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Conjugate Umpolung of β,β‐Disubstituted Enals by Dual Catalysis with an N‐Heterocyclic Carbene and a Brønsted Acid: Facile Construction of Contiguous Quaternary Stereocenters
Author(s) -
Li JunLong,
Sahoo Basudev,
Daniliuc ConstantinG.,
Glorius Frank
Publication year - 2014
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.201405178
Subject(s) - umpolung , stereocenter , carbene , conjugate , stereoselectivity , reactivity (psychology) , steric effects , annulation , chemistry , brønsted–lowry acid–base theory , catalysis , combinatorial chemistry , organocatalysis , stereochemistry , organic chemistry , enantioselective synthesis , mathematics , medicine , mathematical analysis , alternative medicine , pathology , nucleophile
A sterically hindered homoenolate has been generated by the NHC‐catalyzed conjugate umpolung of β,β‐disubstituted enals and successfully employed in a facile stereoselective annulation with isatins. The strategy provides efficient access to spirocyclic oxindoles bearing two highly congested contiguous quaternary carbon centers. The use of a Brønsted acid cocatalyst was found to be crucial for guaranteeing both excellent reactivity and high stereoselectivity.