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

Computational Study on the Co-Mediated Intramolecular Pauson–Khand Reaction of Fluorinated and Chiral N-Tethered 1,7-Enynes

The Co₂(CO)₈-mediated intramolecular Pauson–Khand reaction is an elegant approach to obtain cyclopentenone derivatives containing asymmetric centers. In this work, we employed density functional theory calculations at the M11/6-311+G(d,p) level of theory to investigate the mechanism and reactivity for the Pauson–Khand reaction of fluorinated and asymmetric N-tethered 1,7-enynes. The rate-determining step was found to be the intramolecular alkene insertion into the carbon–cobalt bond. The stereoselectivity of the alkene insertion step was rationalized by the different transition states showing the coordination of the alkene through the Re- and Si-face. The effects of different fluorine groups and steric effects on both the alkenyl and alkynyl moieties were also theoretically investigated.

Pauson-Khand reaction of fluorinated compounds

The Pauson-Khand reaction (PKR) is one of the key methods for the construction of cyclopentenone derivatives, which can in turn undergo diverse chemical transformations to yield more complex biologically active molecules. Despite the increasing availability of fluorinated building blocks and methodologies to incorporate fluorine in compounds with biological interest, there have been few significant advances focused on the fluoro-Pauson-Khand reaction, both in the inter- and intramolecular versions. Furthermore, the use of vinyl fluorides as olefinic counterparts had been completely overlooked. In this review, we collect the advances both on the stoichiometric and catalytic intermolecular and intramolecular fluoro-Pauson-Khand reaction, with special attention to the PKR of enynes containing a fluoride moiety.

Phosphine-Free Ru-Catalyzed Regio- and Stereoselective Addition of Benzoic Acids to Trifluoromethylated Alkynes toward Facile Access to Trifluoromethyl Group-Substituted (E)-Enol Esters

A combination of ruthenium catalyst with silver salt and copper salt was proved to be a highly efficient protocol for the direct addition reaction of benzoic acids with unsymmetrical trifluoromethylated internal alkynes. Diverse trifluoromethyl group-substituted (E)-enol esters were readily obtained for a broad substrate scope in moderate to good yields with excellent regio- and stereoselectivities under mild reaction conditions.

Pauson-Khand reaction of internal dissymmetric trifluoromethyl alkynes. Influence of the alkene on the regioselectivity

The scope of the Pauson-Khand reaction (PKR) of internal trifluoromethyl alkynes, previously described with norbornadiene, is expanded to norbornene and ethylene. A thorough structural analysis of the resulting PK adducts has been carried out to unveil that α-trifluoromethylcyclopentenones are preferred in all cases, independently of the electronic properties of the alkyne. The regioselectivity observed with norbornadiene and ethylene is higher than in the case of norbornene.