Aryl Radical Cyclizations onto Enamine Double Bonds

Article abstract of DOI:10.1021/jo00060a030

Aryl radicals from N-alkyl-N-(2-bromobenzyl)-1-cyclohexenylamine 2 and N-alkyl-N-(2-bromobenzyl)cyclopentenylamine 11 cyclize readily onto the enamine double bond by 6-endo and 5-exo closure.In the case of 2, 6-endo cyclization is the major pathway; however, the 6-endo to 5-exo ratio is dependent upon the N-alkyl substituent.In both cases, the dominant isomer from 6-endo cyclization is the cis isomer.For 2a in toluene, values of k_6-endo and k_5-exo at 80 deg C were 4.6 x 10⁸ s^-1 and 1.5 x 10⁸ s^-1, respectively.