54676-64-1Relevant academic research and scientific papers
Solid State Conformations of Six 1,3,2-Oxazaphospholidines Derived from (-)-Ephedrine: X-Ray Crystal Structures of the 2-Phenoxy-2-oxo, 2-Phenyl-2-oxo and 2-Phenyl-2-thio Analogues
Schwalbe, Carl H.,Chopra, Geetanjlee,Freeman, Sally,Brown, John M.,Carey, Joseph V.
, p. 2081 - 2090 (2007/10/02)
The crystal structure of (2R,4S,5R)-3,4-dimethyl-2-phenoxy-5-phenyl-1,3,2-oxazaphospolidin-2-one (7) exhibits a C(5) envelope in which this atom is below the O(1)-P(2)-N(3)-C(4) plane.The diastereoisomer, (2S,4S,5R) 8 adopts a half-chair conformation with C(4) above and C(5) below the O(1)-P(2)-N(3) plane.Both (2S,4S,5R)- and (2R,4S,5R)-3,4-dimethyl-2,5-diphenyl-1,3,2-oxazaphospholidin-2-one (9 and 10), and (2S,4S,5R)-3,4-dimethyl-2,5-diphenyl-1,3,2-oxazaphospholidin-2-thione (12) adopt C(4) envelopes in the crystal structures, with C(4) above the C(5)-O(1)-P(2)-N(3) plane for 9 and below for 10 and 12. (2R,4S,5R)-3,4-Dimethyl-2,5-diphenyl-1,3,2-oxazaphospholidin-2-thione (11) exists as a half-chair with O(1) above and C(5) below the P(2)-N(3)-C(4) plane.The C(4) and C(5) envelope conformations for 7, 9, 10 and 12 are consistent with the P-O-C-H vicinal coupling constants derived from 1H NMR spectra in solution.
