.beta.-Lactams. 2. Diastereoselective alkylative discrimination of racemic 3-substituted 4-acetoxyazetidin-2-ones and its application to the synthesis of a chiral key intermediate for carbapenem syntheses
作者:Yoshimitsu Nagao、Yunosuke Nagase、Toshio Kumagai、Yasuhiro Kuramoto、Shigeaki Kobayashi、Yoshinori Inoue、Tooru Taga、Hirokazu Ikeda
DOI:10.1021/jo00041a032
日期:1992.7
Alkylation of rac 3-substituted 4-acetoxyazetidin-2-one 4 with chiral tin(II) enolate 8 derived from 3-acetyl-(4S)-ethyl-1,3-thiazolidine-2-thione (ETT) (7) proceeded in a highly diastereoselective manner to give alkylated products 9, 10, and 11 in 42%, 20%, and 9% yields, respectively, after chromatographic purification. Similar alkylation of rac-5 with 8 gave 16, 17, and 18 in 45%, 29%, and 5% yields, respectively. Compound 9 was readily converted to 33, a chiral key intermediate for the synthesis of carbapenems. Analytical separation of rac-4 was effectively done with an HPLC technique employing a chiral column packed with A(S)MBC.