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Search for "sulfuric acid" in Full Text gives 186 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction
- Nadezhda S. Demina,
- Nikita A. Kazin,
- Nikolay A. Rasputin,
- Roman A. Irgashev and
- Gennady L. Rusinov
Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261
- yields of products 4 because of their partial degradation. Therefore, to neutralize the reaction mixtures, we used one equivalent of sulfuric acid relative to the alkali salt used for saponification. The resulting precipitates were then isolated by filtration, and thoroughly washed with water. As a
Graphical Abstract
Figure 1: An example of an earlier developed S,N-heterohexacene [13] and general structure of compounds synthesiz...
Scheme 1: Synthesis of aryl-substituted TT derivatives 3a–k, product scope, and yields.
Scheme 2: Synthesis of thieno[3,2-b]thiophen-3(2H)-one 4a–k, product scope, and yields.
Scheme 3: Synthesis of TTI derivatives 6a–o, substrate and product scopes, and yields.
Scheme 4: Alkylation of TTI 6d.
Figure 2: ORTEP diagram for the X-ray structure of compound 7d. Thermal ellipsoids of 50% probability are sho...
Unexpected one-pot formation of the 1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene system from cyclopentanone, ammonia and dimethyl fumarate. Synthesis of highly strained polycyclic nitroxide and EPR study
- Sergey A. Dobrynin,
- Igor A. Kirilyuk,
- Yuri V. Gatilov,
- Andrey A. Kuzhelev,
- Olesya A. Krumkacheva,
- Matvey V. Fedin,
- Michael K. Bowman and
- Elena G. Bagryanskaya
Beilstein J. Org. Chem. 2019, 15, 2664–2670, doi:10.3762/bjoc.15.259
- and ammonium acetate was refluxed in benzene in a Dean–Stark apparatus. The reaction mixture underwent a strong tarring and after standard extraction with aqueous sulfuric acid, the main product 1 was isolated in a low yield (ca. 5%, see Scheme 1). In another experiment a much higher yield was
- solution and then extracted with 5% sulfuric acid. Acidic extracts were basified with Na2CO3 and extracted with ethyl acetate. The extract was dried with Na2CO3 and the solvent was distilled off in vacuum to give a dark oil, which was purified using column chromatography on silica gel (hexane/ethyl acetate
Graphical Abstract
Scheme 1: Synthesis of compound 1.
Figure 1: X-ray structure of compound 1 (one of the two enantiomers present in the crystal).
Scheme 2: Possible mechanism for the formation of 1.
Figure 2: A possible mechanism for the trans-position of the methyne hydrogens in the azepine ring: the elect...
Figure 3: Selective formation of a single diastereomer in the 1,3-dipolar cycloaddition reaction.
Scheme 3: Synthesis of nitroxide 6.
Figure 4: X-ray structure of compound 6 (one of the two enantiomers present in the crystal).
Scheme 4: A proposed mechanism for nitroxide 6 synthesis.
Figure 5: A, B) Temperature dependence of the electron spin relaxation times in water/glycerol at X-band freq...
Synthetic terpenoids in the world of fragrances: Iso E Super® is the showcase
- Alexey Stepanyuk and
- Andreas Kirschning
Beilstein J. Org. Chem. 2019, 15, 2590–2602, doi:10.3762/bjoc.15.252
- the glassware with sulfuric acid, a distinctive scent of violets was noted which later was linked to ionone (30) being created in the acidic medium. Thus, the category of synthetic ionone (30) and woody smelling compounds was born in 1893 and investigated further in the following years [10][11][12][13
Graphical Abstract
Figure 1: Terpene constituents 1–9 found in geranium and bergamot oils and specified odours of individual com...
Figure 2: Other selected mono- and sesquiterpenes (10–26) as fragrance materials [6].
Figure 3: Main constituents of natural iris oil: irone (27).
Scheme 1: First synthesis of ionone (30) [11].
Scheme 2: First synthesis of Ambrelux (32) [14].
Scheme 3: Industrial synthesis of myrcene (1) by pyrolysis of β-pinene (8).
Scheme 4: First synthesis of Iso E Super® (33), Iso E Super Plus® (34) and Georgywood® (35) as a mixture of i...
Figure 4: Iso E Super® region of GC spectra of Molecule 01 (left, 75 €–100 € per 100 mL; march 2019), a low-p...
Scheme 5: First synthetic route to (−)-Georgywood® (35) by Corey and Hong [33].
Scheme 6: First synthetic route to the odour-active (+)-enantiomer of Iso E Super Plus® (+)-34 [33].
Scheme 7: Analysis of the isomerisation process and formation of products. Most importantly, Iso E Super® (33...
Scheme 8: Isomerisation using additives such as alcohols or carboxylic acids. The product with the γ-position...
Scheme 9: Iso E Super Plus® (34) can undergo a third cyclisation to tetrahydrofuran 59 through compound rac-53...
Figure 5: (Adapted from ref. [8]) Ionone (30, 1893, odour threshold: 0.8 ng L−1), koavone (1982, odour threshold...
Figure 6: Branched, terpene-like cyclohexene derivatives, that are synthetic fragrance components: 60: Iso da...
Scheme 10: New unnatural terpenoid 70 from unnatural farnesyl pyrophosphate derivative 69 and comparison with ...
Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene
- Anna Kmieciak and
- Marek P. Krzemiński
Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242
- sulfuric acid under biphasic conditions. (−)-Isopinocamphone (8) was purified by fractional distillation and isolated in 78% yield. Then, 8 was subjected to an analogous reaction sequence that was used for (+)-verbanone (3), i.e., the synthesis of the enone in the first step followed by its 1,2-reduction
Graphical Abstract
Scheme 1: Synthesis of (1R,2R,4S,5R)-3-methyleneneoisoverbanol (6).
Scheme 2: Synthesis of (1R,2R,3R,5R)-4-methyleneneoisopinocampheol (11).
Scheme 3: Synthesis of allylic alcohols 16 and 18 from β-pinene.
Figure 1: NOE effects in molecules 16 and 18.
Scheme 4: Synthesis of (1R,2R,3R,4R,5R)-3-((diphenylphosphanyl)methyl)isoverbanol (23).
Scheme 5: Synthesis of (((1R,2R,3S,4S,5S)-3-hydroxypinan-4-yl)methyl)diphenylphosphine oxide (27).
Scheme 6: Attempted sigmatropic rearrangement of phosphinites 28 and 29.
Effect of ring size on photoisomerization properties of stiff stilbene macrocycles
- Sandra Olsson,
- Óscar Benito Pérez,
- Magnus Blom and
- Adolf Gogoll
Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233
- precoated silica gel 60 F254 plates, visualized with UV light and Hannessian's stain (5% ammonium molybdate, 1% cerium sulfate and 10% sulfuric acid in water). Flash chromatography (CC) was performed over Matrex silica gel (60 Å, 35–70 µm) on a regular column or on a Grace Reveleris X2 Flash chromatography
Graphical Abstract
Scheme 1: The stiff stilbene photoisomerization from Z to E and vice versa by irradiation at 300 nm and 360 n...
Figure 1: The investigated SS-macrocycles (Z)-1a–d.
Scheme 2: Synthetic route to SS-macrocycles. i. (1) Triflic acid (3 equiv), DCM (dry), Ar atmosphere, MW (110...
Scheme 3: The photoisomerization of the stiff stilbene macrocycles, showing the stretching of the linker (gre...
Scheme 4: Noncyclic stiff stilbene diester 7 used as reference in the photoisomerization study.
Figure 2: The photoisomerization of the SS-macrocycles shows a clear correlation between the Z/E ratio in the...
Figure 3: Gibbs free energy differences (ΔG) between Z- and E-isomers of 1a–d and of the reference compound 7...
Figure 4: Ring strain for E and Z-isomers of 1a–d expressed as the Gibbs free energy difference to an acyclic...
Figure 5: The differences in ring strain between the E- and Z-isomers show an exponential correlation to the ...
Figure 6: Conformer ensembles for the macrocyclic stiff stilbene diethers 1a–d. Dihedral angles between the t...
Figure 7: Distances derived from NOE buildup experiments. Distances between pairs of protons or groups of pro...
Figure 8: Numbering of carbons in compounds 6a–d, showing 6d as an example.
Figure 9: Numbering of carbons in compounds (Z)-1a–d, showing (Z)-1d as an example.
Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms
- A. Lennart Schleper,
- Mariano L. Bossi,
- Vladimir N. Belov and
- Stefan W. Hell
Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227
- good yields by treatment of 3 with elemental iodine and periodic acid in aqueous acetic acid with addition of sulfuric acid, and by treatment of 6 with elemental iodine and periodic acid in concentrated sulfuric acid, respectively. The conditions for monoiodination of 6 have been published recently [5
- ligands. The reaction with pinacolborane (HB(pin)) gave ester 9 in 97% yield [11]. Another ester (10) was synthesized by bromination of 3-thiopheneacetic acid with NBS (applying an ultrasound bath) followed by esterification of the crude product with methanol in the presence of sulfuric acid [12]. Other
Graphical Abstract
Figure 1: Structures of “thiophenylated” DAEs prepared and studied in this work.
Scheme 1: Synthesis routes towards mono- and diiodinated core structures 4, 5, 7, and 8.
Scheme 2: Synthesis of thiophene- and bithiopheneboronic esters 9 and 12 (bpy – 4,4’-di-tert-butyl-2,2’-dipyr...
Scheme 3: Photoswitchable diarylethenes AsTh1, SyTh1, AsTh2, SyTh2, AsOTh1, SyOTh1, AsOTh2, and SyOTh2 synthe...
Scheme 4: Saponification of methyl ester groups in tetraester SyTh2 leading to tetracarboxylic acid SyTh2-H.
Figure 2: Absorption (A) and emission (B) spectra of SyTh2 in acetonitrile in the course of the cyclization r...
Figure 3: Absorption spectra of the OFs (A) and CFs (B) of AsTh1 (a), SyTh1 (b), AsTh2 (c), SyTh2 (d), AsOTh1...
Figure 4: Solutions of compounds AsTh1 (a), SyTh1 (b), AsTh2 (c), SyTh2 (d), AsOTh1 (e), SyOTh1 (f), AsOTh2 (...
Figure 5: Fatigue resistances of compounds SyOTh1 (A and B) and SyTh1 (C). Parts A and C show the absorbance ...
Figure 6: (A) Absorption spectra of compound SyOTh1 in MeCN at the photostationary states under irradiation w...
Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors
- Christoph W. Grathwol,
- Nathalie Wössner,
- Sören Swyter,
- Adam C. Smith,
- Enrico Tapavicza,
- Robert K. Hofstetter,
- Anja Bodtke,
- Manfred Jung and
- Andreas Link
Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214
- EtOH and 16 mL water) or vanillin/sulfuric acid (3.0 g vanillin and 0.5 mL H2SO4 in 100 mL EtOH) reagent. Synthesis was additionally monitored using high speed SFC/MS runs performed by a Nexera SFE-SFC/UHPLC switching system (Shimadzu Corporation, Kyoto, Japan) consisting of a pumping system (one LC
Graphical Abstract
Figure 1: Selisistat (1) and hit compound GW435821X (2a).
Scheme 1: Reagents and conditions: a) appropriate boronic acid, Pd(PPh3)4, Na2CO3, DMF, H2O, microwave, 15 mi...
Scheme 2: Reagents and conditions: a) Pd2(dba)3 or Pd(OAc)2, P(o-tol)3, TEA, DMF, 120–140 °C, 0.7–24 h, 11–75...
Figure 2: (Left) UV–vis spectrum of 2b 50 µM in 5% DMSO (v/v) in assay buffer after varying durations of irra...
Figure 3: (Left) LC chromatogram of the LC–HRMS analysis of 2b after varying durations of irradiation with 25...
Scheme 3: Photocyclization and oxidation reaction of 2b upon UV irradiation.
Figure 4: Calculated and experimental absorption spectra of compounds (E)-2b-B (A), (Z)-2b-A (B), and product...
Scheme 4: Reagents and conditions: a) 4-fluoroaniline, oxone, HAc, 60 °C, 14 d, 42%; b) NH3, MeOH, rt, 3 d, 9...
Figure 5: (Left) UV–vis spectrum of 11, 50 µM in 5% DMSO (v/v), in assay buffer at the thermal equilibrium an...
Characterization of two new degradation products of atorvastatin calcium formed upon treatment with strong acids
- Jürgen Krauß,
- Monika Klimt,
- Markus Luber,
- Peter Mayer and
- Franz Bracher
Beilstein J. Org. Chem. 2019, 15, 2085–2091, doi:10.3762/bjoc.15.206
- structures of the degradation products. Here we report the identification of two novel degradation products of atorvastatin, which are formed only under drastic acidic conditions. While treatment with conc. sulfuric acid led to a loss of the carboxanilide residue (accompanied by an expectable lactonization
- (see Figure 2 and Supporting Information File 1) disclosed the structure of 6, bearing a novel, bridged tricyclic 1,5-methanopyrrolo[1,2-e][1,5]oxazonin-3-one ring system (Scheme 1). In contrast, submission of atorvastatin calcium trihydrate (1) to concentrated sulfuric acid for two hours at 60 °C
- concentrated sulfuric acid, lactonization/dehydration is accompanied by complete loss of the carboxanilide residue to give pyrrole 7. Complete one-step removal of carboxamide residues from aromatic rings has been observed before in investigations of fragmentations of protonated species in mass spectrometry [21
Graphical Abstract
Figure 1: Atorvastatin calcium trihydrate (1) and previously published decomposition products arising from tr...
Scheme 1: Formation of novel artefacts 6 and 7 under extremely strong acidic conditions.
Figure 2: Top: Molecular structure of artefact 6. Shown here is the molecular structure of one of three indep...
Figure 3: Separation of atorvastatin (1; retention time: 5.8 min) from the four decomposition products 2 (ret...
Scheme 2: Proposed mechanism for the formation of desamidated product 7.
Scheme 3: Proposed mechanism for the formation of bridged product 6 under cyclization, isopropyl migration an...
Naphthalene diimides with improved solubility for visible light photoredox catalysis
- Barbara Reiß and
- Hans-Achim Wagenknecht
Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201
- NDI 1 in 90% yield (Scheme 1) [54]. The synthetic module for cNDIs with two substituents at the core is the 2,6-dibromo anhydride derivative 8 that can be synthesized from 7 by elementary bromine, dibromoisocyanuric acid, or 1,3-dibromo-5,5-dimethylhydantoine (DBH) in concentrated sulfuric acid, or
Graphical Abstract
Scheme 1: Synthesis of reference NDI 1 and cNDIs 2–6; bottom: image of saturated solutions of cNDIs 2–6 in DM...
Figure 1: Optical properties of NDI 1 and cNDIs 2 and 6: UV–vis absorbance in CH2Cl2 and in DMF (normal lines...
Scheme 2: Photocatalytic α-alkylation of octanal (12): 500 mM 12, 250 mM 13, 50 mM (20 mol %) organocatalyst ...
Figure 2: Normalized absorbance of cNDI 6 in comparison to normalized emission of the 468 nm, 520 nm, 597 nm,...
Figure 3: Kinetic analysis of yields of product 14 in the presence (solid lines) and in the absence (dashed l...
Attempted synthesis of a meta-metalated calix[4]arene
- Christopher D. Jurisch and
- Gareth E. Arnott
Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195
- tetrapropoxycalix[4]arene 8, which used a combination of nitric acid and acetic acid, proved inconsistent in our hands (see Supporting Information File 1 for more details). We therefore conducted a careful study to optimize the reaction using a more traditional combination of nitric acid and sulfuric acid (Table 1
- ). A solution of tetrapropoxycalix[4]arene 8 in DCM was stirred at 0 °C and treated with nitric acid (70%) and concentrated sulfuric acid; after 300 min the solution had reached 18 °C, at which point the reaction was diluted with water and extracted into methylene chloride. Purification via silica gel
- generated separately, using sulfuric acid and sodium nitrite, prior to being added to the monoaminocalix[4]arene 10 at 0 °C. After diazotization (15 min), an aqueous solution of sodium azide was added dropwise. After two hours at 0 °C the reaction was extracted with ethyl acetate, and the monoazidocalix[4
Graphical Abstract
Figure 1: Inherent chirality generated by meta-substitution – the two structures are non-superposable mirror ...
Figure 2: General approach by Albrecht for MIC directed cyclometalation via C–H activation; M = Ru(II), Ir(II...
Figure 3: Concept of cyclometalated calix[4]arene target.
Scheme 1: Synthesis of model mesoionic carbene 5.
Scheme 2: Attempted Ullmann-coupling to give monoazide 7.
Scheme 3: Synthesis of monoazidocalix[4]arene 7 under optimized conditions.
Scheme 4: Synthesis of the putative calix[4]arene mesoionic carbene ruthenium complex 13.
Figure 4: High-resolution mass spectrum (ESI+) of putative ruthenacycle calix[4]arene 13.
Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF3SO3H. NMR and DFT studies of dicationic electrophilic species
- Dmitry S. Ryabukhin,
- Alexey N. Turdakov,
- Natalia S. Soldatova,
- Mikhail O. Kompanets,
- Alexander Yu. Ivanov,
- Irina A. Boyarskaya and
- Aleksander V. Vasilyev
Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191
- of 1 and give rise to the corresponding 2-diarylmethylbenzimidazoles 9a–l. The best results were obtained in neat TfOH, which gave high yields of reaction products (54–86%) at room temperature after 2–3 h. Other acids were not so efficient. Thus, reactions under the action of sulfuric acid H2SO4 or
Graphical Abstract
Figure 1: Examples of some commercially available pharmaceuticals and agrochemicals containing the benzimidaz...
Figure 2: Formation of cationic species by protonation of 5-formyl-4-methylimidazole in TfOH and their reacti...
Figure 3: Benzimidazoles 1–8 used in this study.
Scheme 1: Reaction of 2-acetylbenzimidazole (2) with TfOH and benzene.
Scheme 2: Reactions of hydroxymethyl-substituted benzimidazole 7 and 8 with TfOH and benzene.
Scheme 3: Reaction mechanism of the formation of compounds 9–11.
Scheme 4: Reaction mechanism of the formation of compounds 12.
Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage
- Gagandeep Kour Reen,
- Ashok Kumar and
- Pratibha Sharma
Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165
Graphical Abstract
Figure 1: Various drugs having IP nucleus.
Figure 2: Participation percentage of various TMs for the syntheses of IPs.
Scheme 1: CuI–NaHSO4·SiO2-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 2: Experimental examination of reaction conditions.
Scheme 3: One-pot tandem reaction for the synthesis of 2-haloimidazopyridines.
Scheme 4: Mechanistic scheme for the synthesis of 2-haloimidazopyridine.
Scheme 5: Copper-MOF-catalyzed three-component reaction (3-CR) for imidazo[1,2-a]pyridines.
Scheme 6: Mechanism for copper-MOF-driven synthesis.
Scheme 7: Heterogeneous synthesis via titania-supported CuCl2.
Scheme 8: Mechanism involving oxidative C–H functionalization.
Scheme 9: Heterogeneous synthesis of IPs.
Scheme 10: One-pot regiospecific synthesis of imidazo[1,2-a]pyridines.
Scheme 11: Vinyl azide as an unprecedented substrate for imidazo[1,2-a]pyridines.
Scheme 12: Radical pathway.
Scheme 13: Cu(I)-catalyzed transannulation approach for imidazo[1,5-a]pyridines.
Scheme 14: Plausible radical pathway for the synthesis of imidazo[1,5-a]pyridines.
Scheme 15: A solvent-free domino reaction for imidazo[1,2-a]pyridines.
Scheme 16: Cu-NPs-mediated synthesis of imidazo[1,2-a]pyridines.
Scheme 17: CuI-catalyzed synthesis of isoxazolylimidazo[1,2-a]pyridines.
Scheme 18: Functionalization of 4-bromo derivative via Sonogashira coupling reaction.
Scheme 19: A plausible reaction pathway.
Scheme 20: Cu(I)-catalyzed intramolecular oxidative C–H amidation reaction.
Scheme 21: One-pot synthetic reaction for imidazo[1,2-a]pyridine.
Scheme 22: Plausible reaction mechanism.
Scheme 23: Cu(OAc)2-promoted synthesis of imidazo[1,2-a]pyridines.
Scheme 24: Mechanism for aminomethylation/cycloisomerization of propiolates with imines.
Scheme 25: Three-component synthesis of imidazo[1,2-a]pyridines.
Figure 3: Scope of pyridin-2(1H)-ones and acetophenones.
Scheme 26: CuO NPS-promoted A3 coupling reaction.
Scheme 27: Cu(II)-catalyzed C–N bond formation reaction.
Scheme 28: Mechanism involving Chan–Lam/Ullmann coupling.
Scheme 29: Synthesis of formyl-substituted imidazo[1,2-a]pyridines.
Scheme 30: A tandem sp3 C–H amination reaction.
Scheme 31: Probable mechanistic approach.
Scheme 32: Dual catalytic system for imidazo[1,2-a]pyridines.
Scheme 33: Tentative mechanism.
Scheme 34: CuO/CuAl2O4/ᴅ-glucose-promoted 3-CCR.
Scheme 35: A tandem CuOx/OMS-2-based synthetic strategy.
Figure 4: Biomimetic catalytic oxidation in the presence of electron-transfer mediators (ETMs).
Scheme 36: Control experiment.
Scheme 37: Copper-catalyzed C(sp3)–H aminatin reaction.
Scheme 38: Reaction of secondary amines.
Scheme 39: Probable mechanistic pathway.
Scheme 40: Coupling reaction of α-azidoketones.
Scheme 41: Probable pathway.
Scheme 42: Probable mechanism with free energy calculations.
Scheme 43: MCR for cyanated IP synthesis.
Scheme 44: Substrate scope for the reaction.
Scheme 45: Reaction mechanism.
Scheme 46: Probable mechanistic pathway for Cu/ZnAl2O4-catalyzed reaction.
Scheme 47: Copper-catalyzed double oxidative C–H amination reaction.
Scheme 48: Application towards different coupling reactions.
Scheme 49: Reaction mechanism.
Scheme 50: Condensation–cyclization approach for the synthesis of 1,3-diarylated imidazo[1,5-a]pyridines.
Scheme 51: Optimized reaction conditions.
Scheme 52: One-pot 2-CR.
Scheme 53: One-pot 3-CR without the isolation of chalcone.
Scheme 54: Copper–Pybox-catalyzed cyclization reaction.
Scheme 55: Mechanistic pathway catalyzed by Cu–Pybox complex.
Scheme 56: Cu(II)-promoted C(sp3)-H amination reaction.
Scheme 57: Wider substrate applicability for the reaction.
Scheme 58: Plausible reaction mechanism.
Scheme 59: CuI assisted C–N cross-coupling reaction.
Scheme 60: Probable reaction mechanism involving sp3 C–H amination.
Scheme 61: One-pot MCR-catalyzed by CoFe2O4/CNT-Cu.
Scheme 62: Mechanistic pathway.
Scheme 63: Synthetic scheme for 3-nitroimidazo[1,2-a]pyridines.
Scheme 64: Plausible mechanism for CuBr-catalyzed reaction.
Scheme 65: Regioselective synthesis of halo-substituted imidazo[1,2-a]pyridines.
Scheme 66: Synthesis of 2-phenylimidazo[1,2-a]pyridines.
Scheme 67: Synthesis of diarylated compounds.
Scheme 68: CuBr2-mediated one-pot two-component oxidative coupling reaction.
Scheme 69: Decarboxylative cyclization route to synthesize 1,3-diarylimidazo[1,5-a]pyridines.
Scheme 70: Mechanistic pathway.
Scheme 71: C–H functionalization reaction of enamines to produce diversified heterocycles.
Scheme 72: A plausible mechanism.
Scheme 73: CuI-promoted aerobic oxidative cyclization reaction of ketoxime acetates and pyridines.
Scheme 74: CuI-catalyzed pathway for the formation of imidazo[1,2-a]pyridine.
Scheme 75: Mechanistic pathway.
Scheme 76: Mechanistic rationale for the synthesis of products.
Scheme 77: Copper-catalyzed synthesis of vinyloxy-IP.
Scheme 78: Regioselective product formation with propiolates.
Scheme 79: Proposed mechanism for vinyloxy-IP formation.
Scheme 80: Regioselective synthesis of 3-hetero-substituted imidazo[1,2-a]pyridines with different reaction su...
Scheme 81: Mechanistic pathway.
Scheme 82: CuI-mediated synthesis of 3-formylimidazo[1,2-a]pyridines.
Scheme 83: Radical pathway for 3-formylated IP synthesis.
Scheme 84: Pd-catalyzed urea-cyclization reaction for IPs.
Scheme 85: Pd-catalyzed one-pot-tandem amination and intramolecular amidation reaction.
Figure 5: Scope of aniline nucleophiles.
Scheme 86: Pd–Cu-catalyzed Sonogashira coupling reaction.
Scheme 87: One-pot amide coupling reaction for the synthesis of imidazo[4,5-b]pyridines.
Scheme 88: Urea cyclization reaction for the synthesis of two series of pyridines.
Scheme 89: Amidation reaction for the synthesis of imidazo[4,5-b]pyridines.
Figure 6: Amide scope.
Scheme 90: Pd NPs-catalyzed 3-component reaction for the synthesis of 2,3-diarylated IPs.
Scheme 91: Plausible mechanistic pathway for Pd NPs-catalyzed MCR.
Scheme 92: Synthesis of chromenoannulated imidazo[1,2-a]pyridines.
Scheme 93: Mechanism for the synthesis of chromeno-annulated IPs.
Scheme 94: Zinc oxide NRs-catalyzed synthesis of imidazo[1,2-a]azines/diazines.
Scheme 95: Zinc oxide-catalyzed isocyanide based GBB reaction.
Scheme 96: Reaction pathway for ZnO-catalyzed GBB reaction.
Scheme 97: Mechanistic pathway.
Scheme 98: ZnO NRs-catalyzed MCR for the synthesis of imidazo[1,2-a]azines.
Scheme 99: Ugi type GBB three-component reaction.
Scheme 100: Magnetic NPs-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 101: Regioselective synthesis of 2-alkoxyimidazo[1,2-a]pyridines catalyzed by Fe-SBA-15.
Scheme 102: Plausible mechanistic pathway for the synthesis of 2-alkoxyimidazopyridine.
Scheme 103: Iron-catalyzed synthetic approach.
Scheme 104: Iron-catalyzed aminooxygenation reaction.
Scheme 105: Mechanistic pathway.
Scheme 106: Rh(III)-catalyzed double C–H activation of 2-substituted imidazoles and alkynes.
Scheme 107: Plausible reaction mechanism.
Scheme 108: Rh(III)-catalyzed non-aromatic C(sp2)–H bond activation–functionalization for the synthesis of imid...
Scheme 109: Reactivity and selectivity of different substrates.
Scheme 110: Rh-catalyzed direct C–H alkynylation by Li et al.
Scheme 111: Suggested radical mechanism.
Scheme 112: Scandium(III)triflate-catalyzed one-pot reaction and its mechanism for the synthesis of benzimidazo...
Scheme 113: RuCl3-assisted Ugi-type Groebke–Blackburn condensation reaction.
Scheme 114: C-3 aroylation via Ru-catalyzed two-component reaction.
Scheme 115: Regioselective synthetic mechanism.
Scheme 116: La(III)-catalyzed one-pot GBB reaction.
Scheme 117: Mechanistic approach for the synthesis of imidazo[1,2-a]pyridines.
Scheme 118: Synthesis of imidazo[1,2-a]pyridine using LaMnO3 NPs under neat conditions.
Scheme 119: Mechanistic approach.
Scheme 120: One-pot 3-CR for regioselective synthesis of 2-alkoxy-3-arylimidazo[1,2-a]pyridines.
Scheme 121: Formation of two possible products under optimization of the catalysts.
Scheme 122: Mechanistic strategy for NiFe2O4-catalyzed reaction.
Scheme 123: Two-component reaction for synthesizing imidazodipyridiniums.
Scheme 124: Mechanistic scheme for the synthesis of imidazodipyridiniums.
Scheme 125: CuI-catalyzed arylation of imidazo[1,2-a]pyridines.
Scheme 126: Mechanism for arylation reaction.
Scheme 127: Cupric acetate-catalyzed double carbonylation approach.
Scheme 128: Radical mechanism for double carbonylation of IP.
Scheme 129: C–S bond formation reaction catalyzed by cupric acetate.
Scheme 130: Cupric acetate-catalyzed C-3 formylation approach.
Scheme 131: Control experiments for signifying the role of DMSO and oxygen.
Scheme 132: Mechanism pathway.
Scheme 133: Copper bromide-catalyzed CDC reaction.
Scheme 134: Extension of the substrate scope.
Scheme 135: Plausible radical pathway.
Scheme 136: Transannulation reaction for the synthesis of imidazo[1,5-a]pyridines.
Scheme 137: Plausible reaction pathway for denitrogenative transannulation.
Scheme 138: Cupric acetate-catalyzed C-3 carbonylation reaction.
Scheme 139: Plausible mechanism for regioselective C-3 carbonylation.
Scheme 140: Alkynylation reaction at C-2 of 3H-imidazo[4,5-b]pyridines.
Scheme 141: Two-way mechanism for C-2 alkynylation of 3H-imidazo[4,5-b]pyridines.
Scheme 142: Palladium-catalyzed SCCR approach.
Scheme 143: Palladium-catalyzed Suzuki coupling reaction.
Scheme 144: Reaction mechanism.
Scheme 145: A phosphine free palladium-catalyzed synthesis of C-3 arylated imidazopyridines.
Scheme 146: Palladium-mediated Buchwald–Hartwig cross-coupling reaction.
Figure 7: Structure of the ligands optimized.
Scheme 147: Palladium acetate-catalyzed direct arylation of imidazo[1,2-a]pyridines.
Scheme 148: Palladium acetate-catalyzed mechanistic pathway.
Scheme 149: Palladium acetate-catalyzed regioselective arylation reported by Liu and Zhan.
Scheme 150: Mechanism for selective C-3 arylation of IP.
Scheme 151: Pd(II)-catalyzed alkenylation reaction with styrenes.
Scheme 152: Pd(II)-catalyzed alkenylation reaction with acrylates.
Scheme 153: A two way mechanism.
Scheme 154: Double C–H activation reaction catalyzed by Pd(OAc)2.
Scheme 155: Probable mechanism.
Scheme 156: Palladium-catalyzed decarboxylative coupling.
Scheme 157: Mechanistic cycle for decarboxylative arylation reaction.
Scheme 158: Ligand-free approach for arylation of imidazo[1,2-a]pyridine-3-carboxylic acids.
Scheme 159: Mechanism for ligandless arylation reaction.
Scheme 160: NHC-Pd(II) complex assisted arylation reaction.
Scheme 161: C-3 arylation of imidazo[1,2-a]pyridines with aryl bromides catalyzed by Pd(OAc)2.
Scheme 162: Pd(II)-catalyzed C-3 arylations with aryl tosylates and mesylates.
Scheme 163: CDC reaction for the synthesis of imidazo[1,2-a]pyridines.
Scheme 164: Plausible reaction mechanism for Pd(OAc)2-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 165: Pd-catalyzed C–H amination reaction.
Scheme 166: Mechanism for C–H amination reaction.
Scheme 167: One-pot synthesis for 3,6-di- or 2,3,6-tri(hetero)arylimidazo[1,2-a]pyridines.
Scheme 168: C–H/C–H cross-coupling reaction of IPs and azoles catalyzed by Pd(II).
Scheme 169: Mechanistic cycle.
Scheme 170: Rh-catalyzed C–H arylation reaction.
Scheme 171: Mechanistic pathway for C–H arylation of imidazo[1,2-a]pyridine.
Scheme 172: Rh(III)-catalyzed double C–H activation of 2-phenylimidazo[1,2-a]pyridines and alkynes.
Scheme 173: Rh(III)-catalyzed mechanistic pathway.
Scheme 174: Rh(III)-mediated oxidative coupling reaction.
Scheme 175: Reactions showing functionalization of the product obtained by the group of Kotla.
Scheme 176: Mechanism for Rh(III)-catalyzed oxidative coupling reaction.
Scheme 177: Rh(III)-catalyzed C–H activation reaction.
Scheme 178: Mechanistic cycle.
Scheme 179: Annulation reactions of 2-arylimidazo[1,2-a]pyridines and alkynes.
Scheme 180: Two-way reaction mechanism for annulations reaction.
Scheme 181: [RuCl2(p-cymene)]2-catalyzed C–C bond formation reaction.
Scheme 182: Reported reaction mechanism.
Scheme 183: Fe(III) catalyzed C-3 formylation approach.
Scheme 184: SET mechanism-catalyzed by Fe(III).
Scheme 185: Ni(dpp)Cl2-catalyzed KTC coupling.
Scheme 186: Pd-catalyzed SM coupling.
Scheme 187: Vanadium-catalyzed coupling of IP and NMO.
Scheme 188: Mechanistic cycle.
Scheme 189: Selective C3/C5–H bond functionalizations by mono and bimetallic systems.
Scheme 190: rGO-Ni@Pd-catalyzed C–H bond arylation of imidazo[1,2-a]pyridine.
Scheme 191: Mechanistic pathway for heterogeneously catalyzed arylation reaction.
Scheme 192: Zinc triflate-catalyzed coupling reaction of substituted propargyl alcohols.
Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks
- Sebastian Hamer,
- Fynn Röhricht,
- Marius Jakoby,
- Ian A. Howard,
- Xianghui Zhang,
- Christian Näther and
- Rainer Herges
Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132
- dibromoisocyanuric acid in fuming sulfuric acid [59]. Subsequent Stille cross coupling (to avoid phthalocyanine formation) using conditions established in the synthesis of linker 3 gave the bis(trimethylsilylethynyl) compounds 15a and 15b in nearly quantitative yields. Analogously to the above-described systems
Graphical Abstract
Figure 1: Interactions of a pair of dipolar rotors in different orientations. The axes of the rotors are para...
Figure 2: Structures of molecular dipolar rotors/linker molecules 1–5.
Scheme 1: General synthetic strategy to prepare the dipolar rotors 1–5.
Scheme 2: Synthesis of 3,3'-(2,3-difluoro-1,4-phenylene)dipropiolic acid (1) starting with diiodination of 1,...
Scheme 3: Synthesis of 3,3'-(5,6-Difluoro-2,1,3-benzothiadiazol-4,7-diyl)dipropiolic acid (2) and 3,3'-(5,6-D...
Scheme 4: Synthesis of 3,3'-(5,6-dicyano-1,3-benzodioxole-4,7-diyl)dipropiolic acid (4) and 3,3'-(6,7-dicyano...
Steroid diversification by multicomponent reactions
- Leslie Reguera,
- Cecilia I. Attorresi,
- Javier A. Ramírez and
- Daniel G. Rivera
Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121
- strong oxidizing Jones reagent, because the oxidizing power of sulfuric acid was not enough to achieve oxidation. Interestingly, the use of microwave irradiation instead of classic heating allowed obtaining the Biginelli product in only 10 min, instead of 12 h as required for the synthesis of pyrimidines
Graphical Abstract
Figure 1: Structures of natural steroids of A) animal and B) plant origin.
Scheme 1: Synthesis of a steroidal β-lactam by Ugi reaction of a cholanic aldehyde [14].
Scheme 2: Synthetic route to steroidal 2,5-diketopiperazines based on a diastereoselective Ugi-4CR with an an...
Scheme 3: Multicomponent synthesis of a heterocycle–steroid hybrid using a ketosteroid as carbonyl component [18]....
Scheme 4: Synthesis of peptidomimetic–steroid hybrids using the Ugi-4CR with spirostanic amines and carboxyli...
Scheme 5: Synthesis of azasteroids using the Ugi-4CR with androstanic and pregnanic carboxylic acids [22].
Figure 2: Ugi-4CR-derived library of androstanic azasteroids with diverse substitution patterns at the phenyl...
Scheme 6: Synthesis of 4-azacholestanes by an intramolecular Ugi-4C-3R [26].
Scheme 7: Synthesis of amino acid–steroid hybrid by multiple Ugi-4CR using steroidal isocyanides [29].
Scheme 8: Synthesis of ecdysteroid derivatives by Ugi-4CR using a steroidal isocyanide [30].
Scheme 9: Stereoselective multicomponent synthesis of a steroid–tetrahydropyridine hybrid using a chiral bifu...
Scheme 10: Pd(II)-catalyzed three-component reaction with an alkynyl seco-cholestane [34].
Scheme 11: Multicomponent synthesis of steroid–thiazole hybrids from a steroidal ketone [36].
Scheme 12: Synthesis of cholanic pseudo-peptide derivatives by novel MCRs based on the reactivity of ynamide [37,38].
Scheme 13: Synthesis of steroid-fused pyrimidines and pyrimidones using the Biginelli-3CR [39,42,43].
Scheme 14: Synthesis of steroidal pyridopyrimidines by a reaction sequence comprising a 4CR followed by a post...
Scheme 15: Synthesis of steroid-fused pyrimidines by MCR of 2-hydroxymethylene-3-ketosteroids [46].
Scheme 16: Synthesis of steroid-fused naphthoquinolines by the Kozlov–Wang MCR using ketosteroids [50,51].
Scheme 17: Conjugation of steroids to carbohydrates and peptides by the Ugi-4CR [62,63].
Scheme 18: Solid-phase multicomponent conjugation of peptides to steroids by the Ugi-4CR [64].
Scheme 19: Solid-phase multicomponent conjugation of peptides to steroids by the Petasis-3CR [68].
Scheme 20: Synthesis of steroidal macrobicycles (cages) by multiple multicomponent macrocyclizations based on ...
Scheme 21: One-pot synthesis of steroidal cages by double Ugi-4CR-based macrocyclizations [76].
Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors
- Sven Grätz,
- Sebastian Zink,
- Hanna Kraffczyk,
- Marcus Rose and
- Lars Borchardt
Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112
- trifluoromethanesulfonic acid or sulfuric acid was developed yielding basically the same polymer but avoiding residual traces of the metal [11]. These synthetic pathways often afford a gel from the dissolved monomers upon the crosslinking that is subsequently washed and dried with a significant volume loss. Still, a high
Graphical Abstract
Figure 1: A: Mechanochemical polymerization of BCMBP (4,4’-bis(chloromethyl)-1,1’-biphenyl) towards the porou...
Figure 2: A: IR spectra of the monomer BCMBP and NG-HCP showing a decrease of the C–Cl vibration after the re...
Figure 3: A: Evolution of pressure in the course of the reaction measured by the GTM system. The addition of ...
Figure 4: The correlation between the liquids’ boiling point and the SSA of the polymer. In general, a lower ...
Figure 5: Physisorption isotherms of benzene vapour at different temperatures on HCP synthesised classically ...
Figure 6: Physisorption isotherms of cyclohexane on mechanochemically synthesised HCP at temperatures 288, 29...
Synthesis of functionalized diazocines for application as building blocks in photo- and mechanoresponsive materials
- Widukind Moormann,
- Daniel Langbehn and
- Rainer Herges
Beilstein J. Org. Chem. 2019, 15, 727–732, doi:10.3762/bjoc.15.68
- (center), and 3,3’-di(aminoethyl)diazocine 6b (right). Continuous lines: 100% cis and dashed lines: PSS (385 nm) at 298.15 K in acetonitrile. Key reactions in diazocine synthesis. Syntheses of the functionalized diazocines 4–7. Reaction conditions: i) Isobutylene, sulfuric acid, DCM; ii) t-BuOK, Br2, THF
Graphical Abstract
Figure 1: (a) Isomerization of parent diazocine 1. Distances of carbon atoms para to the ethylene bridge were...
Figure 2: Synthesized target diazocines 4–7 for applications in responsive materials.
Scheme 1: Key reactions in diazocine synthesis.
Scheme 2: Syntheses of the functionalized diazocines 4–7. Reaction conditions: i) Isobutylene, sulfuric acid,...
Figure 3: UV–vis spectra of 3,3’-diaminodiazocine 2 (left), 3,3’-di(aminomethyl)diazocine 6a (center), and 3,...
Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives
- Mikhail V. Makarov and
- Marie E. Migaud
Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36
- an acid catalyst (Scheme 14). Conditions which use p-toluenesulfonic acid in acetone [58] produced acetonide 29 in 49% yield after column chromatography. Conditions which employed concentrated sulfuric acid in acetonitrile [59][60] yielded the acetonide in 76–96% yield. Large excess of 2,2
Graphical Abstract
Figure 1: Structural formulas of Nam, NA, NR+, NMN, and NAD+.
Figure 2: Main synthetic routes to nicotinamide riboside (NR+X−).
Scheme 1: Synthesis of NR+Cl− based on the reaction of peracylated chlorosugars with Nam.
Figure 3: Predominant formation of β-anomer over α-anomer of NR+X−.
Scheme 2: Synthesis of NR+Cl− by reacting 3,5-di-O-benzoyl-D-ribofuranosyl chloride (5) with Nam (1a).
Figure 4: Mechanism of the formation of the β-anomer of the glycosylated product in the case of the reaction ...
Scheme 3: Synthesis of NR+Br− by reacting bromosugars with Nam (1a).
Scheme 4: Synthesis of NR+OTf− based on the glycosylation of Nam (1a) with tetra-O-acetyl-β-D-ribofuranose (2a...
Scheme 5: Improved synthesis of NR+OTfˉ and NAR+OTfˉ based on the glycosylation of pre-silylated Nam or NA wi...
Scheme 6: Synthesis of triacetylated NAR+OTf− by glycosylation of nicotinic acid trimethylsilyl ester with te...
Scheme 7: Synthesis of NR+Cl− from NR+OTf− by means of ion exchange with sodium chloride solution.
Scheme 8: Synthesis of acylated NR+OTf− by means of ion exchange with sodium chloride.
Scheme 9: Synthesis of triacetylated derivatives of NAR+ by glycosylation of nicotinic acid esters with ribos...
Scheme 10: Synthesis of NR+OTf− from the triflate salt of ethyl nicotinate-2,3,5-triacetyl-β-D-riboside in met...
Scheme 11: Reaction of 2,3,5-tri-O-acetyl-β-phenyl nicotinate riboside triflate salt with secondary and tertia...
Scheme 12: Synthesis of NMN based on the Zincke reaction of N-(2,4-dinitrophenyl)-3-carbamoylpyridinium chlori...
Scheme 13: Synthesis of NMN based on the Zincke reaction of N-(2,4-dinitrophenyl)-3-carbamoylpyridinium chlori...
Scheme 14: Efficacious protection of 2′,3′-hydroxy groups of NR+X−.
Scheme 15: Protection of the 2′,3′-hydroxy groups of NR+Cl– with a mesitylmethylene acetal group.
Figure 5: Reduction of derivatives of NR+Xˉ into corresponding 1,2-; 1,4-; 1,6-NRH derivatives.
Figure 6: Mechanism of the reduction of the pyridinium core with dithionite as adapted from [67].
Scheme 16: Reduction of triacylated NR+OTf– derivatives by sodium dithionite followed by complete removal of a...
Figure 7: Structural formulas of iridium and rhodium catalysts (a)–(d) for regeneration of NAD(P)H from NAD(P)...
Figure 8: Two approaches to synthesis of 5′-derivatives of NR+.
Scheme 17: Synthesis of NMN starting from NR+ salt.
Scheme 18: Efficient synthesis of NMN by phosphorylation of 2′,3′-O-isopropylidene-NR+ triflate followed by re...
Scheme 19: Synthesis of a bisphosphonate analogue of β-NAD+ based on DCC-induced conjugation of 2′,3′-O-isopro...
Scheme 20: Synthesis of 5′-acyl and 2′,3′,5′-triacyl derivatives of NR+.
Figure 9: Structural formulas of NMN analogues 39–41.
Scheme 21: Synthesis of 5′-phosphorylated derivatives of NR+ using a “reduction–modification–oxidation” approa...
Scheme 22: Synthesis of 5′-phosphorylated derivatives of NR+ using a “reduction–modification–reoxidation” appr...
Figure 10: Structural formulas of 5′-phosphorylated derivatives of NR+.
Scheme 23: Synthesis of 5′-phosphorylated derivatives of NR+ using a direct NR+ phosphorylation approach.
Figure 11: Structural formulas of amino acid NR+ conjugates.
Scheme 24: Synthesis of amino acid NR+ conjugates using NRH and protected amino acid under CDI-coupling condit...
Figure 12: Chemical structures of known isotopically labelled NR+ analogues and derivatives.
Scheme 25: Synthesis of [2′-3H]-NR+ and [2′-3H]-NMN.
Scheme 26: Synthesis of α- and β-anomers of [1′-2H]-NMN.
A convenient and practical synthesis of β-diketones bearing linear perfluorinated alkyl groups and a 2-thienyl moiety
- Ilya V. Taydakov,
- Yuliya M. Kreshchenova and
- Ekaterina P. Dolotova
Beilstein J. Org. Chem. 2018, 14, 3106–3111, doi:10.3762/bjoc.14.290
- for the isolation of the β-diketones. Several methods for decomposition of copper chelates were described in literature. Usually sulfuric acid with various concentrations (10–95%) was applied [22][23][34][35], but the thiophene ring is known to be sensitive to sulfuric acid. For this reason, we
Graphical Abstract
Scheme 1: Synthesis of Htta.
Figure 1: Known thiophene-based perfluorinated β-diketones.
Scheme 2: Preparation of 1-(2-thienyl)butane-1,3-dione (5).
Scheme 3: Preparation and cleavage of copper chelates of β-diketones.
Scheme 4: Keto-enol equilibrium of β-diketones.
An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes
- Hashem Sharghi,
- Pezhman Shiri and
- Mahdi Aberi
Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253
- ; biodiesel synthesis; sulfonated carbon materials; sulfonated industrial and laboratory products; sulfonated organic materials; sulfonated silica materials; Review 1. Introduction Mineral acids (sulfuric acid, sulfonic acid, hydrochloric acid, phosphoric acid, and boric acid) as homogeneous catalysts were
- stirred solution of imidazole in dry CH2Cl2 in an ice bath. In the next step, sulfuric acid 98% was added dropwise to the reaction mixture containing the sulfonated imidazole at room temperature to obtain 1,3-disulfo-1H-imidazolium hydrogen sulfate [Dsim]HSO4 (26) as a viscous pale yellow oil catalyst
- this IL with manganese(II) chloride as a co-catalyst also exhibited excellent yield in cellobiose (61) hydrolysis in dilute aqueous sulfuric acid (Scheme 11). The authors found that the highest enhancement in the yield of the product happens at 60 °C. This may be owing to this fact that a weak
Graphical Abstract
Figure 1: Different types of sulfonated materials as acid catalysts.
Scheme 1: Synthetic route of 3-methyl-1-sulfo-1H-imidazolium metal chloride ILs and their catalytic applicati...
Scheme 2: Synthetic route of 1,3-disulfo-1H-imidazolium transition metal chloride ILs and their catalytic app...
Scheme 3: Synthetic route of 1,3-disulfoimidazolium carboxylate ILs and their catalytic applications in the s...
Scheme 4: Synthetic route of [BiPy](HSO3)2Cl2 and [Dsim]HSO4 ILs and their catalytic applications for the syn...
Scheme 5: The catalytic applications of (C4(DABCO-SO3H)2·4Cl) IL for the synthesis of spiro-isatin derivative...
Scheme 6: The catalytic applications of (C4(DABCO-SO3H)2·4Cl) IL for the synthesis of bis 2-amino-4H-pyran de...
Scheme 7: The synthetic route of N,N-disulfo-1,1,3,3-tetramethylguanidinium carboxylate ILs and their catalyt...
Scheme 8: The catalytic application of 1-methyl-3-sulfo-1H-imidazolium tetrachloroferrate IL in the synthesis...
Scheme 9: The synthetic route of 3-sulfo-1H-imidazolopyrimidinium hydrogen sulfate IL and its catalytic appli...
Scheme 10: The results for the synthesis of bis(indolyl)methanes and di(bis(indolyl)methyl)benzenes in the pre...
Scheme 11: The catalytic applications of 1-(1-sulfoalkyl)-3-methylimidazolium chloride acidic ILs for the hydr...
Scheme 12: The synthetic route of immobilized 1,4-diazabicyclo[2.2.2]octanesulfonic acid chloride on SiO2 and ...
Scheme 13: The catalytic application of a silica-bonded sulfoimidazolium chloride for the synthesis of 12-aryl...
Scheme 14: The synthetic route of the SBA-15-Ph-SO3H and its catalytic applications for the synthesis of 2H-in...
Scheme 15: The synthetic route for heteropolyanion-based ionic liquids immobilized on mesoporous silica SBA-15...
Scheme 16: Some mechanism aspects of SSA catalyst for the protection of amine derivatives.
Scheme 17: The synthetic route for MWCNT-SO3H and its catalytic application for the synthesis of N-substituted...
Scheme 18: The sulfonic acid-functionalized polymers (P-SO3H) covalently grafted on multi-walled carbon nanotu...
Scheme 19: The transesterification reaction in the presence of S-MWCNTs.
Scheme 20: The synthetic route for the new hypercrosslinked supermicroporous polymer via the Friedel–Crafts al...
Scheme 21: The synthetic route for a new microporous copolymer via the Friedel–Crafts alkylation reaction of t...
Scheme 22: The synthetic route for sulfonated polynaphthalene and its catalytic application for the amidoalkyl...
Scheme 23: The synthetic route of the acidic carbon material and its catalytic application in the etherificatio...
Scheme 24: The synthetic route of the acidic carbon materials and their catalytic applications for the esterif...
Scheme 25: The sulfonated MWCNTs.
Scheme 26: The sulfonated nanoscaled diamond powder for the dehydration of D-xylose into furfural.
Scheme 27: The synthetic route and catalytic application of the GR-SO3H.
Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives
- Nicholas G. Jentsch,
- Jared D. Hume,
- Emily B. Crull,
- Samer M. Beauti,
- Amy H. Pham,
- Julie A. Pigza,
- Jacques J. Kessl and
- Matthew G. Donahue
Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229
- chloride in THF [30]. Initially, the trimethylsilyl cyanohydrin 16 was subjected to solvolysis in ethanol with aqueous sulfuric acid. Unfortunately, those conditions resulted in displacement of the 4-chloro substituent with ethanol giving the 4-ethyl ether 17 in 35% yield. To circumvent this undesired
Graphical Abstract
Figure 1: Investigational non-catalytic HIV-1 Integrase inhibitors.
Scheme 1: Boehringer Ingelheim retrosynthesis of quinoline 1.
Scheme 2: Quinoline ring condensation strategies.
Scheme 3: Isatoic anhydrides from anthranilic acids with triphosgene.
Scheme 4: Substituted 2-methyl-4-hydroxyquinolines from isatoic anhydrides and ethyl acetoacetate.
Scheme 5: Mechanistic hypothesis for the cyclocondensation reaction.
Scheme 6: Quinoline synthesis with ethyl acetylpyruvate.
Scheme 7: Elaboration of the benzoic acid ethyl ester to the acetic acid residue.
Scheme 8: Umpolung addition of ethoxycarbonyl via a MAC strategy.
Synthesis of dihydroquinazolines from 2-aminobenzylamine: N3-aryl derivatives with electron-withdrawing groups
- Nadia Gruber,
- Jimena E. Díaz and
- Liliana R. Orelli
Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227
- acid or other sources of C2 like ethyl orthoformate [52], diarylformamidines [53] or 1,1-dimethoxy-N,N-dimethylmethanamine [17]. Using an alternative approach, the corresponding 2-ABA was treated with acetic anhydride in concentrated sulfuric acid affording 2-methyl-6-nitro-3-(p-nitrophenyl)-3,4-DHQ
Graphical Abstract
Figure 1: N-Aryl-3,4-dihydroquinazolines 1.
Scheme 1: Synthetic pathway leading to N-aryl-3,4-dihydroquinazolines 1.
Scheme 2: Synthesis of compounds 2.
Figure 2: Reaction intermediate in the synthesis of compound 2a.
Scheme 3: Addition–elimination mechanism for the heterocyclization.
Scheme 4: Proposed mechanism involving an intermediate nitrilium ion.
Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues
- Kai Zhang,
- Jiarong Li,
- Honglin Liu,
- Haiyou Wang and
- Lamusi A
Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207
- reported in the previous study [27], spinosyn A could be hydrolyzed to 17-pseudoaglycone under weak sulfuric acid conditions, indicating that the C9 glycosidic bond was more stable than the C17 glycosidic bond under weak sulfuric acid conditions (Scheme 2). Similar to spinosyn A, both D-forosamine and 2’,3
- sulfuric acid conditions, the 3-O-ethyl-2,4-di-O-methylrhamnose at the C17 position could be removed selectively under the weak acidic conditions to afford 5. The structure of compound 5 was also ascertained by NMR and mass spectrometry. Finally, compound 5 was glycosylated with donor 6 to provide
Graphical Abstract
Figure 1: Structures of spinosad and spinetoram.
Scheme 1: Comparison of previous synthesis and self-protection synthesis.
Scheme 2: Synthesis of spinetoram J from spinosyn A based on a self-protection strategy.
Scheme 3: Synthesis of spinetoram J analogues.
Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH
- Femke Beiroth,
- Tomas Koudelka,
- Thorsten Overath,
- Stefan D. Knight,
- Andreas Tholey and
- Thisbe K. Lindhorst
Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163
- (C23H23F3N2O8) was appended to the elemental composition of FimHtr. Methods and materials for synthesis TLC was performed on silica gel GF254 (Merck). Spots were visualized under UV light and by charring with 10% sulfuric acid in ethanol and subsequent heating. Flash column chromatography was performed on
Graphical Abstract
Figure 1: Principle of photoaffinity labeling of proteins with diazirine derivatives. Photolabile ligands are...
Figure 2: FimH crystal structure (pdb code 1KLF) with docked p-nitrophenyl α-D-mannopyranoside (1, pNPMan). F...
Figure 3: Based on the structure of the known FimH ligands 1 and 2, three photolabile α-D-mannosides, 3–5, we...
Figure 4: Connolly representation of photolabile α-D-mannoside 3 in the closed gate (A, PDB code 1UWF) and op...
Scheme 1: Synthesis of photolabile α-D-mannosides 3 and 4. a) H2, Pd-C, methanol, rt, 6 h, 94%; b) HATU, DIPE...
Figure 5: ESIMS spectra of peptide M2 before (A) and after photoreaction (B) with mannoside 3.
Figure 6: Intact protein ESIMS spectra of FimHtr labeling with diazirine derivative 3 with (A) 50% acetonitri...
Lanyamycin, a macrolide antibiotic from Sorangium cellulosum, strain Soce 481 (Myxobacteria)
- Lucky S. Mulwa,
- Rolf Jansen,
- Dimas F. Praditya,
- Kathrin I. Mohr,
- Patrick W. Okanya,
- Joachim Wink,
- Eike Steinmann and
- Marc Stadler
Beilstein J. Org. Chem. 2018, 14, 1554–1562, doi:10.3762/bjoc.14.132
- procedures Analytical TLC: TLC aluminum sheets silica gel Si 60 F254 (Merck), detection by UV absorption at 254 nm and 366 nm. Spray reagent vanillin/sulfuric acid (prepared by dissolving vanillin (0.5 g) in 100 mL of sulfuric acid) followed by heating to about 120 °C on a hot plate. UV data were recorded on
Graphical Abstract
Figure 1: Lanyamycin (1/2), differing at C-26, isolated from Sorangium cellulosum (Soce 481).
Figure 2: Structure fragments of lanyamycin (1/2) from 1H,1H-COSY spectrum (bold bonds) and selected 1H,13C-H...
Figure 3: Structure of bafilomycin A1.
Figure 4: 3D Model of the macrolactone ring of lanyamycin (1/2) and selected ROESY correlations. Green arrows...
Figure 5: HCV assay: NC = negative control, EGCG = positive control, Cpd1 = lanyamycin (1/2).
One hundred years of benzotropone chemistry
- Arif Dastan,
- Haydar Kilic and
- Nurullah Saracoglu
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
- -expanded product 33. After the reduction of the allylic position with LiAlH4, the treatment of monochloride 34 with concentrated sulfuric acid in ice water afforded a quantitative yield of 4,5-benzotropone (11). The above researchers also proposed a mechanism for the formation of 11 from 31 as shown in
- sulfuric acid were presumed, benzohomotropylium cation 112 was not detected from the reactions of the corresponding alcohol 114 in sulfuric acid [125]. 2.2.3. Reduction-based studies: To define the stereochemical, conformational, and dynamic properties of both benzo[7]annulenones (and related compounds
- -bromo-6-hydroxylamino-2,3-benzotropone oximes 262 were obtained. Hydrolysis of these oximes 262 with sulfuric acid gave 5-bromo-6-hydroxy-2,3-benzotropone and the 4-bromo isomer 263, which were debrominated with catalytic hydrogenation to give 239 (Scheme 41). Although 239 is capable of existing as two
Graphical Abstract
Scheme 1: Tropone (1), tropolone (2) and their resonance structures.
Figure 1: Natural products containing a tropone nucleus.
Figure 2: Possible isomers 11–13 of benzotropone.
Scheme 2: Synthesis of benzotropones 11 and 12.
Scheme 3: Oxidation products of benzotropylium fluoroborate (16).
Scheme 4: Oxidation of 7-bromo-5H-benzo[7]annulene (22).
Scheme 5: Synthesis of 4,5-benzotropone (11) using o-phthalaldehyde (27).
Scheme 6: Synthesis of 4,5-benzotropone (11) starting from oxobenzonorbornadiene 31.
Scheme 7: Acid-catalyzed cleavage of oxo-bridge of 34.
Scheme 8: Synthesis of 4,5-benzotropone (11) from o-xylylene dibromide (38).
Scheme 9: Synthesis of 4,5-benzotropone (11) via the carbene adduct 41.
Scheme 10: Heck coupling strategy for the synthesis of 11.
Scheme 11: Synthesis of benzofulvalenes via carbonyl group of 4,5-benzotropone (11).
Figure 3: Some cycloheptatrienylium cations.
Scheme 12: Synthesis of condensation product 63 and its subsequent oxidative cyclization products.
Figure 4: A novel series of benzo[7]annulenes prepared from 4,5-benzotropone (11).
Scheme 13: Preparation of substituted benzo[7]annulene 72 using the Mukaiyama-Michael reaction.
Figure 5: Possible benzo[7]annulenylidenes 73–75.
Scheme 14: Thermal and photochemical decomposition of 7-diazo-7H-benzo[7]annulene (76) and the trapping of int...
Scheme 15: Synthesis of benzoheptafulvalene 86.
Scheme 16: Synthesis of 7-(diphenylmethylene)-7H-benzo[7]annulene (89).
Scheme 17: Reaction of 4,5-benzotropone (11) with dimethyl diazomethane.
Scheme 18: Synthesis of dihydrobenzomethoxyazocine 103.
Scheme 19: Synthesis and reducibility of benzo-homo-2-methoxyazocines.
Scheme 20: Synthesis of 4,5-benzohomotropones 104 and 115 from 4,5-benzotropones 11 and 113.
Scheme 21: A catalytic deuterogenation of 4,5-benzotropone (11) and synthesis of 5-monosubstituted benzo[7]ann...
Scheme 22: Synthesis of methyl benzo[7]annulenes 131 and 132.
Scheme 23: Ambident reactivity of halobenzo[7]annulenylium cations 133a/b.
Scheme 24: Preparation of benzo[7]annulenylidene–iron complexes 147.
Scheme 25: Synthesis of 1-ethynylbenzotropone (150) and the etheric compound 152 from 4,5-benzotropone (11) wi...
Scheme 26: Thermal decomposition of 4,5-benzotropone (11).
Scheme 27: Reaction of 4,5-benzotropone (11) with 1,2-ethanediol and 1,2-ethanedithiol.
Scheme 28: Conversions of 1-benzosuberone (162) to 2,3-benzotropone (12).
Scheme 29: Synthesis strategies for 2,3-bezotropone (12) using 1-benzosuberones.
Scheme 30: Oxidation-based synthesis of 2,3-benzotropone (12) via 1-benzosuberone (162).
Scheme 31: Synthesis of 2,3-benzotropone (12) from α-tetralone (171) via ring-expansion.
Scheme 32: Preparation of 2,3-benzotropone (12) by using of benzotropolone 174.
Figure 6: Benzoheptafulvenes as condensation products of 2,3-benzotropone (12).
Scheme 33: Conversion of 2,3-benzotropone (12) to tosylhydrazone salt 182 and gem-dichloride 187.
Figure 7: Benzohomoazocines 191–193 and benzoazocines 194–197.
Scheme 34: From 2,3-benzotropone (12) to carbonium ions 198–201.
Scheme 35: Cycloaddition reactions of 2,3-benzotropone (12).
Scheme 36: Reaction of 2,3-benzotropone (12) with various reagents and compounds.
Figure 8: 3,4-Benzotropone (13) and its resonance structure.
Scheme 37: Synthesis of 6,7-benzobicyclo[3.2.0]hepta-3,6-dien-2-one (230).
Figure 9: Photolysis and thermolysis products of 230.
Figure 10: Benzotropolones and their tautomeric structures.
Scheme 38: Synthesis strategies of 4,5-benzotropolone (238).
Scheme 39: Synthesis protocol for 2-hydroxy-4,5-benzotropone (238) using oxazole-benzo[7]annulene 247.
Figure 11: Some quinoxaline and pyrazine derivatives 254–256 prepared from 4,5-benzotropolone (238).
Scheme 40: Nitration product of 4,5-benzotropolone (238) and its isomerization to 1-nitro-naphthoic acid (259)....
Scheme 41: Synthesis protocol for 6-hydroxy-2,3-benzotropone (239) from benzosuberone (162).
Scheme 42: Various reactions via 6-hydroxy-2,3-benzotropone (239).
Scheme 43: Photoreaction of 6-hydroxy-2,3-benzotropone (239).
Scheme 44: Synthesis of 7-hydroxy-2,3-benzotropone (241) from benzosuberone (162).
Scheme 45: Synthesis strategy for 7-hydroxy-2,3-benzotropone (241) from ketone 276.
Scheme 46: Synthesis of 7-hydroxy-2,3-benzotropone (241) from β-naphthoquinone (280).
Scheme 47: Synthesis of 7-hydroxy-2,3-benzotropone (241) from bicyclic endoperoxide 213.
Scheme 48: Synthesis of 7-hydroxy-2,3-benzotropone (241) by ring-closing metathesis.
Figure 12: Various monosubstitution products 289–291 of 7-hydroxy-2,3-benzotropone (241).
Scheme 49: Reaction of 7-hydroxy-2,3-benzotropone (241) with various reagents.
Scheme 50: Synthesis of 4-hydroxy-2,3-benzotropones 174 and 304 from diketones 300/301.
Scheme 51: Catalytic hydrogenation of diketones 300 and 174.
Scheme 52: Synthesis of halo-benzotropones from alkoxy-naphthalenes 306, 307 and 310.
Figure 13: Unexpected byproducts 313–315 during synthesis of chlorobenzotropone 309.
Figure 14: Some halobenzotropones and their cycloadducts.
Scheme 53: Multisep synthesis of 2-chlorobenzotropone 309.
Scheme 54: A multistep synthesis of 2-bromo-benzotropone 26.
Scheme 55: A multistep synthesis of bromo-2,3-benzotropones 311 and 316.
Scheme 56: Oxidation reactions of 8-bromo-5H-benzo[7]annulene (329) with some oxidants.
Scheme 57: Synthesis of 2-bromo-4,5-benzotropone (26).
Scheme 58: Synthesis of 6-chloro-2,3-benzotropone (335) using LiCl and proposed intermediate 336.
Scheme 59: Reaction of 7-bromo-2,3-benzotropone (316) with methylamine.
Scheme 60: Reactions of bromo-2,3-benzotropones 26 and 311 with dimethylamine.
Scheme 61: Reactions of bromobenzotropones 311 and 26 with NaOMe.
Scheme 62: Reactions of bromobenzotropones 26 and 312 with t-BuOK in the presence of DPIBF.
Scheme 63: Cobalt-catalyzed reductive cross-couplings of 7-bromo-2,3-benzotropone (316) with cyclic α-bromo en...
Figure 15: Cycloadduct 357 and its di-π-methane rearrangement product 358.
Scheme 64: Catalytic hydrogenation of 2-chloro-4,5-benzotropone (311).
Scheme 65: Synthesis of dibromo-benzotropones from benzotropones.
Scheme 66: Bromination/dehydrobromination of benzosuberone (162).
Scheme 67: Some transformations of isomeric dibromo-benzotropones 261A/B.
Scheme 68: Transformations of benzotropolone 239B to halobenzotropolones 369–371.
Figure 16: Bromobenzotropolones 372–376 and 290 prepared via bromination/dehydrobromination strategy.
Scheme 69: Synthesis of some halobenzotropolones 289, 377 and 378.
Figure 17: Bromo-chloro-derivatives 379–381 prepared via chlorination.
Scheme 70: Synthesis of 7-iodo-3,4-benzotropolone (382).
Scheme 71: Hydrogenation of bromobenzotropolones 369 and 370.
Scheme 72: Debromination reactions of mono- and dibromides 290 and 375.
Figure 18: Nitratation and oxidation products of some halobenzotropolenes.
Scheme 73: Azo-coupling reactions of some halobenzotropolones 294, 375 and 378.
Figure 19: Four possible isomers of dibenzotropones 396–399.
Figure 20: Resonance structures of tribenzotropone (400).
Scheme 74: Two synthetic pathways for tribenzotropone (400).
Scheme 75: Synthesis of tribenzotropone (400) from dibenzotropone 399.
Scheme 76: Synthesis of tribenzotropone (400) from 9,10-phenanthraquinone (406).
Scheme 77: Synthesis of tribenzotropone (400) from trifluoromethyl-substituted arene 411.
Figure 21: Dibenzosuberone (414).
Figure 22: Reduction products 415 and 416 of tribenzotropone (400).
Figure 23: Structures of tribenzotropone dimethyl ketal 417 and 4-phenylfluorenone (412) and proposed intermed...
Figure 24: Structures of benzylidene- and methylene-9H-tribenzo[a,c,e][7]annulenes 419 and 420 and chiral phos...
Figure 25: Structures of tetracyclic alcohol 422, p-quinone methide 423 and cation 424.
Figure 26: Structures of host molecules 425–427.
Scheme 78: Synthesis of non-helical overcrowded derivatives syn/anti-431.
Figure 27: Hexabenzooctalene 432.
Figure 28: Structures of possible eight isomers 433–440 of naphthotropone.
Scheme 79: Synthesis of naphthotropone 437 starting from 1-phenylcycloheptene (441).
Scheme 80: Synthesis of 10-hydroxy-11H-cyclohepta[a]naphthalen-11-one (448) from diester 445.
Scheme 81: Synthesis of naphthotropone 433.
Scheme 82: Synthesis of naphthotropones 433 and 434 via cycloaddition reaction.
Scheme 83: Synthesis of naphthotropone 434 starting from 452.
Figure 29: Structures of tricarbonyl(tropone)irons 458, and possible cycloadducts 459.
Scheme 84: Synthesis of naphthotropone 436.
Scheme 85: Synthesis of precursor 465 for naphthotropone 435.
Scheme 86: Generation of naphthotropone 435 from 465.
Figure 30: Structures of tropylium cations 469 and 470.
Figure 31: Structures of tropylium ions 471+.BF4−, 472+.BF4−, and 473+.BF4−.
Scheme 87: Synthesis of tropylium ions 471+.BF4− and 479+.ClO4−.
Scheme 88: Synthesis of 1- and 2-methylanthracene (481 and 482) via carbene–carbene rearrangement.
Figure 32: Trapping products 488–490.
Scheme 89: Generation and chemistry of a naphthoannelated cycloheptatrienylidene-cycloheptatetraene intermedia...
Scheme 90: Proposed intermediates and reaction pathways for adduct 498.
Scheme 91: Exited-state intramolecular proton transfer of 505.
Figure 33: Benzoditropones 506 and 507.
Scheme 92: Synthesis of benzoditropone 506e.
Scheme 93: Synthetic approaches for dibenzotropone 507 via tropone (1).
Scheme 94: Formation mechanisms of benzoditropone 507 and 516 via 515.
Scheme 95: Synthesis of benzoditropones 525 and 526 from pyromellitic dianhydride (527).
Figure 34: Possible three benzocyclobutatropones 534–536.
Scheme 96: Synthesis of benzocyclobutatropones 534 and 539.
Scheme 97: Synthesis attempts for benzocyclobutatropone 545.
Scheme 98: Generation and trapping of symmetric benzocyclobutatropone 536.
Scheme 99: Synthesis of chloro-benzocyclobutatropone 552 and proposed mechanism of fluorenone derivatives.
Scheme 100: Synthesis of tropolone analogue 559.
Scheme 101: Synthesis of tropolones 561 and 562.
Figure 35: o/p-Tropoquinone rings (563 and 564) and benzotropoquinones (565–567).
Scheme 102: Synthesis of benzotropoquinone 566.
Scheme 103: Synthesis of benzotropoquinone 567 via a Diels–Alder reaction.
Figure 36: Products 575–577 through 1,2,3-benzotropoquinone hydrate 569.
Scheme 104: Structures 578–582 prepared from tropoquinone 567.
Figure 37: Two possible structures 583 and 584 for dibenzotropoquinone, and precursor compound 585 for 583.
Scheme 105: Synthesis of saddle-shaped ketone 592 using dibenzotropoquinone 584.
