A New Highly Efficient Three-Component Domino Heck–Diels–Alder Reaction with Bicyclopropylidene: Rapid Access to Spiro[2.5]oct-4-ene Derivatives Part 77 in the series “Cyclopropyl Building Blocks in Organic Synthesis”. For Part 76 see: S. Wiedemann, I. Marek, A. de Meijere, Synlett 2002, submitted. Part 75: M. W. Nötzel, K. Rauch, T. Labahn, A. de Meijere, Org. Lett. 2002, 4, 839–841.
作者:Hanno Nüske、Stefan Bräse、Sergei I. Kozhushkov、Mathias Noltemeyer、Mazen Es-Sayed、Armin de Meijere
three-component reaction with a variety of dienophiles to furnish the dominoHeck-Diels-Alder products 18 regioselectively in most cases in good to very high yields (49-100 %). The reaction of 1 with iodobenzene (2-Ph) and 17 a gave 18 a-Ph in virtually quantitative yield-also on a gram scale-using only 1 mol % of catalyst, and even bromobenzene (22) gave 18 a-Ph in 59 % yield. Bicyclopropylidene (1), in the