Reëxamination was made on 2-dimethylamino-6-methoxybenzothiazole, due to some doubts as to published reports, and it was found that it melted at 91°.
As synthetic procedures for 2-dimethylamino-6-(β-diethylaminoethoxy)-benzothiazole, the following three methods were followed and the object was attained in all of them. (A) Application of tetraethylpiperazine di (p-toluenesulfonate) or diethylaminoethyl chloride to 2-dimethylamino-6-hydroxybenzothiazole, or of diethylamine to 2-dimethylamino-6-(β-chloroethoxy)-benzothiazole, and introduction of the side chain at 6-position; (B) application of dimethylamine to 2-chloro-6-(β-diethylaminoethoxy)-benzothiazole and introduction of the side chain in 2-position; and (C) application of bromine to p-(β-diethylaminoethoxy)-phenyldimethylthiocarbamide and final cyclization. 2-Dimethylamino-6-(β-dimethylaminoethoxy)-, 2-dimethylamino-6-(β-piperidinoethoxy)-, and 2-diethylamino-6-(β-diethylaminoethoxy)-benzothiazoles were also prepared.