Synthesis Of1,4-dihydropyrazines And Tetraazatetraasteranes

1,4-Dihydropyrazines are compounds of electron-rich enamine, which werewidely used as medicines and biological agents. Tetraasterane consists two parallelcyclobutanes fused by four cyclohexanes. Its3,9-diazatetraasteranes and3,9-dioxatetraasteranes are organic compounds with C2symmetry and possessinhibitory activity against HIV-1protease and tumor. With parallel double bonds, the[2+2] photocycloaddition of the1,4-dihydropyrazine can be a method of synthesizingtetraazatetraasterane. Based on the survey of the synthesis1,4-dihydropyrazines and[2+2] photocycloaddition, the main contents are the synthesis of1,4-dihydropyrazinesand their photocycloaddition. The results of this study will provide theoretical andexperimental basis for the application of1,4-dihydroprazine and the synthesis oftetraasteranes.By the survey on the synthesis of1,4-dihydropyrazine, the targets compoundswere1,4-ditertbutoxycarbonyl-1,4-dihydropyrazine and1,4-diacyl-1,4-dihydropyrazine. In order to simplify the synthesis of1,4-ditertbutoxycarbonyl-1,4-dihydropyrazine, the optimizated method was used toimprove the yields. In order to increase the yields and shorten the reaction time in thesynthesis of1,4-diacyl-1,4-dihydropyrazine catalysted by Zn, the efficient methodswere established by the improvements on the microwave irradiation and theinvestigations on the reaction factors (such as reactents, solvents, catalyst, and so on)on the example of the synthesis of2,3-dimethyl-1,4-dihydropyrazine.The [2+2] photocycloaddition of the1,4-dihydropyrazine can be a method ofsynthesizing tetraazatetraasterane.[2+2] photocycloadditions of1,4-dihydropyrazinewere explored in solution and in solid state under the selected irradiation. In solution,the factors on the photocycloaddition were explored such as the light wavelength,solvent, photosensitizer and so on. The photoproducts were separated and identified.The photoreaction mechanism of the1,4-dihydropyrazines was speculated to explainthe formation of the photoproducts. In solid state, it was found that the arrangement ofmolecular is critical to the photocycloaddition, so the moleculer template was putforward. The templates were selected by hot stage microscopy, the cocrystals of1,4-dihydropyrazines and templates were preparaed by the mixed solventsevaporation. The cocrystals were irradiated and their products will be tetraazatetraasteranes.Twelve of1,4-dihydropyrazins were synthesized, six of them have not beenreported. And thirteen compounds were obtained by photoreaction, nine of them werephotooxidation products, two of them are syn dimers and two2,5,8,11-tetraazatetraasteranes. The structures of compounds were validated by NMR,HRMS and X-ray diffraction.