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Ruilong Sheng – One of the best experts on this subject based on the ideXlab platform.

  • 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, 2005
    Co-Authors: Nai-xing Wang, Ya-lan Xing, Junping Zhang, Yun-xu Yang, Wu-wei Wang, Ruilong Sheng

    Abstract:

    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.

  • 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, 2005
    Co-Authors: Nai-xing Wang, Ya-lan Xing, Junping Zhang, Yun-xu Yang, Wu-wei Wang, Ruilong Sheng

    Abstract:

    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.

  • 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, 2003
    Co-Authors: Ravindra V Chambhare, Barsu G Khadse, Anil S Bobde, Rajesh H Bahekar

    Abstract:

    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).