Department of Chemistry, Indian Institute of Science Education and Research Bhopal , Bhopal By-pass Road, Bhauri, Bhopal 462066, India.
Org Lett. 2017 Nov 3;19(21):5872-5875. doi: 10.1021/acs.orglett.7b02862.
Chemoselective 1,2- and 1,4-addition of malononitriles to ortho-formyl chalcones using cinchona alkaloid based bifunctional chiral organocatalysts has been shown by tuning the electronic nature of the malononitriles. Alkyl (hard) malononitriles undergo an asymmetric 1,2-addition followed by oxa-Michael reaction cascade to afford 1,3-disubstituted isobenzofurans with high enantio- and diastereoselectivity. Aryl (soft) malononitriles proceed through 1,4-addition followed by an aldol reaction cascade to provide indanols, having three consecutive stereocenters, in good yields and with good to excellent enantio- and diastereoselectivites.
使用金鸡纳生物碱衍生的双功能手性有机催化剂，通过调节丙二腈的电子性质，可以实现丙二腈对邻甲酰基查耳酮的化学选择性 1,2-和 1,4-加成。烷基（硬）丙二腈经历不对称 1,2-加成，然后进行 oxa-Michael 反应级联，以高对映选择性和非对映选择性得到 1,3-二取代异苯并呋喃。芳基（软）丙二腈通过 1,4-加成，然后进行 aldol 反应级联，以良好的收率和良好到优异的对映选择性和非对映选择性得到具有三个连续立体中心的茚满醇。
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