Acylation of 2-aminothiazole-4-carboxylic acid ethyl ester (I) with 2,4,5-trimethoxybenzoyl chloride (II) produced the corresponding amide (III). The 2-methoxy group of (III) was then selectively cleaved by treatment with pyridine hydrochloride, yielding the 2-hydroxybenzamide (IV). Finally, displacement of the ethyl ester group of (IV) by N,N-diisopropyl ethanediamine (V) upon heating at 120 C furnished the target compound, which was isolated as the corresponding hydrochloride salt.
In a closely related procedure, acid chloride (II), prepared by treatment of 2,4,5-trimethoxybenzoic acid (VI) with SOCl2 in hot toluene, was condensed with aminothiazole (I), yielding amide (III). Displacement of the ethyl ester group of (III) by N,N-diisopropyl ethanediamine (V) furnished diamide (VII). Finally, upon formation of the hydrochloride salt of (VII) in isopropanol, the 2-methoxy group was simultaneously cleaved, directly leading to the title compound.