摘要:
The chelate complexes [(1S,2S)-C5H8(PR2)(2)MCl2] [PR2 = PC5H10-cyclo: M = Ni (1), Pd (2), Pt (3); PR2 = P(C6H11)(2): M = Ni (4), Pd (5), Pt (6)] were prepared from NiCl2. 6H(2)O, [(eta (4)-1,5-C8H12)PdCl2] or [(Me2SO)(2)PtCl2] and the required optically active bisphosphane ligand, (1S,2S)-C5H8(PC5H10-cyclo)(2) or (1S,2S)-C5H8[P(C6H11)(2)](2), in order to serve as catalysts for the synthesis of non-racemic 2,2 ' -dimethyl-1,1 ' -binaphthyl by asymmetric cross-coupling of 1-bromo-2-methylnaphthalene with its derived Grignard reagent. The coupling reactions generally suffered from low conversion. Nickel complex 4, the crystal structure of which Was determined by X-ray diffraction, gave the (R)-(-) form of the C-C coupling product in modest enantiomeric excess (26% e.e.). (C) 2001 Elsevier Science B.V. All rights reserved.