- Carbonylative Acetylation of Heterocycles
-
Herein, a new procedure for the carbonylative acetylation of heterocycles has been developed. In this process, organic peroxide acts as the methyl source. Various heterocycles were transformed into the corresponding methyl heterocyclic ketones in moderate to good yields.
- Zhang, Youcan,Yin, Zhiping,Wu, Xiao-Feng
-
p. 213 - 216
(2020/01/22)
-
- A New Facile Sulfenylation of 2-Acetylbenzimidazoles
-
A facile sulfenylation of 2-acetylbenzimidazoles has been achieved by using N-(phenylthio)phthalimide in the presence of potassium tert-butoxide in DMSO. The latter gave N-alkyl-β-phenylsulfenyl-2-acetylbenzimidazole on reaction with alkylating agents in the presence of potassium carbonate in N,N-dimethylformamide.
- Kumar, P. Praveen,Dathu Reddy,Ramana Reddy, Ch. Venkata,Rama Devi,Dubey
-
p. 1775 - 1779
(2015/10/29)
-
- A green and simple synthesis of N-alkyl-2-acetylbenzimidazoles
-
A green and simple synthesis of N-alkyl-2-substituted benzimidazoles has been developed. In this method, 2-acetyl benzimidazole compound (1) was alkylated with reagents such as dimethyl sulfate/diethyl sulfate/benzyl chloride under green conditions i.e., by physical grinding in presence of a mild base like K2CO3 or by using green solvents like PEG-600, ethanol etc. or by using micro-wave irradiation technique to obtain N-alkyl-2-acetylbenzimidazoles compound (2).
- Kumar, P. Kishore,Dubey
-
experimental part
p. 3249 - 3250
(2012/08/29)
-
- Alkylation studies on pyrazolyl and isoxazolyl benzimidazoles
-
2-Acetylbenzimidazole (1) on heating with dimethyl formamide dimethyl acetal gave 1-(1 H-benzimidazolyl)-3-dimethylaminopropenone (2) which on reaction with hycirazpne hydrate gave 2-(1 H-pyrazolyl)-1 H-benzimidazole (3), The reaction of 3 with DMS/DES/ PhCH2CI in CH3CN containing K2CO3 as base and triethylbenzylammonium chloride (TEBAC) as phase trasfer catalyst (PTC) resulted in the formation of 2-(3-pyrazolyl)-1 - substitutedbenzimidazole (4). Alkylation of I with DMS/DES/PhCH2CI under PTC conditions gave the previously known 1-substituted -2-acetyl benzimidazoles (5) which with DMF-DMA gave I -substituted-2-(2-benzimidazolyl)-3.dimethylaminopropenone (6). The latter could also be obtained from 2 by alkylation under PTC conditions. Treatment of 6 with hydrazine hydrate in methanol yielded 4. Reaction of 2 with hydroxylammonium chloride yielded 1 H-(2-benzimidazolyl)-3-isoxazole (8) which on alkylation under PTC conditions gave 1-substituted (2-benzimidazolyl)-3-isoxazole (9). The latter could also be obtained from 6 by treatment with hydroxylammonium chloride.
- Kumar, Kishore,Hemasunder,Naidu,Dubey
-
p. 393 - 398
(2013/09/24)
-
- Solid phase synthesis of benzimidazole ketones and benzimidazole chalcones under solvent-free conditions
-
Oxidation of 1-alkyl/aralkyl-2-(α-hydroxyalkyl/aryl)benzimidazoles 1 with KMnO4 on neutral alumina under solid phase conditions gives the corresponding ketones, 1-alkyl/aralkyl-2-acyl-benzimidazoles 2. Compound 2a (R2 = CH3) on condensation with aromatic aldehydes in the presence of solid NaOH under solvent-free conditions, yields the corresponding chalcones, 1-alkyl/aralkyl-2-benzimidazole aryl vinyl ketone 3.
- Dubey,Kumar, C. Ravi,Babu, Balaji
-
p. 3128 - 3130
(2007/10/03)
-
- Benzimidazolium dichromates: Efficient reagents for selective oxidation of alcohols to carbonyl compounds
-
Benzimidazolium dichromates have been used for the selective and efficient oxidation of simple alcohols to carbonyl compounds. 2-Methylbenzimidazolium dichromate has been used as a standard compound. It has been found to oxidize selectively, primary alcohols to aldehydes, without any over-oxidation, and secondary alcohols to ketones. Of the several solvents explored, acetic acid at RT has been found to be the best medium for oxidation.
- Ramaiah,Dubey,Ramanatham,Kumar, C. Ravi,Grossert
-
p. 1765 - 1767
(2007/10/03)
-
- An unusual resistance to α-bromination by arylacetyl compound: Studies on bromination of 2-acetylbenzimidazoles and their subsequent reactions with sulphur nucleophiles - Synthesis of novel β-ketosulphone derivatives of benzimidazoles
-
Condensation of o-phenylenediamine with lactic acid under Phillips' conditions gave the known 2(α-hydroxyethyl)benzimidazole 1 which on oxidation with acid dichromate furnishes 2-acetylbenzimidazole 2. Reaction of 2 with bromine in acetic acid at room temp. give a novel product 3 but not the expected 2-(α-bromoacetyl)benzimidazole 4. Rational explanation is offered for this anamolous behaviour of 2. Compound 2 on alkylation, give 1- alkyl derivatives which undergo smooth bromination with bromine in acetic acid to give the corresponding 1-alkyl-2(α-bromoacetyl)benzimidazoles. Reactions of latter with sulphur nucleophiles such as PhS-, ArSO2- etc., resulting in substitution of bromine, leading to novel β-ketosulphone derivatives of benzimidazoles, are reported. Products have been characterised by IR, NMR (1H and 13C) and mass spectral data.
- Ramaiah,Dubey,Ramanatham,Grossert,Hooper
-
p. 302 - 307
(2007/10/03)
-