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A Cooperative N‐Heterocyclic Carbene/Chiral Phosphate Catalysis System for Allenolate Annulations
Author(s) -
Lee Anna,
Scheidt Karl A.
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201403446
Subject(s) - enantioselective synthesis , annulation , catalysis , carbene , chemistry , brønsted–lowry acid–base theory , combinatorial chemistry , organocatalysis , phosphate , organic chemistry , stereochemistry
The highly enantioselective NHC‐catalyzed [3+2] annulation reaction with α,β‐alkynals and α‐ketoesters has been developed. A new mode of cooperative catalysis involving the combination of a chiral Brønsted acid and a C 1 ‐symmetric biaryl saturated‐imidazolium precatalyst was required to generate the desired γ‐crotonolactones in high yields and levels of enantioselectivity.