Oxidation of 3-acetylthiophene (I) with selenium dioxide in refluxing dioxan provided 3-thienylglyoxaldehyde hydrate (II). This was then condensed with 4,5-dimethoxy-1,2-phenylenediamine (III) in boiling EtOH to produce the target quinoxaline, which was finally isolated as the hydrochloride salt.