Lewis Base-Borane Complex Enabled Methylation And Radical Catalysis

Lewis base-borane complex is a kind of adduct obtained by complexing Lewis base with borane,mainly including phospine-borane,amine-borane,pyridine-borane and N-heterocyclic carbene-borane.Because of its advantages of simple preparation,high stability to water and air,and easy operation,it has attracted extensive attention in the field of hydrogen storage materials,synthetic chemistry and biochemistry.In this thesis,the author reported a couple of new applications of Lewis base borane complex in organic chemistry.Firstly,a new and practical protocol using an amine-borane/N,N-dimethylformamide(R3N-BH3/DMF)system as the methyl source for the selective α-monomethylation of arylacetonitriles and arylacetamides was disclosed.Significantly,selective installation of CDH2,CD2H,CD3 and 13CD2H units into the products with high level of D-incorporation has also been achieved by tuning the deuterium sources.Morever,a new type of N-heterocyclic carbene(NHC)-boryl radical catalysis was discussed.This method offered a high efficient way for the synthesis of pyrrolo[3,2,1-ij]quinolines.In chapter one,the author described the applications of methylation in organic synthesis with a focus on methyl effect,methylation methods,deuterium effect and deuterium methylation methods.The second chapter introduced a new protocal using R3N-BH3/DMF as the methyl source for the selective monomethylation of aryacetonitriles and arylacetamides under mild reaction conditions.Mechanistic studies revealed that the formyl group of DMF delivered the carbon and one hydrogen atoms of the methyl group,and R3N-BH3 donated the remaining two hydrogen atoms.Such a unique reaction pathway enabled controllable installation of CDH2,CD2H,CD3 and 13CD2H units into the products by tuning the deuterium sources.Further transformation of the resulted deuterated 2-arylpropionitriles to other useful buliding blocks was demonstrated as well.At last,facile synthesis of anti-inflammatory flurbiprofen and its varied deuterium labeled derivatives has been achieved by uing this strategy.In the last chapter,a new type of catalytic reaction was developed which provided a new strategy for the synthesis of pyrrolo[3,2,1-ij]quinolines by NHC-boryl radical-catalized additon/elimination process.The discovery of this reaction will help further explore the new applications of pyrrolo[3,2,1-ij]quinoline compounds and asymmetric synthesis of pyrrolo[3,2,1-ij]quinoline compounds catalyzed by chiral NHC-boryl radical.