3-(1,3-dioxolan-2-ylmethyl)-N-methyl-5-(methylamino)imidazole-4-carboxamide; 1-((1,3-dioxolan-2-yl)methyl)-N-methyl-4-(methylamino)-1H-imidazole-5-carboxamide; Doxofylline Impurity 1; Doxofylline Related Compound B