Ligand-Promoted Reactivity of Alkenes in Dehydrogenative Heck Reactions of Furans and Thiophenes

4,5-Diazafluorenone was found to promote the dehydrogenative Heck reaction of furans and thiophenes with hindered alkenes. High stereoselectivity was achieved in the synthesis of beta,beta-diaryl alpha,beta-unsaturated alkenes. A mechanism, based on ESI-MS studies, kinetic experiments, andcompetitive reactions, was proposed. The ligand influences C-H bond activation, insertion of the alkenes, the stereo-determining step, and the aerobic regeneration of the catalyst.