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Organocatalytic Asymmetric Annulation of ortho ‐Alkynylanilines: Synthesis of Axially Chiral Naphthyl‐C2‐indoles
Author(s) -
Peng Lei,
Li Kai,
Xie Chuandong,
Li Shan,
Xu Da,
Qin Wenling,
Yan Hailong
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201908961
Subject(s) - annulation , chemistry , enantioselective synthesis , organocatalysis , combinatorial chemistry , catalysis , aryl , stereochemistry , organic chemistry , alkyl
A chiral Brønsted base catalyzed asymmetric annulation of ortho ‐alkynylanilines has been developed to access axially chiral naphthyl‐C2‐indoles via vinylidene ortho ‐quinone methide (VQM) intermediates. This strategy provides a unique organocatalytic atroposelective route to axially chiral aryl‐C2‐indole skeletons with excellent enantioselectivity and functional‐group tolerance. This transformation was applicable to decagram‐scale preparation (50.0 g) with perfect enantioselectivity through simple recrystallization. Moreover, the utility of this reaction was demonstrated by a variety of transformations towards chiral naphthyl‐C2‐indoles for a series of carbon–heteroatom bond formations. Furthermore, the prepared axially chiral naphthyl‐C2‐indoles were applied as a chiral skeleton for organocatalytic aza‐Baylis–Hillman reaction and asymmetric formal [4+2] tandem cyclization to give the corresponding adducts in high yields with improved enantioselectivity and diastereoselectivity.