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

<p>The asymmetric benzylation of methyl 4-oxo-3-piperidinecarboxylate has been investigated, and methyl (<i>R</i>)-1,3-dibenzyl-4-oxopiperidine-3-carboxylate (<b>3c</b>) was obtained by using a phase-transfer catalyst <i>O</i>-allyl-<i>N</i>-9-anthracenemethyl-cindexnine bromide (<b>1k</b>). 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.</p>