title: Bismuth(III) salt-catalyzed Westphalen and "backbone" rearrangements of 5 beta,6 beta-epoxysteroids synthesis and structural elucidation of new olefinic 19-nor and 18,19-dinorsteroids.
abstract: A new process using the "ecofriendly" bismuth(III) salts as catalysts for the Westphalen and "backbone" rearrangements of 5 beta,6 beta-epoxysteroids is reported. This method is particularly sensitive to changes on solvent, temperature, stereochemistry of starting epoxysteroid, and its substituent at C17. Depending on the reaction conditions, either Westphalen-type or "backbone" rearranged products were obtained, all being 3 beta-acetoxy-6 beta-hydroxy-substituted. Several new olefinic 19-nor and 18,19-dinorsteroids were obtained and their structural elucidation was fully accomplished using 2D NMR and X-ray crystallography techniques.
authors.affiliation: Laboratório de Química Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, 3000-295 Coimbra, Portugal.
authors.forename: Rui M A
authors.initials: RM
authors.lastname: Pinto
authors.forename: Jorge A R
authors.initials: JA
authors.lastname: Salvador
authors.forename: Christophe
authors.initials: C
authors.lastname: Le Roux
authors.forename: Rui A
authors.initials: RA
authors.lastname: Carvalho
authors.forename: Manuela Ramos
authors.initials: MR
authors.lastname: Silva
authors.forename: Ana Matos
authors.initials: AM
authors.lastname: Beja
authors.forename: José A
authors.initials: JA
authors.lastname: Paixão
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D003516:Cycloparaffins / Q000737:chemistry*; D008968:Molecular Conformation; D009654:Norsteroids / Q000138:chemical synthesis* / Q000737:chemistry; D012492:Salts / Q000737:chemistry; D013696:Temperature
chemical_list: D003516:Cycloparaffins; D009654:Norsteroids; D012492:Salts; D001729:Bismuth