Study On Norrish Type Ⅱ Photochemical Rection And Synthesis Of Cyclopentyl Carbocyclic Nucleosides Pseudo Sugar

Cyclopentyl carbocyclic nucleosides have good biological activity anddisease-resistance toxicity and they are good drug precursors. Therefore, in terms ofdrug development or methodological perspective, it is important and valuable forexploring new synthetic route of cyclopentyl carbocyclic nucleosides. This thesisaims to explore the new synthesis routes of the Norrish Ⅱtype photochemicalreaction as the key step to synthesize cyclopentyl carbocyclic nucleosides.Ⅰn this thesis, we focused on exploration of liquid-phase and solid-phaseasymmetric photochemical behavior of bicyclo [3.1.0] hexyl ketone carbonylderivatives and synthesis of cyclopentyl carbocyclic nucleosides pseudo sugar withthe liquid-phase photochemical product.Firstly, the solution photochemical substrate have been synthesized afterseven-step reactions taking the2,5-norbornadiene as the starting material. Under theliquid-phase, the secondary photochemical reaction intensified as prolonging thereaction time and the cleavage production rate reducing. Under the solid-phase, thereaction time and reaction temperature can influence the cleavage production rateand the ee value of the cleavage product. The ee value is up to75%.Secondly, cyclopentanyl carbocyclic nucleosides pseudo sugar have beensynthesized after five-step reactions from the solution product: catalytichydrogenation, NaBH4reduction, dehydration under weakly acidic conditions,oxidation of the double bond scission, LiAlH4reduction and deprotection with3%HCl methanol; Also, using the solution product as starting material, cyclopentenylcarbocyclic nucleosides pseudo sugar have been synthesized after eight-stepreactions: double bond oxidation, fork acetone protection, NaBH4reduction, alcoholhydroxyl bromide, elimination with DBU, oxidation of the double bond scission,NaBH4reduction and deprotection with TBAF.This thesis realized the purpose of synthesizing cyclopentyl carbocyclicnucleosides pseudo sugar with Norrish Ⅱtype photochemical reaction as the keystep, which is instructive to explore the new synthetic routes of cyclopentylcarbocyclic nucleosides.