title: Steroidal allylic fluorination using diethylaminosulfur trifluoride: a convenient method for the synthesis of 3 beta-acetoxy-7 alpha- and 7 beta-fluoroandrost-5-en-17-one.
abstract: This paper discusses our findings regarding fluorination of the diastereomeric 3 beta-acetoxy-7-hydroxyandrost-5-en-17-ones (3 and 4) at the allylic 7-hydroxyl group using diethylaminosulfur trifluoride under various experimental conditions. The reaction led to the formation of allylic 7 alpha- and 7 beta-fluoro derivatives, 6 and 7, contaminated with small amounts of 3 beta-acetoxy-5 alpha-fluoroandrost-6-en-17-one (8), the rearrangement product, and 3 beta-acetoxyandrosta-4,6-dien-17-one (9), the elimination product. However, synthesis of 3 beta-acetoxy-7 alpha-fluoroandrost-5-en-17-one (6) and 3 beta-acetoxy-7 beta-fluoroandrost-5-en-17-one (7) has been achieved in high isomeric purity by careful manipulation of the experimental conditions. Also included herein is a convenient chemical synthesis of pure 3 beta-acetoxy-7 alpha-hydroxyandrost-5-en-17-one (4) and 3 beta-acetoxy-7 beta-hydroxyandrost-5-en-17-one (3), the starting materials for the present fluorination reaction. The structure of a degradation product, 3 beta-acetoxy-5 alpha-hydroxyandrost-6-en-17-one (5), has been established by X-ray diffraction analysis to ascertain unambiguously its absolute configuration.
authors.affiliation: Institute for Enzyme Research, University of Wisconsin-Madison 53705-4098, USA.
authors.forename: P
authors.initials: P
authors.lastname: Marwah
authors.forename: J B
authors.initials: JB
authors.lastname: Thoden
authors.forename: D R
authors.initials: DR
authors.lastname: Powell
authors.forename: H A
authors.initials: HA
authors.lastname: Lardy
mesh_terms: D000736:Androstenes / Q000138:chemical synthesis*; D004048:Diethylamines / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013237:Stereoisomerism; D014961:X-Ray Diffraction
chemical_list: D000736:Androstenes; D004048:Diethylamines; D005461:Fluorine; C040394:diethylaminosulfur trifluoride