Two-Photon Photochemical Generation of Reactive Enediyne

Abstract
p-Quinoid cyclopropenone-containing enediyne precursor (1) has been synthesized by monocyclopropanation of one of the triple bonds in p-dimethoxy-substituted 3,4-benzocyclodeca-1,5-diyne followed by oxidative demethylation. Cyclopropenone 1 is stable up to 90 °C but readily produces reactive enediyne 2 upon single-photon (Φ300nm = 0.46) or two-photon (σ800nm = 0.5 GM) photolysis. The photoproduct 2 undergoes Bergman cyclization at 40 °C with the lifetime of 88 h.