Homocoupling reactions, organometals

In comparison with the homocoupling of organic electrophiles, Pd-catalyzed homocoupling of organometals requires the presence of an oxidant A generally accepted reaction mechanism is presented in Scheme The homocoupling of organometals... 

Pd-catalyzed homocoupling of terminal alkynes proceeds in the presence of a catalytic amount of Cu(l) salts and amines. During this process a terminal alkyne reacts with copper(I) salt in the presence of an amine to give an alkynyl copper compound that reacts with the Pd catalyst. Therefore, the homocoupling of terminal alkynes falls into the category of homocoupling of organometals and follows the same reaction mechanism. 

Finally, any cross-coupling procedures should, in principle, be applicable to the synthesis of homodimers. In addition, other Pd-catalyzed protocols specifically aimed at the synthesis of homodimers have also been developed. Most of them involve Pd-catalyzed dimerization of organometals or organic electrophiles, rather than the reaction of an organometal with an organic electrophile. Some of these homocoupling procedures can be applied to the synthesis of cycUc CToss-dimers. These reactions are discussed in Sect. 

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