RHODIUM-CATALYZED CARBON-CARBON BOND FORMATION

Recent aspect of rhodium-catalyzed reactions is briefly surveyed from the view point of the carbon-carbon bond formation which is attained under almost neutral conditions. Topics focused here are carbene transfer, [4 +2] cyclocoupling, aldol and Michael type coupling, and carbonylations in which a certain type of rhodium complex behaves efficiently. A unique character of rhodium is demonstrated in the field of incorporation of CO, especially silylformylation which is accomplished by a combined use of triorganosilane, CO, and a rhodium complex in the presence of acetylenic compounds, aldehydes, or epoxides, alpha-Silylmethylene-beta-lactones and lactams are readily derived from the corresponding propargyl alcohol and propargylamine, respectively, under analogous procedure in the presence of a small amount of DBU. Bicyclo [3.3.0] octenone frameworks are also constructed by cyclocarbonylation of 1,6-diyne derivatives.