Access to Spirocyclic Benzothiophenones with Multiple Stereocenters via an Organocatalytic Cascade Reaction

The present report describes an organocatalytic
cascade reaction
between 2-alkylidene benzo­[b]­thiophenone derivatives
and enones in the presence of the Cinchona alkaloid
amine. Spirobenzothiophenonic cyclohexane derivatives containing three
stereocenters were prepared via one-step synthesis in yields ranging
from 88 to 96% and in enantioselectivities (enantiomeric excess (ee))
ranging from 85 to 97%, with diastereoselectivities of approximately
14/2/1. Therefore, this method provides an efficient route for the
synthesis of a new class of optically active 2-spirobenzothiophenones.

本报道描述了一类以金鸡纳碱胺（Cinchona alkaloid amine）为催化剂的有机催化级联反应，该反应的底物为2-亚烷基苯并[b]噻吩酮衍生物与烯酮。通过一步合成法制备得到了含有三个手性中心的螺苯并噻吩酮环己烷衍生物，其产率介于88%至96%之间，对映选择性（对映体过量值(ee)）为85%至97%，非对映选择性约为14/2/1。因此，该方法为一类新型光学活性2-螺苯并噻吩酮类化合物的合成提供了高效途径。