α-PHOSPHORYL SULPHOXIDES. VI; SYNTHESIS OF α-PHOSPHORYLETHYL p-TOLYL SULPHOXIDE AND ASYMMETRIC INDUCTION ON THE α-CARBON ATOM

Article abstract of DOI:10.1016/S0040-4020(01)86835-6

Optically active α-dimethylphosphorylethyl p-tolyl sulphoxide (2a) was prepared by methylation of optically active (+)-(S)-α-dimethylphosphorylmethyl p-tolyl sulphoxide and by treatment of (-)-(S)-menthyl p-toluenesulphinate with dimethylphosphorylethyllithium.In both reactions a substantial asymmetric induction at the α-carbon atom was observed and rationalized.The structure of the major diastereoisomer of the sulphoxide 2a, <α>_D+157 deg, m.p. 98-99 deg C, having the (S)_C(S)_S-configuration was determined by X-ray analysis.C11H17O4SP, orthorombic, space group P2₁2₁2₁, a=24.080(3), b=7.239(1), c=7.754(1) Angstroem, V=1351.64 Angstroem³, Z=4, D_m=1.35 Mg*m^-3, D_c=1.357 Mg*m^-3, F(000)=584.0, μ(CuK_α)=3.13 mm^-1.The structure was solved by direct methods and refined to R=0.085.Racemic α-diethylphosphorylethyl p-tolyl sulphoxide (2b) was obtained by oxidation of the corresponding sulphide.The diastereoselectivity observed in this reaction was rationalized based on the adapted Felkin's model.