Trapping of the 6,6-Dimethylbicyclohept-2-yl Free Radical by SH2 Reaction upon Peracid

Article abstract of DOI:10.1021/jo00369a006

The free radical 6,6-dimethylbicyclo<3.1.1>hept-2-yl (7) has been obtained by decarboxylation of cis- or trans-6,6-dimethylbicyclo<3.1.1>heptane-2-peroxycarboxylic acids (6a and 6b). 7 trapped by reaction with the initial peracid gave a stereochemical mixture of α- and β-nopinol (8a and 8b).The ratio 8b/8a is around 12, independent of the initial peracid 6a or 6b and its initial concentrations.This value is mainly due to the steric effect of one of the methyl groups branched on C⁷ in 7.The structure of 7 is discussed.By a competitive reaction 7 undergoes ring opening to afford 2-(3-cyclohexenyl)-2-propyl free radical (9) which by reaction upon peracid leads to 2-(3-cyclohexenyl)-2-propanol (10). 7 was successfully trapped because its reaction with peracid is rapid enough.The ratio of the two alcohols 8/10 leads to an estimation of 1*10₆ M_-1 s_-1 for the rate constant of the reaction of 7 with peracids