Cadiot-Chodkiewicz coupling

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The Cadiot-Chodkiewicz coupling is a chemical reaction that is used in organic chemistry for the coupling of two terminal alkynes to form diynes . The reaction is catalyzed by copper salts . A terminal alkyne and a bromoalkyne are required as starting materials :

Reaction scheme for the Cadiot – Chodkiewicz coupling

The Cadiot-Chodkiewicz coupling is a further development of the Glaser coupling and is therefore also related to the Hay coupling and the Eglinton coupling .

Reaction mechanism

The course of the reaction starts from the terminal alkyne. This is first of copper (I) ion by forming a π-complex associated . Due to the considerable lack of electrons in the alkyne, the pKa value is reduced from approx. 30 to below 9. Through this so-called activation , the alkyne can be deprotonated in the next step . Bases such as triethylamine are used for this purpose . At the same time, an organic copper (I) compound is formed, to which the bromoalkyne adds oxidatively . The less stable copper (III) compound thus formed breaks down in a rapid subsequent step by reductive elimination to form the diyne and copper (I) bromide , which is available for association with a new terminal alkyne. In this way the catalyst is restored.

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