Substituent directed regioselective synthesis of 2-oxonicotonic acids and methyl nicotinates |
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Authors: | Ramendra Pratap Resmi Raghunandan Vishnu Ji Ram |
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Institution: | a Division of Medicinal and Process Chemistry, Central Drug Research Institute, Lucknow 226 001, India b Molecular and Structural Biology, Central Drug Research Institute, Lucknow 226 001, India |
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Abstract: | An innovative synthesis of aryl tethered 1,2-dihydro-2-oxopyridine-3-carboxylic acids has been developed through nucleophile induced ring transformation of methyl 6-aryl-4-methylsulfanyl-2H-pyran-2-one-3-carboxylates using either cyanamide or arylamidine in excellent yields. Further, the reaction of methyl 6-aryl-4-methylsulfanyl-2H-pyran-2-one-3-carboxylates with formamidine acetate under analogous reaction conditions did not follow the same course of reaction and produced methyl nicotinate, regioselectively, in good yield. Decarboxylation of a 6-aryl-4-methylsulfanyl-1,2-dihydro-2-oxopyridine-3-carboxylic acid has been achieved by heating in PPA. The 4-methylsulfanyl substituent in 3 has also been oxidized to the corresponding methylsulfonyl group with m-chloroperbenzoic acid. |
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Keywords: | 2H-Pyran-2-ones Ring transformation |
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