化学
位阻效应
催化作用
炔烃
立体化学
轴对称性
组合化学
有机化学
结构工程
工程类
作者
Ruijie Mi,Haohua Chen,Xukai Zhou,Nan Li,Danqing Ji,Fen Wang,Yu Lan,Xingwei Li
标识
DOI:10.1002/anie.202111860
摘要
Axially chiral open-chain olefins represent an underexplored class of chiral platform. In this report, two classes of tetrasubstituted axially chiral acyclic olefins have been accessed in excellent enantioselectivity and regioselectivity via C-H activation of (hetero)arenes assisted by a migratable directing group en route to coupling with sterically hindered alkynes. The coupling of indoles bearing an N-aminocarbonyl directing group afforded C-N axially chiral acrylamides with the assistance of a racemic zinc carboxylate additive. DFT studies suggest a β-nitrogen elimination-reinsertion pathway for the directing group migration. Meanwhile, the employment of N-phenoxycarboxamide delivered C-C axially chiral enamides via migration of the oxidizing directing group. Experiments suggest that in both cases the (hetero)arene substrate adopts a well-defined orientation during the C-H activation, which in turn determines the disposition of the alkyne in migratory insertion. Synthetic applications of representative chiral olefins are demonstrated.
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