title: The remarkable influence of steroid A/B-ring junction on the Wittig olefination reaction of the 11-oxo group: towards the synthesis of 5 alpha- and 5 beta-oriented delta 3-isomers of desogestrel.
abstract: The 5 alpha- and 5 beta-oriented delta 3-double bond isomers 8, 9 of the widely used progestin desogestrel (7) were synthesized. Wittig olefination reaction of the 5 alpha-intermediate 12 showed a dramatically reduced reaction rate compared with the olefination of the 5 beta-intermediate 13. Computational studies suggest that different energies of the intermediary 1,2-oxaphosphetanes may, at least partially, have been the reason for this phenomenon.
authors.affiliation: Division of Research and Development, Jenapharm GmbH & Co.KG, Jena, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Ring
authors.forename: G
authors.initials: G
authors.lastname: Weber
authors.forename: A
authors.initials: A
authors.lastname: Hillisch
authors.forename: S
authors.initials: S
authors.lastname: Schwarz
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D017135:Desogestrel / Q000138:chemical synthesis* / Q000737:chemistry; D008432:Mathematical Computing; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D017135:Desogestrel