オキサゾールカルボン酸誘導体の合成について (第4報)

5-あるいは2-オキサゾールカルボン酸およびアミノオキサゾールの合成

抄録

Reaction of ethyl benzoxyacetoacetate (I) and ethyl acetoxybenzoylacetate (II) with carboxamide afforded 2-phenyl-4-methyl-5-oxazolecarboxylic acid (III) from (I) and 2-methyl-4-phenyl-5-oxazolecarboxylic acid (IV) from (II), both in a low yield (Table I). (III), (IV), and ethyl 2, 4-diphenyl-5-oxazolecarboxylate (IV) were obtained in approximately 50% yield respectively from (I), (II), and ethyl benzoyloxybenzoylacetate (V) by the method of Cornforth, et al. Ethyl 4-methyl-5-phenyl-2-oxazolecarboxylate (IX) and 4, 5-diphenyl-2-oxazolecarboxylate (X) were prepared by treatment of the corresponding keto-amine hydrochlorides by the procedure described in Part I and their hydrazides were also prepared.
In order to examine synthetic process for aminoöxazoles, benzylurethans (XI to XIV) (Table II) were prepared and their Curtius decomposition was examined. By heating (XII) with conc. hydrochloric acid, 2-amino-5-phenyloxazole (XV) was obtained in a good yield, while catalytic reduction of (XII) gave 2-amino-5-phenyloxazolidine (XVI), m.p. 110-112°, which was also obtained by reduction of (XV). The objective amines were not obtained from (XII), (XIII), or (XIV) by the Curtius reaction carried out in the present series of experiments.