Study On Highly Selective Cyclodimerization Of Alkynes And Construction Of 3(2H)-furanones By Gold-catalyst

This article is divided into two parts.1 ) Transition-metal-mediated inter-or intramolecular cyclodimerization of alkynes has received considerable attention during the last several decades. Recently, organiczirconium as peculiar character has induced a series of new organic reactions in synthesis chemistry. However, so far, the triple bond moiety of alkynes used in cyclodimerization reactions has only been incorporated in products as double bonds, and there has been no example in which one of the triple bonds is reduced to a single bond, that is, the information of cyclobutene derivates.Highly regi- and diastereoselective tetrasubstituted cyclobutenes were acquired through the reaction of "Cp₂Zr" with heteroaryl- substituted acetylenes in this paper. The reaction condition is moderate and the yield is high. It affords a new reaction of zirconium-induced cyclodimerization of heteroaryl-substituted alkynes. Meanwhile, we found that the stable substituted alkynes pyrrol can be acquired accidentally which enriched organic zirconium transition-metal-mediated reactions.2) The 3(2H)-furanones are an important class of heterocyclic compounds, which are of pharmacological significance and represent useful building blocks for natural products syntheses. The synthetic methods developed so far, however, have some drawbacks, more or less, such as lack of satisfactory general preparative procedures for starting substrates. Due to the increased attention of this important heterocycles, there are needs to enhancing the efficiency of the synthesis of these compounds and generating the 3(2H)-furanones with a wide variety of substituents. On the other hand, transition-metal-catalyzed heteroannulation reactions have been developed with remarkable improvements in terms of efficiency and wide scopes of application, however, there is no report for construction of 3(2H)-furanones using transition metal methods.We are particularly interested in the transition-metal-catalyzed cyclization of allenyl ketones and 3-alkyn-1-ones. It has recently been shown that gold(III) salts and gold(I) complex display effective catalytic activity for this type of reaction due to the excellent alkynophilicity of gold.we have succeeded in developing a gold-catalyzed cyclization of 2-oxo-3-butynoates or dialkynyl-l,2-diones with a various nucleophile under mildreaction conditions, which provided an efficient and general route to 3(2/f)-furanones with a wide range of substituents.