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Stereoselective Construction of Halogenated Quaternary Carbon Centers by Brønsted Base Catalyzed [4+2] Cycloaddition of α‐Haloaldehydes
Author(s) -
Li Qiang,
Zhou Liang,
Shen XuDong,
Yang KaiChuan,
Zhang Xiang,
Dai QingSong,
Leng HaiJun,
Li QingZhu,
Li JunLong
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201711813
Subject(s) - stereocenter , cycloaddition , stereoselectivity , halogen , chemistry , halogenation , catalysis , bifunctional , quaternary carbon , brønsted–lowry acid–base theory , base (topology) , bicyclic molecule , carbon fibers , combinatorial chemistry , stereochemistry , organic chemistry , medicinal chemistry , enantioselective synthesis , alkyl , materials science , mathematics , mathematical analysis , composite number , composite material
Asymmetric construction of halogenated quaternary carbon centers under mild reaction conditions remains challenging. Reported here is an unprecedented and highly stereoselective Brønsted base catalyzed [4+2] cycloaddition between either α‐chloro‐ or α‐bromoaldehydes and cyclic enones. The key intermediate, an α‐halogenated enolate, is susceptible to dehalogenation and can be stabilized and stereochemically controlled using bifunctional tertiary amines. This method provides facile access to a collection of optically pure bicyclic dihydropyrans having three contiguous stereocenters, including a halogen‐bearing quaternary carbon center. Of note, the product can be transformed in situ into densely functionalized spirocyclopropanes in a highly efficient and stereoselective manner.