Keywords: 2-aminobenzylamine, [6,6′]bi[isoquino[3,2-b]quinazoline], dibenzo[b,f][1,8]naphthyridine, isoquino[3,2-b]quinazoline, 2-(cyanomethyl)benzoic acid, oxidation, rearrangement.2-(Cyanomethyl)benzoic acid (1) on condensation with benzylamine [2], aniline [3], and substituted anilines [4] behaves as 1,5-dielectrophilic synthon and gives derivatives of 3-aminoisocarbostyrene. On interaction with anthranilic acid or its esters acid 1 behaves as a monofunctional compound to give derivatives of 2-[(3,4-dihydro-4-oxo-2-quinazolinyl)methyl]benzoic acid [5].In the present work we have investigated the condensation of acid 1 with 2-aminobenzylamine (2). This reaction was studied previously [6, 7], but the structure of the condensation product -5,13-dihydro-11H-isoquino[3,2-b]quinazolin-11-one (3) was not shown conclusively.We have found that compound 3 can be obtained in higher yield (82%) by boiling the reagents in butanol for 5 h than by carrying out the reaction in anyl (6 h, 68% yield [6, 7]. Prolongation the reaction is considerably decreased by using DMF (2 h) as the solvent and the reaction product does not require further purification. However, as a result of unexpected oxidation, the yield of compound 3 in the last case was considerably reduced (<50%).The reaction of 2-(cyanomethyl)benzoic acid with 2-aminobenzylamine may lead to condensation products with either an angular structure -5,6-dihydro-12H-isoquino[2,3-a]quinazolin-12-one (4) or a linear structure -5,13-dihydro-11H-isoquino[3,2-b]quinazolin-11-one (3). It is not possible using IR and 1 H NMR spectra to determine unequivocally the structures of 3 and 4, it can only be said that an enamine structure is present: ν NH 3250 cm -1 , δ NH 9.72 (s) and δ =CH 5.85 ppm (s). In addition the absence of coupling between the protons of the amino and methylene groups (5.06 ppm, 2H, s) indicates the formation of compound 3. _______ * For Communication 26 see [1].
