Synthesis and reactivity of (Z)-3-benzoylamino-4-dimethylamino-2-oxo-3-butene. Preparation of 1-aryl-and 1-heteroaryl-substituted 4-benzoylamino-5-methyl-1H-pyrazoles

摘要

(Z)-3-Benzoylamino-4-dimethylamino-2-oxo-3-butene (4), prepared from 1-benzoylamino-2-propanone (3) and N,N-dimethylformamide dimethyl acetal, was converted regioselectively by reaction with a series of hydrazines (5) into 1-substituted 4-benzoylamino-5-methyl-1H-pyrazoles (8). Reactions of 4 with primary amines (10) and with dimethylbarbituric acid (12) afforded the dimethylamine substitution products (11) and (13), respectively. Treatment of the butenone (13) with ammonia furnished tetrahydropyrido [2,3-d] pyrimidine derivative (14).