Studies On Synthesis Of Tetrahydroisoquinoline Derivatives Via Cycloaddition Reaction Of C,N-Cyclic Azomethine Imines

N-Imide ylides are more stable than other N-ylides, due to the carbonyl N-protecting groups, though the nitrogen atom of the N-imine ylides contain positive and negative charges. Consequently, the N-ylides are applied to synthesize nitrogen-containing heterocyclic compounds in organic synthesis briefly. Among Some representative types of N-imide ylides, C,N-cyclic azomethine imines in which one nitrogen and one carbon atoms are incorporated into a polycyclic system are convenient synthons for building up various heteropolycyclic, fused, and spirocyclic systems. This dissertation mainly centers on several cycloaddition reactions of C,N-cyclic azomethine imines and synthesis of a series of novel cyclic-tetrahydroisoquinoline derivatives.In the first part of this thesis, we developed the amine-catalyzed 1,3-dipolar cycloaddition of C,N-cyclic azomethine imines with N-arylmaleimides to give pyrazolotetrahydroisoquinoline derivatives in high diastereoselectivities. This reaction utilized 1,4-diazabicyclo [2.2.2] octane (DABCO) as the catalyst. By optimizing the other conditions including screening of solvents, the amount of catalyst, ratio of reactants, the temperature and time, the best reaction condition was obtained in the presence of 10 mol% of DABCO, at 60℃ using THF as the solvent. With the optimized conditions in hand, we synthesized 24 products which were characterized by MS, NMR spectroscopy. In additionally, The relative configuration of product was determined on the basis of the 2-D NOESY 1H NMR spectra. Meanwhile, a plausible catalytic cycle of the current [3+2] cycloaddition was proposed.In the second part of this thesis, we documented an organocatalytic [3+3] cycloaddition reaction of C,N-cyclic azomethine imines with 1,4-Dithiane-2,5-diol. Similar to the first part of this work, The reaction was still catalyzed by DABCO, the remaining reaction condtions were optimized by selection of solvents, the amount of catalyst, ratio of reactants, the temperature and time. In this part,15 compounds which fully characterized by MS, NMR spectroscopy were synthesized.In the final part of this thesis, we successfully investigated an efficient [4+3] cycloaddition reaction of in situ generated aza-oquinodimethanes with C,N-cyclic azomethine imines without the use of any catalyst, providing an efficient and mild approach to synthesise the desired products in high yields. The compounds of this reaction were all characterized by IR, NMR, MS spectroscopy. And the single crystal structure of one of these target products was measured by X-ray diffraction method.Finally, it is summarized and prospected on cycloaddition of C,N-cyclic azomethine imines to prepare ring and tetrahydroisoquinoline derivatives.