Dinuclear zinc catalyzed asymmetric tandem Michael addition/acetalization reactions of cyclic diketones and β,γ-unsaturated α-ketoesters

The dinuclear zinc-ProPhenol complex is applied as efficient catalyst in the highly stereoselective tandem Michael addition/acetalization reactions of cyclic 1,3-diketones and β,γ-unsaturated α-ketoesters. A variety of substrates are well-tolerated, and a broad range of synthetically and pharmaceutically useful chiral chromene derivatives are directly produced in good yields of up to 96% and good enantioselectivities of up to 96% ee.