Doubly stereocontrolled asymmetric Michael addition of acetylacetone to nitroolefins promoted by an isosteviol-derived bifunctional thiourea
作者:Zhi-wei Ma、Yu-xia Liu、Li-juan Huo、Xiang Gao、Jing-chao Tao
DOI:10.1016/j.tetasy.2012.03.020
日期:2012.4
A novel class of chiral bifunctionalthioureas bearing a chiral lipophilic beyerane scaffold and a tertiary amino group was designed and prepared. The thioureas were proven to be effective for catalyzing the doubly stereocontrolled asymmetricMichaeladdition between acetylacetone and nitroolefins. The corresponding adducts were obtained in high yields (up to 95%) and with good to excellent enantioselectivities
Chiral amine-squaramide is a kind of effective hydrogen bond donor bifunctional catalyst to promote many asymmetric transformations. In this paper, novel chiral tertiary amine-squaramide derived from the natural product of the stevioside was developed and applied into the asymmetric Michaeladdition of acetylacetone to nitroolefins. This asymmetric reaction performed well, and a series of enantiomerically