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DOI: 10.1055/s-2006-942417
Development of a Catalytic Asymmetric Variant of Hoppe’s O-Alkyl Carbamate Deprotonation Methodology
Publikationsverlauf
Received
24 March 2006
Publikationsdatum:
12. Juni 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.
Key words
asymmetric catalysis - synthesis - organometallic reagents - chiral bases - diamines