Broad-Spectrum Enantioselective Diels−Alder Catalysis by Chiral, Cationic Oxazaborolidines
作者:Do Hyun Ryu、Thomas W. Lee、E. J. Corey
DOI:10.1021/ja027468h
日期:2002.8.1
catalysts for Diels-Alder addition of cyclopentadiene to a wide variety of dienophiles. Adducts have been obtained in excellent yield and enantioselectivity from alpha,beta-unsaturated esters, lactones, and cyclic ketones. The absolute facial selectivity for each of these substrates follows a common pattern which differs from that observed with alpha,beta-enals. The different reaction channels can be
阳离子手性路易斯酸 1 和 2 由相应的中性恶唑硼烷的三氟甲磺酸质子化产生,可作为环戊二烯与各种亲二烯体的 Diels-Alder 加成反应的优良催化剂。已从 α、β-不饱和酯、内酯和环酮以优异的产率和对映选择性获得加合物。这些基质中每一种的绝对面部选择性遵循一个共同的模式,该模式不同于用 alpha,beta-enals 观察到的模式。可以根据通过复合物 3(对于 α、β-烯醛)和 4(对于 α、β-烯酮和酯)的途径来理解不同的反应通道。