Date of Award
Doctor of Philosophy
Richard C. Larock
This dissertation is divided into four parts. The focus of all four parts is on the development of a useful palladium-catalyzed procedure for cross-coupling aryl or vinylic halides and cyclic alkenes;Part One will discuss the development of an improved procedure (procedure C) for palladium-catalyzed allylic arylation of cyclic alkenes. Procedure C is compared with existing procedures (procedures A and B), and the scope and limitation of this improved procedure will be discussed;Part Two will discuss the use of procedure C in the synthesis of a variety of 2-aryl-2,3-dihydrofurans, and the application of this procedure in a key step of a three-step synthesis of trans-2,5-diaryltetrahydrofurans, which are known to be potential platelet activating factor inhibitors. A comparison of this efficient process to existing processes, as well as the scope and limitation of this approach, will be discussed;Part Three will discuss the use of three different palladium procedures for the allylic vinylation of cyclic alkenes. A variety of electron rich and electron poor vinylic halides, and cyclic alkenes containing 5- to 8-membered rings were examined. It has been found that procedure A was effective in the vinylation of cyclopentene, but it provided mixtures of double bond regioisomers when cycloheptene, and 2,3-dihydrofuran were employed. Procedure A was not effective in promoting this vinylation reaction with cyclohexene and cyclooctene. Procedure B, on the other hand, was effective in providing the desired allylic product when cyclohexene was employed, and it provided only the desired regioisomer when cycloheptene and 2,3-dihydrofuran were used. However, cyclooctene proved to be unreactive. Procedure C proved to be problematic, as it caused symmetrical dimerzation of the vinylic halide;Part Four will discuss the use of the different palladium procedures for the intramolecular vinylation of cyclic alkenes to generate a variety of carbo- and hetero-bicyclic compounds. Procedure A provided high yields of mixtures of double bond regioisomers each time, while procedure B was successful in providing only the desired regioisomer in good to excellent yields. The stereochemistry of the ring juncture has been determined to be cis in all cases. However, this method failed to cyclize dienyl halides containing an allylic ester or an electron deficient double bond.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
William H. Gong
Gong, William H., "Palladium-catalyzed arylation and vinylation of cyclic alkenes " (1990). Retrospective Theses and Dissertations. 9372.