ABSTRACT
Protonation of the 1 : 1 intermediate produced in the reaction between trimethyl phosphite and dialkyl acetylenedicarboxylates by N,N′-dimethylbarbituric acid leads to dialkyl 2-(dimethyl phosphoryl)-3-(6-methoxy-1,3-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)-succinates.