- SYNTHESIS OF (25R)-CHOLESTEROL AND 1H N.M.R. AND H.P.L.C. RESOLUTION OF (25R)- AND (25S)-26-HYDROXYCHOLESTEROL
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Yamogenin acetate (1) was isolated from crude diosgenin acetate and converted into (25S)-26-hydroxycholesterol (6a).The absolute configuration at C-25 of (6a) was determined by X-ray crystallography. (25R)-Cholesterol (10) was prepared by reduction of the 26-tosyloxy group by LiAl(2)H4.Reverse-phase h.p.l.c. resolution without derivatization was developed for the diastereoisomers, (25R)- and (25S)-26-hydroxycholesterol.The (+)- or (-)-MTPA esters of these diastereoisomers showed distinctive 1H n.m.r. signals for 26-H.
- Uomori, Atsuko,Seo, Shujiro,Sato, Tomohiro,Yoshimura, Yohko,Takeda, Ken'ichi
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p. 1713 - 1718
(2007/10/02)
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- A New Method for the Oxidation of Alkenes to Enones. An Efficient Synthesis of Δ5-7-Oxo-Steroids
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A variety of cycloalkenes were converted into α,β-unsaturated ketones using t-butyl hydroperoxide in the presence of chromium hexacarbonyl catalyst.The scope of the reaction has been partly invstigated, and it was found that the allylic oxidation proceeds selectively in the presence of some secondary alcohols.High-yield conversions of steroidal 5,6-enes into the corresponding 5,6-en-7-ones are reported.
- Pearson, Anthony J.,Chen, Yong-Shing,Han, Gi Rin,Hsu, Shih-Ying,Ray, Tapan
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p. 267 - 274
(2007/10/02)
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- Comparative Studies on the Constituents of Ophiopogonis Tuber and Its Congeners. I. Studies of the Constituents of the Subterranean Part of Liriope platyphylla Wang et Tang.
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Eight steroidal glycosides, tentatively named glycosides A(1), B(2), C(3), D(4), E(5), F(6), G(7) and H(8), were isolated from the methanol extract of the subterranean part of Liriope platyphylla Wang et Tang (Liliaceae).The structures of these glycosides were established as ruscogenin 3-O-α-L-rhamnopyranoside (1), 25(S)-ruscogenin 1-O-β-D-fucopyranosido-3-O-α-L-rhamnopyranoside (2), 25(S)-ruscogenin 1-O-α-L-rhamnopyranosyl-(1->2)-β-D-fucopyranoside (3), ruscogenin 3-O-β-D-glucopyranosyl(1->3)-α-L-rhamnopyranoside (4), a mixture of 3-O-2)>3)>-β-D-glucopyranosides of diosgenin and yamogenin (=a mixture of ophiopogonin D' and its 25(S)-isomer, 5), a mixture of 3-O-β-chacotriosides of diosgenin and yamogenin (= a mixture of dioscin and its 25(S)-isomer, 6), ruscogenin 1-sulfate 3-O-α-L-rhamnopyranoside (7), and 26-O-β-D-glucopyranosyl-22-O-methylfurost-5-ene-3β,26-diol 3-O-β-chacotrioside (=methyl proto-dioscin, 8).
- Watanabe, Yoshiaki,Sanada, Shuichi,Ida, Yoshiteru,Shoji, Junzo
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p. 1980 - 1990
(2007/10/02)
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- Helicteres isora Linn., a New Source of Diosgenin
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Diosgenin, a steroidal drug intermediate has been isolated for the first time from Helicteres isora Linn.
- Barik, Bikash R.,Dey, A. K.,Das, P. C.
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p. 938 - 939
(2007/10/02)
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