Desymmetrization of Cyclopentenediones via Organocatalytic Cross-Dehydrogenative Coupling

An enantioselective synthesis of cyclopentenediones bearing a pyrazole unit has been achieved through an organocatalytic Michael addition/oxidation process. This desymmetrization reaction led to the desired pyrazole-cyclopentenediones with high yield and good enantioselectivities. The postulated cross-dehydrogenative coupling-mechanism has been investigated via preliminary control experiments.