Influence of Michael Acceptor Stereochemistry on Intramolecular Morita−Baylis−Hillman Reactions
作者:Wen-Dong Teng、Rui Huang、Cathy Kar-Wing Kwong、Min Shi、Patrick H. Toy
DOI:10.1021/jo051802l
日期:2006.1.1
A study of the effect of Michael acceptor stereochemistry on the efficiency of intramolecular Morita−Baylis−Hillman (MBH) reactions has been performed. The reactions were catalyzed by a phosphine, and the reaction substrates studied were enones containing a pendant aldehyde moiety attached at the β-position of the alkene group. In all cases examined with PPh3 as the catalyst, cyclization substrates
进行了迈克尔受体立体化学对分子内Morita-Baylis-Hillman(MBH)反应效率的影响的研究。该反应由膦催化,所研究的反应底物是烯键,该烯键含有连接在烯基β位的醛侧基。在以PPh 3为催化剂检查的所有情况下,在相同反应条件下,具有(Z)-烯烃立体化学的环化底物比E异构体底物提供所需产物的产率高得多。当使用聚合物负载的膦催化剂时,也是如此。虽然两种烯烃异构体都能提供相同的产物,但在平行反应中,Z异构体的产率是相应的E异构体的2.5-8.5倍。有人提出,空间效应是这种反应性显着差异的可能来源。β-取代基与吸电子取代基是顺式的底物比其反式对应物更易于与亲核催化剂反应。这些发现有望用于合成中间体的设计,因为分子内MBH反应正越来越多地用于制备复杂的合成靶标。