Ynone Explained

In organic chemistry, an ynone is an organic compound containing a ketone functional group and a 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.

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]

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

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

Notes and References

1. Wang . Baomin . Bonin . Martine . Micouin . Laurent . A Straightforward Synthesis of Ynones by Reaction of Dimethylalkynylaluminum Reagents with Acid Chlorides . . June 22, 2005 . 70 . 15 . 6126–6128 . 10.1021/jo050760y . 16018717 .
2. Weijiang . Sun . Wang . Yan . Wua . Xuan . Yao . Xiaoquan . Palladium-, ligand-, and solvent-free synthesis of ynones by the coupling of acyl chlorides and terminal alkynes in the presence of a reusable copper nanoparticle catalyst . . 2013 . 15 . 9 . 2356–2360 . 10.1039/c3gc40980e .
3. Wang . Zhaofeng . Li . Li . Yong . Huang . A General Synthesis of Ynones from Aldehydes via Oxidative C–C bond Cleavage under Aerobic Conditions . . August 18, 2014 . 136 . 35 . 12233–12236 . 10.1021/ja506352b . 25133731 .
4. 10.15227/orgsyn.091.0072. Palladium-catalyzed 1,4-Addition of Terminal Alkynes to Conjugated Enones. Organic Syntheses. 91. 72. 2014. Feng Zhou, Liang Chen, Chao-Jun Li. free.
5. 10.15227/orgsyn.084.0199. Electrophilic Cyclization with N-Iodosuccinimide: Preparation of 5-(4-Bromophenyl)-3-Iodo-2-(4-Methyl-Phenyl)Furan. Organic Syntheses. 84. 199. 2007. Adam Sniady, Marco S. Morreale, Roman Dembinski.
6. Wills . M.S.B. . Rick L. Danheiser. Danheiser . R.L. . Intramolecular [4 + 2] Cycloaddition Reactions of Conjugated Ynones. Formation of Polycyclic Furans via the Generation and Rearrangement of Strained Heterocyclic Allenes . . August 28, 1998 . 120 . 36 . 9378–9379 . 10.1021/ja9819209.