Enantioselective benzylation of methyl 4-oxo-3-piperidinecarboxylate with cinchona alkaloids phase-transfer catalysts

The asymmetric benzylation of methyl 4-oxo-3-piperidinecarboxylate has been investigated, and methyl (R)-1,3-dibenzyl-4-oxopiperidine-3-carboxylate (3c) was obtained by using a phase-transfer catalyst O-allyl-N-9-anthracenemethyl-cindexnine bromide (1k). This synthetic method has the advantages of cheap materials, mild reaction conditions and moderate enantioselectivity, and is useful for preparation of biologically active compounds containing a chiral 3-benzylpiperidine backbone.