| Popis: |
Both diiminoisoindoline and phthalonitrile can be used as synthetic precursors for the synthesis of bis-substituted isoindolines. Early investigation by Linstead et al. used diiminoisoindoline as a starting material. Siegle later modified the synthesis by using phthalonitrile as a synthetic precursor. This direct synthetic route did not include the isolation of diiminoisoindolione in the production of the bis-substituted isoindoline. A variety of adducts have been used to investigate the reactivity of phthalonitrile and diiminoisoindoline with primary aromatic amines. These adducts include aminophenol where the amine group can be ortho, meta or para to the alcohol substituent. A unique feature of the 2-aminophenol is that an intramolecular cyclization occurs which forms two benzoxazoles ortho to each other on a benzene which originated as the phthalonitrile. The other adducts such as the 3 and 4-aminophenols simply underwent a nucleophilic addition followed by intramolecular cyclization to produce the diiminoisoindoline-like compound with two adducts attached. In addition to a direct synthetic route of bis-substituted isoindolines, the formation of a three membered ring, 2-amino-phenoxazin-3-one, was produced due to the oxidation and condensation of the 2-aminophenol upon reflux. |
