Difluorocyclopropanation of N‐vinylazoles with the CF3SiMe3–NaI system was studied. It was found that N‐vinylpyrazoles could be transformed into the corresponding N‐difluorocyclopropyl‐substituted derivatives. The method was efficient on a 100 g scale and could be applied for the preparation of various functionalized regioisomeric pyrazole derivatives bearing a gem‐difluorocyclopropane moiety, such as amines, carboxylic acids, aldehydes, bromides, and boronic esters. It was found that N‐difluorocyclopropylpyrazole moiety tolerated many common reagents including nitrating mixture, bromine, aqueous acids and alkali, KMnO4, LiBH4, and Pd0 complexes; it was unstable towards AlCl3, catalytic hydrogenation and lithiation conditions. The products obtained are advanced building blocks which of potential importance to medicinal and agrochemistry.

The reaction of trimethyl(trifluoromethyl)silane–tetrabutylammonium difluorotriphenylsilicate (CF3SiMe3–TBAT) with a series of imidazoles gives products of the formal difluorocarbene insertion into the C–H bond at the C-2 position (i.e., C-difluoromethylation). According to NMR spectra, the corresponding 2-(trimethylsilyl)difluoromethyl-substituted derivatives are likely formed as the intermediates in the reaction, and then, they slowly convert to 2-difluoromethyl-substituted imidazoles. Quantum chemical calculations of two plausible reaction mechanisms indicate that it proceeds through the intermediate imidazolide anion stabilized through the interaction with solvent molecules and counterions. In the first proposed mechanism, the anion reacts with difluorocarbene without an activation barrier, and then, the CF2 moiety of the adduct attacks the CF3SiMe3 molecule. After the elimination of the CF3 anion, 2-(trimethylsilyl)difluromethyl-substituted imidazole is formed. Another possible reaction pathway includes silylation of imidazolide anion at the N-3 atom, followed by the barrierless addition of difluorocarbene at the C-2 atom and then by 1,3-shift of the SiMe3 group from N-3 to the carbon atom of the CF2 moiety. Both proposed mechanisms do not include steps with high activation barriers.

A general approach to gem‐difluorocyclopropenes synthesis based on the reaction of alkynes with Ruppert‐Prakash reagent is reported. The proposed method is evaluated for the synthesis of a wide difluorocyclopropenes scope based on their bench lifespan and hydrolytic stability. The tolerance of the method for common functional groups was shown. Previously unavailable difluorocyclopropenes substituted with aliphatic were prepared using the proposed procedure. The retain of stability was proven by the multigram scale synthesis and further storage in the temperature interval −78 to −4 °C over a year. This makes them attractive building blocks and intermediates for organic synthesis. The reasons for dropping stability were defined. The relations between the structure of the substituents and the stability of the difluorocyclopropene ring were determined and discussed.