The reaction of the chiral lithium amide 4 with the dienoate 5a provides regio- and stereo-selectively the β-amino ester 8 in essentially quantitative yield with >99% diastereoisomeric excess, which can be converted upon sequential treatment with LiNPri2âB(OMe)3âMeCHO to the key intermediate 6 for the β-lactam 7 having the correct absolute configuration.
手性
锂酰胺 4 与二烯酸酯 5a 反应后,可得到具有选择性和立体选择性的 δ-
氨基酯 8,其产量基本定量,非对映异构体过量率大于 99%,经 LiNPri2âB(OMe)3âMeCHO 顺序处理后,可转化为具有正确绝对构型的 δ-内酰胺 7 的关键中间体 6。