The (6-membered) barbituric acid derivative 3 was synthesized and treated with KF/DMF/18-crown-6 to form the ring-enlarged 14-membered compound 8 in good yield.
Photochemical reaction of barbital (1a) and its derivatives gave Norrish type II reaction products. Their photochemical reactivities is discussed in comparison with those of other nitrogen-containing carbonyl compounds.