4‐Amino‐TEMPO as N‐Nucleophile in Palladium‐Catalyzed Aminocarbonylation

Palladium-catalyzed aminocarbonylation of iodobenzene and iodoalkenes (1-iodocyclohexene, alpha-tert-butyl-1iodocyclohexene, alpha-iodostyrene, 17-iodoandrost-16-ene) was carried out using a free radical (4-amino-TEMPO) for the first time. Its reduced form (4-amino-2,2,6,6-tetramethylpiperidine) was also used as N-nucleophile. The free radical was partially reduced under aminocarbonylation conditions; however, the isolation of carbonylated products bearing a stable radical moiety was successfully accomplished. It was proved that the reduction of the 1-oxyl functionality took place to higher extent when more severe conditions (40 bar CO pressure) were used. The mixture of carboxamide and 2-ketocarboxamide products was obtained using iodobenzene because of single and double carbon monoxide insertion, respectively. In turn, carboxamide derivatives were formed exclusively when iodoalkenes were used as substrates.