A Study Of Visible Light Induced Decarboxylation Coupling Reaction Of N-acyloxyphthalimide

N-acyloxyphthalimide esters are a class of commonly used decarboxylation reagents in organic synthesis.Organic chemists have used it to achieve a wide variety of reactions over the past few decades.In this study,a novel N-acyloxyphthalimide alkyl carboxylate was developed as an imidization reagent to activate the nitrogen-neutral C-H of N-methylaniline.The use of N-acyloxyphthalimide esters for the imidization reagent is easy to prepare,is inexpensive,and novelly utilizes the green synthesis method of visible light.Compared to the conventional Geothermal synthesis,using photosynthesis has synthesisadvantages of mild conditions and low pollution.A new green synthesis method for imidization of nitrogen in the ortho-carbon of tertiary amines under the induction of visible light was studied.An N-alkyl substituted aniline was designed as a substrate,and an N-acyloxyphthalimide alkyl carboxylate was used as an imidization reagent.Under the optimal conditions,a series of imidization products of the ortho-carbon of the tertiary amine nitrogen were synthesized under the induction of visible light.The method of tertiary amine imidization developed herein has good universality(23%-72%yield).The free radical capture experiment shows that after the free radical-free radical cross-coupling reaction,under the induction of visible light,the tertiary amine takes an electron to form a nitrogen-positive radical for the excited photocatalyst,under the action of alkali.A proton is removed to form anα-carbon radical,and the reduced photocatalyst gives an electron to the N-acyloxyphthalimide alkyl carboxylate,which undergoes a N-O bond cleavage to form N-hydroxyphthalimide free radical,the last two free radicals undergo a cross-coupling reaction to obtain the final imidized product.The use of alkyl carboxylic acid and N-acyloxyphthalimide cinnamate for the decarboxylation coupling reaction under the induction of visible light was explored.The reaction mechanism is designed to produce an alkenyl radical by the action of a photocatalyst,and then attack the alkyl radical to construct a cross-coupling reaction of Csp~3-Csp~2.Under the induction of visible light,a series of optimized reaction conditions were explored.