A novel synthesis of fluorine-containing cyclopentenones via Pauson–Khand reaction

Intermolecular Pauson–Khand reaction of fluoroalkylated alkynes with 2-norbornene or 2,5-norbornadiene at the reflux temperature of dichloroethane proceeded smoothly to give the corresponding cyclopentenone derivatives in high yields as a mixture of regioisomers. On the other hand, intramolecular Pauson–Khand reaction of fluorine-containing 1,6-enyne proceeded in the presence of NMO or TMANO to give the bicyclic adducts in good yields. Additionally, allyl CF3-propargyl ether also underwent a smooth Pauson–Khand reaction in the presence of amine oxide, the corresponding bicyclic compounds being obtained in a highly diastereoselective manner.

Graphical abstractThe intermolecular and intramolecular Pauson–Khand reaction of fluorine-containing alkynes gave the corresponding fluoroalkylated cyclopentenone derivatives in good to high yields.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Intermolecular PKR was done by using fluoroalkylated alkynes with 2-norbornene. ► Reaction at the reflux gave the cyclopentenones as a diastereomeric mixture. ► Intramolecular PKR was carried out by using teminal enyne compounds. ► Reaction proceeded smoothly in the presence of amine oxide. ► Allyl CF3-propargyl ethers afforded adducts as a single isomer.