The electrocatalytic cascade assembling of isatins, malononitrile and N-alkyl barbiturates: An efficient multicomponent approach to the spiro[indole-3,5′-pyrano[2,3-d]pyrimidine] framework

Electrochemically induced catalytic multicomponent transformation of isatins, barbituric acid or N-alkyl barbiturates and malononitrile in alcohols in an undivided cell results in the formation of substituted 7′-amino-2,2′,4′-trioxo-1,1′,2,2′,3′,4′-hexahydrospiro[indole-3,5′-pyrano[2,3-d]pyrimidine]-6′-carbonitriles in 80–95% yields. The developed efficient electrocatalytic approach to corresponding spiro[indole-3,5′-pyrano[2,3-d]pyrimidine] system is beneficial from the viewpoint of diversity-oriented large-scale processes and represents a new example of the ecologically pure synthetic concept for electrocatalytic multicomponent reactions strategy.