MALONATE RADICAL CYCLIZATIONS OF METHYLENECYCLOPROPANE DERIVATIVES

Cyclisations of various methylenecyclopropyl substituted malonate radi cals have been studied. Radicals derived from malonates 4 and 9 underw ent exclusive 5-exo cyclisation onto the methylenecyclopropane alkene, followed by opening of the resulting cyclopropylmethyl radical, to gi ve methylenecyclohexane products. Radicals derived from malonates 5 an d 10 largely gave bicyclo[1.5.0]octane products, in good yields, as a result of 7-endo cyclisation. Cyclisation of the radical derived from malonate 11 gave a bicyclo[1.5.0]nonane derivative in 31% yield, as a result of an 8-endo cyclisation.