title: N-heterocyclic carbene catalyzed formal [3+2] annulation reaction of enals: an efficient enantioselective access to spiro-heterocycles.
abstract: A highly enantioselective N-heterocyclic carbene (NHC) catalyzed formal [3+2] annulation of α,β-unsaturated aldehydes with azaaurones or aurone generating spiro-heterocycles has been developed. The protocol represents a unique NHC-activation-based approach to access spiro-heterocyclic derivatives bearing a quaternary stereogenic center with high optical purity (up to 95% ee).
authors.affiliation: Westfälische Wilhelms-Universität Münster, Organisch-Chemisches Institut, Corrensstrasse 40, 48149 Münster (Germany) http://www.uni-muenster.de/Chemie.oc/glorius/
authors.forename: Chang
authors.initials: C
authors.lastname: Guo
authors.forename: Michael
authors.initials: M
authors.lastname: Schedler
authors.forename: Constantin G
authors.initials: CG
authors.lastname: Daniliuc
authors.forename: Frank
authors.initials: F
authors.lastname: Glorius
keywords: N-heterocyclic carbenes; asymmetric synthesis; enals; organocatalysis; spiro-heterocycles