The asymmetric reaction of the chiron 2(5H)-furanones (4a-4c) with the Homer-Emmons reagents (5a-5b) has been investigated. The newly chiral organophosphorus derivatives 6 and 7 were obtained using the phosphoryl-stab...The asymmetric reaction of the chiron 2(5H)-furanones (4a-4c) with the Homer-Emmons reagents (5a-5b) has been investigated. The newly chiral organophosphorus derivatives 6 and 7 were obtained using the phosphoryl-stabilized carbanion as a building block in DMSO under mild conditions. Through the asymmetric introduction, the Horner-Emmons reagent could be transformed to a chiral building block to afford the novel functionalized phosphorus derivatives. The structures of the synthesized compounds 6 and 7 were identified on the basis of their elementary and spectroscopic data, such as IR, 1H NMR, 13C NMR, MS and X-ray crystallography. These results provided a valuable approach to the synthesis of potentially interesting chiral organophosphorus derivatives and probing their biological activities.展开更多
All of the four stereoisomers of methyl 4,5-epoxy-3-hydroxy-cyclohex-l-ene-carboxylate （la--ld） are useful chiral building blocks. Novel and efficient syntheses of these four epoxy chiral building blocks from natura...All of the four stereoisomers of methyl 4,5-epoxy-3-hydroxy-cyclohex-l-ene-carboxylate （la--ld） are useful chiral building blocks. Novel and efficient syntheses of these four epoxy chiral building blocks from naturally abun- dant （--）-shikimic acid （2） via cyclic sulfite intermediates are described in this article. The targeted compound （3R,4R,5S）-la was synthesized via four steps from （--）-shikimic acid in 79% overall yield. The other three targeted compounds （3S,4R,5S）-lb, （3S,4S,5R）-1c and （3R,4S,5R）-ld were synthesized via seven steps from （--）-shikimic acid in 56%, 64% and 65% overall yields, respectively.展开更多
The stereoselecfive synthesis of typhoniside, a new cerebroside isolated from Typhonium giganteum Engl. was accomplished. Cerebrosides are a kind of glycolipids highly enriched on the surface of myelin-producing cells...The stereoselecfive synthesis of typhoniside, a new cerebroside isolated from Typhonium giganteum Engl. was accomplished. Cerebrosides are a kind of glycolipids highly enriched on the surface of myelin-producing cells and are composed by CUM, 8-sphingadienine, a-hydroxy acid and a saccharide head. It was the first time that cerebrosides were isolated from this traditional Chinese medicine (TCM) by us. In this paper, C18-4, 8-sphingadienine was synthesized from D-xylose via a SN2 type reaction. α-Hydroxy add was prepared from (R )-4-hydroxyte-trahydrofuran-2-one, which in turn could be obtained from L-ascorbic acid.展开更多
S)-3-Hydroxy-g-butyrolactone was synthesized from L-malic acid by anhydridisation, mono-esterification, and reductive cyclization by NaBH4 and with an overall yield of 79%.
A chiron approach-based enantioselective synthesis of designed tricyclic tyrosine analogue D-2 was developed. A SmI2-mediated free radical cyclization, an intramolecular Friedel-Crafts reaction and an intramolecular M...A chiron approach-based enantioselective synthesis of designed tricyclic tyrosine analogue D-2 was developed. A SmI2-mediated free radical cyclization, an intramolecular Friedel-Crafts reaction and an intramolecular Mannich reaction served as key steps. These key steps were optimized and repeated in good yields. All the stereochemistries in the synthesis were established and confirmed.展开更多
Leukotrienes, arachidonic acid derived metabolites of great biological signifi-cance, are present in tissue at extremely low concentrations, so that experimentalquaatities are only accessible by chemical synthesis. I... Leukotrienes, arachidonic acid derived metabolites of great biological signifi-cance, are present in tissue at extremely low concentrations, so that experimentalquaatities are only accessible by chemical synthesis. In various synthetic routes,[S,S-（E）]-3-（hydroxymethyl） oxiranebutanoic acid methyl ester （1） and （S）-5-（ben-zoyloxy）-6-oxohexanoic acid methyl ester （2） have been frequently used as the C-Cfragment of LTA3 and the C-Cfragment of LTB4, respectively. （Scheme1）展开更多
基金Project supported by the National Natural Science Foundation of China(No.29672004).
文摘The asymmetric reaction of the chiron 2(5H)-furanones (4a-4c) with the Homer-Emmons reagents (5a-5b) has been investigated. The newly chiral organophosphorus derivatives 6 and 7 were obtained using the phosphoryl-stabilized carbanion as a building block in DMSO under mild conditions. Through the asymmetric introduction, the Horner-Emmons reagent could be transformed to a chiral building block to afford the novel functionalized phosphorus derivatives. The structures of the synthesized compounds 6 and 7 were identified on the basis of their elementary and spectroscopic data, such as IR, 1H NMR, 13C NMR, MS and X-ray crystallography. These results provided a valuable approach to the synthesis of potentially interesting chiral organophosphorus derivatives and probing their biological activities.
基金the National Natural Science Foundation of China （No. 20972048） and Shanghai Educational Development Foundation （The Dawn Program： No. 03SG27） for the financial support of this work.
文摘All of the four stereoisomers of methyl 4,5-epoxy-3-hydroxy-cyclohex-l-ene-carboxylate （la--ld） are useful chiral building blocks. Novel and efficient syntheses of these four epoxy chiral building blocks from naturally abun- dant （--）-shikimic acid （2） via cyclic sulfite intermediates are described in this article. The targeted compound （3R,4R,5S）-la was synthesized via four steps from （--）-shikimic acid in 79% overall yield. The other three targeted compounds （3S,4R,5S）-lb, （3S,4S,5R）-1c and （3R,4S,5R）-ld were synthesized via seven steps from （--）-shikimic acid in 56%, 64% and 65% overall yields, respectively.
基金Project supported by the National Natural Science Foundation of China(No.29790126),Chinese Academy of Sciences(No.95-A1504-03)and the Ministry of Science and Technology of China(Nos.970211006-6,G2000077502).
文摘The stereoselecfive synthesis of typhoniside, a new cerebroside isolated from Typhonium giganteum Engl. was accomplished. Cerebrosides are a kind of glycolipids highly enriched on the surface of myelin-producing cells and are composed by CUM, 8-sphingadienine, a-hydroxy acid and a saccharide head. It was the first time that cerebrosides were isolated from this traditional Chinese medicine (TCM) by us. In this paper, C18-4, 8-sphingadienine was synthesized from D-xylose via a SN2 type reaction. α-Hydroxy add was prepared from (R )-4-hydroxyte-trahydrofuran-2-one, which in turn could be obtained from L-ascorbic acid.
文摘S)-3-Hydroxy-g-butyrolactone was synthesized from L-malic acid by anhydridisation, mono-esterification, and reductive cyclization by NaBH4 and with an overall yield of 79%.
基金the Major State Basic Research Development Program (No. G2000077500), the National Natural Science Foundation of China (No. 20321202), and Chinese Academy of Sciences and Shanghai Municipal Commission of Science and Technology.
文摘A chiron approach-based enantioselective synthesis of designed tricyclic tyrosine analogue D-2 was developed. A SmI2-mediated free radical cyclization, an intramolecular Friedel-Crafts reaction and an intramolecular Mannich reaction served as key steps. These key steps were optimized and repeated in good yields. All the stereochemistries in the synthesis were established and confirmed.
基金Project supported by the Chinese Academy of Sciences and the State Committee of Science and Technology of China.
文摘 Leukotrienes, arachidonic acid derived metabolites of great biological signifi-cance, are present in tissue at extremely low concentrations, so that experimentalquaatities are only accessible by chemical synthesis. In various synthetic routes,[S,S-（E）]-3-（hydroxymethyl） oxiranebutanoic acid methyl ester （1） and （S）-5-（ben-zoyloxy）-6-oxohexanoic acid methyl ester （2） have been frequently used as the C-Cfragment of LTA3 and the C-Cfragment of LTB4, respectively. （Scheme1）
