Thiomorpholine → 2-Imino-6-methyl-4-(thiomorpholin-4-yl)pyrimidin-1(2H)-ol

A mixture of 32 g of 4-chloro-1,2-dihydro-2-imino-6-methyl-1-pyrimidinol, 46 g of thiomorphline, and 200 ml of dimethyl sulfoxide was heated at 100°C in a nitrogen atmosphere for 17 hours. The solvent is removed under high vacuum. The residue is shaken with 5% ammonium hydroxide solution and with chloroform. The chloroform layer is washed with water, dried over sodium sulfate and the solvent removed. Trituration of the residue with ether gives 23 g of a solid mp 208°-210°C. Recrystallization from acetone-methanol gives a white crystalline solid, mp 243°-245°C.