35022-83-4Relevant articles and documents
REGIOSELECTIVE SYNTHESIS OF 4-ALKYLPYRIDINES VIA 1,4-DIHYDROPYRIDINE DERIVATIVES FROM PYRIDINE
Akiba, Kin-ya,Iseki, Yuji,Wada, Makoto
, p. 429 - 432 (1982)
N-Ethoxycarbonylpyridinium chloride (1) reacted with at 4-position with almost complete regioselectivity (better than 99percent) to afford the corresponding 1,4-dihydropyridine derivatives (2) in high yields (81 ca. 94percent).The dihydropyridines were readily oxidized by oxygen to give 4-alkylpyridines (4:38 ca. 68percent yields).
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.