5-Azahexenoyl radicals cyclize via nucleophilic addition to the acyl carbon rather than 5-exo homolytic addition at the imine

Molecular orbital calculations predict that the 5-azahexenoyl radical ring closes via nucleophilic addition to the acyl carbon to afford the 5-exo product; CCSD(T)/cc-pVDZ//BHLYP/cc-pVDZ calculations predict energy barriers of 36.1 and 46.9 kJ mol−1 for the exo and endo cyclization modes of the 5-azahexenoyl radical, respectively.