Studies On Palladium-Catalyzed Cyclization Reactions

The thesis aims at the studies on the palladium-catalyzed cyclization reactions. It mainly consists of the following four parts.Part I:The very recent progress in palladium-catalyzed cyclization reactions is summarized, which includes the synthesis of a variety carbo- and heterocycles via palladiumπ-olefin andπ-alkyne chemistry, palladium oxidative addition/reductive elimination chemistry, andπ-allylpalladium chemistry. The mechanistic studies on palladium-catalyzed cyclization reactions and their application in organic synthesis are also surveyed.Part IIA novel three-component coupling-cyclization reaction of propargyl carbonate,β-keto esters, and aryl iodide by palladium-catalyzed has been developed. This three-component coupling-cyclization protocol provides an efficient access to a variety of polysubsituted furans and shows some advantages in terms of its simple operation, easily availability, and diversity of the starting material. Importantly, most of the reactions afforded the corresponding multiply substituted furans products in moderate to good yields with excellent regioselectivities.Part III:An efficient, palladium-catalyzed synthesis of 2-substitued 3-aroylindenes has been developed. A variety of aryl iodides undergo this process, giving the desired products in moderate to good yields with good reaction selectivities. The reaction is believed to proceed via cyclization of the alkyne containing a proximate nucleophilic center promoted by an acylpalladium complex. In particular, three carbon-carbon bonds are formed in a single operative step.Part IV:A straightforward, highly regioselective approach to multiply substituted indenes has been developed. This novel palladium-catalyzed cyclization reaction worked well with a broad range of nucleophiles to afford 2,3-disubstituted indenes in moderate to good yields. The reaction conditions and the scope of the process are examined, and a possible mechanism is proposed. It is the first time studied the cyclization reaction propargylic carbonates with a broad range of carbon nucleophiles via C-alkylation using the palladium catalyst.