The Study Of Photocyclization Reaction In The Act Of Templates

As a focus in organic photochemistry, the reaction of photocyclization is always an important concern of chemists in recent years.The aim of this research is to study the stereoselectivity of photocyclization reaction in the act of chiral template. Firstly, a series of organic molecules which use phthalimido group as electron acceptor, N as electron donor, COO^- as eletrofugal group (E) were synthesized based on SET-promoted photocyclization processes. These compounds were irradiated by 500 W ultraviolet under nitrogen atmosphere in room temperature. After filtration of the photochemical character of these molecules, substrate S1 and S2 were selected as appropriate model reactants. Secondly, the monosubstituted derivatives at the 6-position ofβ-cyclodextrin were synthesized as chiral template of photocyclization.Aimed at substrate S1 and S2, the reation condition is : MeOH: H₂O = 9:1 as solvent, 1 equiv. K₂CO₃ as base. At this reaction condition, a series of chiral templates was mixed in the model reactant in order to control the stereoselectivity of photocyclization reaction, such asβ-cyclodextrin,γ- cyclodextrin, mono-6-amino-6-deoxy-β-cyclodextrin (6-NH₂-β-CD) and mono-6-pyridinium-6-deoxy-β-cyclodextrin Tosylate (6-Py-β-CD). Some conclusions were obtained through analysis and comparison of the ratio of cis- and trans- conformational product: (1) cyclodextrins and its derivatives could achieve the stereoselectivity of this reaction, 6-NH₂-β-CD is the best. (2) the reaction stereoselectivity of substrate S1 is better than S2, the possible reason is S1 was more rigid.Finally, a series of new substrate were synthesized, and some conclusions were obtained through the photocyclization reaction of these substrates.