Synthese und Bioaktivität einiger 4-Oxo-naphtho[1,2-d]thiazolo[3,2-a]pyrimidin-Derivate

Synthesis and Bioactivities of Some Derivatives of Naphtho1,2-d]thiazolo3,2-a]pyrimidin-4-one In continuing the study of the structure-activity relationships of compounds of the naphtho1,2-d]thiazolo3,2-a]pyrimidine series, the 4-oxo derivatives 5a–d were synthesized in addition to the 2-oxo compounds reported previously. The synthesis was accomplished by nucleophilic attack of 2-aminonaphtho1,2-d]thiazole (2) on the corresponding β-keto esters 3a–d . Unlike the 2-oxo derivatives, the products showed no hypotensive effect on normotensive rats. However, all compounds exhibited a pronounced diuretic activity in the same animals after oral administration of 10–30 mg/kg. The activity persisted in most cases for more than five hours.