A substituent directed regioselective synthesis of aryl/pyronyl pendant unusual adipate and tetrahydronaphthalene |
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Authors: | Ramendra Pratap Vishnu Ji Ram |
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Institution: | a Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA b Medicinal and Process Chemistry Division, Central Drug Research Institute, Lucknow 226 001, India |
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Abstract: | An efficient regioselective synthesis of pyronyl pendant ethyl methylthiocarbonylalkanoates 5 has been delineated from the base catalyzed reaction of suitably functionalized 2-pyranone 1 and 2-carbethoxycycloalkanones 2, 6 through successive substitution and regioselective ring opening by in situ generated mercaptide ion. To assess the effect of C-4 substituent on regioselectivity, reactions of 6-aryl-3-cyano-4-(piperidin-1-yl)-2-oxopyran 8 with 2-carbethoxycyclohexanone 6a and 2-carbethoxy-2-methylcyclohexanone 6b were carried out separately under analogous reaction conditions but the compounds isolated were identical and characterized as 4-aryl-8-methyl-2-piperidin-1-yl-5,6,7,8-tetrahydronaphthalene-1-carbonitriles 9. Ethyl 2-(5-amino-4′-bromo-4,6-dicyanobiphenyl-3-yl)-5-methylsulfanylcarbonylpentanoate 10 has also been prepared through base catalyzed ring transformation of ethyl 2-6-(4-bromophenyl)-3-cyano-2-oxo-2H-pyran-4-yl]-5-methylsulfanylcarbonylpentanoate 5d by malononitrile in DMF. |
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Keywords: | 2-Carbethoxycyclopentanone 2-Oxopyran Ring transformation Mercaptide ion |
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