8-[(2-Pyridylmethyl)thio]-2-thiotheophylline

8-[(2-Pyridylmethyl)thio]-1,3-dimethyl-3,7-dihydro-2-thioxo-1H-purin-6-one

3,7-Dihydro-1,3-dimethyl-8-[(pyridin-2-yl)methylthio]-2-thioxo-1H-purin-6(2H)-one