New polymer-supported catalysts were developed by common synthetic polymer poly(vinylidene chloride)(PVDC) grafting with natural cinchona alkalicinchonine. Seven polyvinylidene chloride-bound catalysts were synthesized by cinchonine which activated by p-toluenesulfonyl chloride reacted with polyvinylidene chloridepolyamine resin. And they were tested in the challenging conjugate Michael addition between 1
3-dicarbonyl compounds and N -benzylmaleimide
forming quaternary carbon and tertiary carbon centers. After the investigation of solvent
amount of catalyst and temperature
the optimal catalyst PVDC-tetraethylenepentamine-cinchonine (PVDC-TEPA-CN) obtained good yield (80%)
excellent enantioselectivity (72%) and diastereoselectivity (80 ∶20) at the optimized reaction conditions which were toluene medium
10 mol% catalyst and room temperature. In addition
the catalyst which was applied to six kinds of challenging substrates had a wide scope of substrates
and it can be recovered and reused for at least 3 cycles without loss of its enantioselectivity.
关键词
辛可宁聚偏二氯乙烯负载不对称Michael反应相邻叔碳和季碳中心化合物
Keywords
Cinchona alkaloidsPVDC-supported catalystAsymmetric Michael reactionAdjacent quaternary and tertiary stereocenters