title: 6-s-cis locked analogues of the steroid hormone 1alpha, 25-dihydroxyvitamin D(3). Synthesis Of novel A-ring stereoisomeric 1, 25-dihydroxy-3-epi-19-nor-previtamin D(3) derivatives.
abstract: Efficient syntheses of A-ring synthons 24 and 32 are described from hydroxy ester 16, which is easily available on a preparative scale from (-)-quinic acid. Key features of the syntheses were (a) the ability to selectively perform desilylations in the presence of p-nitrobenzoate esters and (b) the excellent yield and complete stereospecificity with which the configuration of alcohols 16, 18, and 26 could be inverted under Mitsunobu conditions. Thus, A-ring synthons 24 and 32 were both prepared in 35-38% yield (eight steps) from the common precursor 16. The coupling of A-ring synthons 24 and 32 with the appropriate CD-ring/side chain fragment 7 provides access to novel 6-s-cis locked analogues of steroid hormone 1alpha, 25-dihydroxyvitamin D(3): 1alpha, 25-dihydroxy-3-epi-19-nor-previtamin D(3) (37) and 1beta, 25-dihydroxy-3-epi-19-nor-previtamin D(3) (38), which are unable to undergo rearrangement to the respective vitamin D form by virtue of the absence of the C-19 methyl group. Compounds 37 and 38 can be used as tools for studying the genomic and nongenomic mechanisms of action of the previtamin form of the hormone 1alpha, 25-dihydroxyvitamin D(3).
authors.affiliation: Departamento de Química Orgánica e Inorgánica, Facultad de Química, Universidad de Oviedo, 33071-Oviedo, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Díaz
authors.forename: M
authors.initials: M
authors.lastname: Ferrero
authors.forename: S
authors.initials: S
authors.lastname: Fernández
authors.forename: V
authors.initials: V
authors.lastname: Gotor
mesh_terms: D002117:Calcitriol / Q000031:analogs & derivatives*; D002762:Cholecalciferol / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry
chemical_list: D002762:Cholecalciferol; D002117:Calcitriol; C025168:previtamin D(3)