Remarkable Enhancement of the Rate of the Intramolecular Morita–Baylis–Hillman Reaction by the Combination of a Nucleophilic Catalyst and 1,3‐Diphenyl‐2‐thiourea

The rate of the intramolecular Morita‐Baylis–Hillman (MBH) reaction is remarkably enhanced by the combination of catalytic amounts of a nucleophilic catalyst (4‐dimethylaminopyridine (DMAP), 4‐pyrrolidinopyridine (PPY), or PBu 3 ) and 1,3‐diphenyl‐2‐thiourea, and the desired MBH adducts are obtained in good to high yields within a few hours.