オキサゾールカルボン酸誘導体の合成について (第1報)

抄録

Three kinds of oxazole-carboxylic acids were prepared. Cyclization of ethoxalyl-aminoacetophenone (I) with phosphoryl chloride in benzene afforded ethyl 5-phenyloxazole-2-carboxylate (II) as plates, m.p. 60-61°, in 70% yield. 2-Carboxylic acid (III) came as white crystalline powder, m.p. 80-82° (decomp.); hydrazide (IV), pale yellow needles, m.p. 164°. Cyclization of ethyl α-acetaminoacetoacetate (V) with phosphoryl chloride in benzene afforded ethyl 2, 5-dimethyloxazole-4-carboxylate (VI) as colorless oil, b.p₁₁ 117°, in 70% yield; hydrazide, pale yellow needles, m.p. 114-116°. Heating of ethyl α-chloroacetoacetate and benzamide, followed by hydrolysis, afforded 4-methyl-2-phenyloxazole-5-carboxylic acid as colorless needles, m.p. 237° (decomp.), yield, 2.4%.