Abstract
Diketene reacted with barbituric acids in the presence of the basic catalyst and gave the acetoacetyl derivatives (IV-VI) in excellent yields. Condensation of the 5-acetoacetylbarbituric acids with hydrazine and phenylhydrazine gave the pyrazole (IXa, Xa) and phenylpyrazole derivatives (XIa, XIIa) in quantitative yields, respectively. Intramolecular cyclization of 1, 3-dimethyl-5-acetoacetylbarbituric acid in the acidic conditions afforded the γ-pyrone derivative (VIII).
