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Communication | Regular issue | Vol 34, No. 2, 1992, pp.225-228
Published online, 1st January, 1970
DOI: 10.3987/COM-91-5895
Synthesis of 6-Alkylamino-3-pyridazinecarboxylic Acid Derivatives from Methyl 6-Chloro-3-pyridazinecarboxylate

Shoetsu Konno, Mataichi Sagi, Futoshi Siga, and Hiroshi Yamanaka*

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980, Japan

Abstract

The synthesis of methyl 6-alkylamino-3-pyridazinecarboxylates (4a-c) was accomplished by the following reaction sequence. On treatment of methyl 6-chloro-3-pyridazinecarboxylate (1) with methanolic ammonia, 6-chloro-3-pyridazinecarboxamide (5) was precipitated almost quantitatively, which reacted with primary alkylamines to give the corresponding 6-alkylamino-3-pyridazinecarboxamide (6a-c). These products were smoothly converted into the methyl esters (4a-c) by treatment with methanol in the presence of boron trifluoride etherate. The reaction of 1 with butylamine in THF gave a complicated mixture in which N-butyl-6-chloro-3-pyridazinecarboxamide (2), N-butyl-6-butylamino-3-pyridazinecalboxamide (3), 4b, and 1 were involved.