Ruthenium complexes that incorporate a chiro-inositol derived diphosphinite ligand as catalysts for asymmetric hydrogenation reactions

摘要

The diol, ID-1,2,5,6-tetra-O-methyl-chiro-inositol (D-9), can be conveniently prepared from ID-chiro-inositol using a series of standard protection/deprotection steps. Treatment of D-9 with Ph2PCl gives the chiral diphosphinite, ID-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol (D-10). The structure of D-10 has been determined by X-ray crystallography. Using 1L-chiro-inositol as starting material and following the same synthetic sequence used to produce D-10, the other enantiomer of this diphosphinite, IL-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol (L-10) can also be obtained. Ruthenium complexes of these diphosphinite ligands can be conveniently prepared through ligand substitution reactions with appropriate substrate complexes. Thus, treatment of [RuCl2(COD)](n) with D-10 in the presence of triethylamine produces the bis(diphosphinite) complex, RuHCl{kappa(2)(P,P)-1D-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol}(2) (11). In addition, reaction between RuCl2(PPh3)(3), D-10 and (IR,2R)-(+)-1,2-diphenylethylenediamine gives the mono(diphosphinite) complex, RuCl2{kappa(2)(p,p)-1D-3,4bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol} {kappa(2)(N,N)-(IR,2R)-(+)-1,2-diphenylethylenediamine} (12). The closely related complex RuCl2,{kappa(2)(p,p)-1D-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol} {kappa(2)(N,N)-(l S,2S)-(-)- 1,2-diphenylethylenediamine} (13) can be obtained in a similar manner using (1S,2S)-(-)-1,2-diphenylethylenediamine in place of the corresponding (+)-isomer. These new chiral, diphosphinite complexes catalyse the hydrogenation of the ketones acetophenone and 3-quinuelidinone to give the corresponding alcohols with low to moderate enantiomeric excesses. The complexes are not catalytically active for the hydrogenation of the olefin dimethylitaconate or the alpha-ketoester methyl benzoylformate. (c) 2006 Elsevier Ltd. All rights reserved.