i imidazoisoindolediones can be prepared by several distinct synthesis routes hereinafter described in accordance with this invention formula i imidazoisoindolediones can be prepared by cyclization of a phthalimidocarboxamide or a dioxoisoindolineacetamide cyclization can be achieved by reacting the phthalimido derivative or isoindolineacetamide with a strong base at an elevated temperature in the presence of an organic solvent the cyclization reaction is preferably conducted at a temperature of from 80 u00b0 to 150 u00b0 c in the presence of a base such as sodium or potassium hydroxide or a catalyst such as an aromatic sulfonic acid and a solvent which will form an azeotropic mixture with water permitting virtually immediate removal thereof from the reaction mixture as it is formed among the solvents which may be employed are toluene benzene xylenes and cyclohexane bases which may be used include alkali metal hydroxides alkali metal hydrides alkali metal oxides tertiary amines such as diisopropyl ethylamine 1 5 diazobicyclo 3 4 0 nonene 5 1 5 diazobicyclo 5 4 0 undecene 5 1 4 diazobicyclo 2 2 2 octane tetramethylquanidine potassium fluoride and quaternary ammonium hydroxides such as trimethylbenzyl ammonium hydroxide and strongly basic ion exchange resins acidic reagents which may be employed include aromatic sulfonic acids such as p toluenesulfonic acid u03b2 naphthalenesulfonic acid naphthalenedisulfonic acid and the like in many cases the ring closure may also be achieved by a simple.