(90:10 dr) and (−)-11 (85:15 dr) were prepared from the alkylation–reduction sequence of a common α-amino nitrile (+)-4 derivative that has been conveniently prepared by anodic cyanation. Elaboration of the pyrrolidine ring of the title compound was cleanly achieved by two efficient ring closures methods involving (a) the displacement of a halogen atom and (b) the formation of a cyclic iminium cation to
描述了
四氢异喹啉(THIQ)
生物碱香晶A的两种对映体的立体选择性会聚全合成。THIQ前体(-)- 6(90:10 dr)和(-)- 11(85:15 dr)是根据一种常见的α-
氨基腈(+)- 4衍
生物的烷基化还原序列制备的通过阳极
氰化方便地制备。标题化合物的
吡咯烷环的精制是通过两种有效的闭环方法完成的,其中包括(a)取代卤素原子和(b)形成环亚
氨基阳离子,从而获得90%的(-)-crispine A和85%的收率。含有1当量(-)-D
BTA的对映体富集(-)-crispine A(90:10 er)的结晶得到
酒石酸盐(-)- 14(≥98:2 dr),产率为81%。简单地从
酒石酸盐(-)- 14的X射线数据检查中可以得出(-)crispine A的绝对S构型。同样,在七个后处理步骤中以30%的总收率制备了天然(+)crispine A,并用(+)-D
BTA相互结晶,得到了≥98:2 dr的对映体
酒石酸盐(+)-