A stereoselective process for chiral intermediates to 1-carbapenem and 1-carbacephalosporins is provided comprising the use of an N-acyl(4R)substituted-1,3-thiazolidine-2-thione as a chiral auxiliary in boron enolate mediated aldol condensation with a protected-β-keto ester aldehyde. Benzyl 3,3-(ethylenedioxy)-4-formylbutyrate is condensed with the boron enolate formed with nbutyryl (4R)-methoxycarbonyl-1,3-thiazolidine-2-thione to provide benzyl 3,3-ethylenedioxy-(5R)-hydroxy-6-[(4R)-methoxycarbonyl-1,3-thiazolidine-2-thione-3-ylcarbonyl]octanoate. Displacement of the thiazolidine-2-thione chiral auxiliary moiety with an O-alkyl, O-acyl or O-aralkyl hydroxyamine provides the corresponding chiral intermediate as the hydroxamate.
本发明提供了一种 1-碳青霉烯类和 1-碳
头孢菌素手性中间体的立体选择性工艺,包括使用 N-酰基(4R)取代的-1,3-
噻唑烷-2-
硫酮作为手性辅助剂,在烯酸
硼介导的醛醇缩合中与受保护的-β-
酮酯醛缩合。3,3-(亚乙二氧基)-4-甲酰基
丁酸苄酯与正丁酰基(4R)-甲氧羰基-1,3-
噻唑烷-2-
硫酮形成的
硼烯醇缩合,得到 3,3-亚乙二氧基-(5R)-羟基-6-[(4R)-甲氧羰基-1,3-
噻唑烷-2-
硫酮-3-基羰基]
辛酸苄酯。用 O-烷基、O-酰基或 O-芳基
羟胺置换
噻唑烷-2-
硫酮手性辅助基团,可得到相应的羟基
氨基甲酸酯手性中间体。