| Tin(II) Chloride reagent is an important reducing agent, as well as a good catalyst. It shows high reactivity and selectivity and many reactions it caused can be carride out under mild conditions. Our interest is to investigate the intramolecular and the intermolecular reductive reactions of the multi-functional compounds induced by Tin(II) Chloride to synthesis of a number of heterocyclic compounds.In the second chapter substituted quinoline N-oxides and the compositions SnL2Cl2 (L=2-aminoquinoline N-oxides) were accomplished in good yields by treating 3-(2-nitrophenyl)acrylonitriles with the aid of SnCl2·2H2O reagent. The structures of the products were determined by IR, 1H NMR, HRMS and X-ray analysis. And a possible reaction mechanism was put forward.In the third chapter a novel reductive cyclization of 2-nitrobenzamides with haloketones or keto acids mediated by SnCl2·2H2O system has been described. A series of 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazolin-5(1H)-one and 2,3,3a,4-tetrahydro- pyrrolo[1,2-a]quinazoline-1,5-dione were synthesized in good yields. The structures of the products were determined by IR, 1H NMR, 13C NMR, HRMS and X-ray analysis. A possible reaction mechanism was put forward.In the forth chapter the intermolecular reductive cyclization of 2-(2-nitrophenyl)-1H-imidazoles with isothiocyanates or isocyanates mediated by SnCl2·2H2O system were studied and a series of imidazo[1,2-c]quinazoline- 5(6H)-thione and imidazo[1,2-c]quinazolin-5(6H)-one were formed. The structures of the products were determined by IR, 1H NMR and HRMS. A possible reaction mechanism was put forward.In the fifth chapter various 2,3-dihydro-2-thioxoquinazolin-4(1H)-ones were efficiently synthesized in excellent yields by the reaction of 2-nitrobenzamides and isothiocyanates promoted by SnCl2·2H2O. The structures of the products were determined by IR, 1H NMR. A possible reaction mechanism was put forward.In the sixth chapter a short and reductive cyclization of o-nitrobenzamides and isatins induced by SnCl2·2H2O reagent was investigated. A series of 1'H-spiro- [isoindoline-1,2'-quinazoline]-3,4'(3'H)-dione derivatives were synthesized in good yields. The structures of the products were determined by IR, 1H NMR, HRMS and X-ray analysis.The remarkable advantages of the above mentioned reactions are mild, neutral, simple operation, good yields and atomic economy. |
