Acylation of diastereomers of 2,4-disubstituted 4(R)-alkoxycarbonyl thiazolidines and oxazolidines with acyl chlorides affords (2R,4R)-3-acyl isomer as only product without any racemization. The reaction proceeds via concomitant epimeriaztion at C-2 of (2S,4R) diastereomer of the substrates.
2,4-二取代的 4(R)-烷
氧羰基
噻唑烷和
噁唑烷的非对映异构体与酰基
氯进行酰化反应,得到的唯一产物是 (2R,4R)-3-酰基异构体,且无任何外消旋现象。该反应是通过底物的 (2S,4R) 非对映异构体在 C-2 处同时发生外显子作用而进行的。