NMR AND POLYMORPHISM OF A STEROIDAL ANESTHETIC

Two modifications of 11 alpha-dimethylamino-2 beta-ethoxy-3 alpha-hydr oxy-5 alpha-pregnan-20-one have been characterised by DSC, IR and Rama n spectroscopies and by solid-state C-13 and N-15 NMR. Differences hav e been related to variations of hydrogen bonding as revealed by publis hed single-crystal X-ray results. Solution-state H-1 and C-13 NMR resu lts are also presented. The dimethylamino methyl groups are not exchan ging on the NMR timescale, but their C-13 chemical shifts vary substan tially between the solution and solid phases, suggesting a change of c onformation. (C) 1998 Elsevier Science B.V. All rights reserved.