COBALT-MEDIATED INTERMOLECULAR RADICAL ADDITIONS TO CARBON-TO-CARBON DOUBLE-BONDS LEADING TO NEW FUNCTIONALIZED ALKENES

Alkyl radicals generated by photolytic homolysis of cobalt salophen reagents, e.g. (6) and (15), are shown to add to activated carbon-to-carbon double bonds, i.e. ethyl acrylate, methyl vinyl ketone, acrylonitrile, and styrene, producing preparatively useful yields of new alkene products, viz. (9), (10), (12) and (14) [from (6)], and (16) [from (15)]. The reactions proceed via radical (Michael) additions, followed by 'dehydrocobaltation' from the presumed organocobalt intermediates (2) (Scheme 4). By use of this chemistry, in combination with the Schrauzer 'hydrocobaltation' reaction of alkenes, a new method for the cross-coupling reactions between two alkenes, leading to new functionalised alkenes, e.g. (24), (25), (26), (27), (28), and (29), is developed [Equation (2)].