Synthesis of Novel 5,6-Disubstituted Pyrrolo [2,3‑<i>d</i>]Pyrimidine-2,4-Diones Via One-Pot Three-Component Reactions

A simple and novel method for the synthesis of 5,6-disubstituted pyrrolo­[2,3-<i>d</i>]­pyrimidine-2,4-diones has been reported using arylglyoxal-based three-component reactions. Under microwave heating conditions, arylglyoxal, 6-amino uracil, or its derivatives reacts with various thiols in acetic acid medium to provide a series of pyrrolo­[2,3-<i>d</i>]­pyrimidine-2,4-diones (<b>4</b>) having a thioether and an aryl ring in 5 and 6 positions, respectively. On the other hand reaction of arylglyoxal, amino uracil and malononitrile in place of thiols, provided corresponding 5,6-disubstituted pyrrolo­[2,3-<i>d</i>]­pyrimidine-2,4-diones (<b>5</b>) with selectively converting one of the −CN to −CONH₂ group both in conventional (method A) and microwave heating conditions (method B). This methodology is a simple and efficient protocol for the synthesis of diverse 5,6-disubstituted pyrrolo­[2,3-<i>d</i>]­pyrimidine-2,4-diones from the readily available starting materials in good yields