Pathways of Pd-catalyzed cyclopropanation of tetrahydroindene with diazomethane

The Pd-catalyzed cyclopropanation of 3a,4,7,7a-tetrahydro-1H-indene with diazomethane unexpectedly affords monoand dicyclopropanation products in good yields, the cyclopentene double bond being approximately three times more reactive than the cyclohexene one. In contrast, similar independent competitive cyclopropanation of a cyclopentene–cyclohexene mixture has shown that cyclohexene exhibits an abnormally low reactivity differing by about two orders of magnitude.