Arylation and Alkynylation of Neutral Organocopper Compounds

16 Transition Metal-Mediated Alkenylations, Arylations, and Alkynylations 

At the same time a Cu(I) compound is formed. This is required in catalytic amounts only if it additionally acts to convert a less efficient nucleophile into a more efficient copper-containing nucleophile in situ. 

You should feel challenged to explicitly identify the four steps described above in all the reaction examples following in this section—and you should be pleased to hear that there is no need to learn a new mechanism every single time  

A modem variant of the Ullmann coupling also uses the less expensive bromo- mstead ot.  

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