Visible-light-induced Site-selective N~1-alkylation Of Benzotriazoles

Visible-light induced reactions have become an efficient and powerful method in organic synthesis due to their energy sustainability,mild reaction conditions and unique reactivity of the generated intermediates.Benzotriazolesarekind of important organic compounds in organic synthesis,which can be used as starting material for the synthesis of various drug-active molecules,thereby have important application in medicine chemistry.N-alkylated benzotriazoleshavea variety of biological activities.However,the mixture of N1-and N2-alkylated productswere often obtained in organic synthesis due to the tautomeric equilibrium between 1H-and 2H-tautomers of benzotriazole,which makes the site-selective N-alkylation of benzotriazole highly challenging.In recent years,N1-alkylation or N2-alkylation reactions of benzotriazole have been reported successively,but in most of cases,transition metal catalysts were used,with harsh reaction conditions and poor substrate applicability,which prompted people to develop new synthetic methods to achieve selective N-alkylation ofbenzotriazole.In this thesis,on the basis of a full investigation of the literature,according to the research status and shortage of visible-induced regioselective N1-alkylation of benzotriazole,the visible-light-induced site-selective N1-alkylation of benzotriazoles with diazo compounds and methylene quinones has beenstudied.The main research contents of this thesis include the following two parts:PartⅠ: Visible-light-induced site-selective N1-alkylation of benzotriazole with diazo compounds.The visible light-induced and highly selective N1-alkylation reaction of benzotriazole with diazo was realized under the mild condition without usage of metal catalyst.When PBQ and TBN were used as catalysts,it was found that different benzotriazole and various substitueddiazo compounds could participate in the reaction,and the corresponding N1-alkylation products were obtained with high yield and good selectivity.The mechanistic studies indicated that a radical process plays a key role for the high site-selectivity.Themethod has features of simple and readily availablesubstrates,mild reaction conditions,highly efficient,good toleranceforwide range of substrates,easiness to scale-upand further transformation,and provides a new method for the late-stage modification of natural products andbioactive molecules.Part Ⅱ: Visible-light-induced site-selective N1-alkylation of benzotriazoles with p-methylene quinones.The visible light inducedselective N1-alkylation of benzotriazole with p-methylene quinones has been achieved.Thereaction only used PBQ as photocatalyst,without usage of metal catalyst and additive,and the reaction condition is mild.It provides a new synthetic way for the alkylation reaction of benzotriazoles with p-methylene quinones.