Enantioselective synthesis of spirocyclohexadienones by NHC-catalyzed formal [3+3] annulation reaction of enals

TitleEnantioselective synthesis of spirocyclohexadienones by NHC-catalyzed formal [3+3] annulation reaction of enals
Publication TypeJournal Article
Year of Publication2016
AuthorsYetra, SReddy, Mondal, S, Mukherjee, S, Gonnade, RG, Biju, AT
JournalAngewandte Chemie-International Edition
Volume55
Issue1
Pagination268-272
Date PublishedJAN
ISSN1433-7851
Keywordsannulation reactions, asymmetric catalysis, N-heterocyclic carbenes, organocatalysis, spiro compounds
Abstract

The enantioselective synthesis of pyrazolone-fused spirocyclohexadienones was demonstrated by the reaction of alpha,beta-unsaturated aldehydes with alpha-arylidene pyrazolinones under oxidative N-heterocyclic carbene (NHC) catalysis. This atom-economic and formal [3+3] annulation reaction proceeds through a vinylogous Michael addition/spiroannulation/dehydrogenation cascade to afford spirocyclic compounds with an all-carbon quaternary stereocenter in moderate to good yields and excellent ee values. Key to the success of the reaction is the cooperative NHC-catalyzed generation of chiral alpha,beta-unsaturated acyl azoliums from enals, and base-mediated tandem generation of dienolate/enolate intermediates from pyrazolinones.

DOI10.1002/anie.201507802
Type of Journal (Indian or Foreign)

Foreign

Impact Factor (IF)11.709
Divison category: 
Center for Material Characterization (CMC)
Organic Chemistry