Condensation of Pyrazol-5-ones Unsubstituted in the Position 1 with β-Keto Esters. Synthesis of Pyrano[2,3-c]pyrazol-6-ones

The thermal condensation of β-keto esters and N-unsubstituted pyrazol-5-ones gives good yields of pyrano[2,3-c]pyrazol-6-ones. Other potential routes for the condensation are not realized. The β-diketones react via another scheme to form noncyclic reaction products.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 444–449, March, 2005.