チオフェン誘導体の合成化学的研究(第8報) : 2-Substituted-5-[1-arylまたはheteroaryl-2-(5-nitro-2-thienyl)vinyl]-1,3,4-oxadiazole類の合成

抄録

3-(5-Nitro-2-thienyl)-2-aryl(or heteroaryl) acrylic acids (VI) were derived, through the corresponding acid chlorides, to 3-(5-nitro-2-thienyl)-2-aryl(or heteroaryl)acrylic acid hydrazides (VII) by the usual method. In order to obtain 2-substituted 5-[1-aryl(or heteroaryl)-2-(5-nitro-2-thienyl)vinyl]-1, 3, 4-oxadi-azole, VII was reacted with ethyl orthoformate and gave 5-[1-aryl(or heteroaryl)-2-(5-nitro-2-thienyl)vinyl]-1, 3, 4-oxadiazole (V : R₂=H). The reaction of VII and acyl chloride gave 1-acyl-2-[3-(5-nitro-2-thienyl)-2-aryl(or heteroaryl)acrylic acid]hydrazide (XI) whose reaction with phosphoryl chloride under reflux afforded the anticipated 2-alkyl(aryl or heteroaryl)-5-[1-aryl(or heteroaryl)-2-(5-nitro-2-thienyl)vinyl]-1, 3, 4-oxadiazole (V). Heating of VII with bromine cyanide, in sodium hydrogencarbonate solution gave 2-amino-5-[1-aryl(or heteroaryl)-2-(5-nitro-2-thienyl)vinyl]-1, 3, 4-oxadiazole (V : R₂=NH₂).