Structural Determination of cis- and trans-5-Hydroxymethyl-5-methyl-2-thiono-r-2-ethoxy-1,3,2-dioxaphosphorinane by NMR and X-ray Crystallography: Model Compounds for the Reaction Mechanism Study of Organophosphorus Pesticides

  • Kim, Jeong Han (School of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University) ;
  • Toia, Robert F. (Department of Environmental Sciences, University of San Francisco, San Francisco) ;
  • Craig, Donald C. (School of Chemistry, University of New South Wales)
  • Received : 2000.02.15
  • Published : 2000.03.31

Abstract

1,3,2-Dioxaphosphorinanes are suitable compounds for studying the stereochemistry of substitution at phosphorus. Cis- and trans-5-hydroxymethl-5-methyl-2-thiono-2ethoxy-1,3,2-dioxaphosphorinane were prepared, and their structures and stereochemistry unambiguously assigned by NMR and X-ray crystallography with acetoxy and 3,5-dinitrobenzoyloxy derivatives, respectively. Trans isomer gave $^{31}P$ NMR signal at higher field than cis isomer, and the ring proton Spectrum of cis isomer showed characteristic pattern for identifying its geometry. In X-ray crystallography they adopted a chair conformation with the ethoxy groups in the axial positions, and the sulfide groups in the equatorial positions. A flattening of the ring around the phosphorus center was noted, the POC bond angles were about $120^{\circ}$, and the C-O bonds in the ring were significantly longer than the C-O bond for the ethoxy group or the C-O bond for hydroxyl group.

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