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Ruilong Sheng - One of the best experts on this subject based on the ideXlab platform.
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A convenient synthesis of 1-[6-fluoro-(2S)-3H,4H-dihydro-2H-2-chromenyl](1R)-1,2-ethanediol and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl](1R)-1,2-ethanediol
Synlett, 2005Co-Authors: Nai-xing Wang, Ya-lan Xing, Junping Zhang, Yun-xu Yang, Wu-wei Wang, Ruilong ShengAbstract:Benzopyran compounds possess diverse pharmacological properties such as β-blockade, anticonvulsant and antimicrobial.[1,2] Our interest has been focused on the synthesis of 1-[6-Fluoro-2S]-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (6) and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (7) which are particularly convenient precursor to (S,R,R,R)-NE (8). 8 containing four asymmetrical carbon atoms was reported to be the most active isomer.[3] Chandrasekhar[4] has reported on the synthesis of 8. The key step to synthesize this compound is to obtain the chiral chromanone 6 and 7. 6 was accomplished in 8 steps by the Clasien rearrangement and a one-pot Sharpless asymmetric epoxidation, but the compound 7 was accomplished in 10 steps. Johannes[5] used Zr-catalytic kinetic resolution of allylic ethers and Mo-catalyzed chromene formation to synthesize 8 in 14 steps. However both of the methods request many synthetic steps and expensive reagents.……
Nai-xing Wang - One of the best experts on this subject based on the ideXlab platform.
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A convenient synthesis of 1-[6-fluoro-(2S)-3H,4H-dihydro-2H-2-chromenyl](1R)-1,2-ethanediol and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl](1R)-1,2-ethanediol
Synlett, 2005Co-Authors: Nai-xing Wang, Ya-lan Xing, Junping Zhang, Yun-xu Yang, Wu-wei Wang, Ruilong ShengAbstract:Benzopyran compounds possess diverse pharmacological properties such as β-blockade, anticonvulsant and antimicrobial.[1,2] Our interest has been focused on the synthesis of 1-[6-Fluoro-2S]-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (6) and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (7) which are particularly convenient precursor to (S,R,R,R)-NE (8). 8 containing four asymmetrical carbon atoms was reported to be the most active isomer.[3] Chandrasekhar[4] has reported on the synthesis of 8. The key step to synthesize this compound is to obtain the chiral chromanone 6 and 7. 6 was accomplished in 8 steps by the Clasien rearrangement and a one-pot Sharpless asymmetric epoxidation, but the compound 7 was accomplished in 10 steps. Johannes[5] used Zr-catalytic kinetic resolution of allylic ethers and Mo-catalyzed chromene formation to synthesize 8 in 14 steps. However both of the methods request many synthetic steps and expensive reagents.……
Rajesh H Bahekar - One of the best experts on this subject based on the ideXlab platform.
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synthesis and preliminary evaluation of some n 5 2 furanyl 2 methyl 4 oxo 4h thieno 2 3 d pyrimidin 3 yl carboxamide and 3 substituted 5 2 furanyl 2 methyl 3h thieno 2 3 d pyrimidin 4 ones as antimicrobial agents
European Journal of Medicinal Chemistry, 2003Co-Authors: Ravindra V Chambhare, Barsu G Khadse, Anil S Bobde, Rajesh H BahekarAbstract:Two series of N-[5-(2-furanyl)-2-methyl-4-oxo-4H-thieno[2,3-d]pyrimidin-3-yl]-carboxamide (4a-m) and 3-substituted-5-(2-furanyl)-2-methyl-3H-thieno[2,3-d]pyrimidin-4-ones (5a-m) were synthesised using appropriate synthetic route. All the test compounds 4a-m and 5a-m were assayed in vitro for antibacterial activity against two different strains of Gram-negative (Escherichia coli and S. typhi) and Gram-positive (S. aureus, B. subtilis) bacteria and the antimycobacterial activity was evaluated against M. tuberculosis and M. avium strains. The minimum inhibitory concentration (MIC) was determined for test compounds as well as for reference standards. The test compounds have shown significant antibacterial and antimycobacterial activity against all the microbial strains used, when tested in vitro. In general, along with the thienopyrimidinone ring, substituted amido or imino side chain at position 3 is essential for antimicrobial activity. Among the compounds tested, compounds 4c, 4e and 4g in N-[5-(2-furanyl)-2-methyl-4-oxo-4H-thieno[2,3-d]pyrimidin-3-yl]-carboxamide series and compounds 5c, 5e and 5g in 3-substituted-5-(2-furanyl)-2-methyl-3H-thieno[2,3-d]pyrimidin-4-ones series were found to be the most potent. Further the toxicity of most potent compounds 4c, 4e and 4g and 5c, 5e and 5g were assessed using hemolytic assay and minimal hemolytic concentration (MHCs) were determined. In general, test compounds were found to be non-toxic up to a dose level of 200 micromol L(-1) (MHC).
Michel Havaux - One of the best experts on this subject based on the ideXlab platform.
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The plastoquinone pool outside the thylakoid membrane serves in plant photoprotection as a reservoir of singlet oxygen scavengers
Plant Cell & Environment, 2018Co-Authors: Brigitte Ksas, Bertrand Legeret, Ursula Ferretti, Anne Chevalier, Pavel Pospíšil, Jean Alric, Michel HavauxAbstract:30 The Arabidopsis vte1 mutant is devoid of tocopherol and plastochromanol (PC-8). When exposed to 31 excess light energy, vte1 produced more singlet oxygen (1 O2) and suffered from extensive oxidative 32 damage compared to the wild type. Here we show that overexpressing the SOLANESYL DIPHOSPHATE 33 SYNTHASE 1 (SPS1) gene in vte1 induced a marked accumulation of plastoquinone (PQ-9) and rendered 34 the vte1 SPS1oex plants tolerant to photooxidative stress, indicating that PQ-9 can replace tocopherol 35 and PC-8 in photoprotection. High PQ-9 levels were associated with a noticeable decrease in 1 O2 36 production and with higher levels of PQ-C, a 1 O2-specific PQ-9 oxidation product. The extra PQ-9 37 molecules in the vte1 SPS1oex plants were stored in the plastoglobules and the chloroplast envelopes, 38 rather than in the thylakoid membranes, whereas PQ-C was found almost exclusively in the thylakoid 39 membranes. Upon exposure of wild-type plants to high light, the thylakoid PQ-9 pool decreased, while 40 the extra-thylakoid pool remained unchanged. In vte1 and vte1 SPS1oex plants, the PQ-9 losses in high 41 light were strongly amplified, affecting also the extra-thylakoid pool, and PQ-C was found in high 42 amounts in the thylakoids. We conclude that the thylakoid PQ-9 pool acts as a 1 O2 scavenger and is 43 replenished from the extra-thylakoid stock. 44 45 KEYWORDS 46 plastoquinone, antioxidant, reactive oxygen species, photoprotection, tocopherol 47 48 49
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The plastoquinone pool outside the thylakoid membrane serves in plant photoprotection as a reservoir of singlet oxygen scavengers
Plant Cell & Environment, 2018Co-Authors: Brigitte Ksas, Bertrand Legeret, Ursula Ferretti, Anne Chevalier, Pavel Pospíšil, Jean Alric, Michel HavauxAbstract:30 The Arabidopsis vte1 mutant is devoid of tocopherol and plastochromanol (PC-8). When exposed to 31 excess light energy, vte1 produced more singlet oxygen (1 O2) and suffered from extensive oxidative 32 damage compared to the wild type. Here we show that overexpressing the SOLANESYL DIPHOSPHATE 33 SYNTHASE 1 (SPS1) gene in vte1 induced a marked accumulation of plastoquinone (PQ-9) and rendered 34 the vte1 SPS1oex plants tolerant to photooxidative stress, indicating that PQ-9 can replace tocopherol 35 and PC-8 in photoprotection. High PQ-9 levels were associated with a noticeable decrease in 1 O2 36 production and with higher levels of PQ-C, a 1 O2-specific PQ-9 oxidation product. The extra PQ-9 37 molecules in the vte1 SPS1oex plants were stored in the plastoglobules and the chloroplast envelopes, 38 rather than in the thylakoid membranes, whereas PQ-C was found almost exclusively in the thylakoid 39 membranes. Upon exposure of wild-type plants to high light, the thylakoid PQ-9 pool decreased, while 40 the extra-thylakoid pool remained unchanged. In vte1 and vte1 SPS1oex plants, the PQ-9 losses in high 41 light were strongly amplified, affecting also the extra-thylakoid pool, and PQ-C was found in high 42 amounts in the thylakoids. We conclude that the thylakoid PQ-9 pool acts as a 1 O2 scavenger and is 43 replenished from the extra-thylakoid stock. 44 45 KEYWORDS 46 plastoquinone, antioxidant, reactive oxygen species, photoprotection, tocopherol 47 48 49
Ya-lan Xing - One of the best experts on this subject based on the ideXlab platform.
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A convenient synthesis of 1-[6-fluoro-(2S)-3H,4H-dihydro-2H-2-chromenyl](1R)-1,2-ethanediol and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl](1R)-1,2-ethanediol
Synlett, 2005Co-Authors: Nai-xing Wang, Ya-lan Xing, Junping Zhang, Yun-xu Yang, Wu-wei Wang, Ruilong ShengAbstract:Benzopyran compounds possess diverse pharmacological properties such as β-blockade, anticonvulsant and antimicrobial.[1,2] Our interest has been focused on the synthesis of 1-[6-Fluoro-2S]-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (6) and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (7) which are particularly convenient precursor to (S,R,R,R)-NE (8). 8 containing four asymmetrical carbon atoms was reported to be the most active isomer.[3] Chandrasekhar[4] has reported on the synthesis of 8. The key step to synthesize this compound is to obtain the chiral chromanone 6 and 7. 6 was accomplished in 8 steps by the Clasien rearrangement and a one-pot Sharpless asymmetric epoxidation, but the compound 7 was accomplished in 10 steps. Johannes[5] used Zr-catalytic kinetic resolution of allylic ethers and Mo-catalyzed chromene formation to synthesize 8 in 14 steps. However both of the methods request many synthetic steps and expensive reagents.……
