Cation-Directed Enantioselective N-Functionalization of Pyrroles

Dedicated to Prof. Steven V. Ley on the occasion of his 70^th birthday

Abstract

A catalytic enantioselective N-functionalization of pyrroles has been developed. Imines formed in situ via condensation underwent cation-directed cyclization with complete N-regioselectivity. The cyclized products were obtained with enantiomeric ratios up to 96:4 for aldimine substrates and up to 99:1 for trifluoromethyl ketimines. The reaction proceeds without an acidifying group on the pyrrole and offers a new approach to the generation of chiral nonracemic aminals.

Key words

pyrroles - phase-transfer catalysis - organocatalysis - asymmetric synthesis - chiral aminals

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