Eco-friendly Synthesis Of Some Nitrogen-containing Benzoheterocyclic Compounds

Benzoazoles are of great importance in medical and industry apprication.This thesis focused on green synthesis of 2-substituted benzothiazole derivates,1,2-disubstituted benzimidazole derivates, dihydrogen quinazolinone and quinazolinone derivates.(1) Several kinds of amino ionic liquid catalysts were preparation by simple acid-base reaction. Among of these ionic liquid catatysts, L-proline based ionic liquid catalyst gain the best result in synthsis of 2-substituted benzothiazole derivates at80?in ethyl lactate as solvent. This method has many advantages such as the low cost of raw materials, the biodegradability of solvents, good applicability of the substrate.In addition, this method can be applied in gram scale reaction, and ionic liquid catalyst can be recycled five times without loss of catalytic activity. Combined with the above advantages, the strategy has a broad prospect for industrial production.(2) To synthesis of 1,2-disubstituted benzimidazoles from aldehydes and o-phenylenediamine was a very common strategy. However, Schiff base and2-substituted benzothiazoles are also formed as by-product in this reaction. From various kinds of solvent, we founded the lactic acid can be used as hydrogen bond donor to promote the formation of 1,2-disubstituted benzimidazole selectively. When the proportion of o-phenylenediamine with aldehydes even was 1:1, the product of1,2-disubstituted benzimidazoles still got high yield. This method has many advantages such as cheap raw materials, green solvent, mild condition good applicability of the substrate,excellent chemical selectivity. Therefore, this strategy fully complies with the requirements of green synthesis.(3) Several sulfonic acid ionic liquid catalysts were prepared. As catalysts, the sulfonic acid ionic liquid catalysts with the strong Br?nsted acid activity can promote the aerobic oxidation of Dihydrogen quinazoline to form quinazolinone easily. Based on the experimental results, we think that the polarization of solvent and the state of the proton in the solution may disturb the intermolecular hydrogen bond ofdihydrogen quinazoline. So the different compounds can be obtained in different solvent. Finally, we developed an efficient method to tunable synthesis of dihydrogen quinazoline and quinazolinone by using different solvents or catalysts. Besides, the catalytic activity of such sulfonic acid ionic liquid catalyst can be recycled three times without loss of catalytic activity. Above of all, this method may become a good choose for green synthesis of dihydrogen quinazolines and quinazolinones.