Site‐Selective C−H Oxygenation via Aryl Sulfonium Salts

Abstract

Herein, we report a two‐step process forming arene C−O bonds in excellent site‐selectivity at a late‐stage. The C−O bond formation is achieved by selective introduction of a thianthrenium group, which is then converted into C−O bonds using photoredox chemistry. Electron‐rich, ‐poor and ‐neutral arenes as well as complex drug‐like small molecules are successfully transformed into both phenols and various ethers. The sequence differs conceptually from all previous arene oxygenation reactions in that oxygen functionality can be incorporated into complex small molecules at a late stage site‐selectively, which has not been shown via aryl halides.

Regio‐ and Stereoselective Thianthrenation of Olefins To Access Versatile Alkenyl Electrophiles

“…We have recently published a site‐selective aromatic C(sp 2 )−H functionalization reaction of in situ activated thianthrene‐ S ‐oxides with trifluoroacetic anhydride . The formed aryl thianthrenium salts were used as aryl electrophiles to form challenging bonds such as aryl C−SCF 3 , C−CF 3 , C−N, C−O, and C−F bonds. An extension of aromatic substitution chemistry to olefins is generally not successful because olefins typically react with electrophiles by addition.…”

Site-Selective Late-Stage C–H Functionalization via Thianthrenium Salts

“…In combination with a metal, such as copper, which traps the aryl radical and subsequently undergoes reductive elimination, various carbon-heteroatom bond formations are possible (Scheme 9). 10,[14][15][16][17][18] Copper(III) performs very well at reductive elimination, however, oxidative addition to copper(I) is often difficult. By using the oxidative ligation of arylradicals to copper, the challenging oxidative addition can be circumvented.…”

A Broad-Spectrum, Catalytic Amidation of Sulfonyl Fluorides and Fluorosulfates

“…NMR data were in agreement with the literature data. [33] N-(4-methoxybenzyl)-2,4,6-trimethylbenzenesulfonamide (3q)…”