A chiral phosphorous derivatizing agent prepared from PCl3 and (S)-BINOL was described. It is used to determine the enantiomeric excess of chiral alcohols and amines by 31P NMR.
Kang Ying LI1, Zheng Hong ZHOU1, Chi Hung YEUNG2, Chu Chi TANG* 1State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071 2Laboratory of Chiral Technology and Department of Applied Biology and Chemical Technology, The Hong Ko
Menthol reacts with phosphorus trichloride to afford menthyl phosphorodichloridite 2, which further reacts with racemic 1, 1-binaphthalene-2, 2-diol to give phosphite (+)-3 in the presence of triethylamine. (+)-3 can be easily separated by fractional crystallization to form the crystal (+)-(S)-3 and the mother liquor (-)-(R)-3. Then both the crystal and the mother liquor are treated with AcOH-H2O to obtain enantiomeric pure (-)-(S)-1 and (+)-(R)-1 respectively, with enantiomeric excess up to 99.7%.
The title compound (+)-(a-hydroxybenzyl)phenylphosphinic acid (C13H13O3P, Mr = 248.20) has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 293(2) K indicates that the compound belongs to monoclinic system, space group C2 with cell parameters: a = 23.560(8), b = 6.947(2), c = 7.854(3) ? b = 91.273(6)? V = 1285.2(7) 3, Z = 4, Dc = 1.283 g/cm3, F(000) = 520 and m(MoKa) = 0.207 mm-1. The number of independent reflections amounts to 1991, of which 1507 are observed reflections. The crystal structure has been determined by direct methods (SHELXL-97). The structure parameters are refined by full-matrix least-squares on F2 to R = 0.0437 and wR = 0.0893. The flack x parameter is 0.0001. The absolute configuration of the a-carbon in the title compound is S.
