title: Efficient synthesis and biological evaluation of all A-ring diastereomers of 1alpha,25-dihydroxyvitamin D3 and its 20-epimer.
abstract: An improved synthesis of the diastereomers of 1alpha,25-dihydroxyvitamin D3 (1) was accomplished utilizing our practical route to the A-ring synthon. We applied this procedure to synthesize for the first time all possible A-ring diastereomers of 20-epi-1alpha,25-dihydroxyvitamin D3 (2). Ten-step conversion of 1-(4-methoxyphenoxy)but-3-ene (6), including enantiomeric introduction of the C-3 hydroxyl group to the olefin by the Sharpless asymmetric dihydroxylation, provided all four possible stereoisomers of A-ring enynes (3). i.e., (3R,5R)-, (3R,5S)-, (3S,5R)- and (3S,5S)-bis[(tert-butyldimethylsilyl)oxy]oct-1-en-7-yne, in good overall yield. Palladium-catalyzed cross-coupling of the A-ring synthon with the 20-epi CD-ring portion (5), (E)-(20S)-de-A,B-8-(bromomethylene)cholestan-25-ol, followed by deprotection, afforded the requisite diastereomers of 20-epi-1alpha,25-dihydroxyvitamin D3 (2). The biological profiles of the synthesized stereoisomers were assessed in terms of affinities for vitamin D receptor (VDR) and vitamin D binding protein (DBP). HL-60 cell differentiation-inducing activity and in vivo calcium-regulating potency in comparison with the natural hormone.
authors.affiliation: Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fujishima
authors.forename: K
authors.initials: K
authors.lastname: Konno
authors.forename: K
authors.initials: K
authors.lastname: Nakagawa
authors.forename: M
authors.initials: M
authors.lastname: Kurobe
authors.forename: T
authors.initials: T
authors.lastname: Okano
authors.forename: H
authors.initials: H
authors.lastname: Takayama
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D002117:Calcitriol / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D004341:Drug Evaluation; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D018167:Receptors, Calcitriol / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: D000954:Antigens, Surface; D018167:Receptors, Calcitriol; D002117:Calcitriol