Enantioselective Desymmetrizations of Diesters to Synthesize Fully Substituted Chiral Centers of 3,4-Dihydrocoumarins and Related Compounds

In this communication, a preparation of novel enantioenriched 1,4-dioxanones, 1,4-morpholinones and 3,4-dihydrocoumarins is described. The outlined procedure utilizes a desymmetrization strategy of prochiral diesters whereby a chiral phosphoric acid catalyzes an intramolecular lactonization to yield enantioenriched fully substituted chiral centers. This desymmetrization strategy yielded various lactones with excellent to moderate enantioselectivity and yields (12 examples up to 99% ee and 96% yield).