Enhancement of the reactivity of photochemically generated enediynes via keto-enol tautomerization.
Ten- and eleven-membered-ring cyclic enediynes that possess a carbonyl group in a beta position with respect to the one of acetylenic termini undergo very facile cycloaromatization at ambient temperatures. Kinetic data and deuterium-labeling experiments indicate that this reaction proceeds via rate-determining tautomerization to the allene-eneyne form followed by very rapid Myers-Saito cyclization.