Asymmetric catalysis. LXXX. An optically-active tetrakispyrazolylborate: Synthesis and use in Cu-catalyzed enantioselective cyclopropanation

Article abstract of DOI:10.1016/0022-328X(93)80027-9

The synthesis of the optically-active sodium salt of tetrakis(4,5,6,7-tetrahydro-7,8,8-trimethyl-2H-4,7-methanoindazolyl)borate, (1) is reported.Cu-based in situ catalysts containing give an enantiomeric excess of up to 62percent in the enantioselective cyclopropanation of styrene with ethyl diazoacetate.