Studies on synthesis of 2-acetylbenzimidazole and related benzimidazole derivatives

Citation
K. Ramaiah et al., Studies on synthesis of 2-acetylbenzimidazole and related benzimidazole derivatives, J INDIAN CH, 76(3), 1999, pp. 140-144
Citations number
31
Categorie Soggetti
Chemistry
Journal title
JOURNAL OF THE INDIAN CHEMICAL SOCIETY
ISSN journal
00194522 → ACNP
Volume
76
Issue
3
Year of publication
1999
Pages
140 - 144
Database
ISI
SICI code
0019-4522(199903)76:3<140:SOSO2A>2.0.ZU;2-Y
Abstract
Condensation of o-phenylenediamine (1) with propanoic acid under Phillips' conditions gives 2-ethylbenzimidazole (2). Attempts to oxidise 2 to 2-acety lbenzimidazole (3) using H2O2, SeO2, KMnO4/acetone were unsuccessful, Conde nsation of 2 with benzaldehyde yields 2-(alpha-methylstyryl)benzimidazole ( 4) which on oxidation with KMnO4 gives benzimidazole-2-carboxylic acid (5) as the sole product. Reaction of 1 with pyruvic acid results in 3-methylben zo-1H-dihydropyrazine-2-one (7) rather than 3 as the major product, Treatme nt of 1 with formic acid gives the known compound benzimidazole (9) which w ith acetic anhydride in the presence of NaOAc does not yield 3. Reaction of 1 with lactic acid under Phillips' conditions gives 2-(alpha-hydroxyethyl) benzimidazole (10) which on oxidation with acid dichromate, however, yields 3. Studies on syntheses and spectral properties of related benzimidazoles are reported.