STUDIES ON MERCURY(II)-MEDIATED OPENING OF BICYCLOPROPANE AND TERCYCLOPROPANE ARRAYS

The first examples of the mercury(II)-mediated ring opening of bicyclo propane and tercyclopropane arrays have been investigated. The presenc e of an adjacent cyclopropyl group dramatically increased the rate of the mercury-mediated opening of the first cyclopropane in a cyclopropa ne array. In contrast to the mercury-mediated ring opening of monocycl opropanes which usually undergo a concerted ring-opening mechanism, el ectrophilic openings of cyclopropane arrays occurred through a stabili zed, free carbocation. Excellent regio- and stereoselectivities were o bserved in the mercury-mediated intramolecular openings of the second cyclopropanes in the cyclopropane arrays, giving rise to the formation of enantiomerically pure, highly substituted tetrahydrofurans.