.beta.-Lactams. 1. Highly diastereoselective alkylation of 4-acetoxyazetidin-2-one useful for 1.beta.-methylcarbapenem synthesis
作者:Yoshimitsu Nagao、Toshio Kumagai、Yunosuke Nagase、Satoshi Tamai、Yoshinori Inoue、Motoo Shiro
DOI:10.1021/jo00041a031
日期:1992.7
On the basis of the principle of hard and soft acids and bases, a highly diastereoselective ''asymmetric soft acid-soft base imine alkylation'' was developed. 4-Acetoxyazetidin-2-one (5) was alkylated with the tin(II) enolates of 3-acyl-(4S)-ethyl(and isopropyl)-1,3-thiazolidine-2-thiones 7a,b and 21a,b. The resultant alkylation products (9a,b and 24a,b) could be converted to 17, the key intermediate for the syntheses of both thienamycin (2) and imipenem (3), and to 35, the key intermediate for the synthesis of 1-beta-methylcarbapenem.