4,4'-Ethane-1,2-diylbis(piperazine-2,6-dione) in DMF is heated at 130 C for 10 min. Aqueous formaldehyde is then gradually added, and the mixture is heated at 130 C for 1.5 h. 4,4'-Ethane-1,2-diylbis[1-(hydroxymethyl)piperazine-2,6-dione] precipitates from the solution on cooling. It can be purified by recrystallization from dioxane. The hydroxymethyl compound (II) is then stirred with pyridine and chloroform at 10 C. Isobutoxycarbonyl chloride is gradually added, and the mixture is stirred for 6 h at room temperature. The resulting solution is diluted with chloroform. The combined solution is washed with water and then dried. Evaporation of the chloroform gives MST-16. It can be purified by recrystallization from ethylene glycol monomethyl ether.