Short synthesis of methylenecyclopentenones by intermolecular Pauson-Khand reaction of allyl thiourea

N,N,N′-Trimethylallylthiourea promotes the intermolecular Pauson-Khand reaction with alkynes in the presence of Co2(CO)8 and moderate pressure of CO followed by thiourea elimination allowing the formation of methylenecyclopentenone derivatives.