Asymmetric Pauson-Khand-type reactions of 1,6-enynes using formaldehyde as a carbonyl source by cooperative dual rhodium catalysis

A dual neutral-cationic rhodium(I)-catalyzed Pauson-Khand-type reaction using formaldehyde as a carbonyl source is described. The simultaneous use of neutral rhodium(I) and cationic rhodium(I) complexes is required for efficient cooperative catalysis, which involves the neutral rhodium(I)-catalyzed decarbonylation of formaldehyde and the cationic rhodium(I)-catalyzed cyclocarbonylation of 1,6-enynes using the resulting carbonyl moiety.