The Study Of Amination By Decarboxylation

Carboxylic acid or substituted carboxylic acid is a kind of very important organic compounds,which has rich structural diversity and has a wide range of sources.Many carboxylic acids can even be obtained directly from natural resources.In chemical reaction,carboxyl group is considered to be a good chemical and regionally selective ionized group.The product is CO₂ gas,which has high atomic utilization rate.In addition,some natural carboxylic acids have one or more chiral centers and can be used to synthesize optically pure isomers if the decarboxylation reaction can be stereoselective or configuration-preserving.Because of these characteristics,carboxylic acids are often used in organic synthesis as a cheap and readily available organic compound,among which decarboxylation coupling is one of the most important reactions.However,there are few reports on decarboxylation amination reactions.Based on this,the decarboxylation selective amination of aromatic carboxylic acids and the decarboxylation amidation of?-keto acids were studied in this paper.In the first part,the selective decarboxylation of aromatic carboxylic acid with o-aminobenzamide catalyzed by Cu???/Ag???was studied.The coupling of o-nitrobenzoic acid and o-aminobenzamide was used as a model reaction to optimize the influence factors of catalyst type and dosage,base,additive,solvent,reaction time and temperature.Under the optimum reaction conditions[Cu?OTf?₂?1.5 equiv.?,AgOTf?1.0 equiv.?,K2CO3?2 equiv.?,4?MS?160 mg?,DMSO?2.0 mL?,Ar protection,120?,24 h],the yield of the model reaction was 62%.The structure of the product was further confirmed to be the selective N-aromatization product of aromatic amines by X-ray single crystal diffraction analysis.Under this catalytic system,the results of substrate applicability showed that the coupling reaction of various substituted o-nitrobenzoic acid with o-aminobenzamide containing various substitutes could proceed smoothly and 17 diarylamines were synthesized in medium yield,of which 14 were new compounds.At the same time,the mechanism of selective decarboxylation of aromatic carboxylic acid and o-aminobenzamide catalyzed by Cu/Ag was proposed.This reaction provides a new idea for selective amination of o-aminobenzamide.In the second part,the decarboxylation amidation of?-keto acids with azide reagent catalyzed by non-metal was studied.Taking the amidation of benzoyl formic acid with diphenyl azide phosphate?DPPA?as a model reaction,the influencing factors such as azide reagent,base,reaction solvent,reaction temperature and time were optimized.Under the optimum reaction conditions[K₃PO₄?2.0 equiv.?,DMF?2.0 mL?,100?,24 h],the yield of the model reaction was 91%.Substrate applicability of the catalytic system showed that all kinds of substituted benzoyl formic acid,naphthalene cyclohexanoic acid and heterocyclic glyoxylic acid could proceed smoothly.Twenty aromatic amides were synthesized in 71-95%yield.In summary,two kinds of catalytic systems for decarboxylation amination have been established to achieve selective decarboxylation of aromatic carboxylic acids with substrates containing both amino and amide groups,and decarboxylation of?-keto acids with azide reagents.Two catalytic systems have developed and improved the methods of decarboxylation of aromatic carboxylic acids to construct C-N bonds.