ALKYLTHIO SUBSTITUTED TRICARBONYL(ETA(6)-ARENE)CHROMIUM(0) COMPLEXES AS SUBSTRATES FOR ASYMMETRIC OXIDATION

Oxidation of methylthio substituted tricarbonyl (eta(6)-arene)chromium (0) complexes with Ti(OPri)(4) /diethyl tartrate/ H2O / cumene hydrope roxide (2:4:2:1.3) gives methylsulfinyl substituted tricarbonyl(eta(6) -arene)chromium(0) complexes in 60-73% yield and 81-86% e.e. (29-60% y ield and 90 greater than or equal to 95% e.e. after crystallisation); diethyl tartrate gives higher optical and chemical yields than dimethy l or diisopropyl tartrates and the reaction conditions are ineffective for other alkylthio and arylthio substituents; diethyl L-(+)-tartrate and diethyl D-(-)-tartrate lead to complexes of R and S configuration respectively; although an attempted kinetic resolution of tricarbonyl [eta(6)-(methylsulfinyl)benzene] was unsuccessful, subjecting [eta(6)- 1-methyl-2-(methylthio)benzene]chromium(0) to kinetic resolution condi tions led to the isolation of recovered starting material and the corr esponding sulfinyl substituted complex with enantiomeric excesses of 5 9 and 60% respectively.