The aza-ene reaction of heterocyclic ketene aminals with activated carbonyl compounds: a novel and efficient synthesis of γ-lactam-fused diazaheterocycles
作者:Jian-Heng Zhang、Mei-Xiang Wang、Zhi-Tang Huang
DOI:10.1039/a808328b
日期:——
Reactions of heterocyclic ketene aminals with activated carbonylcompounds are strongly influenced by the structure of the heterocycle moiety. Six-membered heterocyclic ketene aminals with or without an N-methyl group such as 3 and 4 underwent efficient addition and consecutive cyclocondensationreactions with diethyl oxomalonate 9 to produce γ-lactam-fused pyrimidine derivatives 10 and 11 in moderate
Acylation of Heterocyclic Ketene Aminals with Propionyl Chloride
作者:Zhi-Tang Huang、Jian-Chao Wang、Li-Ben Wang
DOI:10.1080/00397919608004539
日期:1996.6
Abstract Heterocyclicketeneaminals 1 or 2 reacted with propionyl chloride to give both the mono-N-and C-acylated products 4 and 5 or 6 and 7. While N-methyl heterocyclicketeneaminals 3 reacted with propionyl chloride under the same condition, the reaction took place in complexity. Besides N-and C-acylation, the O-attack and heterocyclic ring cleavage also occurred to give products 8 and 9.
The stereoselective synthesis of O-galactosides of benzoyl-substituted heterocyclic ketene aminals was investigated. The benzoyl-substituted heterocyclic ketene aminals 1-4 reacted with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide (5) in the presence of calcium hydride to give O-galactosides of benzoyl-substituted heterocyclic ketene aminals 6-9 with the Z-configuration. In comparison, 1-2 reacted with 5 in the presence of mercuric cyanide to give O-galactosides of benzoyl-substituted heterocyclic ketene aminals 10-11 with the E-configuration. Satisfactory results have been obtained in terms of both stereoselectivity and yield, and the beta-anomers are the sole products. (C) 1998 Elsevier Science Ltd. All rights reserved.