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

Synthesis and Application of β‐Substituted Pauson–Khand Adducts: Trifluoromethyl as a Removable Steering Group

“…The pure complex 2 a was subjected to the thermal PKR (toluene, 70 °C) with norbornadiene. Both 1 H and 19 F NMR spectra of the reaction crude showed only one PK adduct, which was isolated in 81 % yield 13. The NMR spectra led us to assign the product to the α‐trifluoromethylated PK adduct 3 a .…”

Pauson–Khand reaction of fluorinated compounds

“…In 2012, Konno and co-workers studied the intramolecular PKR using fluorine-containing 1,6-enynes 32 (Scheme 15) [54]. The PKR of fluorinated propargyl allyl ether 32a afforded the corresponding cis bicyclic product 33a in moderate yield and high diastereoselectivity (dr > 20:1).…”

“…In 2012, Konno and co-workers reported the synthesis of 2-fluoralkyl-2-cyclopentenones through an intermolecular Co-mediated PKR of various trifluoromethyl alkynes with 2-norbornene (Scheme 40) [54]. In this process, the authors did not use NMO as a promoter due to its negative effect on the reaction yield.…”

“…Intermolecular PKR of trifluoromethylalkynes with 2-norbornene reported by the group of Konno[54].Scheme 41: Intermolecular PKR of diarylalkynes with 2-norbornene reported by the group of Helaja[80].…”

Synthesis and Application of β‐Substituted Pauson–Khand Adducts: Trifluoromethyl as a Removable Steering Group

“…Both 1 H and 19 F NMR spectra of the reaction crude showed only one PK adduct, which was isolated in 81 % yield. [13] The NMR spectra led us to assign the product to the a-trifluoromethylated PK adduct 3 a. The regiochemical outcome, which was the opposite of the standard selectivity on the basis of electronic criteria, led us to propose that the electronic effect of the trifluoromethyl substituent is much weaker than expected, so the reaction outcome is determined by steric effects.…”