Kinetics and regioselectivity of ring opening of 1-bicyclo[3.1.0] hexanylmethyl radical

Article abstract of DOI:10.1021/jo702010v

(Chemical Equation Presented) Rate constants for the rearrangement of 1-bicyclo[3.1.0]-hexanylmethyl radical (2) to 3-methylenecyclohexenyl radical (3) and 2-methylenecyclopentyl-1-methyl radical (1) were measured using the PTOC-thiol competition method. The ring-expansion pathway is described by the rate equation, log(k/s^-1) = (12.5 ± 0.1) - (4.9 ± 0.1)/θ; the non-expansion pathway is described by log(k/s^-1) = (11.9 ± 0.6) - (6.9 ± 0.8)/θ. Employing the slower trapping agent, tri-n-butylstannane, favors methylenecyclohexane over 2-methyl-methylenecyclopentane by more than 120:1 at ambient or lower temperatures.