有機硫黄化合物の合成化学的研究(第2報) : 2-Thiopicolinanilide誘導体のBifunctional化合物に対する反応性

抄録

Since the reaction of thioanilide-type compounds and aromatic primary amines easily affords amidine compounds by dehydrosulfuration, reaction between 2-thiopicoline anilides (I) and ortho-substituted bifunctional compounds (o-phenylenediamine, o-amino-phenol) was carried out and it was found that cyclization occurred by liberation of hydrogen sulfide and anilide group, resulting in the formation of imidazole and oxazole rings. Optimal conditions for cyclization by this kind of reaction were examined from reaction temperature, time and solvents used. Liberation of the anilide group from thioanilides suggested the effect of a substituent group in the anilide on the rate of formation of cyclization. Therefore, some 2-thiopicoline anilides were prepared having p-methyl, p-methoxy, p-ethoxy, p-ethoxycarbonyl, o-methyl, o-methoxy, and m-methyl as a substituent. It was thereby found that electron-donating groups tended to decrease the formation rate, both in the formation of 2-(2-pyridyl) benzimidazoles and 2-(2-pyridyl) benzoxazoles.