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Report | Regular issue | Vol 22, No. 1, 1984, pp.151-157
Published online, 1st January, 1970
DOI: 10.3987/R-1984-01-0151
Regioselective Addition of Grignard Reagents to the 1-Phenoxycarbonyl Salts of Alkyl Nicotinates

Daniel L. Comins,* Eric D. Stroud, and James J. Herrick

*Department of Chemistry abd Biochemistry, Utah State University, Logan, Utah 84332-0300, U.S.A.

Abstract

The addition of Grignard reagents to the 1-phenoxycarbonyl salts of alkyl nicotinates affords substituted 1,2- and 1,4-dihydropyridines. The crude dihydropyridines were aromatized with o-chloranil or sulfur to give 6- and 4-substituted alkyl nicotinates. The regioselectivity of this two-step process, 6- vs. 4- substitution, was examined and found to be dependent upon the structure of the Grignard reagent. When a catalytic amount of cuprous iodide is present during the Grignard reaction, nearly exclusive 1,4-addition results. The crude 1,4-dihydropyridines were aromatized with sulfur to provide 4-substituted methyl nicotinates in moderate yield and high isomeric purity.