Ynone

In organic chemistry, an ynone is an organic compound containing a ketone (>C=O) functional group and a C≡C triple bond. Many ynones are α,β-ynones, where the carbonyl and alkyne groups are conjugated. Capillin is a naturally occurring example. Some ynones are not conjugated.

An ynone structure

Synthesis of α,β-ynones

One method for synthesizing ynones is the acyl substitution reaction of an alkynyldimethylaluminum with an acyl chloride. An alkynyldimethylaluminum compound is the reaction product of trimethylaluminum and a terminal alkyne.^[1]

Synthesis of an ynone

An alternative is the direct coupling of an acyl chloride with a terminal alkyne, using a copper-based nanocatalyst:^[2]

Synthesis of an ynone

Other methods utilize an oxidative cleavage of an aldehyde, followed by reaction with a hypervalent alkynyl iodide, using a gold catalyst.^[3]

An alternative but longer synthetic method involves the reaction of an alkynyllithium compound with an aldehyde. The reaction produces a secondary alcohol that then can be oxidized via the Swern oxidation.

Synthesis of β,γ- and γ,δ-ynones

Terminal alkynes add across α,β-unsaturated ketones in the presence of palladium catalysts. The reaction affords γ,δ-ynones.^[4] Terminal alkynes add across epoxides to given yneols, which can be oxidized to give β,γ-ynones.^[5]

Further reading

• Bis-ynones can undergo an intramolecular cycloaddition to form furan derivatives.^[6]

See also

• Diketone