title: BF₃·Et₂O-induced stereoselective aldol reaction with benzaldehyde, and steroid sapogenins and its application to a convenient synthesis of dinorcholanic lactones.
abstract: Treatment of steroid sapogenins with benzaldehyde and BF(3)·Et(2)O cleanly produces E-23(23')-benzylidenspirostanes in good yields in a reaction pathway which consists on an aldol reaction followed by a dehydration step. The obtained E-23(23')-benzylidenspirostanes can be easily converted to dinorcholanic lactones by treatment with CrO(3) in acetic acid. The synthetic sequence to dinorcholanic lactones is compatible with the presence of double bonds and carbonyl groups in the steroid framework.
authors.affiliation: Departamento de Química Orgánica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Mexico, DF, Mexico.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Ruíz-Pérez
authors.forename: Margarita
authors.initials: M
authors.lastname: Romero-Ávila
authors.forename: Verónica
authors.initials: V
authors.lastname: Tinajero-Delgado
authors.forename: Marcos
authors.initials: M
authors.lastname: Flores-Álamo
authors.forename: Martín A
authors.initials: MA
authors.lastname: Iglesias-Arteaga
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D001547:Benzaldehydes / Q000737:chemistry*; D001880:Boranes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007783:Lactones / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D012502:Sapogenins / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D001547:Benzaldehydes; D001880:Boranes; D007783:Lactones; D012502:Sapogenins; C101707:boron trifluoride etherate; D019342:Acetic Acid; C032175:benzaldehyde