ALKYLTHIO SUBSTITUTED TRICARBONYL(ETA(6)-ARENE)CHROMIUM(0) COMPLEXES AS SUBSTRATES FOR ASYMMETRIC OXIDATION (VOL 5, PG 1847, 1994)

Oxidation of methylthio substituted tricarbonyl(eta(6)-arene)chromium( 0) complexes with Ti(OPri)4 / diethyl tartrate / H2O / cumene hydroper oxide (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% yi eld and 90-greater than or equal to 95% e.e. after crystallisation); d iethyl tartrate gives higher optical and chemical yields than dimethyl 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 condit ions led to the isolation of recovered starting material and the corre sponding sulfinyl substituted complex with enantiomeric excesses of 59 and 60% respectively.