Stereoselective synthesis of 2-(α-hydroxyalkyl)benzimidazoles
摘要:
Lithiated oxazolo[3,4-a]benzimidazole 4 reacted with various alkyl halides to give oxazolo[3,4-a]benzimidazoles 5a-d in good yields as single diastereoisomers. (R)-Benzimidazol-2-y1 carbinols 6a-d were obtained upon hydrolysis under acidic conditions of 1H,3H-oxazolo[3,4-a]benzimidazole derivatives. (C) 1998 Elsevier Science Ltd. All rights reserved.
Asymmetric induction using chiral 1,2,4-triazole and benzimidazole derivatives
摘要:
Lithiated N-substituted 1,2,4-triazoles 3 and 8 and benzimidazole 11 reacted with (1R)-fenchone to give derivatives 5c, 9 and 12 in good yields as single diastereoisomers. (S)-Lactic acid 16 reacted with o-phenylenediamine 15 to give optically pure (S)-2-(I-hydroxyethyl)benzimidazole 17 (85%). Ring closures converted the fenchone derivative 12 into novel tricyclic fused benzimidazoles 13 and 14, and converted oxazolidine derivative 17 into compound 18 in yields of 50-70% as single diastereoisomers. Lithiated derivative 18 was alkylated to give compound 19 as a single diastereoisomer in high yield. (C) 1997 Elsevier Science Ltd.