Cyclopropanation of α,β-Unsaturated Aldehydes with a Supported Peptide

Key words

resin-supported peptides - asymmetric cyclopropanation - α,β-unsaturated aldehydes

Significance

The amphiphilic resin-supported peptide 1 catalyzed the diastereo- and enantioselective cyclopropanation of aromatic α,β-unsaturated aldehydes 2 with dimethylphenacylsulfonium bromide in the presence of NaHCO₃ to give the corresponding cyclopropanes 3 in 83–88% yield with 98–99% ee and 92–97% diastereoselectivity (9 examples, eq. 1). In the formation of 3g, the catalyst was recovered by filtration and reused five times without significant loss of its catalytic performance (1^st reuse: 87% yield, 99% ee, 94% diastereoselectivity; 5^th reuse: 83% yield, 99% ee, 95% diastereoselectivity).

Comment

The authors have previously reported the preparation of a series of amphiphilic resin-supported peptides and their application to asymmetric hydrogenation (Org. Lett. 2008, 10, 2035), asymmetric Friedel–Crafts-type alkylation (Adv. Synth. Catal. 2012, 354, 1280) and asymmetric Michael addition (Angew. Chem. Int. Ed. 2012, 51, 12786).