- Acylated and non-acylated flavonol monoglycosides from the Indian minor spice Nagkesar (Mammea longifolia).
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A methanol extract of nagkesar (buds of Mammea longifolia), which showed strong radical scavenging activity, yielded 13 compounds by separations using column chromatography and HPLC. Structure elucidation of these compounds was achieved by (1)H and (13)C NMR, including DQF-COSY, TOCSY, DEPT, HMQC, HSQC, and HMBC. They include two new compounds, quercetin 3-O-(2' ',4' 'di-E-p-coumaroyl)-alpha-L-rhamno-pyranoside and quercetin 3-O-(3' ',4' '-di-E-p-coumaroyl)-alpha-L-rhamnopyranoside, along with known compounds kaempferol, quercetin, the isopropylidenedioxy derivative of shikimic acid, kaempferol 3-O-(2' ',4' '-di-E-p-coumaroyl)-alpha-L-rhamnopyranoside, kaempferol 3-O-(3' ',4' '-di-E-p-coumaroyl)-alpha-L-rhamnopyranoside, kaempferol 3-O-alpha-L-rhamnopyranoside, quercetin 3-O-alpha-L-rhamnopyranoside, shikimic acid, kaempferol 3-O-beta-D-glucopyranoside, quercetin 3-O-beta-D-glucopyranoside, and beta-sitosterol 3-O-beta-D-glucopyranoside.
- Jagan Mohan Rao, Lingamallu,Yada, Hiroshi,Ono, Hiroshi,Yoshida, Mitsuru
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- Enantiospecific synthesis of (-)-5-epi-shikimic acid and (-)-shikimic acid
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Diastereoselective reaction of 2,3-O-isopropylidene-D-ribose with allylmagnesium chloride gave a 5 : 1 mixture of triols 4 and 5, which were then converted to nitrones 8 and 9. Intramolecular nitrone cycloaddition gave the isoxazolidines 10 and 11, which on acetylation gave the corresponding acetates 12 and 13 which were separated by repeated crystallisation. The major adduct 12 was converted to (-)-5-epi-shikimic acid 2. Reaction of the ribonolactone derivative 20 with allylmagnesium chloride gave the hemiacetal 21. Reduction of compound 21 with DIBAL afforded exclusively the diol 22, which was desilylated to give the triol 5. Similar chemistry to that employed for the synthesis of (-)-5-epi-shikimic acid 2 with the diol 5 resulted in the synthesis of (-)-shikimic acid 1.
- Jiang, Shende,McCullough, Kevin J.,Mekki, Boualem,Singh, Gurdial,Wightman, Richard H.
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p. 1805 - 1814
(2007/10/03)
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- Enantiospecific synthesis of (-)-5-epi-shikimic acid and a new route to (-)-shikimic acid
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(-)-Shikimic acid (1) and (-)-5-epi-shikimic acid (2) have each been prepared enantiospecifically and with high diastereoselectivity from D-ribose.
- Jiang, Shende,Mekki, Boualem,Singh, Gurdial,Wightman, Richard H.
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p. 5505 - 5508
(2007/10/02)
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- Synthesis of shikimic acid and its phosphonate analogue via knoevenagel condensation
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The Knoevenagel condensation and intramolecular olefination have been successfully exploited in a novel synthesis of shikimic acid 1 and its phosphonate analogue 2 from D-lyxose 5-aldehyde 7.
- Mirza, Sohail,Harvey, Jeremy
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p. 4111 - 4114
(2007/10/02)
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