Barbituric acid Minoxidil

Barbituric acid Minoxidil Barium hydroxide Cyclobutyroi Barium nitrite I nosine... 

Six-membered heterocycles are generally more stable, though there are exceptions as shown by the fragmentation observed with many barbituric acid derivatives (barbital) (Sch. 21) (47-49). A class that is invariably characterized by photochemical reactivity is that of TV-oxides such as minoxidil (50) or clordiazepoxide (44). 

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