Triethylamine → 3-Hydroxy-2-phenylthiazolo[3,2-b]thieno[2,3-d]pyridazin-4-ium hydroxide

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Reaction Steps

66.95 g of thieno[2 3-d]pyridazine-7(6H)-thione are suspended in 3200 ml of methylene chloride under argon, whereupon 102.7 g of α-bromophenylacetyl chloride are added dropwise thereto. The mixture is stirred at room temperature for about 30 minutes and then 121 ml of triethylamine are added dropwise thereto, whereby the mixture is cooled to 25°-30°. It is stirred for about 40 minutes. After evaporation of the solvent in vacuo the residue is taken up in 1000 ml of water and 200 ml of ether, whereupon the mixture is stirred for about 30 minutes. The separated crystals are filtered off under suction, washed with water and ether and dried overnight. The dried crystals are again triturated with 1000 ml of water. After suction filtration the red-violet crystals are washed with water and dried in vacuo. There is obtained 3-hydroxy-2 -phenylthiazolo[3,2-b]thieno[2,3-d]-pyridazin-4-ium hydroxide (internal salt) of m.p. 260°-264° (decomposition).

Provenance & Evidence