Pd-Catalyzed Domino Cyclization And Carboxylation Or Methenylation With Carbenes

Carbenes as important organic intermediates, have been widely used in organic synthesis. The reaction of carbene mainly in cyclization, X-Y bond insertion, rearrangement, and the preparation of high activity catalysts by the use of transition metals. Since the discovery of Heck reaction in1968, great achievements have been made in Pd-catalyzed organic transformation. In addition to expanding the types of reactions and substrate scope, great achievements also have been made in Pd-catalyze cascade reactions, which greatly expanded the scope of Pd chemistry. In this dissertation, we used Pd as catalyst and developed a series of cascade reactions of Heck reaction with carbenes such as N-tosyl hydrazones and dichlorocarbene. These results expanded the scope of the application of Pd-catalyzed reactions and the use of carbene intermediates in metal-catalyzed reactions.This dissertation is divided into four chapters.Chapter1:The research progress in the hydrocarboxylation reaction of unsaturated C-C bondsThe hydrocarboxylation reactions which between carboxylated reagents and unsaturated bond have been extensive studied in organic synthesis. We reviewed some important chievements of hydrocarboxylation methods include the reactions of CO, CO2, formic acid and its derivatives and highlighted their advantages and disadvantages and applications.Chapter2:Pd-catalyzed Heck-(hydro)carboxylation/methenylation reactionsWe developed a new protocol to generate sp3C-Pd intermediate via Heck-type cyclization, P-H elimination and reinsertion. Linear carboxylic acid products can be synthesized by the reaction of the above sp3C-Pd intermediate with dichlorocarbene which was in-situ generated from chloroform under aqueous basic conditions. The method was also applied to the reaction of N-tosylhydrazones as carbene precursors instead of dichlorocarbene, and the Heck-cyclization and hyromethenylation products could be obtained.Chapter3:Pd-catalyzed Heck-olefination reactions with N-tosylhydrazonesWe also studied the cascade reactions between N-tosylhydrazones and neopentylpalladium which fromed from Heck cyclization. The reaction has broad scope and good functional group tolerance and can be used to build five/six-membered rings as well as spiro compounds.Chapter4:Pd-catalyzed Heck-carboxylation reactions with dichlorocarbene In this section, we realized a domino Heck-cyclization and carboxylation reaction by the use of dichlorocarbene as CO source. This reaction was high efficiency and could tolerant a wide range of substrates. A series of benzo rings containing carboxylic acid can be achieved with this method.