368879-75-8Relevant articles and documents
Novel chiral phosphine ligands and complexes from amino acid esters
Slawin, Alexandra M.Z.,Woollins, J. Derek,Zhang, Qingzhi
, p. 621 - 632 (2001)
N-Diphenylphosphinoamino acid methyl/ethyl esters RCH(NHPPh2)CO2R′ la-le were prepared in high yield from equimolar amounts of amino acid methyl/ethyl ester hydrochloride and chlorodiphenylphosphine. The reaction proceeds with configurational retention. Oxidation of la (R = R′ = CH3) with H2O2 or S8 leads to the N-diphenyl-phosphinoylalanine methyl ester 2a or N-diphenylthiophosphinoylalanine methyl ester 3a. la-le function as monodentate ligands to [PtC12(cod)], [RhCl(cod)]2 and [AuCl(tht)] to give cis-[PtC12(1-P)2], [RhCl(cod)(1-P)] and [AuCi(1-P)]. Two equivalents of chlorodiphenylphosphine react with alanine methyl ester hydrochloride in CH2C12 to give N,N-bis(diphenylphosphino)alanine methyl ester, bdppal. This is an excellent bidentate ligand, the chelate complexes [MC12(bdppal-P,P′)] (M =Pd or Pt) being prepared and studied by X-ray analysis. Oxidation at one P atom in bdppal with either H2O2 or S8 gives N-diphenylphosphino-N-diphenylphosphinoylalanine methyl ester, bdppalO, and N-diphenylphosphino-N-diphenylthiophosphinoylalanine methyl ester, bdppalS, respectively, bdppalO is very difficult to isolate but does react in situ with [PdC12(cod)] to give [PdC12(bdppalO-O,P)]. bdppalS reacts with [MCl2(cod)] (M = Pd or Pt) giving [MC12(bdppalS-P,S)]. The dioxidised product N,N-bis(diphenylphosphinoyl)alanine methyl ester, bdppalO2, does not react with [MC12(cod)] (M =Pd or Pt), whereas N,N-bis(diphenylthiophosphinoyl)alanine methyl ester, bdppalS2, reacts with [PdC12(cod)] to give [PdC12(bdppal-S,S′)]. All the compounds are chiral and have been fully characterised by microanalysis, IR, 31P-{1H}, 1H NMR, and FAB+ mass spectroscopies, and in several cases structures are confirmed by X-ray analysis. The crystal structures described and those previously determined reveal the configurational retention of the reactions.
