CONFORMATIONAL STUDIES OF 2-ANILINO-SUBSTITUTED 1,3,2-OXAZAPHOSPHOLANES

A series of 2-anilino-2-thio-1,3,2-oxazaphospholanes derived from ephe drine has been synthesized and conformationally studied by proton NMR and X-ray crystallography. The NMR data can be interpreted in terms of twist-envelope conformations in which the anilino substituents on pho sphorus adopt predominantly equatorial positions. X-ray crystal struct ures of (2R,4S,5S)-2-anilino-2-thio-3,4-dimethyl-5-phenyl- 1,3-2-oxaza phospholane, (2R,4S,5S)-2-(4-fluoroanilino)-2-thio-3, 4-dimethyl-5-phe nyl-1,3,2-oxazaphospholane, and -thio-3,4-dimethyl-5-phenyl-1,3,2-oxaz aphospholane have been carried out, and these compounds adopt envelop, twist-envelope, and twist-envelope conformations, respectively, with the anilino moieties equatorial.