Abstract Thiofluorescein was synthesized in a preparative yield by successive demethylation of 3, 3′-dimethoxydiphenyl sulfide to 3, 3′-dihydroxydiphenyl sulfide and condensation of the latter with phthalic anhydride in H 2 SO 4. The title compound was also obtained in a higher yield from 3, 3′-dimethoxydiphenyl sulfide directly in a one-pot process combining the condensation in H 2 SO 4 and demethylation in 2 Py· H 2 SO 4.
![3',6'-dihydroxyspiro[isobenzofuran-1(3H),9'-[9H]thioxanthene]-3-one结构式](https://image.chemsrc.com/caspic/283/94109-78-1.png)
