Syntheses of Optically Active Tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones and Hexahydroimidazo[1,2-a]pyridin-2(3H)-ones

• Published in: Journal of organic chemistry 2002-07, Vol.67 (14), p.4951-4956
• Main Authors: Katritzky, Alan R, He, Hai-Ying, Wang, Jing
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Organic chemistry; Preparations and properties
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo010842w

The reactions of (2S)-2-amino-2-substituted-N-(4-nitrophenyl)acetamides 16a − c, succindialdehyde (13), and benzotriazole afforded enantiopure (3S,5R,7aR)-5-(1H-1,2,3-benzotriazol-1-yl)-3-substituted-1-(4-nitrophenyl)tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones 17a − c, which were converted by sodium borohydride into (3S,7aR)-3-substituted-1-(4-nitrophenyl)tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones 18a − c. Chiral (2S)-2-amino-2-substituted-N-(4-methylphenyl)acetamides 12a − d, easily prepared in two steps from N-Boc-α-amino acids 10a − d, similarly reacted with glutaraldehyde (20) and benzotriazole to generate 5-benzotriazolyl-3-substituted-hexahydroimidazo[1,2-a]pyridin-2(3H)-ones 21a − d, which were converted by sodium borohydride directly into optically active 3-substituted-hexahydroimidazo[1,2-a]pyridin-2(3H)-ones 22a − d.