Enantioselective Iodolactonization of Disubstituted Olefinic Acids Using a Bifunctional Catalyst

The enantioselective iodolactonizations of a series of diversely substituted olefinic carboxylic acids are promoted by a BINOL-derived, bifunctional catalyst. Reactions involving 5-alkyl- and 5-aryl-4(<i>Z</i>)-pentenoic acids and 6-alkyl- and 6-aryl-5(<i>Z</i>)-hexenoic acids provide the corresponding γ- and δ-lactones having stereogenic C–I bonds in excellent yields and >97:3 er. Significantly, this represents the first organocatalyst that promotes both bromo- and iodolactonization with high enantioselectivities. The potential of this catalyst to induce kinetic resolutions of racemic unsaturated acids is also demonstrated