Synthesis 2006(13): 2233-2241  
DOI: 10.1055/s-2006-942417
PAPER
© Georg Thieme Verlag Stuttgart · New York

Development of a Catalytic Asymmetric Variant of Hoppe’s O-Alkyl Carbamate Deprotonation Methodology

Matthew J. McGrath, Peter O’Brien*
Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
Fax: +44(1904)432516; e-Mail: paob1@york.ac.uk;
Further Information

Publication History

Received 24 March 2006
Publication Date:
12 June 2006 (online)

Abstract

The optimisation of a ligand-exchange approach to catalytic asymmetric deprotonation of O-alkyl carbamates and subsequent electrophilic trapping (the ‘Hoppe reaction’) is presented. The method uses s-BuLi and sub-stoichiometric amounts of a chiral diamine [(-)-sparteine or the (+)-sparteine surrogate] in conjunction with an achiral ‘regenerating’ diamine (bisisopropyl bispidine) for the deprotonation and proceeds with good yields (up to 84%) and high enantioselectivity (up to 94:6 er). The first applications of this catalytic asymmetric deprotonation methodology in natural product synthesis are also described.