Synthesis Of 3-Dihydriquinazolin-12 Lab Report

2.4.General procedure for the synthesis of 2,3-dihydriquinazolin-4(1H) ones derivatives: A stirred mixture of isatoic anhydride (1 mmol), amines containing 2-aminobenzothiazole or 2-amino benzimidazole (1.1mmol), aromatic aldehydes (1 mmol) and 0.045 g of H-ZSM-5 nanozeolite was reacted in an oil bath at 100 oC for the appropriated times. Completion of the reaction was indicated by TLC. After completion of reaction, the mixture was cooled to room temperature. The solid residue was dissolved in hot ethanol and the catalyst filtered off. The filtrate solution was concentrated and the solid product was recrystallized in aqueous EtOH (70%) to give pure products.
Selected spectra:
3 -(2′-benzothiazolo)-2,3-dihydro-2-(4-chlorophenyl)-quinazolin-4(1H)-ones ( Table 1 Entry 1): m.p 229-239 oC; IR (KBr): υ = 3335, 1634, 1502, 1406, 1254, 740cm-1; 1H NMR (400 MHz, DMSO-d6): δ = 6. 81 (t, 1H, J = 8 Hz), 6.85 (d, 1H, J = 8 Hz), 7.30 (d, 2H, J = 8 Hz), 7.36 (t, 3H, J = 8 Hz),
3
3.3. Catalytic activity of H-ZSM-5 nanozeolite At first, to choose optimum conditions, we tried to prepare 2,3-dihydriquinazolin-4(1H)ones from the reaction of 4-chlorobenzaldehyde (1 mmol), isatoic anhydride (1 mmol), and 2-aminobenzothiazole(1.1mmol) as a model, under solvent-free conditions in different temperatures in the presence of catalyst (0.02 g). Next, the model was examined at different amounts of catalyst at 100 oC (Table 2). As shown as table 2 the best result was obtained at 100 oC and 0.045 g of the catalyst.
Table 2
We applied the above optimal conditions to a diversity of aryl aldehydes, with isatoic anhydride and 2-aminobenzothiazole, studied the scope and versatility of this reaction for preparation of varieties of 3-(2/- benzothiazolo)-2,3-dihydroquinazolin-4(1H)-ones derivatives (Table 3, Entry 1-9). In continuation, 2-aminobenzimidazole was used in reaction to obtain 3-(2′-benzimidazolo)-2,3-dihydro-2-quinazolin-4(1H)-one derivatives in high yields (Table 3, Entry 10