74788-58-2Relevant articles and documents
Phosphine-Substituted Chelate Ligands, XXV. Diastereoselective Complexation of Chiral Phosphinothioformamides with Remote Asymmetric Centre
Kunze, Udo,Burghardt, Roland
, p. 860 - 866 (2007/10/02)
For further studies of the diastereoselective complex formation of ambidentate chiral chelating ligands, we prepared the racemic phosphinothioformamides, Ph2P(X)C(S)NHC*HR1R2, with X = 2e- (R1 = Ph, R2 = Et: 1a; R1 = Ph, R2 = iPr: 2a; R1 = Me, R2 = Et: 3a) and X = O (1b, 2b) according to a previously reported route.The coordination of 1a-3a to CpM(CO)3Cl (M = Mo, W) in methanol gives the diastereomeric P,S-chelate complexes, (Mo: 4-6, W :7-9).In solution, epimerisation proceeds to an equilibrium ratio of B/A = 1.5 in case of 4, 5, 7, and 8, but less than 1.1 with 6 and 9.A reduced diastereoselectivity (d.e. 10-20percent) is also observed during the formation of the analogous molybdenum complexes 10a-d with phosphine ligands derived from α-amino acid esters, Ph2PC(S)NHC*H(R)COOMe .The results indicate a significant asymmetric induction despite of the four bond distance of the chiral centres. - Diastereoselectivity, Chiral Phosphinothioformamides, Amino Acid Esters, Remote Asymmetric Centre, Cyclopentadienyl Molybdenum and Tungsten Complexes