Imidazoquinazolinodiones - New results

X-Ray crystal structure determinations and spectral analyses (NMR, MS) shed new light on the reaction of 5-(Z)-arylidene-2-methylthioimidazolin-4-one (5b) with anthranilic acid, in which apart from the expected 2-(Z)-1-arylid ene-2,3,5, 10-tetrahydroimidazo[2, 1-b]quinazoline-3,5-dione (6b) a new con densed heterocyclic system was identified, i.e. 2-(Z)-arylidene-1,2,4,5-tet rahydroimidazo [1.2-a]quinazoline-1,5-dione (8b). Reaction of the sodium sa lt of the 4-chloro-substituted arylidene derivative (6a) with methyl iodide surprisingly afforded 2- [(Z)-1-(4-chlorophenyl)methylene]-3-methyl-1,2,3, 5-tetrahydroimidazo[1,2-a]-quinazoline-1,5-dione (15).