diastereoselectivities of 80 to >97% (Scheme). The primary products 2–8 thus obtained are converted to protected β2-amino acids by standard procedures (Table 1). Many of the DIOZ derivatives are highly crystalline compounds (31 X-ray crystal structures in Table 2). The chiral auxiliary DIOZ, readily prepared in either enantiomeric form, is recovered with high yield.
多克量的适当保护的β 2 -
氨基酸与20个蛋白原侧链17通过的相应的3-酰基-4-异丙基-5,5-二diphenyloxazolidin -2-栗,B或Ti烯醇化物非对映选择性反应制备具有适当亲电试剂(酰胺甲基化,羟烷基化,(苄氧羰基)甲基化)的化合物(酰基-DIOZ;1),产率为55-90%,非对映选择性为80-> 97%(方案)。初级产品2 - 8由此获得转化成受保护的β 2 -
氨基通过标准程序酸(表1)。许多DIOZ衍
生物是高度结晶的化合物(表2中的31个X射线晶体结构)。容易制备成对映体形式的手性辅助DIOZ,可以高收率回收。