PROCESS FOR PREPARING 3,7-DIALKYL XANTHINES

摘要

Process for preparing 3,7-dialkyl xanthines of formula (I), where R<1> and R<2> are C1-C4 alkyl groups, by reacting 4-aminoimidazole-carboxamide-(5) of formula (II) with an alkali metal cyanate in aqueous solution at pH 3 to 5, followed by cyclization of the resultant urea derivative at pH 8 to 14.