Chemistry: A European Journal 2008-01-01

Selective mono- and 1,2-difunctionalisation of cyclopentene derivatives via Mg and Cu intermediates.

Christina Despotopoulou, Richard C Bauer, Arkady Krasovskiy, Peter Mayer, Jeffrey M Stryker, Paul Knochel

Index: Chemistry 14 , 2499, (2008)

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Abstract

A single Br/Mg exchange of 1,2-dibromocyclopentene with iPrMgCl LiCl provides the corresponding beta-bromocyclopentenylmagnesium reagent, which can then be reacted with various electrophiles (yields: 65-82 %). In the presence of a secondary alkylmagnesium halide and Li2CuCl4 (2 mol %), these 2-bromoalkenylmagnesium compounds undergo bromine substitution and can then further react with electrophiles to give 1,2-difunctionalised cyclopentenes (63-79 %). The mechanism of this process is discussed.