Long-acting contraceptive agents: X-Ray study of levonorgestrel esters

✍ Scribed by Pierre Crabbé; Elmer O. Schlemper

• Publisher: Wiley (John Wiley & Sons)
• Year: 2010
• Weight: 455 KB
• Volume: 92
• Category: Article
• ISSN: 0037-9646
• DOI: 10.1002/bscb.19830920312

✦ Synopsis

The X-ray crystal structure determinations of levonorgestrel (1) and its esters (2) to

In the most active compounds, &, levonorgestrel butyrate (<), cyclopropylcarboxylate ( I ) have been performed in order to assign the molecular features and attempt to correTate the conformation of the molecules with their long-acting contraceptive activity.

( 6 ) , and cyclobutylcarboxylate (7), the unusual orientation of the ester chains seems to affect the entire steroid framework. while the tetracyclic skeleton exhibits a more planar conformation than that of levonorgestrel

(1) or the other esters (2), (3), and (5), and the ester grouping shields the 0 (17) ester position much more in esters (T), (6), and ( 7 ) . Since levonorgestrel (1) and norethisterone (S) have very similar conformalions7 additional factors, different from-the molecular geometry, seem to be responsible for the dramatic long-acting contraceptive properties associated with these esters.

The stereochemistry of ring A is only slightly modified -11.211 (2) 12.300( 4) 16.404( 3) 90 90 90 2262 p212121 'XH34'3 l.l58g/cm