Rhodium Complex-Catalyzed Pauson−Khand-Type Reaction with Aldehydes as a CO Source

Abstract

With aldehydes as a CO source under solvent-free conditions, rhodium complex efficiently catalyzed an intramolecular carbonylative alkene−alkyne coupling (Pauson−Khand-type reaction) and various bicyclic enones were obtained in high yield. Experiments under argon flow and a ¹³C-labeling experiment suggested that almost no free carbon monoxide was generated in this reaction. When noncationic rhodium complex with chiral phosphine was used as a chiral catalyst, the reaction proceeded enantioselectively to give various chiral cyclopentenones in up to 90% ee under solvent-free conditions.