title: Crystal structures of 10alpha-gon-5-enes from the synthetic pathway to desogestrel.
abstract: X-ray crystallographic studies performed on the product of the ketalization reaction of 13beta-ethyl-11alpha-hydroxy-gon-5-ene-3,17-dione have lead to the unequivocal assignment of the 10alpha stereochemistry to C10, showing that an inversion of configuration occurred during formation of the 3,17-diketal. From the Swern oxidation of this compound, 11alpha-(methylthio)methoxy-10alpha-gonene was obtained as the major product instead of the desired 11-ketone. Modeling studies showed that the configurational instability at C10 is determined by the presence of the 11alpha-hydroxyl group.
authors.affiliation: Dipartimento di Chimica, Biochimica e Biotecnologie per la Medicina, Università di Milano, 20133 Milano, Italy.
authors.forename: Emilia
authors.initials: E
authors.lastname: Modica
authors.forename: Diego
authors.initials: D
authors.lastname: Colombo
authors.forename: Fiamma
authors.initials: F
authors.lastname: Ronchetti
authors.forename: Antonio
authors.initials: A
authors.lastname: Scala
authors.forename: Gabriella
authors.initials: G
authors.lastname: Bombieri
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Marchini
authors.forename: Lucio
authors.initials: L
authors.lastname: Toma
mesh_terms: D018360:Crystallography, X-Ray; D017135:Desogestrel / Q000138:chemical synthesis*; D006067:Gonanes / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure
chemical_list: D006067:Gonanes; D017135:Desogestrel