A process for preparing 2-(2-(5-dimethylaminomethylfuran-2-ylmethylthio)ethylamino)-5-(2-metho xypyrid-4- ylmethyl)pyrimidin-4-one which comprises reacting 2-(2-(furan-2-ylmethylthio)ethylamino)-5-(2-methoxypyrid-4-ylmethyl)py rimidin-4- one with a organic solution of bis(dimethylamino)methane at a pH of about 1.3 to about 2.5. The product is an H2-antagonist and also is of value in forming 2-(2-(5-dimethylaminomethylfuran-2-yl-methylthio)ethylamino)-5-(2-hydr oxypyrid-4 -ylmethyl)pyrimidin-4-one by deprotecting.