Optically active pyrazolylborate: synthesis, characterization and uses in enantioselective cyclopropanation reaction
作者:Udai P. Singh、Preeti Babbar、Bernd Hassler、H. Nishiyama、H. Brunner
DOI:10.1016/s1381-1169(02)00075-4
日期:2002.7
Optically active sodium salt of tetrakis(4,5,6,7-tetrahydro-7,8,8-trimethyl-2H-4,7-methanoindazolyl)borate, [NaB(camphpz)(4)] (1) was synthesized by the reaction of 4,5,6,7-tetrahydro-7,8,8-trimethyl-2H-4,7-methanoindazole and NaBH4 whereas sodium salt of hydrotris((-)-3(5)-methyl-1-phenylethylaminomethylpyrazolyl)borate, [NaHB(Pl)3] (2) was prepared by the reaction of (-)-3(5)-methyl-1-phenylethylaminomethylpyrazole with NaBH4. Their uses in various metal-catalysed enantioselective cyclopropanation reactions of styrene and several diazoacetates gave the corresponding trans- and cis-phenylcyclopropane-1-carboxylates with moderate to reasonably good enantioselectivities. (C) 2002 Elsevier Science B.V. All rights reserved.