PHOTO ELECTRO AND THERMAL CARBONYLATION OF ALKYL IODIDES IN THE PRESENCE OF GROUP-7 AND 8-10 METAL-CARBONYL CATALYSTS

Various transition-metal complexes including Group 7 and 8-10 metal carbonyls are highly active catalyst precursors for the photochemical carbonylation of alkyl iodides having beta-hydrogens on saturated Sp3-carbons at room temperature under 1 atm of carbon monoxide. Primary, secondary and tertiary alkyl iodides are smoothly carbonylated by this catalyst system without beta-hydride elimination (dehydrohalogenation) to give the corresponding esters or amides in high yields. In employment of Mn2(CO)10 as a catalyst, electrochemical carbonylation of alkyl iodides also occurred via generation of an anionic manganese carbonyl intermediate. Actually, anionic manganese carbonyl complexes (pentacarbonylmanganates) showed high catalytic activity for thermal carbonylation of alkyl iodides at room temperature-under 1 atm of carbon monoxide without photo-irradiation and electrolysis. Mechanistic studies were performed with kinetics and ESR and it was suggested that the present photo-, electro- and thermal carbonylation would involve a non-chain radical mechanism.