Mesoionic xanthine analogs as inhibitors of cyclic AMP phosphodiesterase

Several derivatives of two mesoionic xanthine analogs, mesoionic thiazolo[3,2-alpha]pyrimidine-5,7-diones and mesoionic 1,3,4-thiadiazolo[3,2-alpha]pyrimidine-5,7-diones, were synthesized and evaluated as inhibitors of cyclic AMP phosphodiesterase. A significant number of these compounds demonstrated theophylline-like activity.