Novel amino acid derivatives of the formula
wherein R1 is a protecting group removable under reducing or acid conditions, and R2 and R5 are hydrogen or carboxylic protecting groups, are useful as intermediates in preparing stereospecific carbapenam/carbapenem derivatives. R1 is removed under reducing conditions to form a pyrrolidine derivative, which is further cyclised from the R5= H compound to form a β-lactam ring. Stereospecificity at the 6-position is achieved by treatment with lithium di-isopropylamide (LDA) and quenching at different temperatures. Compound (I) can be prepared by treating R1-protected R3-pyrrolidone carboxylic acid R2- ester with a lithium enolate of the formula R4CHLiCO2R5. The lithium enolate can be formed from R4CH2CO2R5 by treatment with LDA.
式中的新型
氨基酸衍
生物
其中 R1 是在还原或酸性条件下可去除的保护基团,R2 和 R5 是氢或羧基保护基团,可用作制备立体特异性碳青霉烯/碳青霉烯衍
生物的中间体。在还原条件下除去 R1,形成
吡咯烷衍
生物,再从 R5= H 化合物环化形成β-内酰胺环。通过
二异丙基酰胺
锂(
LDA)处理并在不同温度下淬火,可实现 6 位的立体特异性。化合物 (I) 可通过用式 R4CHLiCO2R5 的
锂烯醇处理 R1 保护的 R
3-吡咯烷酮羧酸 R2- 酯来制备。烯酸
锂可通过
LDA 处理从 R4CH2CO2R5 生成。