Divergent Regio‐ and Stereoselective Gold‐catalyzed Synthesis of α‐Fluorosulfones and β‐Fluorovinylsulfones from Alkynylsulfones

Abstract

We developed a widely applicable, highly efficient synthesis of α-fluorosulfone and β-fluorovinylsulfone catalyzed by gold. Starting with alkynyl sulfone 1, an [Au]/HF/N-oxide system gives α-fluorosulfone 3 via a gold carbene intermediate, and, if no N-oxide is used, direct addition of HF to 1 gives vinyl sulfone 4 via a vinylfluoro gold intermediate. Both methods have good functional group tolerance and the reactions can be conducted in ambient atmosphere.

A HF Loaded Lewis‐Acidic Aluminium Chlorofluoride for Hydrofluorination Reactions

“…Indeed, the groups of Nolan, Toste, Miller, and Sadighi, used Et 3 HF⋅3 HF together with various catalysts and succeeded in the formation of monofluorinated alkenes . Hammond reported on a gold‐catalyzed hydrofluorination of alkynes to yield olefins with DMPU/HF as well as with pyridine⋅(HF) x . Moreover, the synthesis of β‐fluorovinyl sulfones was studied by the group of Fustero, using copper‐based catalysts together with Et 3 N/HF .…”

Stereodivergent Alkyne Hydrofluorination Using Protic Tetrafluoroborates as Tunable Reagents

“…It is noteworthy that in hydrofluorination reactions employing alkyl aryl acetylenes,t he vinyl fluoride products were delivered exclusively with C À Fb ond formation taking place adjacent (a)t ot he aryl group.T hese results complement Au-catalyzed hydrofluorination procedures,w hich deliver the fluorine to the carbon atom adjacent to the alkyl group, b to the aryl group. [7][8][9][10][11][12] This divergence likely stems from the ability for the aryl group to stabilize both an adjacent positive charge in the case of the current metal-free process and an adjacent C(sp 2 ) À Au bond in case of the Au-catalyzed protocols to give the a-a nd b-fluorinated regioisomers, respectively.…”

“…[6] As an alternative to the aforementioned approaches,t he hydrofluorination of alkynes represents aparticularly general and atom-economical synthesis of vinyl fluorides,e specially considering the broad range of alkyne substrates that are easily accessed from inexpensive,c ommercially available building blocks.S everal metal-catalyzed systems for the hydrofluorination of alkynes have been developed in recent years. [7][8][9][10][11][12][13][14][15] Following the initial disclosure of aA u-catalyzed process by Sadighi and co-workers, [7] an umber of coinage metal complexes have been employed as catalysts for the hydrofluorination of alkynes using Lewis-base adducts of hydrogen fluoride as the fluorinating reagents (Scheme 1B). [7][8][9][10][11][12][13] In the Au-catalyzed systems, Z-vinyl fluorides are formed with high stereoselectivity,a nd for aryl alkyl alkynes,the major regioisomer formed is the one in which the fluorine is delivered to the carbon atom adjacent to the alkyl group (b to the aryl group,S cheme 1Ba).…”

“…[7][8][9][10][11][12][13][14][15] Following the initial disclosure of aA u-catalyzed process by Sadighi and co-workers, [7] an umber of coinage metal complexes have been employed as catalysts for the hydrofluorination of alkynes using Lewis-base adducts of hydrogen fluoride as the fluorinating reagents (Scheme 1B). [7][8][9][10][11][12][13] In the Au-catalyzed systems, Z-vinyl fluorides are formed with high stereoselectivity,a nd for aryl alkyl alkynes,the major regioisomer formed is the one in which the fluorine is delivered to the carbon atom adjacent to the alkyl group (b to the aryl group,S cheme 1Ba). Since the initial report of Au-catalyzed alkyne hydrofluorination in 2007, the scope of this process has seen considerable expansion and now includes alkynes bearing either electron-withdrawing groups or directing groups,a sw ell as terminal alkynes.…”

Visible‐Light‐Assisted Gold‐Catalyzed Fluoroarylation of Allenoates

“…Initially,t odistinguish the mode of activation of the allenic ester,either by Au I or Au III species,acontrol experiment between 1q and Et 3 N·3 HF was carried out in the absence of arenediazonium salt, which resulted in no formation of the anticipated hydrofluorination product, thus disfavoring the Au I activation scenario (Scheme 3a). [18] To further corroborate the alternative activation mode, the hypothetically active Ar-Au III complex II' ' was independently prepared using ar eported method. [19] Thef inding that complex II' ' not only underwent stoichiometric reaction with 1q but also acted as an effective catalyst for the reaction between 1q and 2n strongly supports the involvement of an Ar-Au III intermediate (Scheme 3b,c).…”