Synthesis of 1-amino-2-naphthalenecarboxylic acid derivatives via the intramolecular cyclization of 4-(2-cyanophenyl)-2-butenoic acid derivatives and its application to the one-pot preparation of benzo[h]quinazoline-2,4(1H,3H)-diones

The reaction of 2-(lithiomethyl)benzonitrile with 2-phenylrhio-2-alkenoic acid derivatives in diglyme at -78 degrees C, followed by oxidation with sodium metaperiodate in aqueous MeOH at room temperature and the subsequent elimination reaction in refluxing toluene, gave 4-(2-cyanophenyl)-2-butenoic acid derivatives in moderate-to-fair overall yields. Intramolecular cyclization of these products using NaH in DMF at 0 degrees C gave 1-amino-2-naphthalenecarboxylic acid derivatives almost quantitatively. Successive treatments with an isocyanate without isolation of the aminonaphthalenecarboxylates under reflux afforded benzo[h]quinazoline-2,4(1H,3K)-diones in moderate-to-good yields.