Synthesis of 1,2-Disubstituted Cyclopentenes by Palladium-Catalyzed Reaction of Homopropargyl-Substituted Dicarbonyl Compounds with Organic Halides via 5-Endo-Dig Cyclization

Palladium catalysts with bulky biaryl phosphine ligands allow homopropargyl-substituted dicarbonyl compounds to undergo intramolecular addition via a rare 5-endo-dig pathway. C–C bond forming reductive elimination follows the addition to introduce alkenyl and alkynyl as well as aryl groups by using the corresponding organic halides. The cyclization is versatile enough to be applicable to the synthesis of highly substituted dihydropyrrole and a fused tricyclic compound.