Organocatalytic Asymmetric Synthesis of Functionalized 4H-Chromenes via a One-Pot Domino Michael-Hemiacetalization and Dehydration Sequence
作者:Dieter Enders、Gregor Urbanietz、Gerhard Raabe
DOI:10.1055/s-0030-1260017
日期:2011.6
A one-pot thiourea-catalyzed enantioselective synthesis of polyfunctionalized 4H-chromenes via a domino Michael-hemiacetalization reaction and subsequent dehydration is reported. Starting from 2-nitrovinylphenols and β-keto esters, the new protocol affords the 4H-chromenes bearing a variety of functional groups with good to excellent yields (76-95%) and enantioselectivities ranging from 30-99% ee.
据报道,通过多米诺骨牌迈克尔-半缩醛化反应和随后的脱水,一锅硫脲催化的对映选择性合成多官能化的4 H-色烯。从2-硝基乙烯基苯酚和β-酮酸酯开始,新方案提供了带有各种官能团的4 H-色烯,具有良好至优异的产率(76-95%),对映选择性为30-99%ee。根据所使用的麻黄碱或伪麻黄碱基硫脲催化剂,两种对映体均可随意获得。 有机催化-级联反应-硫脲-一锅法-4 H-色烯