Thiosemicarbazide → N-Methyl-N-[3-(3-amino-1,2,4-triazolo[4,3-b]pyridazin-6-yl)phenyl]acetamide

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Reaction Steps

A solution of 3.0 g N-methyl-N-[3-(6-chloro-3-pyridazinyl)phenyl]acetamide and 2.0 g thiosemicarbazide in 100 ml ethanol was heated at reflux for 5.5 hours. The ethanol was removed in vacuo, 100 ml glacial acetic acid added and the mixture was refluxed for 18 hours. The acetic acid was removed in vacuo and the yellow residue added to 300 ml water. This mixture was brought to pH~7 with aqueous sodium bicarbonate and extracted with 100 ml portions of dichloromethane and dichloromethane-ethyl acetate. The combined extracts were dried, the solvent removed in vacuo, and the product mixture chromatographed on silica gel using dichloromethane-methanol (95.5) as solvent. Recombining the pure fractions and recrystalizing from ether-methanol-hexane afforded 1.10 g yellow crystals, mp 206°-207° C.

Provenance & Evidence