwent a Horner–Wadsworth–Emmons
- reaction with triethylphosphonoacetate to give ester 11 [19] in 94% yield (Scheme 1). Hydrogenation of the alkene followed by protection of the phenol gave benzyl ether 12 in 88% yield over two steps. Initially the preparation of alkene 13 through the allylation of ester 12 was attempted, however keto
Graphical Abstract
Figure 1: Hyperaspidinols A (1) and B (2) and other compounds 3-6 from Hypericum chinense.
Figure 2: Hyperaspidinol A (1), target compound 7 and proposed precursors.
Scheme 1: Reagents and conditions: (i) triethylphosphonoacetate, DBU, THF, 48 h, 94%; (ii) H2, 10% Pd/C, EtOA...
Scheme 2: Reagents and conditions: (i) H3C(CH3O)NH·HCl, n-BuLi, THF, −78 °C, 4 h, 81%; (ii) 1-bromo-3,4-methy...
Figure 3: NOESY correlations in isomers 7a and 7b.
Figure 4: 3D representation of 7a.
Figure 5: 3D representation of 7b.
Figure 6: Possible mechanism for the formation of furo[2,3-b]chromenes 7a and 7b.
Stereocontrolled synthesis of 5-azaspiro[2.3]hexane derivatives as conformationally “frozen” analogues of L-glutamic acid
- Beatrice Bechi,
- David Amantini,
- Cristina Tintori,
- Maurizio Botta and
- Romano di Fabio
Beilstein J. Org. Chem. 2014, 10, 1114–1120, doi:10.3762/bjoc.10.110
- optimized by replacing step c) CH2N2 (diazomethane) with TMSCHN2 (trimethylsilyl diazomethane). This intermediate was transformed into intermediate 17 by a Horner–Wadsworth–Emmons reaction [23][24], thereby obtaining 17 as the single E-isomer in 68% yield after purification by flash chromatography (Scheme 3
Graphical Abstract
Figure 1: Glutamate receptor ligands.
Scheme 1: Proposed synthetic plan for the preparation of compound of type Ib.
Scheme 2: Synthesis of 3-azetidinone derivative 16.
Scheme 3: Synthetic routes to prepare target cyclopropyl derivatives 20. Reagents and conditions: a) (EtO)2PO...
Figure 2: Mechanism for the attack of the carbene intermediate to the olefin moiety 18.
Figure 3: Representation of the lowest energy conformation of each diastereoisomers.
Scheme 4: Synthesis of glutamate “frozen” analogues 4-carboxy-1-(ethoxycarbonyl)-5-azaspiro[2.3]hexane.
Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae)
- Armin Tröger,
- Teris A. van Beek,
- Martinus E. Huigens,
- Isabel M. M. S. Silva,
- Maarten A. Posthumus and
- Wittko Francke
Beilstein J. Org. Chem. 2014, 10, 767–773, doi:10.3762/bjoc.10.72
- investigations. In analogy to the structure of A, compound B was assigned to be (2E,4E,6S,8S,10S)-4,6,8,10-tetramethyltrideca-2,4-dien-1-ol (23) or its enantiomer. According to the procedure described by Markiewicz et al. [23], racemic 23 was prepared by vinylogous Horner–Wadsworth–Emmons reaction of the
Graphical Abstract
Figure 1: Published 70 eV EI mass spectra of the naturally occurring compounds A and B [12].
Figure 2: Synthesis of tetramethyltrideca-2,4-dienes 8, 14 and 15. Conditions: a: LiAlH4, Et2O, −30 °C to rt,...
Figure 3: 70 eV EIMS of synthetic tetramethyltrideca-2,4-dienes 8, 14 and 15. These spectra were run under th...
Figure 4: Synthesis of (2E,4EZ)-syn,syn-4,6,8,10-tetramethyltrideca-2,4-diene (22), as well as (2E,4E)- and (2...
Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis
- Frank Hahn,
- Nadine Kandziora,
- Steffen Friedrich and
- Peter F. Leadlay
Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55
- should be accessible from aldehyde 11 through a Horner–Wadsworth–Emmons reaction and the Still–Gennari olefination as well as by a Wittig olefination with stabilised phosphoranes, respectively. The aldehyde 11 should be accessible from the known molecule 13 via 12 [15]. Synthesis of the common precursor
- assay mixture, the latter will be transformed into their corresponding methyl esters by saponification and following methylation with trimethylsilyldiazomethane. The fully protected E-isomer 10a was obtained in 18% yield by a Horner–Wadsworth–Emmons reaction with phosphonate 25 or, alternatively, in 64
Graphical Abstract
Figure 1: a) Structure of borrelidin (1); b) PKS intermediates are attached to an acyl carrier protein domain...
Scheme 1: Retrosynthetic analysis of surrogate substrates for BorDH3 and reference molecules for enzyme assay...
Scheme 2: Synthesis of the common precursor aldehyde 11. Compound 13 was prepared in six steps and with an ov...
Scheme 3: Synthesis of the BorDH3 substrates. a) Thiophenolpropionate, Cy2BCl, Me2EtN, Et2O, −78 °C to −20 °C...
Scheme 4: Synthesis of reference compounds for the BorDH3 assay. a) 24, CH2Cl2, 50 °C, 3 h (88% over two step...
Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products
- Alexander O. Terent'ev,
- Dmitry A. Borisov,
- Vera A. Vil’ and
- Valery M. Dembitsky
Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6
Graphical Abstract
Figure 1: Five and six-membered cyclic peroxides.
Figure 2: Artemisinin and semi-synthetic derivatives.
Scheme 1: Synthesis of 3-hydroxy-1,2-dioxolanes 3a–c.
Scheme 2: Synthesis of dioxolane 6.
Scheme 3: Photooxygenation of oxazolidines 7a–d with formation of spiro-fused oxazolidine-containing dioxolan...
Scheme 4: Oxidation of cyclopropanes 10a–e and 11a–e with preparation of 1,2-dioxolanes 12a–e.
Scheme 5: VO(acac)2-catalyzed oxidation of silylated bicycloalkanols 13a–c.
Scheme 6: Mn(II)-catalyzed oxidation of cyclopropanols 15a–g.
Scheme 7: Oxidation of aminocyclopropanes 20a–c.
Scheme 8: Synthesis of aminodioxolanes 24.
Figure 3: Trifluoromethyl-containing dioxolane 25.
Scheme 9: Synthesis of 1,2-dioxolanes 27a–e by the oxidation of cyclopropanes 26a–e.
Scheme 10: Photoinduced oxidation of methylenecyclopropanes 28.
Scheme 11: Irradiation-mediated oxidation.
Scheme 12: Application of diazene 34 for dioxolane synthesis.
Scheme 13: Mn(OAc)3-catalyzed cooxidation of arylacetylenes 37a–h and acetylacetone with atmospheric oxygen.
Scheme 14: Peroxidation of (2-vinylcyclopropyl)benzene (40).
Scheme 15: Peroxidation of 1,4-dienes 43a,b.
Scheme 16: Peroxidation of 1,5-dienes 46.
Scheme 17: Peroxidation of oxetanes 53a,b.
Scheme 18: Peroxidation of 1,6-diene 56.
Scheme 19: Synthesis of 3-alkoxy-1,2-dioxolanes 62a,b.
Scheme 20: Synthesis of spiro-bis(1,2-dioxolane) 66.
Scheme 21: Synthesis of dispiro-1,2-dioxolanes 68, 70, 71.
Scheme 22: Synthesis of spirohydroperoxydioxolanes 75a,b.
Scheme 23: Synthesis of spirohydroperoxydioxolane 77 and dihydroperoxydioxolane 79.
Scheme 24: Ozonolysis of azepino[4,5-b]indole 80.
Scheme 25: SnCl4-mediated fragmentation of ozonides 84a–l in the presence of allyltrimethylsilane.
Scheme 26: SnCl4-mediated fragmentation of bicyclic ozonide 84m in the presence of allyltrimethylsilane.
Scheme 27: MCl4-mediated fragmentation of alkoxyhydroperoxides 96 in the presence of allyltrimethylsilane.
Scheme 28: SnCl4-catalyzed reaction of monotriethylsilylperoxyacetal 108 with alkene 109.
Scheme 29: SnCl4-catalyzed reaction of triethylsilylperoxyacetals 111 with alkenes.
Scheme 30: Desilylation of tert-butyldimethylsilylperoxy ketones 131a,b followed by cyclization.
Scheme 31: Deprotection of peroxide 133 followed by cyclization.
Scheme 32: Asymmetric peroxidation of methyl vinyl ketones 137a–e.
Scheme 33: Et2NH-catalyzed intramolecular cyclization.
Scheme 34: Synthesis of oxodioxolanes 143a–j.
Scheme 35: Haloperoxidation accompanied by intramolecular ring closure.
Scheme 36: Oxidation of triterpenes 149a–d with Na2Cr2O7/N-hydroxysuccinimide.
Scheme 37: Curtius and Wolff rearrangements to form 1,2-dioxolane ring-retaining products.
Scheme 38: Oxidative desilylation of peroxide 124.
Scheme 39: Synthesis of dioxolane 158, a compound containing the aminoquinoline antimalarial pharmacophore.
Scheme 40: Diastereomers of plakinic acid A, 162a and 162b.
Scheme 41: Ozonolysis of alkenes.
Scheme 42: Cross-ozonolysis of alkenes 166 with carbonyl compounds.
Scheme 43: Ozonolysis of the bicyclic cyclohexenone 168.
Scheme 44: Cross-ozonolysis of enol ethers 172a,b with cyclohexanone.
Scheme 45: Griesbaum co-ozonolysis.
Scheme 46: Reactions of aryloxiranes 177a,b with oxygen.
Scheme 47: Intramolecular formation of 1,2,4-trioxolane 180.
Scheme 48: Formation of 1,2,4-trioxolane 180 by the reaction of 1,5-ketoacetal 181 with H2O2.
Scheme 49: 1,2,4-Trioxolane 186 with tetrazole fragment.
Scheme 50: 1,2,4-Trioxolane 188 with a pyridine fragment.
Scheme 51: 1,2,4-Trioxolane 189 with pyrimidine fragment.
Scheme 52: Synthesis of aminoquinoline-containing 1,2,4-trioxalane 191.
Scheme 53: Synthesis of arterolane.
Scheme 54: Oxidation of diarylheptadienes 197a–c with singlet oxygen.
Scheme 55: Synthesis of hexacyclinol peroxide 200.
Scheme 56: Oxidation of enone 201 and enenitrile 203 with singlet oxygen.
Scheme 57: Synthesis of 1,2-dioxanes 207 by oxidative coupling of carbonyl compounds 206 and alkenes 205.
Scheme 58: 1,2-Dioxanes 209 synthesis by co-oxidation of 1,5-dienes 208 and thiols.
Scheme 59: Synthesis of bicyclic 1,2-dioxanes 212 with aryl substituents.
Scheme 60: Isayama–Mukaiyama peroxysilylation of 1,5-dienes 213 followed by desilylation under acidic conditio...
Scheme 61: Synthesis of bicycle 218 with an 1,2-dioxane ring.
Scheme 62: Intramolecular cyclization with an oxirane-ring opening.
Scheme 63: Inramolecular cyclization with the oxetane-ring opening.
Scheme 64: Intramolecular cyclization with the attack on a keto group.
Scheme 65: Peroxidation of the carbonyl group in unsaturated ketones 228 followed by cyclization of hydroperox...
Scheme 66: CsOH and Et2NH-catalyzed cyclization.
Scheme 67: Preparation of peroxyplakoric acid methyl ethers A and D.
Scheme 68: Hg(OAc)2 in 1,2-dioxane synthesis.
Scheme 69: Reaction of 1,4-diketones 242 with hydrogen peroxide.
Scheme 70: Inramolecular cyclization with oxetane-ring opening.
Scheme 71: Inramolecular cyclization with MsO fragment substitution.
Scheme 72: Synthesis of 1,2-dioxane 255a, a structurally similar compound to natural peroxyplakoric acids.
Scheme 73: Synthesis of 1,2-dioxanes based on the intramolecular cyclization of hydroperoxides containing C=C ...
Scheme 74: Use of BCIH in the intramolecular cyclization.
Scheme 75: Palladium-catalyzed cyclization of δ-unsaturated hydroperoxides 271a–e.
Scheme 76: Intramolecular cyclization of unsaturated peroxyacetals 273a–d.
Scheme 77: Allyltrimethylsilane in the synthesis of 1,2-dioxanes 276a–d.
Scheme 78: Intramolecular cyclization using the electrophilic center of the peroxycarbenium ion 279.
Scheme 79: Synthesis of bicyclic 1,2-dioxanes.
Scheme 80: Preparation of 1,2-dioxane 286.
Scheme 81: Di(tert-butyl)peroxalate-initiated radical cyclization of unsaturated hydroperoxide 287.
Scheme 82: Oxidation of 1,4-betaines 291a–d.
Scheme 83: Synthesis of aminoquinoline-containing 1,2-dioxane 294.
Scheme 84: Synthesis of the sulfonyl-containing 1,2-dioxane.
Scheme 85: Synthesis of the amido-containing 1,2-dioxane 301.
Scheme 86: Reaction of singlet oxygen with the 1,3-diene system 302.
Scheme 87: Synthesis of (+)-premnalane А and 8-epi-premnalane A.
Scheme 88: Synthesis of the diazo group containing 1,2-dioxenes 309a–e.
Figure 4: Plakortolide Е.
Scheme 89: Synthesis of 6-epiplakortolide Е.
Scheme 90: Application of Bu3SnH for the preparation of tetrahydrofuran-containing bicyclic peroxides 318a,b.
Scheme 91: Application of Bu3SnH for the preparation of lactone-containing bicyclic peroxides 320a–f.
Scheme 92: Dihydroxylation of the double bond in the 1,2-dioxene ring 321 with OsO4.
Scheme 93: Epoxidation of 1,2-dioxenes 324.
Scheme 94: Cyclopropanation of the double bond in endoperoxides 327.
Scheme 95: Preparation of pyridazine-containing bicyclic endoperoxides 334a–c.
Scheme 96: Synthesis of 1,2,4-trioxanes 337 by the hydroperoxidation of unsaturated alcohols 335 with 1O2 and ...
Scheme 97: Synthesis of sulfur-containing 1,2,4-trioxanes 339.
Scheme 98: BF3·Et2O-catalyzed synthesis of the 1,2,4-trioxanes 342a–g.
Scheme 99: Photooxidation of enol ethers or vinyl sulfides 343.
Scheme 100: Synthesis of tricyclic peroxide 346.
Scheme 101: Reaction of endoperoxides 348a,b derived from cyclohexadienes 347a,b with 1,4-cyclohexanedione.
Scheme 102: [4 + 2]-Cycloaddition of singlet oxygen to 2Н-pyrans 350.
Scheme 103: Synthesis of 1,2,4-trioxanes 354 using peroxysilylation stage.
Scheme 104: Epoxide-ring opening in 355 with H2O2 followed by the condensation of hydroxy hydroperoxides 356 wi...
Scheme 105: Peroxidation of unsaturated ketones 358 with the H2O2/CF3COOH/H2SO4 system.
Scheme 106: Synthesis of 1,2,4-trioxanes 362 through Et2NH-catalyzed intramolecular cyclization.
Scheme 107: Reduction of the double bond in tricyclic peroxides 363.
Scheme 108: Horner–Wadsworth–Emmons reaction in the presence of peroxide group.
Scheme 109: Reduction of ester group by LiBH4 in the presence of 1,2,4-trioxane moiety.
Scheme 110: Reductive amination of keto-containing 1,2,4-trioxane 370.
Scheme 111: Reductive amination of keto-containing 1,2,4-trioxane and a Fe-containing moiety.
Scheme 112: Acid-catalyzed reactions of Н2О2 with ketones and aldehydes 374.
Scheme 113: Cyclocondensation of carbonyl compounds 376a–d using Me3SiOOSiMe3/CF3SO3SiMe3.
Scheme 114: Peroxidation of 4-methylcyclohexanone (378).
Scheme 115: Synthesis of symmetrical tetraoxanes 382a,b from aldehydes 381a,b.
Scheme 116: Synthesis of unsymmetrical tetraoxanes using of MeReO3.
Scheme 117: Synthesis of symmetrical tetraoxanes using of MeReO3.
Scheme 118: Synthesis of symmetrical tetraoxanes using of MeReO3.
Scheme 119: MeReO3 in the synthesis of symmetrical tetraoxanes with the use of aldehydes.
Scheme 120: Preparation of unsymmmetrical 1,2,4,5-tetraoxanes with high antimalarial activity.
Scheme 121: Re2O7-Catalyzed synthesis of tetraoxanes 398.
Scheme 122: H2SO4-Catalyzed synthesis of steroidal tetraoxanes 401.
Scheme 123: HBF4-Catalyzed condensation of bishydroperoxide 402 with 1,4-cyclohexanedione.
Scheme 124: BF3·Et2O-Catalyzed reaction of gem-bishydroperoxides 404 with enol ethers 405 and acetals 406.
Scheme 125: HBF4-Catalyzed cyclocondensation of bishydroperoxide 410 with ketones.
Scheme 126: Synthesis of symmetrical and unsymmetrical tetraoxanes 413 from benzaldehydes 412.
Scheme 127: Synthesis of bridged 1,2,4,5-tetraoxanes 415a–l from β-diketones 414a–l and H2O2.
Scheme 128: Dimerization of zwitterions 417.
Scheme 129: Ozonolysis of verbenone 419.
Scheme 130: Ozonolysis of O-methyl oxime 424.
Scheme 131: Peroxidation of 1,1,1-trifluorododecan-2-one 426 with oxone.
Scheme 132: Intramolecular cyclization of dialdehyde 428 with H2O2.
Scheme 133: Tetraoxanes 433–435 as by-products in peroxidation of ketals 430–432.
Scheme 134: Transformation of triperoxide 436 in diperoxide 437.
Scheme 135: Preparation and structural modifications of tetraoxanes.
Scheme 136: Structural modifications of steroidal tetraoxanes.
Scheme 137: Synthesis of 1,2,4,5-tetraoxane 454 containing the fluorescent moiety.
Scheme 138: Synthesis of tetraoxane 458 (RKA182).
Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products
- Mikko Passiniemi and
- Ari M.P. Koskinen
Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300
- reactive compared to their non-stabilized counterparts, they tend to epimerize the existing chiral center of 1 a lot less, if at all (pKaH value of 69 in DMSO is 8.5 compared to the pKa value of Ph3(Me)PBr, which is 22.5) [109]. Another method to prepare α,β-unsaturated esters is the Horner–Wadsworth
- –Emmons reaction (HWE). The HWE reaction has many advantages over the Wittig olefination. The phosphonate anions tend to be more nucleophilic (less basic) than the corresponding phosphorous ylides. The byproducts, dialkyl phosphates are water soluble and hence easier to remove from the product compared to
Graphical Abstract
Figure 1: Structures of limonene, carvone and thalidomide.
Figure 2: Structure of Garner’s aldehyde.
Scheme 1: (a) i) Boc2O, 1.0 N NaOH (pH >10), dioxane, +5 °C → rt; ii) MeI, K2CO3, DMF, 0 °C → rt (86% over tw...
Scheme 2: (a) AcCl, MeOH, 0 °C → reflux (99%); (b) i) (Boc)2O, Et3N, THF, 0 °C → rt → 50 °C (89%); ii) Me2C(O...
Scheme 3: (a) LiAlH4, THF, rt (93–96%); (b) (COCl)2, DMSO, iPr2NEt, CH2Cl2, −78 °C → −55 °C (99%).
Scheme 4: The Koskinen procedure for the preparation of Garner’s aldehyde. (a) i) AcCl, MeOH, 0 °C → 50 °C (9...
Scheme 5: Burke’s synthesis of Garner’s aldehyde. BDP - bis(diazaphospholane).
Figure 3: Structures of some iminosugars (7, 9), peptide antibiotics (8) and sphingosine (10) and pachastriss...
Scheme 6: Use of Garner’s aldehyde 1 in multistep synthesis.
Scheme 7: Explanation of the anti- and syn-selectivity in the nucleophilic addition reaction.
Scheme 8: Herold’s method: (a) Lithium 1-pentadecyne, HMPT, THF, −78 °C (71%); (b) Lithium 1-pentadecyne, ZnBr...
Scheme 9: (a) Ethyl lithiumpropiolate, HMPT, THF, −78 °C; (b) (S)- or (R)-MTPA, DCC, DMAP, THF, rt (18, 81%) ...
Scheme 10: Coleman’s selectivity studies and their transition state model for the co-ordinated delivery of the...
Scheme 11: (a) PhMgBr, THF, −78 °C → 0 °C [62] or (a) PhMgBr, Et2O, 0 °C [63].
Scheme 12: (a) cat. RhCl3·3H2O, cat. 26, NaOMe, Ph-B(OH)2, aq DME, 80 °C (24, 71%); (b) cat. RhCl3·3H2O, cat. ...
Scheme 13: Lithiated dithiane (3 equiv), CuI (0.3 equiv), BF3·Et2O (6 equiv), THF, −50 °C, 12 h (70%).
Scheme 14: Addition reaction reported by Lam et al. (a) 1-Hexyne, n-BuLi, THF, −15 °C or −40 °C.
Scheme 15: (a) n-BuLi, HMPT, toluene, −78 °C → rt (85%); (b) n-BuLi, ZnCl2, toluene/Et2O, −78 °C → rt (65%).
Scheme 16: (a) n-BuLi, 34, THF, −40 °C [69]; (b) n-BuLi, 35, THF, −78 °C → rt (80%) [70]; (c) n-BuLi, 35, HMPT, THF, −...
Scheme 17: (a) cat. Rh(acac)(CO)2, 42, THF, 40 °C (74%).
Scheme 18: (a) 1-PropynylMgBr, CuI, THF, Me2S, −78 °C (95%); (b) Ethynyltrimethylsilane, EtMgBr, CuI, THF, Me2...
Scheme 19: (a) cat. 50, toluene, 0 °C (52%); (b) cat. 51, toluene, 0 °C (51%); (c) cat. 52, toluene, 0 °C (50%...
Scheme 20: (a) (iPr)3SiH, cat. Ni(COD)2, dimesityleneimidazolium·HCl, t-BuOK, THF, rt.
Scheme 21: (a) Cp2Zr(H)Cl, cat. AgAsF6, CH2Cl2, rt; (b) Cp2Zr(H)Cl, 1-pentadecyne, cat. ZnBr2 in THF for anti-...
Scheme 22: (a) i) 31, n-BuLi, THF, −78 °C; ii) (S)-1, THF, −78 °C; (b) Red-Al, THF, 0 °C.
Scheme 23: (a) 61, n-BuLi, DMPU, toluene, −78 °C, then (S)-1, toluene, −95 °C (57%); (b) 61, n-BuLi, ZnCl2, to...
Scheme 24: Olefin A as an intermediate in natural product synthesis.
Scheme 25: (a) Ph3(Me)PBr, KH, benzene (66%, rac-64) or (b) AlMe3, Zn, CH2I2, THF (76%) [101]; (c) Ph3(Me)PBr, n-Bu...
Scheme 26: (a) Benzene, rt (82%) [108]; (b) K2CO3, MeOH (85%) [89]; (c) iPrOH, [Ir(COD)Cl]2, PPh3, THF, rt (81%) [114].
Scheme 27: Mechanism of the Still–Gennari modification of the HWE reaction leading to both olefin isomers.
Cyclopamine analogs bearing exocyclic methylenes are highly potent and acid-stable inhibitors of hedgehog signaling
- Johann Moschner,
- Anna Chentsova,
- Nicole Eilert,
- Irene Rovardi,
- Philipp Heretsch and
- Athanassios Giannis
Beilstein J. Org. Chem. 2013, 9, 2328–2335, doi:10.3762/bjoc.9.267
- became accessible. Partial reduction to the lactol (DIBAl-H, THF, −78 °C to −65 °C, 88%) and Horner–Wadsworth–Emmons reaction by using previously reported dimethyl {3-[(4-methoxybenzyl)oxy]-2-oxopropyl}phosphonate [32], (Ba(OH)2, THF/H2O, 80 °C, 50%) led to 15 which, in turn, was methylenated by
- %) and the benzenesulfonylamine (sodium naphthalenide, DME, −78 °C, 95%) gave 20-demethyl-bis-exo-cyclopamine 19 in 7% overall yield starting from 14. Starting from azido lactone 14 (see Scheme 2) a partial reduction to the lactol (DIBAl-H, THF, −78 °C to −65 °C, 88%) and the Horner–Wadsworth–Emmons
- reaction by using triethyl phosphonoacetate (Ba(OH)2, THF/H2O, 80 °C, 55%) led to ethyl ester 20. Reduction of the azide moiety in 20 was carried out by using Staudinger’s protocol (Ph3P, THF/H2O, 50 °C). Immediate protection of the obtained amine (benzenesulfonyl chloride, Et3N, CH2Cl2, 40 °C, 97% over 2
Graphical Abstract
Figure 1: Structures of cyclopamine and exo-cyclopamine.
Scheme 1: Synthesis of 25-epi-exo-cyclopamine 5, bis-exo-cyclopamine 6, and derivatives 8 and 9. Reaction con...
Scheme 2: Synthesis of 20-demethyl-bis-exo-cyclopamine 19 and F-nor-20,25-bis-demethyl-exo-cyclopamine 23. Re...
Figure 2: IC50 values of Shh inhibition by compounds 5, 6 and 23 in a Gli1-reporter gene assay. Data were obt...
The chemistry of isoindole natural products
- Klaus Speck and
- Thomas Magauer
Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243
- olefination. Installation of the phosphonate and desilylation gave 76, which, after oxidation, reacted in the presence of sodium 2,2,2-trifluoroethanol (NaOTFE) in 2,2,2-trifluoroethanol (TFE) via an intramolecular Horner–Wadsworth–Emmons reaction to 77. Cytochalasin L-696,474 (78) was obtained from 77 via
- sequence. The asymmetric intramolecular Diels–Alder reaction was then catalyzed by Kristensens’ catalyst (201) to give 202. A base-promoted epimerization of the aldehyde and a Horner–Wadsworth–Emmons reaction furnished 203, the most advanced intermediate reported so far. Just recently, the group of
Graphical Abstract
Figure 1: a) Structural features and b) selected examples of non-natural congeners.
Scheme 1: Synthesis of isoindole 18.
Scheme 2: Staining amines with 1,4-diketone 19 (R = H).
Figure 2: Representative members of the indolocarbazole alkaloid family.
Figure 3: Staurosporine (26) bound to the adenosine-binding pocket [19] (from pdb1stc).
Figure 4: Structure of imatinib (34) and midostaurin (35).
Scheme 3: Biosynthesis of staurosporine (26).
Scheme 4: Wood’s synthesis of K-252a via the common intermediate 48.
Scheme 5: Synthesis of 26, 27, 49 and 50 diverging from the common intermediate 48.
Figure 5: Selected members of the cytochalasan alkaloid family.
Scheme 6: Biosynthesis of chaetoglobosin A (57) [56].
Scheme 7: Synthesis of cytochalasin D (70) by Thomas [63].
Scheme 8: Synthesis of L-696,474 (78).
Scheme 9: Synthesis of aldehyde 85 (R = TBDPS).
Scheme 10: Synthesis of (+)-aspergillin PZ (79) by Tanis.
Figure 6: Representative Berberis alkaloids.
Scheme 11: Proposed biosynthetic pathway to chilenine (93).
Scheme 12: Synthesis of magallanesine (97) by Danishefsky [84].
Scheme 13: Kurihara’s synthesis of magallanesine (85).
Scheme 14: Proposed biosynthesis of 113, 117 and 125.
Scheme 15: DNA lesion caused by aristolochic acid I (117) [102].
Scheme 16: Snieckus’ synthesis of piperolactam C (131).
Scheme 17: Synthesis of aristolactam BII (104).
Figure 7: Representative cularine alkaloids.
Scheme 18: Proposed biosynthesis of 136.
Scheme 19: The syntheses of 136 and 137 reported by Castedo and Suau.
Scheme 20: Synthesis of 136 by Couture.
Figure 8: Representative isoindolinone meroterpenoids.
Scheme 21: Postulated biosynthetic pathway for the formation of 156 (adopted from George) [143].
Scheme 22: Synthesis of stachyflin (156) by Katoh [144].
Figure 9: Selected examples of spirodihydrobenzofuranlactams.
Scheme 23: Synthesis of stachybotrylactam I (157).
Scheme 24: Synthesis of pestalachloride A (193) by Schmalz.
Scheme 25: Proposed mechanism for the BF3-catalyzed metal-free carbonyl–olefin metathesis [149].
Scheme 26: Preparation of the isoindoline core of muironolide A (204).
Scheme 27: Proposed biosynthesis of 208.
Scheme 28: Model for the biosynthesis of 215 and 217.
Scheme 29: Synthesis of lactonamycin (215) and lactonamycin Z (217).
Figure 10: Hetisine alkaloids 225–228.
Scheme 30: Biosynthetic proposal for the formation of the hetisine core [167].
Scheme 31: Synthesis of nominine (225).
