/sup 1/H, /sup 13/C, and /sup 31/P NMR spectra and the structures of the stereoisomers of 2,5-dimethyl-1-phenylphosphorinan-4-one 1-oxide, 1-sulfide, and 1-selenide

According to NMR-spectral data the stereoisomers of 2,5-dimethyl-1-phenylphosphorinan-4-one 1-oxide, 1-sulfide, and 1-selenide preserve the conformation found in the crystalline state by x-ray structure analysis. The main features of the /sup 1/H and /sup 13/C NMR spectra of the phosphorinones studied are determined by the influence of the phenyl group attached to the phosphorus atom. In the twist conformation the values of the vicinal constants /sup 3/J(PH) differ substantially from the values characteristic for the chair conformation.