- Synthesis, biological activity, and conformational analysis of CD-ring modified trans-decalin 1α,25-dihydroxyvitamin D analogs
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A novel series of analogs of 1.25-dihydroxyvitamin D3, the hormonally active metabolite of vitamin D3, characterised by the presence of a trans-fused decalin CD-ring system, possesses surprising biological activities in combination w
- Chen, Yong-Jun,Gao, Ling-Jie,Murad, Ibrahim,Verstuyf, Annemieke,Verlinden, Lieve,Verboven, Christel,Bouillon, Roger,Viterbo, Davide,Milanesio, Marco,Van Haver, Dirk,Vandewalle, Maurits,De Clercq, Pierre J.
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p. 257 - 267
(2007/10/03)
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- An effective procedure for the synthesis of 1α,25-dihydroxy-cholecalciferol (calcitriol) starting with 1α,3β, 25-trihydroxy-cholesta-5,7-diene (pro-calcitriol)
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In order to develop an effective synthesis of the important vitamin D metabolite 1α,25-(OH)2-cholecalciferol (calcitriol) 5a starting with pro-calcitriol 1a the influence of reaction temperature and degree of turnover of 1a to the compositions of the photoproducts at irradiation in a 500 ml photoreactor were investigated. The combination of the highly photostable filter solution consisting of 2,7-dimethyl-3,6-diaza-cyclohepta-1,6-diene-tetrafluoroborate and biphenyl in ethanol realizes the double wavelength irradiation in the range of 290 to 300 nm and>330 nm resulting in a highly amount of the desired pre-calcitriol 2a. The reversible photoisomers of pre-calcitriol 2a 1α,25-(OH)2-lumisterol3 4a and 1α,25-(OH)2-tachysterol3 3a were isolated from an irradiation mixture in pure form by means of an appropriate combination of flash-chromatography, MPLC and preparative HPLC, respectively. The isomers 2a, 3a and 4a were characterized chromatographically and spectroscopically. Photoisomerization of 1a at -45°C using the filter solution mentioned above and recycling all reversible photoisomers resulted in highly pure 5a after thermally induced isomerization of 2a isolated from the irradiation mixture by means of flash-chromatography on Ag+-impregnated silica with a yield of 68%. Johann Ambrosius Barth 1996.
- Reichenbaecher,Gliesing,Lange,Gonschior,Schoenecker
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p. 634 - 641
(2007/10/03)
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- 14-Epi stereoisomers of 25-hydroxy- and 1α,25-dihydroxyvitamin D3: Synthesis, isomerization to previtamins, and biological studies
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The C-14 epimers of vitamin D, 14-epi-25-hydroxyvitamin D3 (4) and 14- epi-1α,25-dihydroxyvitamin D3 (5), were synthesized, and their isomerization via [1,7]-sigmatropic hydrogen shifts to the corresponding previtamin forms (4' and 5
- Maynard,Trankle,Norman,Okamura
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p. 2387 - 2393
(2007/10/02)
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- Studies on the A-Ring Diastereomers of 1α,25-Dihydroxyvitamin D3
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The three A-ring diastereomers 3b (compound HL), 4a (compound HJ), and 4b (compound HH), of the steroid hormone 1α,25-dihydroxyvitamin D3 (1α,25-(OH)2-D3, 3a, compound C) have been synthesized and biologically evaluated. (R)-Carvone was converted in seven steps to the enantiomerically pure A-ring enyne 7a.Palladium-catalyzed cross-coupling of the latter with the CD-ring triflate 8 resulted in silyloxy dienyne 10, which was converted in three steps to 1β,25-(OH)2-3-epi-D3 (4b).Oxidation of the latter with Dess-Martin reagent afforded trienone 6c, which upon reduction with sodium borohydride followed by thermolysis generated the 1α-epimer 4a.An identical sequence converted 1α,25-(OH)2-D3 to its 1β-epimer 3b via trienone 5c.Reduction of the latter with sodium triacetoxyborohydride followed by thermal isomerization regenerated the hormone 3a.Relative competitive indices (RCIs) of these analogues, which reflect their ability to bind to the chick intestinal nuclear receptor under in vitro conditions, were determined.Analogues 3b, 4a, and 4b had RCI values of 0.8 +/- 0.1 percent, 24.0 +/- 4.5 percent, and 0.22 +/- 0.01 percent, respectively, in comparison to 1α,25-(OH)2-D3 whose value is 100 percent by definiton.In addition, in vivo biological evaluation of these analogues was performed to determine their ability to induce intestinal calcium absorption (ICA) and bone calcium mobilization (BCM) in vitamin D deficient chicks.Analogue 4a was effective in stimulating ICA and BCM whereas analogues 3b and 4b exhibited little potency in eliciting these biological effects.
- Muralidharan, K. Raman,Lera, Angel R. de,Isaeff, Shawn D.,Norman, Anthony W.,Okamura, William H.
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p. 1895 - 1899
(2007/10/02)
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- AN EFFICIENT SYNTHESIS OF 1α,25-DIHYDROXY VITAMIN D3
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An efficient synthesis of the title compound is reported based on C-1 functionalization of the triazoline Diels-Alder adduct of 25-OH previtamin D3 (2c).
- Vanmaele, L.,Clerq, P. J. de,Vandewalle, M.
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p. 141 - 144
(2007/10/02)
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