Catalytic Asymmetric Synthesis of Chiral Dihydrobenzofurans through a Formal [4+1] Annulation Reaction of Sulfur Ylides and In Situ Generated<i>ortho</i>-Quinone Methides
作者:Qing-Qing Yang、Wen-Jing Xiao
DOI:10.1002/ejoc.201601186
日期:2017.1.10
The first example of a catalytic asymmetric formal [4+1] annulation reaction between sulfur ylides and in situ generated ortho-quinone methides (o-QMs) is reported in this work. A C2-symmetric chiral urea was identified to be the best H-bonding catalyst, affording a wide range of chiral 2,3-dihydrobenzofurans in high yields and moderate enantioselectivities [70–98 % yields, up to 89:11 e.r. (enantiomeric
在这项工作中报道了硫叶立德与原位生成的邻醌甲基化物 (o-QMs) 之间的催化不对称形式 [4+1] 环化反应的第一个例子。一种 C2 对称手性尿素被认为是最好的 H 键合催化剂,可提供范围广泛的手性 2,3-二氢苯并呋喃,收率高,对映选择性适中 [70–98% 收率,高达 89:11 er )]。