Ethanol → 9-(2-hydroxyethyl)-4,4a,5,6-tetrahydrothieno[2',3':2,3]thiepino[4,5-c]pyridazin-3(2H)-one

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Reaction Steps

A mixture of 1.4 g of 4-oxo-4,5,6,7-tetrahydrothieno[2,3-b]thiepin-5-acetic acid and 1.5 g of 2-hydroxyethylhydrazine in 50 ml of ethanol is refluxed under heating for 10 hours. After the mixture is concentrated, to the residue is added water and the mixture is extracted with ethyl acetate. The extract is washed with water, dried over magnesium sulfate and concentrated. To the residue is added isopropyl ether and the solution is allowed to stand. The precipitated crystals are collected by filtration and recrystallized from isopropyl alcohol to give 1.7 g of 9-(2-hydroxyethyl)-4,4a,5,6-tetrahydrothieno[2',3':2,3]thiepino[4,5-c]pyridazin-3(2H)-one as pale yellow crystals, melting at 165°-167° C.

Provenance & Evidence