Cp*rhodium and iridium complexes with bisoxazolines: synthesis, fluxionality and applications as asymmetric catalysts for Diels–Alder reactions
作者:David L Davies、John Fawcett、Shaun A Garratt、David R Russell
DOI:10.1016/s0022-328x(02)01859-4
日期:2002.11
Reaction of the dimers [MCl2CP*](2) (M = Rh, It) with bis-oxazolines [N-N = bis(2-oxazoline) (box), 2,2-bis(2-oxazolinyl)propane (bop), 1,2-bis(2-oxazolinyl)benzene (benbox)] in the presence of NaSbF6 (or KPF6) gives complexes [MCl(N-N)Cp*] [EF6] (E = P or Sb) which have been fully characterised. Treatment of some of these with AgSbF6 generates dications [Rh(OH2)(N-N)Cp*]2(+), some of which are fluxional at room temperature. One of these is an enantioselective catalyst for the Diels-Alder reaction of methacrolein and cyclopentadiene. Three complexes, [RhCl(Pr-i-box)Cp*][SbF6], [RhCl(Pr-i-bop)Cp*][SbF6] and [RhCl(Et-benbox)Cp*][SbF6] have been characterised by X-ray crystallography. (C) 2002 Elsevier Science B.V. All rights reserved.