Sequential Ag-catalyzed carboxylative coupling/Ru-catalyzed cross-metathesis reactions for the synthesis of functionalized 2-alkynoates

Abstract

Sequential reactions can provide efficient access to a variety of important organic compounds that would be otherwise difficult to obtain using conventional methods and readily available starting materials. Based on the importance of 2-alkynoates in organic synthesis, the current research aimed to develop a method for the convenient synthesis of functionalized 2-alkynoates from terminal alkynes, CO 2 , terminal alkene-derived bromides, and methyl acrylate using a combination of the carboxylative coupling and cross-metathesis reactions. The initial ligand-free silver-catalyzed carboxylative coupling reactions of a variety of different aryl-substituted terminal alkynes and CO 2 with 5-bromopentene and 6-bromohexene provided a series of 4-pentenyl 2-alkynoates and 5-hexenyl 2-alkynoates, respectively, in good yield. These resulting 2-alkynoates were further transformed into methyl ( E )-6-acetylenecarboxy-2-hexenoates and ( E )-7-acetylenecarboxy-2-heptenoates in moderate to good yields by their cross-metathesis reactions with methyl acrylate in the presence of the Grubbs-Hoveyda catalyst. All of the new products characterized spectroscopically. 通过将Ag催化的羧化偶联反应与Ru催化的交叉复分解反应串联, 用端炔/二氧化碳/端烯基取代的溴代物和甲基丙烯酸甲酯高效高产率地合成了一系列官能团化的炔酸酯. An efficient and convenient method has been developed for the synthesis of functionalized 2-alkynoates in good yield from terminal alkynes, CO 2 , terminal alkene-derived bromides, and methyl acrylate via the combination of silver-catalyzed carboxylative coupling and ruthenium-catalyzed cross-metathesis reactions.