Pauson—Khand‐Type Reaction Mediated by Rh(I) Catalysts.

Abstract

Cocyclization of alkynes, alkenes, and carbon monoxide by transition metals (known as Pauson-Khand reaction when dicobalt octacarbonyl complexes are used) has been accepted as one of the most powerful tools in the synthesis of cyclopentenones. Despite sig- nificant progress in the various aspects of the reaction, we still needed new catalysts to expand the scope of the reaction further. We found rhodium (I) catalysts, e.g., RhCl(PPh 3 ) 3 , trans-RhCl(CO)(PPh 3 ) 2 , RhCl- (CO)(dppe), and trans-(RhCl(CO)(dppp)) 2 , were also effective for this transformation. The scope and the efficiencies of the reaction could be tuned and expanded by the choice of cat- alysts. For example, we were able to devise an enantioselective PK-type reaction and a tan- dem strategy employing two catalysts in one pot. These results will be presented.