Studies On Cyclo-oligomerization And Nucleophilic Addition Reactions Of Alkynes/Arynes

Alkyne and aryne reactions, which provide an important method for the construction of carbon-carbon bonds, have been of particular interest due to the broad applications in the synthesis of natural products, alkaloids and drug intermediates. Our research falls into the following two aspects:Studies on cyclo-oligomerization and nucleophilic addition reactions of alkynes/arynes. This dissertation can be described as the following four parts:1. Studies on cyclo-oligomerization of propiolate esters with transition metal (gold, platinum and silver) catalytic. Tetramerization of electron-deficient alkynes catalyzed by trivalent gold, is achieved for the first time. A novel regioselective tetramerization of propiolate esters catalyzed by AuCl3 under mild conditions afforded 1,2,5,6-tetrasubstituted-cyclooctatetraene (1,2,5,6-COT) in moderate yields.2. Studies on cyclo-oligomerization of arynes with transition metal (gold, platinum and silver) catalytic. A novel and efficient Au(I)-catalyzed cyclotrimerization of arynes, is described for the first time. At the same time the reaction is neither air nor moisture sensitive, which only decreased the yields slightly.3. Studies on hydroalkoxylation of propiolate esters with transition metal (gold and platinum) catalytic. Results indicate that:PtCl2 was found to efficiently catalyze intermolecular additions of propiolate esters with alcohols. The reaction of propiolate esters and alcohols in the presence of PtCl2 gave (E)-vinyl ethers as the major products at 60 ℃, whereas alkyl 3,3-dialkoxypropanoates were predominantly obtained when the reaction temperature was set to 80 ℃.4. Studies on a-Monoarylation of 1,3-dicarbonyl compounds with arynes. Results indicate that: The reactions led to the formation of a-arylmalonates in up to 88%yield with high chemoselectivities and diarylmethane derivatives in good yields under mild conditions. Malonates carry out nucleophilic addition to aryne effectively under mild conditions.When a glut of malonates, mainly generated a-arylmalonates substitution; When aryne excessive, mainly generated methylene aryl derivatives.