Asymmetric Alkylation Using Resin-Supported Peptide Catalysts

Significance

The PS-PEG supported N-terminal prolyl peptide 1 bearing a polyleucine moiety promoted the Friedel-Crafts-type alkylation of indoles and pyrroles 3 with α,β-unsaturated aldehydes 2 in aqueous THF to give the corresponding products 4 in 56-85% yield with 52-88% ee (6 examples). Catalyst 1 was recovered by simple filtration and reused five times without loss of catalytic activity and stereoselectivity for the formation of 4a (1^st-5^th reuse; 70-76% yield, 88-90% ee).