- 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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- Highly Stereoselective Grignard Reaction of an Aldopyranose: A Simple Synthesis of 6-Deoxy-D-idose from D-Xylose
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Grignard reaction of 2,3,4-tri-O-benzyl-D-xylopyranose yielded a single product with very high stereoselectivity.A threo relationship of the newly created chiral center with respect to C2 was established by converting the product into the δ-lactone of D-ido configuration, then to the unsaturated lactone of threo configuration.The result made possible a stereoselective synthesis of 6-deoxy-D-idose from D-xylose in a small number of steps.Models accounting for the high stereoselectivity in the Grignard reaction of aldoses are discussed.Keywords - Grignard reaction; stereoselectivity; configuration of unsaturated lactones; 2,3,4-tri-O-benzyl-D-xylose; 1-deoxy-D-sorbose; 6-deoxy-D-iono-1,5-lactone; 6-deoxy-D-idose; stereocontrol models
- Tsuda, Yoshisuke,Nunozawa, Tetsuji,Yoshimoto, Kimihiro
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p. 3223 - 3231
(2007/10/02)
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