Studies On Photochemical Synthesis Of Novel Structural Diazaasteranes

Polyhedrons,with several CH vertexes,are compounds in three dimensions with flat polygonal faces,straight edges and sharp corners.As one of polyhedrons,the azatetraasterane has distinctive physical and chemical properties caused by geometric symmetry and aesthetic features,which attracted more and more researchers'attention.By comprehensive research on[2+2]photocycloaddition of 1,4-dihydropyridines,we focuses on the photochemical synthesis of novel diazatetraasteranes,such as C₂-3,9-diazatetraasteranes,non-C₂-3,9-diazatetraasteranes and 3,6-diazatetraasteranes.The studies on the synthesis of novel diazatetraasteranes will provide theoretical and experimental basis for their applications in pharmacological studies.The synthesis of C₂-3,9-diazatetraasteranes was based on the[2+2]photocycloaddition of N-aryl-1,4-dihydropyridines and N-benzyl-1,4-dihydropyridines.A series of C₂-3,9-diazatetraasteranes were synthesized by investigation on the synthetic methods and irradiation modes of this two 1,4-dihydropyridines.In order to gain an efficient synthetic method,the microwave irradiation was adopted in the synthesis of 1,4-dihydropyridines.The synthetic strategy of C₂-3,9-diazatetraasteranes was established after exploring the effects of light sources,wavelength,solvents and solution concentration on the reactions,where 6 syn-dimeric intermediates and 5 C₂-3,9-diazatetraasteranes were obtained.The proposal mechanism of[2+2]photocycloaddition of N-aryl-1,4-dihydropyridines and N-benzyl-1,4-dihydropyridines showed that a syn-dimeric intermediate formed firstly through an intermolecular[2+2]photocycloaddition and then an intramolecular[2+2]photocycloaddition occurred to give C₂-3,9-diazatetraasteranes.The synthesis of non-C₂-3,9-diazatetraasteranes was based on the cross[2+2]photocycloaddition of different 1,4-dihydropyridines and the functionalization of C₂-3,9-diazatetraasteranes.A series of non-C₂-3,9-diazatetraasteranes were synthesized by investigation on the irradiation modes and the reaction conditions of functionalization.7 novel 3,6,12-triaryl-3,9-diazatetraasteranes were synthesized under the conditions optimized by the effects of light sources,wavelengths,solvents and solution concentrations.The functionalization of C₂-3,9-diazatetraasterane was the acylation,five 3-arylacyl-6,12-diaryl-3,9-diazatetraasteranes were obtained by the investigation on the factors of weight ratio,solvent and acid binding agent.According to the structural features of C₂-3,9-diazatetraasteranes and non-C₂-3,9-diazatetraasteranes,the NMR data was discussed in detail to provide an experimental basis for structural characterization of azatetraasteranes.The studies on the synthesis of 3,6-diazatetraasteranes were based on the regio-controlled[2+2]photocycloaddition by covalent bonding between 1,4-dihydropyridines and Linker with two acyl groups.The target 3,6-diazatetraasteranes were obtained by the investigations on the structures of Linkers,reaction factors of Linker with 1,4-dihydropyridine and the irradiation modes.Phthaloyl,isophthaloyl and butanedicyl were chosen as Linkers.The process conditions of bis-dihydropyridines were optimized in the solvents,acid-binding agents,and reagents ratio.9 novel 3,6-diazatetraasteranes were synthesized after optimizing the photochemical conditions by investigating on irradiation mode,solvents and light sources.The mechanism studies on regio-controlled[2+2]photocycloaddition showed that the Linker must be rigid and two terminal acyl groups must be in a proper distance.The 1,4-dihydropyridines were tethered covalently by phthaloyl to direct a proximate parallel arrangement in head-to-head orientation by the rotation of C-C single bonds in solution.An intramolecular[2+2]photocycloaddition proceeded subsequently by the excitation of UV lights to give the desired 3,6-diazatetraasteranes.In the synthesis of novel diazatetraasteranes,57 new compounds were obtained includingtwenty-three1,4-dihydropyridinederivativesand34[2+2]photocycloaddition products with 27 novel diazatetraasteranes in them.All new compounds were characterized by ¹H and ¹³C NMR spectroscopy,HRMS and X-ray diffraction.