Alkynes carboxylic acids, palladium® chloride

On the other hand, the oxidative addition of aliphatic acid chlorides occurs in the absence of alkyne, but the oxidative addition complex could not be isolated due to fast decarbonylation followed by facile /1-hydrogen elimination. The decarbonylation of carboxylic acid was reported with palladium catalysts as well [47-56], In general, the reactions to acid anhydride as the intermediate need relatively high temperatures. 

The conversion of acetylenes into olefinic esters by use of addition reactions has been illustrated by the following two examples, (i) 1-Alkenyl boranes, which are readily prepared by the hydroboration of alkynes, are converted into a,fi-unsaturated carboxylic esters in good yield by reaction with carbon monoxide in the presence of palladium chloride and sodium acetate in methanol the process is carried out at atmospheric pressure and occurs with retention of configuration with respect to the alkenyl borane. (ii) Carboxylic acids add to acetylenes in the presence of silver carbonate to provide a novel synthesis of enol esters, which are formed in an 8 2 mixture of isomers. ... 

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