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Report | Regular issue | Vol 22, No. 6, 1984, pp.1395-1402
Published online, 1st January, 1970
DOI: 10.3987/R-1984-06-1395
Syntheses and Reactions of Pyridazine Derivatives XX. Studies on the Radical Methylation of the 1,2-Diazine System

Gottfried Heinisch* and Gerhard Lötsch

*Institut für Pharmazeutische Chemie, Universität Wien , Pharmaziezentrum, Althanstrasse, 14 A-1090 Wien, Austria


Protonated pyridazines (1,2,3) on reaction with methyl radical (generated by oxidative decarboxylation of acetic acid or by redox reaction of t-BuOOH/FeSO4·7H2O) are shown mainly to be attacked at positions β to the nitrogen atoms. However, formation of compounds 2,4,5,6,8,9 and 10 indicates lower degree of regioselectivity compared with homolytic benzylation or acylation of the 1,2-diazine system. Synthesis of ethyl 5-styryl-4-pyridazinecarboxylates (13,14) was achieved by homolytic methylation of ethyl 4-pyridazinecarboxylate (11) followed by condensation with aromatic carbaldehydes.