Copper decarboxylative amidation

The copper-catalyzed arylation of propiolic acids was disclosed by You s (Scheme 4.65) [66] and Jiao s groups [67] independently. The latter group also reported the copper-catalyzed decarboxylative amidation of propiolic acids to produce the corresponding amides (Scheme 4.66) [68]. 

Synthetic and degradative use has been made in several instances of the easy decarboxylation of phenanthridine-6-carboxylio acids.30, 80, 324 The corresponding iV-oxide is decarboxylated by heating in aqueous sulfuric acid.77 Phenanthridine-3,8-dicarboxylic acids are more resistant to decarboxylation, which can be achieved (in poor yield) by heating with copper powder in quinoline.194 The usual carboxyl derivative inter con versions (esterification, amide formation, ester and amide hydrolyses, etc.) proceed normally with both phenanthridine-6-carboxylic acid and its A-oxide,77, 232, 352 although an unsuccessful attempt to prepare 6-acetylphenanthridine from the acid with methyllithium has been reported.232... 

Decarboxylation of 5,7-dimethyl-8-oxo-6-aza-8//-indeno[2,1 - ]thiophene-4-carboxylic acid could be effected by heating an admixture of it and copper powder <87H(26)1535). Direct sublimation in vacuo afforded the desired product (58%). 9-Chloro-2- and 3-methyltriazolo[4,5-/]quinoline-7-carboxylic acids are decarboxylated under similar conditions <93H(36)259>. The cyano group of 8-cyano-7-oxo-4,5,6,7-tetrahydrothiazolo[4,5-/]quinolines can be converted into an amino group by cone. HC1 mediated hydrolysis to the amide, followed by Hofmann rearrangement <89H(29)I517>. 

In addition to the desired product, route C produces hydrogen, sodium chloride and additional ammonia (from quenching of the sodium amide with ammonium chloride), zinc and copper hydroxides from the reduction (for simplicity we will assume one mole of each, and no other by-products), one third of a mole of phosphorous acid, sodium bromide, ethanol (from the ester hydrolysis) and carbon dioxide (from the decarboxylation). The molecular weights involved are therefore 126, 1,... 

Song Q, Feng Q, Yang K (2014) Synthesis of primary amides via copper-catalyzed aerobic decarboxylative ammoxidation of phenylacetic acids and a-hydroxyphenylacetic acids with ammonia in water. Org Lett 16(2) 624-627... 

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