Search for "Michael additions" in Full Text gives 51 result(s) in Beilstein Journal of Organic Chemistry.
Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220
Graphical Abstract
Scheme 1: Precursors of nitrosoalkenes NSA.
Scheme 2: Reactions of cyclic α-chlorooximes 1 with 1,3-dicarbonyl compounds.
Scheme 3: C-C-coupling of N,N-bis(silyloxy)enamines 3 with 1,3-dicarbonyl compounds.
Scheme 4: Reaction of N,N-bis(silyloxy)enamines 3 with nitronate anions.
Scheme 5: Reaction of α-chlorooximes TBS ethers 2 with ester enolates.
Scheme 6: Assembly of bicyclooctanone 14 via an intramolecular cyclization of nitrosoalkene NSA2.
Scheme 7: A general strategy for the assembly of bicyclo[2.2.1]heptanes via an intramolecular cyclization of ...
Scheme 8: Stereochemistry of Michael addition to cyclic nitrosoalkene NSA3.
Scheme 9: Stereochemistry of Michael addition to acyclic nitrosoalkenes NSA4.
Scheme 10: Stereochemistry of Michael addition to γ-alkoxy nitrosoalkene NSA5.
Scheme 11: Oppolzer’s total synthesis of 3-methoxy-9β-estra(1,3,5(10))trien(11,17)dione (25).
Scheme 12: Oppolzer’s total synthesis of (+/−)-isocomene.
Figure 1: Alkaloids synthesized using stereoselective Michael addition to conjugated nitrosoalkenes.
Scheme 13: Weinreb’s total synthesis of alstilobanines A, E and angustilodine.
Scheme 14: Weinreb’s approach to the core structure of apparicine alkaloids.
Scheme 15: Weinreb’s synthesis of (+/−)-myrioneurinol via stereoselective conjugate addition of malonate to ni...
Scheme 16: Reactions of cyclic α-chloro oximes with Grignard reagents.
Scheme 17: Corey’s synthesis of (+/−)-perhydrohistrionicotoxin.
Scheme 18: Addition of Gilman’s reagents to α,β-epoxy oximes 53.
Scheme 19: Addition of Gilman’s reagents to α-chlorooximes.
Scheme 20: Reaction of silyl nitronate 58 with organolithium reagents via nitrosoalkene NSA12.
Scheme 21: Reaction of β-ketoxime sulfones 61 and 63 with lithium acetylides.
Scheme 22: Electrophilic addition of nitrosoalkenes NSA14 to electron-rich arenes.
Scheme 23: Addition of nitrosoalkenes NSA14 to pyrroles and indoles.
Scheme 24: Reaction of phosphinyl nitrosoalkenes NSA15 with indole.
Scheme 25: Reaction of pyrrole with α,α’-dihalooximes 70.
Scheme 26: Synthesis of indole-derived psammaplin A analogue 72.
Scheme 27: Synthesis of tryptophanes by reduction of oximinoalkylated indoles 68.
Scheme 28: Ottenheijm’s synthesis of neoechinulin B analogue 77.
Scheme 29: Synthesis of 1,2-dihydropyrrolizinones 82 via addition of pyrrole to ethyl bromopyruvate oxime.
Scheme 30: Kozikowski’s strategy to indolactam-based alkaloids via addition of indoles to ethyl bromopyruvate ...
Scheme 31: Addition of cyanide anion to nitrosoalkenes and subsequent cyclization to 5-aminoisoxazoles 86.
Scheme 32: Et3N-catalysed addition of trimethylsilyl cyanide to N,N-bis(silyloxy)enamines 3 leading to 5-amino...
Scheme 33: Addition of TMSCN to allenyl N-siloxysulfonamide 89.
Scheme 34: Reaction of nitrosoallenes NSA16 with malodinitrile and ethyl cyanoacetic ester.
Scheme 35: [4 + 1]-Annulation of nitrosoalkenes NSA with sulfonium ylides 92.
Scheme 36: Reaction of diazo compounds 96 with nitrosoalkenes NSA.
Scheme 37: Tandem Michael addition/oxidative cyclization strategy to isoxazolines 100.
Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170
Graphical Abstract
Scheme 1: Generally accepted ion-pairing mechanism between the chiral cation Q+ of a PTC and an enolate and s...
Scheme 2: Reported asymmetric α-fluorination of β-ketoesters 1 using different chiral PTCs.
Scheme 3: Asymmetric α-fluorination of benzofuranones 4 with phosphonium salt PTC F1.
Scheme 4: Asymmetric α-fluorination of 1 with chiral phosphate-based catalysts.
Scheme 5: Anionic PTC-catalysed α-fluorination of enamines 7 and ketones 10.
Scheme 6: PTC-catalysed α-chlorination reactions of β-ketoesters 1.
Scheme 7: Shioiri’s seminal report of the asymmetric α-hydroxylation of 15 with chiral ammonium salt PTCs.
Scheme 8: Asymmetric ammonium salt-catalysed α-hydroxylation using oxygen together with a P(III)-based reduct...
Scheme 9: Asymmetric ammonium salt-catalysed α-photooxygenations.
Scheme 10: Asymmetric ammonium salt-catalysed α-hydroxylations using organic oxygen-transfer reagents.
Scheme 11: Asymmetric triazolium salt-catalysed α-hydroxylation with in situ generated peroxy imidic acid 24.
Scheme 12: Phase-transfer-catalysed dearomatization of phenols and naphthols.
Scheme 13: Ishihara’s ammonium salt-catalysed oxidative cycloetherification.
Scheme 14: Chiral phase-transfer-catalysed α-sulfanylation reactions.
Scheme 15: Chiral phase-transfer-catalysed α-trifluoromethylthiolation of β-ketoesters 1.
Scheme 16: Chiral phase-transfer-catalysed α-amination of β-ketoesters 1 using diazocarboxylates 38.
Scheme 17: Asymmetric α-fluorination of benzofuranones 4 using diazocarboxylates 38 in the presence of phospho...
Scheme 18: Anionic phase-transfer-catalysed α-amination of β-ketoesters 1 with aryldiazonium salts 41.
Scheme 19: Triazolium salt L-catalysed α-amination of different prochiral nucleophiles with in situ activated ...
Scheme 20: Phase-transfer-catalysed Neber rearrangement.
Beilstein J. Org. Chem. 2017, 13, 762–767, doi:10.3762/bjoc.13.75
Graphical Abstract
Scheme 1: Desymmetrization of cyclohexadienone by tethered nucleophile.
Scheme 2: Scope of the transformation.
Figure 1: Chiral iminophosphorane catalysts surveyed.
Scheme 3: Convex facial additions.
Scheme 4: Attempted oxidative deacylation.
Scheme 5: Attempted desulfurization with Raney nickel.
Beilstein J. Org. Chem. 2017, 13, 65–75, doi:10.3762/bjoc.13.9
Graphical Abstract
Figure 1: Typical pilot scale single screw extruder (left) and a laboratory scale twin screw extruder (right)....
Figure 2: PTFE screw employed in single screw extrusion, with increasing root diameter (RD) from 45 mm to 95 ...
Figure 3: Modulated stainless steel intermeshing co-rotating screws employed typically in twin screw extrusio...
Scheme 1: Polymerisation of styrene using s-BuLi as an initiator.
Scheme 2: Telescoping process of the formation of polystyrene, followed by post polymerisation functionalisat...
Scheme 3: Proposed mechanism for the branching of polylactide. Adapted from [23].
Scheme 4: Chemical reaction between isocyanate and an alcohol to form polyurethane.
Figure 4: Representative diagram explaining the process involved in step growth polymerisation, which involve...
Scheme 5: Generic polycondensation reaction to produce polyamides.
Figure 5: Comparison of choline chloride/D-fructose DES prepared via twin screw extrusion (left) and conventi...
Scheme 6: Synthesis of HKUST-1, ZIF-8 and Al(fumarate)OH by twin screw extrusion. Adapted from [2].
Figure 6: Synthesis of Ni(NCS)2(PPh3)2 and [Ni(salen)] by twin screw extrusion. Adapted from [2].
Beilstein J. Org. Chem. 2016, 12, 2378–2389, doi:10.3762/bjoc.12.232
Graphical Abstract
Figure 1: Structures of used monomers and the time-conversion plot of the corresponding free-radical polymeri...
Scheme 1: Stereospecific propagation of chiral MLA illustrating the triade formation [15].
Figure 2: Plot of log Pn versus log [In] of the polymerization of MLA with different mol % AIBN.
Scheme 2: Postulated mechanism of the self-initiation of MLA.
Figure 3: DFT-calculated C–C binding length (yellow) of (A) MLA and (B) the corresponding radical.
Figure 4: IR spectra of (A) MLA and of (B) poly(MLA) prepared by the self-initiated polymerization at 70 °C.
Figure 5: Conversion plot of the polymerization of MLA in 1,4-dioxane and DMF (cMLA = 1.8 mol L−1, cAIBN = 1....
Figure 6: UV–vis spectra of the reaction mixture with DPPH radical at the beginning (violet line, 0.23 mM) of...
Figure 7: Copolymer composition curves for the systems MLA with styrene and MMA.
Figure 8: 1H NMR spectrum of MLA with 1 equiv of thioacetic acid and 0.15 equivalents of an inhibitor 4-metho...
Scheme 3: Mechanism of RAFT polymerization [24].
Figure 9: Structures of used RAFT agents examined in the polymerization of MLA.
Figure 10: A) Kinetic plot for the RAFT copolymerization of MLA and DMA for the ratio 90/10 employing EMP. B) ...
Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227
Graphical Abstract
Figure 1: Stereoisomeric inositols.
Scheme 1: Retrosynthetic approach to inositols from aldohexos-5-uloses.
Figure 2: Hypothesis of the preferred transition state.
Figure 3: Stereoselective reduction of inosose intermediate.
Scheme 2: Intramolecular cyclization of an orthogonally protected L-lyxo-aldohexos-5-ulose derivative.
Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174
Graphical Abstract
Figure 1: Tetrahydroquinoline (THQ) and dihydroquinoline (DHQ) scaffolds to be synthesised.
Scheme 1: Proposed retrosynthesis scheme to access N-isopropyl-THQ 2.
Scheme 2: Synthesis of THQ 3 by initial N-alkylations, followed by PPA-mediated cyclisation.
Scheme 3: Bromination of 3 and attempted halogen exchange of the intermediate 7.
Scheme 4: Synthesis of THQ 10, by initial aza-Michael addition, followed by formation of the tertiary alcohol ...
Scheme 5: Synthesis of THQ 14 by initial acylation, cyclisation with H2SO4 and reduction with borane·dimethyl...
Scheme 6: N-Alkylation of 13 and 14.
Scheme 7: Facile route for the synthesis of 20a.
Scheme 8: Synthesis of THQ 21 and DHQ 22 using borane·dimethyl sulphide complex or DIBAL, respectively.
Figure 2: Simulated structure of 22 indicates a flattened quinoline-like structure. Hartree–Fock calculations...
Scheme 9: Postulated mechanism for the formation of 22 using DIBAL.
Figure 3: Combined, normalised absorption and emission spectra of 28 in chloroform. Absorption spectrum was r...
Scheme 10: Miyaura borylation of 21 and 22 to give crystalline boronic esters 29 and 30.
Figure 4: Comparison of the crystal structures of 29 (left) and 30 (right) as viewed along the plane of the a...
Figure 5: Combined, normalised absorption and emission spectra of 30 in diethyl ether. Absorption spectrum wa...
Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148
Graphical Abstract
Scheme 1: Schematic description of the cyclisation reaction catalysed by TE domains. In most cases, the nucle...
Scheme 2: Mechanisms for the formation of oxygen heterocycles. The degree of substitution can differ from tha...
Scheme 3: Pyran-ring formation in pederin (24) biosynthesis. Incubation of recombinant PedPS7 with substrate ...
Scheme 4: The domain AmbDH3 from ambruticin biosynthesis catalyses the dehydration of 25 and subsequent cycli...
Scheme 5: SalBIII catalyses dehydration of 29 and subsequent cyclisation to tetrahydropyran 30 [18].
Figure 1: All pyranonaphtoquinones contain either the naphtha[2,3-c]pyran-5,10-dione (32) or the regioisomeri...
Scheme 6: Pyran-ring formation in actinorhodin (34) biosynthesis. DNPA: 4-dihydro-9-hydroxy-1-methyl-10-oxo-3H...
Scheme 7: Pyran formation in granaticin (36) biosynthesis. DNPA: 4-dihydro-9-hydroxy-1-methyl-10-oxo-3H-napht...
Scheme 8: Pyran formation in alnumycin (37) biosynthesis. Adapted from [21].
Scheme 9: Biosynthesis of pseudomonic acid A (61). The pyran ring is initially formed in 57 after dehydrogena...
Scheme 10: Epoxidation–cyclisation leads to the formation of the tetrahydropyran ring in the western part of t...
Scheme 11: a) Nonactin (70) is formed from heterodimers of (−)(+)-dimeric nonactic acid and (+)(−)-dimeric non...
Figure 2: Pamamycins (73) are macrodiolide antibiotics containing three tetrahydrofuran moieties, which are a...
Scheme 12: A PS domain homolog in oocydin A (76) biosynthesis is proposed to catalyse furan formation via an o...
Scheme 13: Mechanism of oxidation–furan cyclisation by AurH, which converts (+)-deoxyaureothin (77) into (+)-a...
Scheme 14: Leupyrrin A2 (80) and the proposed biosynthesis of its furylidene moiety [69,70].
Scheme 15: Asperfuranone (93) biosynthesis, adapted from [75].
Figure 3: The four major aflatoxins produced by Aspergilli are the types B1, B2, G1 and G2 (94–97). In the di...
Scheme 16: Overview on aflatoxin B1 (94) biosynthesis. HOMST = 11-hydroxy-O-methylsterigmatocystin [78,79,82-106].
Scheme 17: A zipper mechanism leads to the formation of oxygen heterocycles in monensin biosynthesis [109-111].
Scheme 18: Formation of the 2,6-dioxabicyclo[3.2.1]octane (DBO) ring system in aurovertin B (118) biosynthesis ...
Figure 4: Structures of the epoxide-containing polyketides epothilone A (119) and oleandomycin (120) [123-125].
Scheme 19: Structures of phoslactomycin B (121) (a) and jerangolid A (122) (b). The heterocycle-forming steps ...
Scheme 20: a) Structures of rhizoxin (130) and cycloheximide (131). Model for the formation of δ-lactones (b) ...
Scheme 21: EncM catalyses a dual oxidation sequence and following processing of the highly reactive intermedia...
Figure 5: Mesomeric structures of tetronates [138,139].
Figure 6: Structures of tetronates for which gene clusters have been sequenced. The tetronate moiety is shown...
Scheme 22: Conserved steps for formation and processing in several 3-acyl-tetronate biosynthetic pathways were...
Scheme 23: In versipelostatin A (153) biosynthesis, VstJ is a candidate enzyme for catalysing the [4 + 2] cycl...
Scheme 24: a) Structures of some thiotetronate antibiotics. b) Biosynthesis of thiolactomycin (165) as propose...
Scheme 25: Aureusidine synthase (AS) catalyses phenolic oxidation and conjugate addition of chalcones leading ...
Scheme 26: a) Oxidative cyclisation is a key step in the biosynthesis of spirobenzofuranes 189, 192 and 193. b...
Scheme 27: A bicyclisation mechanism forms a β-lactone and a pyrrolidinone and removes the precursor from the ...
Scheme 28: Spontaneous cyclisation leads to off-loading of ebelactone A (201) from the PKS machinery [163].
Scheme 29: Mechanisms for the formation of nitrogen heterocycles.
Scheme 30: Biosynthesis of highly substituted α-pyridinones. a) Feeding experiments confirmed the polyketide o...
Scheme 31: Acridone synthase (ACS) catalyses the formation of 1,3-dihydroxy-N-methylacridone (224) by condensa...
Scheme 32: A Dieckmann condensation leads to the formation of a 3-acyl-4-hydroxypyridin-2-one 227 and removes ...
Scheme 33: a) Biosynthesis of the pyridinone tenellin (234). b) A radical mechanism was proposed for the ring-...
Scheme 34: a) Oxazole-containing PKS–NRPS-derived natural products oxazolomycin (244) and conglobatin (245). b...
Scheme 35: Structure of tetramic acids 251 (a) and major tautomers of 3-acyltetramic acids 252a–d (b). Adapted...
Scheme 36: Equisetin biosynthesis. R*: terminal reductive domain. Adapted from [202].
Scheme 37: a) Polyketides for which a similar biosynthetic logic was suggested. b) Pseurotin A (256) biosynthe...
Figure 7: Representative examples of PTMs with varying ring sizes and oxidation patterns [205,206].
Scheme 38: Ikarugamycin biosynthesis. Adapted from [209-211].
Scheme 39: Tetramate formation in pyrroindomycin aglycone (279) biosynthesis [213-215].
Scheme 40: Dieckmann cyclases catalyse tetramate or 2-pyridone formation in the biosynthesis of, for example, ...
Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116
Graphical Abstract
Figure 1: Two general pathways for conjugate addition followed by enantioselective protonation.
Scheme 1: Tomioka’s enantioselective addition of arylthiols to α-substituted acrylates.
Scheme 2: Sibi’s enantioselective hydrogen atom transfer reactions.
Scheme 3: Mikami’s addition of perfluorobutyl radical to α-aminoacrylate 11.
Scheme 4: Reisman’s Friedel–Crafts conjugate addition–enantioselective protonation approach toward tryptophan...
Scheme 5: Pracejus’s enantioselective addition of benzylmercaptan to α-aminoacrylate 20.
Scheme 6: Kumar and Dike’s enantioselective addition of thiophenol to α-arylacrylates.
Scheme 7: Tan’s enantioselective addition of aromatic thiols to 2-phthalimidoacrylates.
Scheme 8: Glorius’ enantioselective Stetter reactions with α-substituted acrylates.
Scheme 9: Dixon’s enantioselective addition of thiols to α-substituted acrylates.
Figure 2: Chiral phosphorous ligands.
Scheme 10: Enantioselective addition of arylboronic acids to methyl α-acetamidoacrylate.
Scheme 11: Frost’s enantioselective additions to dimethyl itaconate.
Scheme 12: Darses and Genet’s addition of potassium organotrifluoroborates to α-aminoacrylates.
Scheme 13: Proposed mechanism for enantioselective additions to α-aminoacrylates.
Scheme 14: Sibi’s addition of arylboronic acids to α-methylaminoacrylates.
Scheme 15: Frost’s enantioselective synthesis of α,α-dibenzylacetates 64.
Scheme 16: Rovis’s hydroheteroarylation of α-substituted acrylates with benzoxazoles.
Scheme 17: Proposed mechanism for the hydroheteroarylation of α-substituted acrylates with benzoxazoles.
Scheme 18: Sodeoka’s enantioselective addition of amines to N-benzyloxycarbonyl acrylamides 75 and 77.
Scheme 19: Proposed catalytic cycle for Sodeoka’s enantioselective addition of amines.
Scheme 20: Sibi’s enantioselective Friedel–Crafts addition of pyrroles to imides 84.
Scheme 21: Kobayashi’s enantioselective addition of malonates to α-substituted N-acryloyloxazolidinones.
Scheme 22: Chen and Wu’s enantioselective addition of thiophenol to N-methacryloyl benzamide.
Scheme 23: Tan’s enantioselective addition of secondary phosphine oxides and thiols to N-arylitaconimides.
Scheme 24: Enantioselective addition of thiols to α-substituted N-acryloylamides.
Scheme 25: Kobayashi’s enantioselective addition of thiols to α,β-unsaturated ketones.
Scheme 26: Feng’s enantioselective addition of pyrazoles to α-substituted vinyl ketones.
Scheme 27: Luo and Cheng’s addition of indoles to vinyl ketones by enamine catalysis.
Scheme 28: Curtin–Hammett controlled enantioselective addition of indole.
Scheme 29: Luo and Cheng’s enantioselective additions to α-branched vinyl ketones.
Scheme 30: Lou’s reduction–conjugate addition–enantioselective protonation.
Scheme 31: Luo and Cheng’s primary amine-catalyzed addition of indoles to α-substituted acroleins.
Scheme 32: Luo and Cheng’s proposed mechanism and transition state.
Figure 3: Shibasaki’s chiral lanthanum and samarium tris(BINOL) catalysts.
Scheme 33: Shibasaki’s enantioselective addition of 4-tert-butyl(thiophenol) to α,β-unsaturated thioesters.
Scheme 34: Shibasaki’s application of chiral (S)-SmNa3tris(binaphthoxide) catalyst 144 to the total synthesis ...
Scheme 35: Shibasaki’s cyanation–enantioselective protonation of N-acylpyrroles.
Scheme 36: Tanaka’s hydroacylation of acrylamides with aliphatic aldehydes.
Scheme 37: Ellman’s enantioselective addition of α-substituted Meldrum’s acids to terminally unsubstituted nit...
Scheme 38: Ellman’s enantioselective addition of thioacids to α,β,β-trisubstituted nitroalkenes.
Scheme 39: Hayashi’s enantioselective hydroarylation of diphenylphosphinylallenes.
Scheme 40: Hayashi’s enantioselective hydroarylation of diphenylphosphinylallenes.
Figure 4: Togni’s chiral ferrocenyl tridentate nickel(II) and palladium(II) complexes.
Scheme 41: Togni’s enantioselective hydrophosphination of methacrylonitrile.
Scheme 42: Togni’s enantioselective hydroamination of methacrylonitrile.
Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90
Graphical Abstract
Figure 1: Some α-substituted heterocycles for asymmetric catalysis, their reactivity patterns against enoliza...
Figure 2: 1H-Imidazol-4(5H)-ones 1 and thiazol-4(5H)-ones 2.
Scheme 1: a) Synthesis of 2-thio-1H-imidazol-4(5H)-ones [55] and b) preparation of the starting thiohydantoins [59].
Scheme 2: Selected examples of the Michael addition of 2-thio-1H-imidazol-4(5H)-ones to nitroalkenes [55]. aReact...
Scheme 3: Michael addition of thiohydantoins to nitrostyrene assisted by Et3N and catalysts C1 and C3. aAbsol...
Scheme 4: Elaboration of the Michael adducts coming from the Michael addition to nitroalkenes [55].
Figure 3: Proposed model for the Michael addition of 1H-imidazol4-(5H)-ones and selected 1H NMR data which su...
Scheme 5: Michael addition 2-thio-1H-imidazol-4(5H)-ones to the α-silyloxyenone 29 [55].
Scheme 6: Elaboration of the Michael adducts coming from the Michael addition to nitroolefins [55].
Scheme 7: Rhodanines in asymmetric catalytic reactions: a) Reaction with rhodanines of type 44 [78-80]; b) reactions...
Scheme 8: Michael addition of thiazol-4(5H)-ones to nitroolefins promoted by the ureidopeptide-like bifunctio...
Figure 4: Ureidopeptide-like Brønsted bases: catalyst design. a) Previous known design. b) Proposed new desig...
Scheme 9: Ureidopeptide-like Brønsted base bifunctional catalyst preparation. NMM = N-methylmorpholine, THF =...
Scheme 10: Selected examples of the Michael addition of thiazolones to different nitroolefins promoted by cata...
Scheme 11: Elaboration of the Michael adducts to α,α-disubstituted α-mercaptocarboxylic acid derivatives [85].
Scheme 12: Effect of the nitrogen atom at the aromatic substituent of the thiazolone on yield and stereoselect...
Scheme 13: Michael addition reaction of thiazol-4(5H)ones 74 to α’-silyloxyenone 29 [73].
Scheme 14: Elaboration of the thiazolone Michael adducts [73].
Scheme 15: Enantioselective γ-addition of oxazol-4(5H)-ones and thiazol-4(5H)-ones to allenoates promoted by C6...
Scheme 16: Enantioselective γ-addition of thiazol-4(5H)-ones and oxazol-4(5H)-ones to alkynoate 83 promoted by ...
Scheme 17: Proposed mechanism for the C6-catalyzed γ-addition of thiazol-4(5H)-one to allenoates. Adapted from ...
Scheme 18: Catalytic enantioselective α-amination of thiazolones promoted by ureidopeptide like catalysts C5 a...
Scheme 19: Iridium-catalized asymmetric allyllation of substituted oxazol-4(5H)-ones and thiazol-4(5H)-ones pr...
Beilstein J. Org. Chem. 2016, 12, 628–635, doi:10.3762/bjoc.12.61
Graphical Abstract
Figure 1: Parent and supported bifunctional thioureas used in this work.
Scheme 1: Reaction of nitrostyrene with diethyl malonate and 2-ethoxycarbonyl cyclopentanone.
Scheme 2: Reaction of nitrostyrenes with malonates and β-diketones.
Scheme 3: Reaction of nitrostyrenes with β-keto esters and β-dicarbonyl compounds.
Scheme 4: Reaction of nitrostyrenes with α-nitrocyclohexanone and ethyl α-nitropropionate.
Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50
Graphical Abstract
Figure 1: Different configurations of 1,2-aminoindanol 1a–d.
Scheme 1: Asymmetric F–C alkylation catalyzed by thiourea 4.
Figure 2: Results for the F–C reaction carried out with catalyst 4 and the structurally modified analogues, 4'...
Figure 3: (a) Transition state TS1 originally proposed for the F–C reaction catalyzed by thiourea 4 [18]. (b) Tra...
Scheme 2: Asymmetric F–C alkylation catalyzed by thiourea ent-4 in the presence of D-mandelic acid as a Brøns...
Figure 4: Transition state TS2 proposed for the activation of the thiourea-based catalyst ent-4 by an externa...
Scheme 3: Friedel–Crafts alkylation of indoles catalyzed by the chiral thioamide 6.
Scheme 4: Scalable tandem C2/C3-annulation of indoles, catalyzed by the thioamide ent-6.
Scheme 5: Plausible tandem process mechanism for the sequential, double Friedel–Crafts alkylation, which invo...
Scheme 6: One-pot multisequence process that allows the synthesis of interesting compounds 14. The pharmacolo...
Scheme 7: Reaction pathway proposed for the preparation of the compounds 14.
Scheme 8: The enantioselective synthesis of cis-vicinal-substituted indane scaffolds 21, catalyzed by ent-6.
Scheme 9: Asymmetric domino procedure (Michael addition/Henry cyclization), catalyzed by the thioamide ent-6 ...
Scheme 10: The enantioselective addition of indoles 2 to α,β-unsaturated acyl phosphonates 24, a) screening of...
Figure 5: Proposed transition state TS7 for the Friedel–Crafts reaction of indole and α,β-unsaturated acyl ph...
Scheme 11: Study of aliphatic β,γ-unsaturated α-ketoesters 26 as substrates in the F–C alkylation of indoles c...
Figure 6: Possible transition states TS8 and TS9 in the asymmetric addition of indoles 2 to the β,γ-unsaturat...
Figure 7: Transition state TS10 proposed for the asymmetric addition of dialkylhydrazone 28 to the β,γ-unsatu...
Scheme 12: Different β-hydroxylamino-based catalysts tested in a Michael addition, and the transition state TS...
Scheme 13: Enantioselective addition of acetylacetone (36a) to nitroalkenes 3, catalyzed by 37 and the propose...
Scheme 14: Addition of 3-oxindoles 39 to 2-amino-1-nitroethenes 40, catalyzed by 41.
Scheme 15: Michael addition of 1,3-dicarbonyl compounds 36 to the nitroalkenes 3 catalyzed by the squaramide 43...
Scheme 16: Asymmetric aza-Henry reaction catalyzed by the aminoindanol-derived sulfinyl urea 50.
Figure 8: Results for the aza-Henry reaction carried out with the structurally modified catalysts 50–50''.
Scheme 17: Diels–Alder reaction catalyzed by the aminoindanol derivative ent-41.
Scheme 18: Asymmetric Michael addition of 3-pentanone (55a) to the nitroalkenes 3 through aminocatalysis.
Scheme 19: Substrate scope extension for the asymmetric Michael addition between the ketones 55 and the nitroa...
Scheme 20: A possible reaction pathway in the presence of the catalyst 56 and the plausible transition state T...
Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60
Graphical Abstract
Scheme 1: Generic mechanism for the conjugate addition reaction.
Figure 1: Methods to activate unsaturated amide/lactam systems.
Scheme 2: DCA of Grignard reagents to an L-ephedrine derived chiral α,β–unsaturated amide.
Figure 2: Chiral auxiliaries used in DCA reactions.
Scheme 3: Comparison between auxiliary 5 and the Oppolzer auxiliary in a DCA reaction.
Scheme 4: Use of Evans auxiliary in a DCA reaction.
Figure 3: Lewis acid complex of the Evans auxiliary [43].
Scheme 5: DCA reactions of α,β-unsaturated amides utilizing (S,S)-(+)-pseudoephedrine and the OTBS-derivative...
Figure 4: Proposed model accounting for the diastereoselectivity observed in the 1,4-addition of Bn2NLi to α,...
Scheme 6: An example of a tandem conjugate addition–α-alkylation reaction of an α,β-unsaturated amide utilizi...
Scheme 7: Conjugate addition to an α,β-unsaturated bicyclic lactam leading to (+)-paroxetine and (+)-femoxeti...
Scheme 8: Intramolecular conjugate addition reaction to α,β-unsaturated amide.
Scheme 9: Conjugate addition to an α,β-unsaturated pyroglutamate derivative.
Scheme 10: Cu(I)–NHC-catalyzed asymmetric silylation of α,β-unsaturated lactams and amides.
Scheme 11: Asymmetric copper-catalyzed 1,4-borylation of an α,β-unsaturated amide.
Scheme 12: Asymmetric cross-coupling 49 to phenyl chloride.
Scheme 13: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated lactam.
Scheme 14: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide.
Scheme 15: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide using a chiral bicyclic dien...
Scheme 16: Synthesis of (R)-(−)-baclofen through a rhodium-catalyzed asymmetric 1,4-arylation of lactam 58.
Scheme 17: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide and lactam employing organo[...
Scheme 18: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated lactam employing benzofuran-2-ylzi...
Figure 5: Further chiral ligands that have been used in rhodium-catalyzed 1,4-additions of α,β-unsaturated am...
Scheme 19: Palladium-catalyzed asymmetric 1,4-arylation of arylsiloxanes to a α,β-unsaturated lactam.
Scheme 20: SmI2-mediated cyclization of α,β-unsaturated Weinreb amides.
Figure 6: Chiral Lewis acid complexes used in the Mukaiyama–Michael addition of α,β-unsaturated amides.
Scheme 21: Mukaiyama–Michael addition of thioester silylketene acetal to α,β-unsaturated N-alkenoyloxazolidino...
Scheme 22: Asymmetric 1,4-addition of aryl acetylides to α,β-unsaturated thioamides.
Scheme 23: Asymmetric 1,4-addition of alkyl acetylides to α,β-unsaturated thioamides.
Scheme 24: Asymmetric vinylogous conjugate additions of unsaturated butyrolactones to α,β-unsaturated thioamid...
Scheme 25: Gd-catalyzed asymmetric 1,4-cyanation of α,β-unsaturated N-acylpyrroles [205].
Scheme 26: Lewis acid-catalyzed asymmetric 1,4-cyanation of α,β-unsaturated N-acylpyrazole 107.
Scheme 27: Lewis acid mediated 1,4-addition of dibenzyl malonate to α,β-unsaturated N-acylpyrroles.
Scheme 28: Chiral Lewis acid mediated 1,4-radical addition to α,β-unsaturated N-acyloxazolidinone [224].
Scheme 29: Aza-Michael addition of O-benzylhydroxylamine to an α,β-unsaturated N-acylpyrazole.
Scheme 30: An example of the aza-Michael addition of secondary aryl amines to an α,β-unsaturated N-acyloxazoli...
Scheme 31: Aza-Michael additions of anilines to a α,β-unsaturated N-alkenoyloxazolidinone catalyzed by palladi...
Scheme 32: Aza-Michael additions of aniline to an α,β-unsaturated N-alkenoylbenzamide and N-alkenoylcarbamate ...
Scheme 33: Difference between aza-Michael addition ran using the standard protocol versus the slow addition pr...
Scheme 34: Aza-Michael additions of aryl amines salts to an α,β-unsaturated N-alkenoyloxazolidinone catalyzed ...
Scheme 35: Aza-Michael addition of N-alkenoyloxazolidiniones catalyzed by samarium diiodide [244].
Scheme 36: Asymmetric aza-Michael addition of p-anisidine to α,β-unsaturated N-alkenoyloxazolidinones catalyze...
Scheme 37: Asymmetric aza-Michael addition of O-benzylhydroxylamine to N-alkenoyloxazolidinones catalyzed by i...
Scheme 38: Asymmetric 1,4-addition of purine to an α,β-unsaturated N-alkenoylbenzamide catalyzed by (S,S)-(sal...
Scheme 39: Asymmetric 1,4-addition of phosphites to α,β-unsaturated N-acylpyrroles.
Scheme 40: Asymmetric 1,4-addition of phosphine oxides to α,β-unsaturated N-acylpyrroles.
Scheme 41: Tandem Michael-aldol reaction catalyzed by a hydrogen-bonding organocatalyst.
Scheme 42: Examples of the sulfa-Michael–aldol reaction employing α,β-unsaturated N-acylpyrazoles.
Scheme 43: Example of the sulfa-Michael addition of α,β-unsaturated N-alkenoyloxazolidinones.
Figure 7: Structure of cinchona alkaloid-based squaramide catalyst.
Scheme 44: Asymmetric intramolecular oxa-Michael addition of an α,β-unsaturated amide.
Scheme 45: Formal synthesis atorvastatin.
Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218
Graphical Abstract
Figure 1: Cyclic chiral phosphines based on bridged-ring skeletons.
Figure 2: Cyclic chiral phosphines based on binaphthyl skeletons.
Figure 3: Cyclic chiral phosphines based on ferrocene skeletons.
Figure 4: Cyclic chiral phosphines based on spirocyclic skeletons.
Figure 5: Cyclic chiral phosphines based on phospholane ring skeletons.
Figure 6: Acyclic chiral phosphines.
Figure 7: Multifunctional chiral phosphines based on binaphthyl skeletons.
Figure 8: Multifunctional chiral phosphines based on amino acid skeletons.
Scheme 1: Asymmetric [3 + 2] annulations of allenoates with electron-deficient olefins, catalyzed by the chir...
Scheme 2: Asymmetric [3 + 2] annulations of allenoate and enones, catalyzed by the chiral binaphthyl-based ph...
Scheme 3: Asymmetric [3 + 2] annulations of N-substituted olefins and allenoates, catalyzed by the chiral bin...
Scheme 4: Asymmetric [3 + 2] annulations of 2-aryl-1,1-dicyanoethylenes with ethyl allenoate, catalyzed by th...
Scheme 5: Asymmetric [3 + 2] annulations of 3-alkylideneindolin-2-ones with ethyl allenoate, catalyzed by the...
Scheme 6: Asymmetric [3 + 2] annulations of 2,6-diarylidenecyclohexanones with allenoates, catalyzed by the c...
Scheme 7: Asymmetric [3 + 2] annulations of allenoate with alkylidene azlactones, catalyzed by the chiral bin...
Scheme 8: Asymmetric [3 + 2] annulations of C60 with allenoates, catalyzed by the chiral phosphine B6.
Scheme 9: Asymmetric [3 + 2] annulations of α,β-unsaturated esters and ketones with an allenoate, catalyzed b...
Scheme 10: Asymmetric [3 + 2] annulations of exocyclic enones with allenoates, catalyzed by the ferrocene-modi...
Scheme 11: Asymmetric [3 + 2] annulations of enones with an allenylphosphonate, catalyzed by the ferrocene-mod...
Scheme 12: Asymmetric [3 + 2] annulations of 3-alkylidene-oxindoles with ethyl allenoate, catalyzed by the fer...
Scheme 13: Asymmetric [3 + 2] annulations of dibenzylideneacetones with ethyl allenoate, catalyzed by the ferr...
Scheme 14: Asymmetric [3 + 2] annulations of trisubstituted alkenes with ethyl allenoate, catalyzed by the fer...
Scheme 15: Asymmetric [3 + 2] annulations of 2,6-diarylidenecyclohexanones with allenoates, catalyzed by the f...
Scheme 16: Asymmetric [3 + 2] annulations of α,β-unsaturated ketones with ethyl allenoates, catalyzed by the f...
Scheme 17: Asymmetric [3 + 2] annulations of α,β-unsaturated esters with allenoates, catalyzed by the ferrocen...
Scheme 18: Asymmetric [3 + 2] annulations of alkylidene azlactones with allenoates, catalyzed by the chiral sp...
Scheme 19: Asymmetric [3 + 2] annulations of α-trimethylsilyl allenones and electron-deficient olefins, cataly...
Scheme 20: Asymmetric [3 + 2] annulations of α,β-unsaturated ketones with an allenone, catalyzed by the chiral...
Scheme 21: Asymmetric [3 + 2] annulations of cyclic enones with allenoates, catalyzed by the chiral α-amino ac...
Scheme 22: Asymmetric [3 + 2] annulations of arylidenemalononitriles and analogues with an allenoate, catalyze...
Scheme 23: Asymmetric [3 + 2] annulations of α,β-unsaturated esters with an allenoate, catalyzed by the chiral...
Scheme 24: Asymmetric [3 + 2] annulations of 3,5-dimethyl-1H-pyrazole-derived acrylamides with an allenoate, c...
Scheme 25: Asymmetric [3 + 2] annulations of maleimides with allenoates, catalyzed by the chiral phosphine H10....
Scheme 26: Asymmetric [3 + 2] annulations of α-substituted acrylates with allenoate, catalyzed by the chiral p...
Scheme 27: Asymmetric [3 + 2] annulation of an N-tosylimine with an allenoate, catalyzed by the chiral phosphi...
Scheme 28: Asymmetric [3 + 2] annulations of N-tosylimines with an allenoate, catalyzed by the chiral phosphin...
Scheme 29: Asymmetric [3 + 2] annulations of N-tosylimines with an allenoate, catalyzed by the chiral phosphin...
Scheme 30: Asymmetric [3 + 2] annulations of N-diphenylphosphinoyl aromatic imines with butynoates, catalyzed ...
Scheme 31: Asymmetric [3 + 2] annulations of N-tosylimines with allenylphosphonates, catalyzed by the chiral p...
Scheme 32: Asymmetric [3 + 2] annulation of an N-tosylimine with an allenoate, catalyzed by the chiral phosphi...
Scheme 33: Asymmetric [3 + 2] annulations of N-diphenylphosphinoyl aromatic imines with allenoates (top), cata...
Scheme 34: Asymmetric [3 + 2] annulation of N-diphenylphosphinoylimines with allenoates, catalyzed by the chir...
Scheme 35: Asymmetric [3 + 2] annulation of an azomethine imine with an allenoate, catalyzed by the chiral pho...
Scheme 36: Asymmetric [3 + 2] annulations between α,β-unsaturated esters/ketones and 3-butynoates, catalyzed b...
Scheme 37: Asymmetric intramolecular [3 + 2] annulations of electron-deficient alkenes and MBH carbonates, cat...
Scheme 38: Asymmetric [3 + 2] annulations of methyleneindolinone and methylenebenzofuranone derivatives with M...
Scheme 39: Asymmetric [3 + 2] annulations of activated isatin-based alkenes with MBH carbonates, catalyzed by ...
Scheme 40: Asymmetric [3 + 2] annulations of maleimides with MBH carbonates, catalyzed by the chiral phosphine ...
Scheme 41: A series of [3 + 2] annulations of various activated alkenes with MBH carbonates, catalyzed by the ...
Scheme 42: Asymmetric [3 + 2] annulations of an alkyne with isatins, catalyzed by the chiral phosphine F1.
Scheme 43: Asymmetric [4 + 2] annulations catalyzed by the chiral phosphine B1.
Scheme 44: Asymmetric [4 + 2] annulations catalyzed by the chiral phosphine H5.
Scheme 45: Asymmetric [4 + 2] annulations catalyzed by the chiral phosphines H13 and H12.
Scheme 46: Asymmetric [4 + 2] annulations catalyzed by the chiral phosphine H6.
Scheme 47: Kerrigan’s [2 + 2] annulations of ketenes with imines, catalyzed by the chiral phosphine B7.
Scheme 48: Asymmetric [4 + 1] annulations, catalyzed by the chiral phosphine G6.
Scheme 49: Asymmetric homodimerization of ketenes, catalyzed by the chiral phosphine F5 and F6.
Scheme 50: Aza-MBH/Michael reactions, catalyzed by the chiral phosphine G1.
Scheme 51: Tandem RC/Michael additions, catalyzed by the chiral phosphine H14.
Scheme 52: Intramolecular tandem RC/Michael addition, catalyzed by the chiral phosphine H15.
Scheme 53: Double-Michael addition, catalyzed by the chiral aminophosphine G9.
Scheme 54: Tandem Michael addition/Wittig olefinations, mediated by the chiral phosphine BIPHEP.
Scheme 55: Asymmetric Michael additions, catalyzed by the chiral phosphines H7, H8, and H9.
Scheme 56: Asymmetric γ-umpolung additions, catalyzed by the chiral phosphine A1.
Scheme 57: Asymmetric γ-umpolung additions, catalyzed by the chiral phosphines E2 and E3.
Scheme 58: Intramolecular γ-additions of hydroxy-2-alkynoates, catalyzed by the chiral phosphine D2.
Scheme 59: Intra-/intermolecular γ-additions, catalyzed by the chiral phosphine D2.
Scheme 60: Intermolecular γ-additions, catalyzed by the chiral phosphines B5 and B3.
Scheme 61: Intermolecular γ-additions, catalyzed by the chiral phosphines E6 and B4.
Scheme 62: Asymmetric allylic substitution of MBH acetates, catalyzed by the chiral phosphine G2.
Scheme 63: Allylic substitutions between MBH acetates or carbonates and an array of nucleophiles, catalyzed by...
Scheme 64: Asymmetric acylation of diols, catalyzed by the chiral phosphines E4 and E5.
Scheme 65: Kinetic resolution of secondary alcohols, catalyzed by the chiral phosphine E8 and E9.
Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195
Graphical Abstract
Figure 1: Examples of phosphonamide reagents used in stereoselective synthesis.
Figure 2: Natural products and bioactive molecules synthesized using phosphonamide-based chemistry (atoms, bo...
Scheme 1: Olefination with cyclic phosphonamide anions, mechanistic rationale, and selected examples 27a–d [18].
Scheme 2: Asymmetric olefination with chiral phosphonamide anions and selected examples 31a–d [1,22].
Scheme 3: Synthesis of α-substituted phosphonic acids 33a–e by asymmetric alkylation of chiral phosphonamide ...
Scheme 4: Asymmetric conjugate additions of C2-symmetric chiral phosphonamide anions to cyclic enones, lacton...
Scheme 5: Asymmetric conjugate additions of P-chiral phosphonamide anions generated from 40a and 44a to cycli...
Scheme 6: Asymmetric cyclopropanation with chiral chloroallyl phosphonamide 47, mechanistic rationale, and se...
Scheme 7: Asymmetric cyclopropanation with chiral chloromethyl phosphonamide 28d [59].
Scheme 8: Stereoselective synthesis of cis-aziridines 57 from chiral chloroallyl phosphonamide 47a [62].
Scheme 9: Synthesis of phosphonamides by (A) Arbuzov reaction, (B) condensation of diamines with phosphonic a...
Figure 3: Original and revised structure of polyoxin A (69) [24-26].
Scheme 10: Synthesis of (E)-polyoximic acid (9) [24-26].
Figure 4: Key assembly strategy of acetoxycrenulide (10) [41,42].
Scheme 11: Total synthesis of (+)-acetoxycrenulide (10) [41,42].
Scheme 12: Synthesis squalene synthase inhibitor 19 by asymmetric sulfuration (A) and asymmetric alkylation (B...
Figure 5: Key assembly strategy of fumonisin B2 (20) and its tricarballylic acid fragment 105 [45,46].
Scheme 13: Final steps of the total synthesis of fumonisin B2 (20) [45,46].
Figure 6: Selected examples of two subclasses of β-lactam antibiotics – carbapenems (111 and 112) and trinems...
Scheme 14: Synthesis of tricyclic β-lactam antibiotic 123 [97].
Scheme 15: Total synthesis of (−)-anthoplalone (8) [56].
Figure 7: Protein tyrosine phosphatase (PTP) inhibitors 130, 131 and model compounds 16, 132 and 133 [68].
Scheme 16: Synthesis of model PTP inhibitors 16a,b [68].
Scheme 17: Synthesis of aziridine hydroxamic acid 17 as MMP inhibitor [63].
Scheme 18: Synthesis of methyl jasmonate (11) [48].
Figure 8: Structures of nudiflosides A (137) and D (13) [49].
Scheme 19: Total synthesis of the pentasubstituted cyclopentane core 159 of nudiflosides A (151) and D (13) an...
Figure 9: L-glutamic acid (161) and constrained analogues [57,124].
Scheme 20: Stereoselective synthesis of DCG-IV (162) [57].
Scheme 21: Stereoselective synthesis of mGluR agonist 21 [124].
Figure 10: Key assembly strategy of berkelic acid (15) [43].
Scheme 22: Total synthesis of berkelic acid (15) [43].
Figure 11: Key assembly strategy of jerangolid A (22) and ambruticin S (14) [27,28].
Scheme 23: Final assembly steps in the total synthesis of jerangolid A [27].
Scheme 24: Key assembly steps in the total synthesis of ambruticin S (14) [28].
Figure 12: General steroid construction strategy based on conjugate addition of 212 to cyclopentenone 48, exem...
Scheme 25: Total synthesis of estrone (12) [44].
Beilstein J. Org. Chem. 2014, 10, 1159–1165, doi:10.3762/bjoc.10.116
Graphical Abstract
Figure 1: The phacelocarpus 2-pyrones 1 and 2.
Scheme 1: Generalised O-functionalisation of 6-alkyl-4-hydroxy-2-pyrones 3.
Scheme 2: Synthesis of alkylated 2-pyrones 3b–e.
Scheme 3: Michael addition of 3a to allene 8 and internal alkyne 10.
Beilstein J. Org. Chem. 2014, 10, 459–465, doi:10.3762/bjoc.10.43
Graphical Abstract
Scheme 1: Summary of the transformations involved in the synthesis of compounds 5, containing chromone and β-...
Scheme 2: Synthesis of compounds 5.
Figure 1: X-ray structure of compound 5h.
Scheme 3: Initial mechanistic proposal to explain the formation of compounds 5 that was ruled out by deuterat...
Scheme 4: Alternative mechanistic proposal based on a carbon monoxide-induced deoxygenation.
Beilstein J. Org. Chem. 2014, 10, 224–236, doi:10.3762/bjoc.10.18
Graphical Abstract
Figure 1: Thiourea, squaramide, P-triamide and cyclodiphosphazane with computed distances between H-atoms.
Figure 2: Urea, squaramide, P-triamide and cyclodiphosphazane coordinated to nitrobenzene, with the computed ...
Scheme 1: Chiral PV-amide catalysts based on BINOL and chinchona backbones.
Scheme 2: Exclusive formation of the mono- and trisubstituted product from thiophosphoryl chloride and anilin...
Figure 3: X-ray structure of 6-dimer. The hydrogen atoms are omitted for clarity, except at all nitrogens.
Figure 4: X-ray structure of 7a-dimer. The hydrogen atoms are omitted for clarity, except at all nitrogens.
Scheme 3: Synthesis of chiral cyclodiphosphazane catalysts 14a/b, 15 and 16.
Figure 5: X-ray structure of 14a. The hydrogen atoms are omitted for clarity, except at nitrogen.
Figure 6: 31P{1H} NMR spectrum in CDCl3 at rt showing C2 symmetry of 14a at rt.
Figure 7: X-ray structure of 15. The hydrogen atoms are omitted for clarity, except at nitrogen.
Figure 8: X-ray structure of 16. The hydrogen atoms are omitted for clarity, except at nitrogen.
Figure 9: Enantiodetermining transition states TS-14a/TS-14b arising from the addition of 2-hydroxynapthoquin...
Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191
Graphical Abstract
Figure 1: Some representative molecules having chromene, thiochromene or 1,2-dihydroquinolin structural motif...
Figure 2: Screened chiral proline and its derivatives as organocatalysts. Rb = rubidium.
Figure 3: Screened chiral bifunctional thiourea, its derivatives, cinchona alkaloids and other organocatalyst...
Scheme 1: Diarylprolinolether-catalyzed tandem oxa-Michael–aldol reaction reported by Arvidsson.
Scheme 2: Tandem oxa-Michael–aldol reaction developed by Córdova.
Scheme 3: Domino oxa-Michael-aldol reaction developed by Wei and Wang.
Scheme 4: Chiral amine/chiral acid catalyzed tandem oxa-Michael–aldol reaction developed by Xu et al.
Scheme 5: Modified diarylproline ether as amino catalyst in oxa-Michael–aldol reaction as reported by Xu and ...
Scheme 6: Chiral secondary amine promoted oxa-Michael–aldol cascade reactions as reported by Wang and co-work...
Scheme 7: Reaction of salicyl-N-tosylimine with aldehydes by domino oxa-Michael/aza-Baylis–Hillman reaction, ...
Scheme 8: Silyl prolinol ether-catalyzed oxa-Michael–aldol tandem reaction of alkynals with salicylaldehydes ...
Scheme 9: Oxa-Michael–aldol sequence for the synthesis of tetrahydroxanthones developed by Córdova.
Scheme 10: Synthesis of tetrahydroxanthones developed by Xu.
Scheme 11: Diphenylpyrrolinol trimethylsilyl ether catalyzed oxa-Michael–Michael–Michael–aldol reaction for th...
Scheme 12: Enantioselective cascade oxa-Michael–Michael reaction of alkynals with 2-(E)-(2-nitrovinyl)-phenols...
Scheme 13: Domino oxa-Michael–Michael–Michael–aldol reaction of 2-(2-nitrovinyl)-benzene-1,4-diol with α,β-uns...
Scheme 14: Tandem oxa-Michael–Henry reaction catalyzed by organocatalyst and salicylic acid, as reported by Xu....
Scheme 15: Asymmetric synthesis of nitrochromenes from salicylaldehydes and β-nitrostyrene, as reported by San...
Scheme 16: Domino Michael–aldol reaction between salicyaldehydes with β-nitrostyrene, as reported by Das and c...
Scheme 17: Enantioselective synthesis of 2-aryl-3-nitro-2H-chromenes, as reported by Schreiner.
Scheme 18: (S)-diphenylpyrrolinol silyl ether-promoted cascade thio-Michael–aldol reactions, as reported by Wa...
Scheme 19: Organocatalytic asymmetric domino Michael–aldol condensation of mercaptobenzaldehyde and α,β-unsatu...
Scheme 20: Organocatalytic asymmetric domino Michael–aldol condensation between mercaptobenzaldehyde and α,β-u...
Scheme 21: Hydrogen-bond-mediated Michael–aldol reaction of 2-mercaptobenzaldehyde with α,β-unsaturated oxazol...
Scheme 22: Domino Michael–aldol reaction of 2-mercaptobenzaldehydes with maleimides catalyzed by cinchona alka...
Scheme 23: Domino thio-Michael–aldol reaction between 2-mercaptoacetophenone and enals developed by Córdova an...
Scheme 24: Enantioselective tandem Michael–Henry reaction of 2-mercaptobenzaldehyde with β-nitrostyrenes repor...
Scheme 25: Enantioselective tandem Michael–Knoevenagel reaction between 2-mercaptobenzaldehydes and benzyliden...
Scheme 26: Cinchona alkaloid thiourea catalyzed Michael–Michael cascade reaction, as reported by Wang and co-w...
Scheme 27: Domino aza-Michael–aldol reaction between 2-aminobenzaldehydes and α,β-unsaturated aldehydes, as re...
Scheme 28: (S)-Diphenylprolinol TES ether-promoted aza-Michael–aldol cascade reaction, as developed by Wang’s ...
Scheme 29: Domino aza-Michael–aldol reaction reported by Hamada.
Scheme 30: Organocatalytic asymmetric synthesis of 3-nitro-1,2-dihydroquinolines by a dual activation protocol...
Scheme 31: Asymmetric synthesis of 3-nitro-1,2-dihydroquinolines by cascade aza-Michael–Henry–dehydration reac...
Beilstein J. Org. Chem. 2012, 8, 1630–1636, doi:10.3762/bjoc.8.186
Graphical Abstract
Scheme 1: Conditions for the cyclization of 2’-hydroxycinnamate and related precursors to coumarins. (a) Ther...
Scheme 2: Hypothetical catalytic cycle: Nucleophile-assisted cyclization of (E)-ethyl 2’-hydroxycinnamate (1)...
Scheme 3: Proposed catalytic cycle, based on 31P NMR spectroscopic and color evidence.
Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168
Graphical Abstract
Scheme 1: Synthesis of guanidine-thiourea organocatalyst 7.
Scheme 2: Henry reaction of 3-phenylpropionaldehyde (8) with nitromethane (9).
Scheme 3: Michael addition of (12) and (14) to trans-β-nitrostyrene (11).
Figure 1: Optimized geometries of four conformers of catalyst 7. Energies are in kcal·mol−1, B3PW91/6–31G(d) ...
Scheme 4: Energy profile for the first step of the reaction between catalyst 7 and malonate 14. Energies are ...
Figure 2: Complexes (CatN1–CatN5) between catalyst 7 and nitrostyrene 11. Energies are in kcal·mol−1, B3PW91/...
Scheme 5: Two possible routes for ternary complex formation. Energies are in kcal·mol−1, B3PW91/6–31G(d) (fir...
Figure 3: Geometries of transition states for R and S products. Relative energies (with respect to Init10) ar...
Figure 4: Geometries of transition states for R and S products. Relative energies (with respect to Init10) ar...
Figure 5: B3PW91/6–31G(d) (first entry), DFT-PCM (second entry), MP2/6–31G(d)//B3PW91/6–31G(d) (third entry) ...
Figure 6: Geometries of transition states for R and S products with 7-TABD catalyst. Relative energies (to In...
Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166
Graphical Abstract
Figure 1: Second-order rate constants for reactions of electrophiles with nucleophiles.
Figure 2: Mechanism of amine-catalyzed conjugate additions of nucleophiles [23-28].
Figure 3: Kinetics of the reactions of the iminium ion 3a with the silylated ketene acetal 7a [35].
Figure 4: Laser flash photolytic generation of iminium ions 3a.
Figure 5: Correlations of the reactivities of the iminium ions 3a and 3b toward nucleophiles with the corresp...
Figure 6: Comparison of the electrophilicities of cinnamaldehyde-derived iminium ions 3a–3i.
Figure 7: Nucleophiles used in iminium activated reactions [35,42,44-52].
Figure 8: Counterion effects in electrophilic reactions of iminium ions 3a-X (at 20 °C, silyl ketene acetal 7b...
Figure 9: Comparison of calculated and experimental rate constants of electrophilic aromatic substitutions wi...
Figure 10: Aza-Michael additions of the imidazoles 15 with the iminium ion 3a [58].
Figure 11: Plots of log k2 for the reactions of enamides 17a–17e with the benzhydrylium ions 18a–d in CH3CN at...
Figure 12: Comparison of the nucleophilicities of enamides 17 with those of several other C nucleophiles (solv...
Figure 13: Experimental and calculated rate constants k2 for the reactions of 17b and 17g with 3a and 3b in th...
Figure 14: Comparison between experimental and calculated (Equation 1) cyclopropanation rate constants [64].
Figure 15: Electrostatic activation of iminium activated cyclopropanations with sulfur ylides.
Figure 16: Sulfur ylides inhibit the formation of iminium ions.
Figure 17: Enamine activation [65].
Figure 18: Electrophilicity parameters E for classes of compounds that have been used as electrophilic substra...
Figure 19: Quantification of the nucleophilic reactivities of the enamines 32a–e in acetonitrile (20 °C) [83]; a d...
Figure 20: Proposed transition states for the stereogenic step in proline-catalyzed reactions.
Figure 21: Kinetic evidence for the anchimeric assistance of the electrophilic attack by the carboxylate group....
Figure 22: Differentiation of nucleophilicity and Lewis basicity (in acetonitrile at 20 °C): Rate (left) and e...
Figure 23: NHCs 41, 42, and 43 are moderately active nucleophiles and exceptionally strong Lewis bases (methyl...
Figure 24: Nucleophilic reactivities of the deoxy Breslow intermediates 45 in THF at 20 °C [107].
Figure 25: Comparison of the proton affinities (PA, from [107]) of the diaminoethylenes 47a–c with the methyl catio...
Figure 26: Berkessel’s synthesis of a Breslow intermediate (51, keto tautomer) from carbene 43 [112].
Figure 27: Synthesis of O-methylated Breslow intermediates [114].
Figure 28: Relative reactivities of deoxy- and O-methylated Breslow intermediates [114].
Figure 29: Reactivity scales for electrophiles and nucleophiles relevant for organocatalytic reactions (refere...
Beilstein J. Org. Chem. 2012, 8, 1443–1451, doi:10.3762/bjoc.8.164
Graphical Abstract
Figure 1: General structure of sulfoximines 1 and one of the enantiomers of S-methyl-S-phenylsulfoximine ((S)-...
Figure 2: Structures of chiral mono- and bifunctional (bis-)thioureas that have been used as organocatalysts.
Scheme 1: Synthesis of compound (S)-3.
Scheme 2: Organocatalytic desymmetrization of the cyclic anhydride 4 with (S)-3.
Scheme 3: Attempted synthesis of sulfonimidoyl-substituted thiourea (R)-9.
Scheme 4: Synthesis of the sulfonimidoyl-containing thioureas (S)-12 and (S)-13.
Scheme 5: Syntheses of ethylene-linked sulfonimidoyl-containing thioureas (SS,SC)-18 and (RS,SC)-19.
Beilstein J. Org. Chem. 2012, 8, 534–538, doi:10.3762/bjoc.8.61
Graphical Abstract
Scheme 1: Michael addition under catalyst- and solvent-free conditions.
Figure 1: The grinding effect of different grinding aids. Conditions: β-nitrostyrene (14.9 mg, 0.1 mmol), 1,3...
Figure 2: Yields of the model reaction in different solvents. Conditions: β-nitrostyrene (14.9 mg, 0.1 mmol),...
Figure 3: The effect of the amount of quartz sand on the yield. Conditions: β-nitrostyrene (14.9 mg, 0.1 mmol...
Beilstein J. Org. Chem. 2012, 8, 379–389, doi:10.3762/bjoc.8.41
Graphical Abstract
Figure 1: Structure and atomic numbering of 2,2’:6’,2’’-terpyridines.
Scheme 1: Synthesis of furanyl-substituted terpyridines 12–14 by using Kröhnke’s method.
Scheme 2: Synthesis of terpyridines under solvent-free conditions.
Scheme 3: Preparation of 4,4′,4′′-trisubstituted terpyridine containing carboxylate moieties.
Scheme 4: Synthetic pathway for the preparation of a furanyl-functionalised quinquepyridine.
Scheme 5: Utilization of an iminium salt in the preparation of a furanyl-substituted tpy.
Figure 2: Chemical structure of U- and S-shaped isomers.
Scheme 6: Preparation of an asymmetric furanyl-substituted terpyridine.
Scheme 7: Synthesis of tpy by Stille cross-coupling reaction.
Scheme 8: Oxidation of the furan ring of furanyl-substituted terpyridines.
Scheme 9: Direct oxidation of a furan ring attached on Ru(II) tpy complexes.
Figure 3: Example of polyoxometalate frameworks functionalised with tpy ligands and tpy-complex (reprinted wi...
Scheme 10: Synthetic pathway to europium(III) and samarium(III) chelates 56 and 57.
Scheme 11: Synthetic pathway to prepare thiocyanato-functionalised tpys as potential biomolecule-labelling age...
Scheme 12: Synthetic sequence envisioned for biomolecules labelling by click-chemistry.
Figure 4: Structure of pyrrolyl (66), thienyl (67) and bithienyl (68)-substituted complexes analogous to comp...