Synthesis of Xanthene Derivatives having Antispasmodic Action. IX. Derivatives of Xanthene-and Thioxanthene-9-alcohol

Abstract

9-(2-Diethylcarbamoyloxyethyl)xanthene (IVa) was prepared from xanthene-9-acetic acid (Ia) via ethyl xanthene-9-acetate (IIa) and 9-(2-hydroxyethyl)xanthene (IIIa). Similarly, 9-(2-diethylcarbamoyloxyethyl)thioxanthene (IVb) and its 10, 10-dioxide (IVc) were prepared. 9-(Diethylcarbamoyloxyethyl)xanthene (VIIIa) was prepared from xanthene-9-carboxylic acid (Va) via ethyl xanthene-9-carboxylate (VIa) and 9-hydroxy-methylxanthene (VIIa). Similarly, 9-(diethylcarbamoyloxymethyl)thioxanthene (VIIIb) was prepared. Oxidation of thioxanthene-9-carboxylic acid (Vb) with hydrogen peroxide did not afford. its 10, 10-dioxide, but thioxanthen-9-one 10, 10-dioxide (IX). Therefore, ethyl thioxanthene-9-carboxylate 10, 10-dioxide (VIc) was obtained by oxidation of ethyl thioxanthene-9-carboxylate (VIb) with hydrogen peroxide, but VIc was not reduced to 9-hydroxymethyl-thioxanthene 10, 10-dioxide with lithium aluminium hydride or lithium borohydride. 9-(Diethylcarbamoyloxymethyl) thioxanthene 10, 10-dioxide (VIIIc) was obtained by oxidation of VIIIb with hydrogen peroxide at 70°. Oxidation of VIIIb at 100° afforded 9-methylenethioxanthene 10, 10-dioxide (X). VIIIc decomposes gradually to X.