Studies On Gold-Catalyzed Tandem Cyclization Reactions Of 4-Acyl-1,6-diynes

Transition-metal-catalyzed organic reaction has become one of the most important areas in modern organic chemistry due to highly atom economical and chemoselective properties. In recent years, it was found that gold-catalyzed organic reactions not only have the general features of transition mental-catalyzed organic reactions, but also have other advantages, such as mild condition, high yields and less use of the catalyst. Therefore, the gold-catalyzed organic reactions have become a new area in organometallic chemistry.In gold-catalyzed organic reactions, the cyclization reactions of alkynyl ketones/aldehydes have emerged as a powerful strategy for the construction of various cyclic ring systems through attack of the carbonyl-oxygen atom of alkynyl ketones and aldehyde to the Au-coordinated carbon-carbon triple bond. Recently, we reported a highly efficient, atom-economical, highly regio- and diastereoselective approach to polyfunctionalized fused bicyclic ketals via AuCl3-catalyzed multicomponent domino reactions of 4-acyl-1,6-diynes and with H2O and alkanols, i.e., the cycloisomerization, intramolecular oxo-assisted alkyne hydration, cycloisomerization, alkanolysis, isomerization, and alkanolysis (intermolecular or intramolecular) sequence. On the basis of the above experimental results together with considering of the above reaction mechanism, we speculate that a series of bridged tricyclic ketals could be synthesized through via a similar AuCl3-catalyzed multicomponent domino reactions of 4-acyl-1,6-diynes with the hydroxyl oxygen group at proper position as intramolecular nucleophile and with H2O and alkanols. The following statements are the brief of my work.First, the aldol reactions of 4-acyl-1,6-diynes with aromatic aldehydes were investigated under base conditions.Second, a series of bridged tricyclic ketals were obtained via AuCl3-catalyzed multicomponent domino reactions of 4-acyl-1,6-diynes and with H2O and alkanols.In this thesis, many new compounds were synthesized and characterized by IR, Mass and NMR (1H, 13C) spectrum.