18113-81-0Relevant articles and documents
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Craig,Jacobs
, p. 427,429,432 (1942)
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Regioselective Addition of Grignard Reagents to 1-Acylpyridinium Salts. A Convenient Method for the Synthesis of 4-Alkyl(aryl)pyridines
Comins, Daniel L.,Abdullah, Abdul H.
, p. 4315 - 4319 (2007/10/02)
The addition of Grignard reagents to 1-acylpyridinium salts afforded 1-acyl-2-alkyl(aryl)-1,2-dihydropyridines and 1-acyl-4-alkyl(aryl)-1,4-dihydropyridines.The regioselectivity of this reaction, 1,2- vs. 1,4-addition, was examined and found to be dependent upon the structures of the Grignard reagent and the 1-acyl group.Pyridine, 2-picoline, and 3-picoline were studied, and in most cases, significant amounts of 1,4-addition occurred.When a catalytic amount of cuprous iodide was present, nearly exclusive 1,4-addition resulted.The crude 1,4-dihydropyridines were aromatized by heating with sulfur to provide 4-substituted pyridines and picolines in good yield and high isomeric purity.
Catalytic Reactions of Pyridines. V. Alkylation of α-, β-, and γ-Picolines with Alcohols catalyzed by Ammonium Halides
Kashiwagi, Hiroshi,Enomoto, Saburo
, p. 2213 - 2218 (2007/10/02)
A new method was found for the homogeneous liquid-phase alkylation of α-, β-, and γ-picolines with either methanol or ethanol.Addition of a catalytic amount of an ammonium halide to a mixture of a picoline and an alcohol resulted in a great increase in the yields of both side-chain and α-alkylated derivatives of the starting picoline when the reaction was carried out at 320-335 deg C in an atmosphere of nitrogen.The higher the reaction temperature, the greater the yields of side-chain alkylated derivatives became.In practice, this alkylation gave 2-ethylpyridine, and 2,6-lutidine from α-picoline with methanol, 3-ethylpyridine and 2,5-lutidine from β-picoline from methanol, 4-ethylpyridine and 2,4-lutidine from γ-picoline with methanol, 2-propylpyridine and 2-ethyl-6-methylpyridine from α-picoline with ethanol, 2-ethyl-5-methylpyridine from β-picoline with ethanol, and 4-propylpyridine and 2-ethyl-4-methylpyridine from γ-picoline with ethanol.Keywords-alkylation; catalyst; ammonium halide; α-picoline; β-picoline; γ-picoline; ethylpyridine; propylpyridine; methanol; ethanol