Study On Visible Light Induced Imine Hydrogenation And Enyne Cyclization

Secondary amines and pyran compounds are widely present in chiral materials and pharmaceutical molecules,and have attracted attention in organic synthesis and medicinal chemistry due to their unique intrinsic structure and pharmaceutically active activity.In recent years,visible light-induced chemical reactions have rapidly developed into a hot research field due to their unique advantages,and the free radical addition reaction of unsaturated double bonds has attracted interest from chemists.In this paper,the free radical addition reaction of visible light-induced unsaturated double bonds is studied.The free radical addition of carbon-carbon double bonds and carbon-nitrogen double bonds is realized under simple and mild reaction conditions,which opens up the synthesis of secondary amines and pyran compounds.Under the visible light induction,the free radical addition reaction of carbonnitrogen double bonds was studied by using N-benzylidene imine as raw material.The hydrogenation of imine compounds was successfully achieved by the reduction of thiophenol.Under the optimal reaction conditions,15 different types of secondary amine products(21%-75% yield)were synthesized,which proved that the reaction has good universality.The reaction uses low-cost water as a solvent,which is conducive to cost savings.According to the free radical trapation experiment,the addition reaction process of carbon-nitrogen double bond and free radical is determined,and the formed imine anion intermediate synthesizes the secondary amine product under acidic conditions.The use of 1,7-enyne compounds as raw materials for the free radical addition reaction of carbon-carbon double bonds.Benzoylformic acid decarboxylates under the induction of visible light catalyst fac-Ir(ppy)3 to form benzoyl radicals,and the coupling of cyclization of 1,7-enyne compounds with benzoyl radicals to synthesize pyran compounds.The effects of photocatalyst,solvent,substrate concentration,oxidant and other conditions on the reaction were explored,and the optimal conditions of the reaction were determined to obtain a yield of 61 %.The reaction can synthesize a pyran compound value in one step,and the synthesis efficiency is improved.