- Facile construction of the 7,8-olefin linkage in vitamin D3: A practical synthesis benefiting the vitamin D3 analog study
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A facile procedure for construction of the 7,8-olefin linkage in vitamin D3 is described. Treatment of a mixture of A-ring phosphine oxide and CD-ring ketone in THF with lithium hexamethyldisilazide (LHMDS) at -20°C followed by gradual heating
- Ono, Yoshiyuki,Kashiwagi, Hirotaka,Takahashi, Tadakatsu
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- Process for the synthesis of vitamin d compounds and intermediates for the synthesis of the compounds
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An object of the present invention is to provide a process for synthesizing a vitamin D compound by simple procedures at lower costs. The present invention provides a process for preparing a vitamin D compound and an intermediate thereof, comprising the s
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Page/Page column 25; 30; 31
(2008/06/13)
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- Efficient convergent synthesis of 1alpha,25-dihydroxyvitamin D3 and its analogues by Suzuki-Miyaura coupling.
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[reaction: see text] 1alpha,25-Dihydroxyvitamin D(3) was synthesized by the Suzuki-Miyaura coupling of the A-ring intermediate 1, which was efficiently prepared from readily available 1,7-enyne 2, with the corresponding boronate compound of the C,D-ring portion. The method was applied to prepare des-C,D analogues of 1alpha,25-dihydroxyvitamin D(3).
- Hanazawa, Takeshi,Koyama, Akiko,Wada, Takeshi,Morishige, Eiko,Okamoto, Sentaro,Sato, Fumie
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p. 523 - 525
(2007/10/03)
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- New Convergent Synthesis of 1α,25-Dihydroxyvitamin D3 and Its Analogues by Suzuki-Miyaura Coupling between A-Ring and C,D-Ring Parts
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A new convergent method for the synthesis of 1α,25 -dihydroxyvitamin D3 and its analogues has been developed that involves efficient preparation of the A-ring part 1a, (Z)-(3S,5R)-1-bromom-ethylene-3,5-bis(tert-butyldimethylsilyloxy) -2-methylenecyclohexane, starting from epichlorohydrin (4) and its Suzuki-Miyaura coupling reaction with the C,D-ring part 12. Thus, (R)-4 was converted to (3S,5R)-5-(tert-butyldimethylsilyloxy)-8-(trimethylsilyl)-oct-l-en-7-yn-3-ol (3a) through a ten-step reaction sequence in 49% overall yield. Compound 3a thus obtained was treated with a Ti(O-i-Pr)4/2 i-PrMgCl reagent and then with NBS to afford (Z)-(1S,2S,5R)-2-bromomethyl-3-[bromo-(trimethylsilyl)methylene] -5-(tert-butyldimethylsilyloxy)cyclohexanol (10a) in 51% yield, from which la was obtained in 87% yield by sequential treatment with TBSCl/imidazole, DBU, and Cs2CO3. The resulting A-ring intermediate 1a was reacted with alkenylboronate 12 in the presence of a PdCl2(dppf) catalyst to furnish 1α,25 -dihydroxyvitamin D3 in 82% yield after protodesilylation. Similarly, all of the other three possible stereoisomers of A-ring parts 1b, 1c, and 1d were prepared, from which 1-epi-, 3-epi-, and 1,3-di-epi-1α,25-dihydroxyvitamin D3 were synthesized by coupling with 12 in excellent yield, respectively. Starting from 1a and 1c, des-C,D-1α,25-dihydroxyvitamin D3 analogues, retiferol 13 and its 3-epi derivative, were also prepared, respectively.
- Hanazawa, Takeshi,Koyama, Akiko,Nakata, Kunio,Okamoto, Sentaro,Sato, Fumie
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p. 9767 - 9772
(2007/10/03)
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