In 1914, Johnson and Nicolet were unsuccessful in attempts to synthesize 5-ureido-2, 4, 6- pyrimidinetrione (pseudouric acid) from diethyl ureidomalonate and urea in the presence of sodium ethoxide. 2 Later, Garner showed that diethyl ureidomalonates readily cyclize in the presence of sodium ethoxide to form sodium salts of 5-carbethoxyhydantoins (1). Mild acidification with strong cation-exchange resin gave the free hydantoins (2). 3 The present ...