Reattività di enini in presenza di nucleofili all’ossigeno e metalli di transizione

Abstract

Metal-catalyzed enyne cycloisomerizations represents one of the most powerful tool for the construction of a variety of polycyclic systems. In particular, in this work, three different reactivities were investigated. The reactivity of 1,6-enynes with all-metal aromatic trinuclear complexes and carboxylic acids; gold(I)-catalysed cycloisomerization of 1,6-enynols; cascade reactions of 1,6-enynol in the presence of MnO2. In the first project, the proper choice of the catalyst (a tripalladium or triplatinum complex) allowed the chemoselective synthesis of valuable classes of cyclic and bicyclic derivatives in good yields and functional group tolerance. Regarding the second project, we described the first cycloisomerization of (E)-enynols catalysed by a phosphite gold(I) complexes. The highly diastereoselective methodology enabled the synthesis of two families of highly functionalized polyheterocycles under ambient conditions, with good yields and notable functional group tolerance. Finally, we have reported the unprecedented use of MnO2 in a cascade reactions of 1,6-enynols, involving the formation of products bearing 5- and 6-membered rings. A small library of substrates, was synthesized in order to prove the generality of this methodology. The corresponding cyclic products were chemoselectively delivered in synthetically useful yields.