Synthesis of Trifluoromethylated Sultones from Alkenols Using a Copper Photoredox Catalyst

Abstract

A photo-redox-catalyzed procedure for the one-step formation of sultones from α,ω-alkenols and trifluoromethylsulfonyl chloride is described. Using [Cu(dap)2]Cl (1 mol %), a wide range of substrates can be cleanly converted to the target compounds, while commonly employed photoelectron transfer catalysts such as [Ru(bpy)3]Cl2 or fac-Ir(ppy)3 fail in this transformation. The obtained fluorinated sultones are attractive as potential electrolyte additives or as structural motifs in drug synthesis, with the latter being demonstrated with the synthesis of a trifluoroethyl-substituted analogue of a benzoxathiin that has high anti-arrhythmic activity.

Photoredox Catalysis with Metal Complexes Made from Earth‐Abundant Elements

“…After establishing the proof of concept, the Reiser group applied the trifluoromethylchlorosulfonylation to a,w-alkenols and therebyg ained unusually direct access to internal esters of hydroxysulfonic acids, so-called sultones. [31] Pent-4-en-1-ol (29)a sabenchmark substrate reacts with triflyl chloride in presenceo f[ Cu(dap) 2 ] + and K 2 HPO 4 to the sultone 30 (Scheme 8a). The base acts as as cavenger for HCl that is liberated in the course of ester formation.…”

Photogenerated Neutral Nitrogen Radical Catalyzed Bifunctionalization of Alkenes

“…The Whitham group has disclosed that benzoyl peroxide (BPO)‐derived benzoyl radical could initiate this process in CHCl 3 heated to reflux . It must also be noted that the Reiser group has reported an unprecedented visible‐light‐driven copper‐catalyzed trifluoromethylchlorosulfonylation of alkenes by using triflyl chloride, without SO 2 extrusion; this reaction provides a new method for carbosulfonylations of alkenes but with only single triflyl chloride used. Quite recently, Zhu et al.…”

Photokatalyse mit sichtbarem Licht: Welche Bedeutung hat sie für die organische Synthese?

“…Mit diesen Katalysatoren kçnnen Perhalogenalkane und a-Carbonylhalogenide (Schema 72, rechts), aber auch elektronenarme Benzylhalogenide [262] mit Alkenen gekuppelt werden (Schema 72, rechts). [264] Das unterschiedliche Verhalten von [265,266] [260,263] WiefürRu II oder Ir III diskutiert (Schema 82), kçnnten die Cu I -katalysierten, durch sichtbares Licht vermittelten ATRA-Prozesse sowohl einem Photoredoxzyklus als auch einem Radikalkettenmechanismus unterliegen.…”

“…[265,266] 8.1.5. a-Tri(per)fluoralkylierung von Carbonylverbindungen (sp 3sp 3 ) [265,266] 8.1.5. a-Tri(per)fluoralkylierung von Carbonylverbindungen (sp 3sp 3 )…”

“…Letzterer wurde fürd ie Kupfer(I)-katalysierten Azidierung von Toluolen vorgeschlagen. [264] Das unterschiedliche Verhalten von [265,266]…”