prepared from crotonamide 5 (Scheme 2). Particularly hemiacetal 7, but also 6 and the ‘dimer’ 8 (obtained from 7) may serve as homochiral auxiliaries. The structure of 8 was determined by X-ray analysis. By arenesulfonyl halides, tryptimines 12–14 of 4 were diastereoselectively transformed into spirotricycles 15–17 and 19.
由
巴豆酰胺5(方案2)制备
乙醛酰胺4的粗
水合物6和结晶
半缩醛7。特别是
半缩醛7,但也可以是6和'二聚体' 8(由7获得)可以用作同手性助剂。通过X射线分析确定8的结构。由
芳烃磺酰基卤化物,tryptimines 12-14的4进行非对映选择性转化为spirotricycles 15-17和19。