(NHC)AgCl catalyzed bromofluorocyclopropanation of alkenes with CFBr2CO2Na

Fluorohalomethylsulfonium Salts as a Fluorohalocarbene Source

Synthesis of fluoroorganic compounds is of great importance due to their extensive application in medicinal chemistry, agrochemicals, and materials. Herein, we report efficient synthesis of novel diaryl fluorohalomethyl sulfonium salts. The application showcased proficient reagents for Freon-free fluorochloro-, fluorobromo-, and fluoroiodocarbene transfer to alkenes. The developed mild, room temperature conditions for the cyclopropanation do not require any metal catalysts and allow synthetic access to diverse cyclopropanes.

Recent Advances in Monofluorinated Carbenes, Carbenoids, Ylides, and Related Species

The synthesis of monofluorinated compounds is of great interest because of the vast applications of organofluorine compounds. Recently, the introduction of monofluorocarbene synthons has emerged as an important strategy for the synthesis of fluorine-containing products. In contrast to direct fluorination, in which C-F bonds are formed, the use of monofluorinated carbenes and related reactive species involves C-C or C-X bond formation while delivering valuable fluorine atoms into the target structure. Owing to increased knowledge on carbon-carbon and carbon-heteroatom bond formations, monofluorinated carbenes have enormous potential for the synthesis of organofluorine compounds, which, in our opinion, has not yet been fully exploited. This review summarizes the recent advances in the synthetic applications of monofluorinated carbenes, carbenoids, ylides, and related species.

gem-Halofluorocyclopropanes via [2 + 1] Cycloadditions of In Situ Generated CFX Carbene with Alkenes

An efficient and operationally simple synthesis of gem-bromofluorocyclopropanes under mild conditions has been developed. The method employs ethyl dibromofluoroacetate (EDBFA) as an accessible and inexpensive source of the bromofluorocarbene (:CFBr) intermediate. The protocol provides the bromofluorocyclopropane products in excellent yields, including examples synthesized in multigram scales. The chlorinated ester, ethyl dichlorofluoroacetate (EDCFA), is also utilized to make the analogous gem-chlorofluorocyclopropanes.

(2-Fluoroallyl)pyridinium tetrafluoroborates: novel fluorinated electrophiles for Pd-catalyzed allylic substitution

An efficient two-step approach to 2-fluoroallyl amines was developed that involves the synthesis of (2-fluoroallyl)pyridinium tetrafluoroborates from readily available gem-bromofluorocyclopropanes and the application of the former as novel and stable 2-fluoroallyl electrophiles for Pd-catalyzed allylic substitution.

Synthesis of Fluoro-, Monofluoromethyl-, Difluoromethyl-, and Trifluoromethyl-Substituted Three-Membered Rings

This Minireview describes recent advances toward the synthesis of fluoro-, monofluoromethyl-, difluoromethyl-, and trifluoromethyl-substituted three-membered rings such as cyclopropanes, aziridines, epoxides, episulfides, cyclopropenes, and 2 H-azirines. The main synthetic methodologies since 2016 for cyclopropanes and since 2010 for the other three-membered rings are reported.

TMSCFX2 (X = Cl, Br) as halofluorocarbene sources for the synthesis of halofluorocyclopropanes

TMSCFX2 (X = Cl, Br; TMS = trimethylsilyl) have been developed as halofluorocarbene (CFX, X = Cl, Br) precursors for [2+1] cyclopropanation with alkenes. Structurally diverse halofluorocyclopropanes were obtained in good to excellent yields. It was found that the reactivity order of the three halofluorocarbene reagents (TMSCF2Br, TMSCFCl2, and TMSCFBr2) in halofluorocyclopropanation with 1,1-diphenylethylene can be very different under different reaction conditions.