Autocatalytic and DMSO-promoted regioselective synthesis of pyrimidine-fused quinolines from anilines and barbituric acids.

Autocatalytic and DMSO-participating regioselective synthesis of N,N-disubstituted pyrimido[4,5-b]quinoline-2,4(1H,3H)-diones from anilines and barbituric acids has been achieved. In this newly developed one-pot tandem reaction, DMSO serves as a solvent cum methine source. Additionally, barbituric acid plays a dual role by acting as a substrate and a catalyst, making this reaction an environmentally benign approach to accessing valuable heterocycles. This method offers an auto-catalytic, additive-free, and operationally simple approach with a wide substrate scope and excellent tolerance for various functional groups. Furthermore, a few controlled experiments were conducted to gain insight into the reaction mechanism. Moreover, large-scale experiments have further enriched this methodology.