反应详情

In a manner analogous to that described in Example 1, starting from 4-ethylthiophenol there is obtained 3-(4-ethylphenylthio)-propionic acid, melting point 59°-60°, which is converted into 6-ethyl-2,3-dihydro-4H-1-benzothiopyran-4-one (red oil). This is converted into an oxime with isopentyl nitrite, and the resulting crude potassium salt of 6-ethyl-3-hydroxyimino-2,3-dihydro-4H-1-benzothiopyran-4-one is converted with concentrated hydrochloric acid into 3-amino-2-chloro-6-ethyl-4H-1-benzothiopyran-4-one, melting point 79°-81°. After hydrogenation there is obtained 3-amino-6-ethyl-4H-1-benzothiopyran-4-one having a melting point of 106°-107°.