Regioselective ring-opening and dimerisation of methyl 3,3-dimethylcyclopropenecarboxylate
Abstract
Methyl 3,3-dimethylcyclopropenecarboxylate (1) undergoes dimerisation at 0 to –20 °C over a period of several days to give the bicyclobutane (7), which in turn rearranges to the triene (2). In the presence of an alkene no intermediates can be trapped. Dimerisation of (1) in the presence of copper(I) iodide leads to the tricyclohexane (10; R = CO2Me). X-Ray structure determinations are reported for compounds (2) and (10; R = CO2H).