Radical-mediated vicinal addition of alkoxysulfonyl/fluorosulfonyl and trifluoromethyl groups to aryl alkyl alkynes

Abstract

The addition of sulfonyl radicals to alkenes and alkynes is a valuable method for constructing useful highly functionalized sulfonyl compounds. The underexplored alkoxy- and fluoro-sulfonyl radicals are easily accessed by...

Photoactive Copper Complexes: Properties and Applications

“…In this perspective, the use of Grushin’s reagent [Cu­(bpy)­(CF 3 ) 3 ] ([Cu­( NN 261 )­(CF 3 ) 3 ]), which was previously shown to be readily activated under irradiation and quite efficient for trifluoromethylation reactions, as discussed in section 3.1.1.2.2, was further extended in 2021 to the photoinduced addition of sulfonyl and trifluoromethyl groups onto aromatic internal alkynes 41 (Scheme ). Upon reaction with allyl sulfonyl reagents 108 in the presence of excess [Cu­(bpy)­(CF 3 ) 3 ] ([Cu­( NN 261 )­(CF 3 ) 3 ]) and ammonium persulfate as the oxidant, a broad range of alkynes could be readily transformed to the corresponding conjugated alkenes 109 with average to excellent yield. The nature of the substituents on the starting internal aromatic alkyne influenced both the yields and stereoselectivity, and the reaction would be initiated by the addition of the trifluoromethyl radical to the allylic sulfonate/sulfonyl fluoride, initiating its fragmentation and releasing a sulfur-centered radical species that would then add to the starting alkyne, with the resulting vinylic radical species recombining with a copper­(II) trifluoromethyl complex evolving, through reductive elimination, to the final product 109 .…”

Alkoxysulfonyl radical species: acquisition and transformation towards sulfonate esters through electrochemistry

“…So far, strategies reported for the construction of alkoxysulfonyl radicals have been limited to radical exchange processes, in which radical species would react with chlorosulfonate, arylsulfonate or allylsulfonate to generate alkoxysulfonyl radicals. [23][24][25][26] With this strategy, direct synthesis of sulfonate esters could be achieved. However, prefunctionalized sulfonate esters were utilized as the alkoxysulfonyl radical sources, which restricted the applicability of these methods.…”

Recent Advances in the Functionalization of Terminal and Internal Alkynes

“…In 2021, Wu and co‐workers described copper‐catalyzed radical mediated 1,2‐addition of sulfonyl radicals to aryl alkyl alkynes to afford vinyl radicals that are trapped by trifluoromethyl group to provide tetra‐substituted alkenes (Scheme 47). [44] This strategy showed great functional group tolerance and the optimum conditions for this reaction were as follows: bpyCu(CF 3 ) 3 (1.2 equiv. ), (NH 4 ) 2 S 2 O 8 (3 equiv.)…”