Sonogashira coupling, metal-alkyne complexes

The coupling of terminal alkynes with aryl or vinyl halides under palladium catalysis is known as the Sonogashira reaction. This catalytic process requires the use of a palladium(0) complex, is performed in the presence of base, and generally uses copper iodide as a co-catalyst. One partner, the aryl or vinyl halide, is the same as in the Stille and Suzuki couplings but the other has hydrogen instead of tin or boron as the metal to be exchanged for palladium. 

Using transition-metal catalysts for C-C bond forming at carbons bearing acidic protons, such as the position a- to a carbonyl group is discussed in Section 2.11, as the C-H bond is activated by its position, and not primarily by the metal. The coupling of terminal alkynes, the Sonogashira reaction, is also discussed in Section 2.8. The use of carbene and nitrene complexes for bond formation through C-H activation is a well-established process. This is discussed in Section 8.5.2. 

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