Electrophilic cleavage of cyclopropanes. The areneselenenylation of tetracyclo[3.2.0.02,7.04,6]heptane (quadricyclene)1,2

Abstract

The reaction of benzeneselenenyl chloride with tetracyclo[3.2.0.02,7.04,6]heptane (quadricyclene) yields, under conditions of kinetic control, adducts of both 1,3- and conjugative 1,6-addition, the latter being formed preferentially. Electrophilic cleavage of the cyclopropane ring occurs by both retention and inversion of configuration. In agreement with the known propensity for bond cleavage in this system only the C5—C6 and/or the C1—C7 bonds are broken. The rate of cyclopropane ring cleavage is found to follow second order kinetics, first order in quadricyclene and first order in selenenyl chloride; kobs = 1850 vs. 12 300 dm3 mol−1 s−1 for bicyclo[2.2.1]hepta-2,5- diene at 24.5 °C in methylene chloride solvent. The use of nucleophilic solvents such as HOAc, CH3OH, and CH3CN gives products of solvent-incorporation, preferentially via 1,3-addition.