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

Abstract

Palladium‐catalyzed aminocarbonylation of iodobenzene and iodoalkenes (1‐iodocyclohexene, 4‐tert‐butyl‐1‐iodocyclohexene, α‐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.