The Cyclopropyl Group as a Neglected Donor in Donor-Acceptor Cyclopropane Chemistry

D-A cydopropanes bearing a simple, cydopropyl group as donor are shown to undergo a variety of [3+n]-cydaddition reactions (n = 2-4). This behavior contrasts sharply with that of common D-A cyclopropipes with aliphatic donors: Kinetic experiments demonstrate that, in terms of donor ability the cydopropyl substituent lies between electron-rich and electron-neutral aryl donors.