Alkylation of 8-chlorotheophylline by alkenyl(propargyl) halides yields 7-alkenyl(propargyl)-8-chlorotheophylline. The reaction of 8-chlorotheophylline with 1,3-dichloropropan-2-ol leads to the formation of oxazolo[2,3- f ]purinium system. 7-Alkenyl-8-chlorotheophyllines react with bromine to give dibromoalkyl-8- chlorotheophyllines. The reaction of 7-methallyl-8-chlorotheophylline with m -chloroperbenzoic acid affords the corresponding oxirane.