A variety of β-trifluoromethyl ketones have been easily prepared by CuCl-catalyzed ring-opening trifluoromethylation of cyclopropanols with Togni reagent.

Chikungunya virus (CHIKV; genus Alphavirus ) is the causative agent of chikungunya fever. CHIKV replication can be inhibited by some broad-spectrum antiviral compounds; in contrast, there is very little information about compounds specifically inhibiting the enzymatic activities of CHIKV replication proteins. These proteins are translated in the form of a nonstructural (ns) P1234 polyprotein precursor from the CHIKV positive-strand RNA genome. Active forms of replicase enzymes are generated using the autoproteolytic activity of nsP2. The available three-dimensional (3D) structure of nsP2 protease has made it a target for in silico drug design; however, there is thus far little evidence that the designed compounds indeed inhibit the protease activity of nsP2 and/or suppress CHIKV replication. In this study, a set of 12 compounds, predicted to interact with the active center of nsP2 protease, was designed using target-based modeling. The majority of these compounds were shown to inhibit the ability of nsP2 to process recombinant protein and synthetic peptide substrates. Furthermore, all compounds found to be active in these cell-free assays also suppressed CHIKV replication in cell culture, the 50% effective concentration (EC ₅₀ ) of the most potent inhibitor being ∼1.5 μM. Analysis of stereoisomers of one compound revealed that inhibition of both the nsP2 protease activity and CHIKV replication depended on the conformation of the inhibitor. Combining the data obtained from different assays also indicates that some of the analyzed compounds may suppress CHIKV replication using more than one mechanism.

Tertiary cyclopropanols undergo ring-opening oxidative sulfonylation to afford γ-keto sulfones when reacting with sulfinate salts in the presence of a copper(II) acetate catalyst and an oxidant (tert-butyl hydroperoxide or atmospheric oxygen). Various fluoroalkyl, aryl and alkyl sulfinate salts are successfully employed as sulfonylation reagents, affording the corresponding sulfones in up to 94% yields. The experimental protocol is mild and tolerates a number of functionalities in the cyclopropanol substrate. The reaction proceeds via a one-pot oxidation–Michael addition mechanism and can serve as a useful addition to the existing methods for the preparation of γ-keto sulfones based on the sulfa-Michael reaction.

Tertiary cyclopropanols easily available from carboxylic esters have been used in the synthesis of distally fluorinated ketones. Cyclopropane ring cleavage reactions in methanol with aqueous tert-butyl hydroperoxide in the presence of a copper(II) acetate catalyst and sodium triflinate (Langlois reagent) afford β-trifluoromethyl ketones in 16–74% isolated yields. Sodium triflinate serves as a precursor of reactive trifluoromethyl copper species, enabling ring-opening trifluoromethylation, as evidenced by mechanistic studies. We also demonstrate here that other sulfinate salts, such as sodium 1,1-difluoroethanesulfinate, sodium 2-(4-bromophenyl)-1,1-difluoroethanesulfinate and sodium 1-(trifluoromethyl)cyclopropanesulfinate, can be used as fluoroalkylation reagents, resulting in the corresponding fluorinated ketones.