Chiral dirhodium catalysts design, synthesis and application in asymmetric carbenoid transformations and silver-catalysis of vinylogous fluorination

The first chapter gives an overview about carbene precursors, dirhodium catalysts and general metallocarbene transformations. Dirhodium catalysts are exceptional for transformations of diazo compounds. In contrast to acceptor only substituted metal carbenes, the rhodium-bound donor/acceptor carbenes have attenuated reactivity due to the donor group, enabling highly selective carbene reactions to be achieved. Also, the ligand around the dirhodium core can further control the reactivity and selectivity profile of carbenes.;The second chapter is devoted to exploring the D4-symmetric dirhodium phosphonate catalysis of cyclopropanation and C--H functionalization via decomposition of donor/acceptor diazoacetates. The combination of 3,4-dimethoxyphenyldiazoacetate with enantiomerically pure Rh2(R-BNP) 4 in the presence of styrene affords a cyclopropane moiety in highly diastereo- and enantioselective fashion. The newly designed dirhodium phosphonate Rh2(S-CBNP)4 proves to catalyze highly selective C--H functionalization of 1,4-cyclohexadiene with 3,4-dimethoxyphenyldiazoacetate.;The third chapter describes the development of dirhodium tetrakis-( R)-(1-(4- bromophenyl)-2,2-diphenylcyclopropane carboxylate) [Rh 2(R-BTPCP)4], which was found to be an effective chiral catalyst for enantioselective reactions of aryl- and styryldiazoacetates. Cyclopropanations, tandem cyclopropanation/Cope rearrangements and a combined C--H functionalization/Cope rearrangement were also achieved using Rh2(R-BTPCP)4 as catalyst in highly enantioselective manner. The advantages of Rh2 (RBTPCP)4 include its ease of synthesis and its tolerance to the size of the ester group in the styryldiazoacetates and the use of dichloromethane as solvent. Computational studies suggest that the catalyst adopts a D2-symmetric arrangement, but when the carbene binds to the catalyst, two of the ligands rotate outwards to make room for the carbenoid and the approach of the substrate to the carbenoid.;The fourth chapter focuses on enantioselective synthesis of 2-arylbicyclo[1.1.0]butanecarboxylates. The dirhodium-catalyzed reaction of 2-diazo-5-arylpent-4-enoates can be controlled by appropriate choice of catalyst and catalyst loading to form either 2- arylbicyclo[1.1.0]butane carboxylates or cyclohexene derivatives. Both products are produced in a highly diastereoselective manner, with 2-arylbicyclo[1.1.0]butane carboxylates preferentially formed under low catalyst loadings. When the reaction is catalyzed by Rh 2(R-BTPCP)4, the 2-arylbicyclo[1.1.0]butane carboxylates are generated with high levels of asymmetric induction.