Recent developments in decarboxylative cross-coupling reactions between carboxylic acids and N-H compounds

Abstract

Carboxylic acids and their derivatives are ubiquitous compounds in organic chemistry, and are widely commercially available in a large structural variety. Recently, carboxylic acids have been frequently used as non-toxic and environmentally benign alternatives to traditional organohalide coupling partners in various carbon-carbon and carbon-heteroatom cross-coupling reactions. Along this line, several methods have been reported for the synthesis of nitrogen-containing organic compounds through decarboxylative cross-coupling reactions between carboxylic acids and N-H compounds. This review focuses on recent advances and discoveries on these reactions with special attention on the mechanistic aspects of the reactions.

Fig. 1. Decarboxylative C–N cross-coupling reactions.

Scheme 1. (a) I₂-catalyzed decarboxylative C–N coupling reactions of primary α-amino acids 1 and 2-aminobenzoketones 2 developed by Wang; (b) synthesis of 2-arylquinazolines 6 through decarboxylative amination of arylacetic acids 4 with 2-aminobenzoketones 5 and NH₄OAc.

Scheme 2. Mechanistic proposal for the formation of quinazoline derivatives 3.

Scheme 3. Cu(ii)-catalyzed intramolecular decarboxylative C–N coupling reaction of primary aliphatic carboxylic acids 7.

Scheme 4. Site-selectivity controlled by a directing group in the intramolecular decarboxylative C–N coupling process.

Scheme 5. Mechanism proposed to explain the formation of cyclic amines 8.

Scheme 6. Decarboxylative cross-coupling of alkyl carboxylic acids 11 with nitrogen nucleophiles 12 developed by MacMillan research team.

Scheme 7. Plausible mechanism for reaction in Scheme 6.

Scheme 8. (a) Cu(ii)-catalyzed decarboxylative C–N coupling reaction between ortho-substituted benzoic acid derivatives 14 and nitrogen nucleophiles 15; (b) mechanism proposed to explain the N-arylated products 16 synthesis.

Scheme 9. Jia's synthesis of diarylamines 19.

Scheme 10. Decarboxylative ipso-amination of benzoic acids 20 with aliphatic amines 21 reported by Gooßen.

Scheme 11. Ru-catalyzed decarboxylative amidation of α-keto acids 23 with amines 24 reported by Lei.

Scheme 12. Mechanism proposed to explain the secondary amides 25 synthesis.

Scheme 13. Synthesis of imides 28via Pd-catalyzed decarboxylative amidation of α-keto acids 26 with N-benzylpicolinamides 27.

Scheme 14. Plausible mechanism for Liu–Wang's synthesis of imides 28.

Scheme 15. Ag-catalyzed synthesis of secondary amides 31 from α-keto acids 29 and anilines 30via a decarboxylative process.

Scheme 16. Cu(ii)-catalyzed amidation of propiolic acids 32 with nitrogen nucleophiles 33.

Scheme 17. Plausible mechanism for the reaction in Scheme 16.

Scheme 18. Bolm's synthesis of sulfoximidoyl-functionalized alkynes 37.

Sattar Arshadi

Saeideh Ebrahimiasl

Akram Hosseinian

Aazam Monfared

Esmail Vessally