反应详情

Scheme IX illustrates the synthesis of compounds represented by Formula XVI. Reaction of a mixture of 3-chloro-2,5-pentanedione and formamide in refluxing formic acid yields 4-methyl-5-acetyloxazole. Reaction of the sodium salt of 4-methyl-5-acetyloxazole and diethyl oxalate in ethanol affords the corresponding ketoacetate. Reaction of the ketoacetate with hydrazine in refluxing ethanol yields 3-ethoxycarbonyl-5-[4-(methyl)oxazol-5-yl]pyrazole which is alkylated to yield isomers XXIIa and XXIIb. Substituting triethyl orthoacetate for triethyl orthoformate in the reaction described in Scheme V yields isomeric compounds represented by. Formula XVIIa and XVIIb ##STR12##

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