Peptide-catalyzed consecutive 1,6- and 1,4-additions of thiols to α,β,γ,δ-unsaturated aldehydesElectronic supplementary information (ESI) available: Experimental details, spectroscopic data, and copies of 1H and 13C NMR spectra and HPLC traces. See DOI: 10.1039/c4ob00565a

Regio- and enantioselective addition of thiols to α,β,γ,δ-unsaturated aldehydes was performed with a resin-supported peptide catalyst. It was shown that a 1,4-adduct was generated mainly at the initial stage of the reaction, and this was eventually converted to a thermodynamically stable 1,6- and 1,4-diadduct through retro-addition/addition reactions. Addition of thiols to 2,4-dienals catalyzed by a resin-supported peptide gave thermodynamically favorable 1,6- and 1,4-diadducts in an enantioselective manner.