摘要
This paper describes the influence of replacement of one of the rhodium atoms by bismuth in a chiral dirhodium tetracarboxylate catalyst on asymmetric induction in the cyclopropanation and C-H functionalization chemistry of trichloroethyl aryldiazoacetates. The chiral ligand used in this study is S-tert-butylsulphonylprolinate (S-TBSP), which was used in the first highly enantioselective dirhodium tetracarboxylate catalyst. Even though the replacement of a Rh atom with a Bi atom has changed the electronic properties of the system, the RhBi complexes have several similarities to the corresponding Rh 2 catalysts, with regard to their reactions with donor/acceptor carbenes. The asymmetric induction with RhBi(S-TBSP) 4 is very similar to that achieved with Rh 2 (S-TBSP) 4 . The major differences between the two systems are the rates of reactions with the Rh 2 complexes reacting much faster, and the scope of the C-H functionalization with Rh 2 complexes capable of catalyzing reactions with a much wider range of substrates. An unexpected structural feature of the RhBi(S-TBSP) 4 catalyst is the arrangement of the arylsulfonyl groups in the periphery of the catalyst, leading to a C 4 symmetric structure.