Sonogashira coupling
A terminal alkyne is joined to an aromatic ring. The alkyne loses its hydrogen to a base, copper carries it to the palladium, and the two are joined there.
What it needs, and what it gives
- Reaction class
- Cross-coupling
- A palladium source, usually a copper salt, and an amine that serves as both base and solvent. Room temperature is often enough with an iodide.
- balanced — the co-products are written out, not dropped
- Mechanism
- Sonogashira coupling (catalytic cycle), 4 steps
How it is thought to happen
The metal inserts into the aryl-halide bond, the alkyne loses its hydrogen and is carried across, and the two groups join and leave together.
- The metal inserts into the aryl-halide bond
- The base takes the alkyne's hydrogen
- The alkyne is carried to the metal
- The two groups are joined and the metal lets go
Try it on your own structures
Enter your reactants in the Reaction Lab. If this transformation matches what you drew, it is applied and the outcome is shown next to the records that back it — with the count of documented reactions doing the same thing on substrates like yours, rather than a confidence score.
Other cross-coupling transformations
Heck coupling
Palladium inserts into the aryl-halide bond, the alkene inserts into the aryl-palladium bond, and the hydride is eliminated to leave the alkene where it started, now carrying the ring.
Suzuki coupling
Palladium inserts into the aryl-halide bond, the boron hands its carbon to the metal, and the two organic groups are joined as the metal lets go.
Buchwald-Hartwig amination
Palladium joins an amine to an aromatic ring, on rings that are not activated and would not react on their own.
Copper-catalysed ether coupling
Copper joins an alcohol or a phenol to an aromatic ring that would not accept it on its own.