8-chloro-3,7-dimethyl-3,7-dihydro-purine-2,6-dione

3,7-dimethyl-6-methylthio-2(3H)-purinone

6-氨基-1-甲基尿嘧啶

6-氨基-5-溴-1-甲基尿嘧啶

6-氨基-1-甲基-5-(甲基氨基)尿嘧啶