Fluoromethylene Transfer from Diarylfluoromethylsulfonium Salts: Synthesis of Fluorinated Epoxides

Abstract

Diarylfluoromethyl sulfonium salts are efficient fluoromethylene transfer reagents equivalent to fluorocarbene, which is difficult to access. This was demonstrated by the development of a monofluorinated Johnson–Corey–Chaykovsky reaction with ketones and aldehydes, delivering uncommon 2‐unsubstituted fluoroepoxides. This is the first evidence for the feasibility of sulfur fluoromethylylide and its action as a reaction intermediate.

Ylide‐Functionalization via Metalated Ylides: Synthesis and Structural Properties

“…This is well in line with a very recent report on the use of fluoromethyl sulfonium salts as fluoromethylene transfer reagents. Here, the fluorinated ylide was also suggested to act as a fluorocarbene equivalent . The reactivity of the two α‐fluoroylides 1‐F and 2‐F is well in line with these observations and the structural parameters.…”

“…Here, the fluorinated ylide was also suggested to act as a fluorocarbene equivalent. [21] The reactivity of the two α-fluoroylides 1-F and 2-F is well in line with these observations and the structural parameters. As such, preparation of 1-F and 2-F was found to be accompanied by the formation of several decomposition products and both compounds exhibited limited stabilities in solution at room temperature, thus resulting in lower isolated yields compared to the ylide-functionalized compounds (c.f.…”

Synthesis and Properties of the Fluoromethylating Agent (Fluoromethyl)triphenylphosphonium Iodide

“…Very recently new techniques for the transfer of “CHF” and “CIF” units to organic substrates starting from diarylfluoromethyl sulfonium salts or CH 2 FI in combination with the use of special bases have been reported . In addition to the fluoromethyl halides CH 2 FBr and CH 2 FI other more effective fluoromethylating agents have been developed in the last years (Figure ) , , .…”

Synthetic Applications of Monofluoromethylsulfonium Salts

“…In 2019, the Veliks group demonstrated first example of fluoromethylsulfonium salt 1a as a direct fluoromethylene (CHF) transfer reagent in the synthesis of fluoroepoxides. 14 Moreover, this approach was the first evidence for the feasi-bility of a sulfur fluoromethylide as a synthetic equivalent to the otherwise challenging fluoromethylene synthon. Diaryl(fluoromethyl)sulfonium salt 1a as bench-stable, user friendly reagent 10,13 was used to develop an efficient method for the formation of the uncommon 16i,28 2-unsubstituted fluoroepoxides 62 in a monofluorinated version of the Johnson-Corey-Chaykovsky reaction (Scheme 11).…”