Engaging sulfinate salts via Ni/photoredox dual catalysis enables facile C_sp2–SO₂R coupling

Abstract

A new, mild, functional-group tolerant approach to the construction aryl- and heteroaryl sulfones via Ni/photoredox dual catalysis is described.

Photoredox-catalyzed branch-selective pyridylation of alkenes for the expedient synthesis of Triprolidine

“…Design plan. We hypothesized that sodium sulfinates would be the ideal reusable radical precursors, due to the unique properties of which: (i) sufinates have been recently employed as efficient sulfonyl coupling partners in photoredox catalysis [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] ; (ii) it is well known that the alkyl sulfones would be prone to undergo desulfonylation under basic conditions [63][64][65] . As depicted in Fig.…”

Late‐Stage Functionalization of Histidine in Unprotected Peptides

“…Lower conversions were observed when primary radicals were used and a second addition of sulfinate was needed to afford the desired products in synthetically useful yields ( 2 l – n ; 36–45 % UPLC yields). It should be noted that aryl‐ and heteroaryl‐sulfinate salts were not suitable C−H arylation reagents, even when warmed up to 90 °C, as these substrates presumably fail to undergo the C−S scission necessary to produce the respective hetero(aryl) radicals . This methodology provides a unique opportunity to study the fine‐tuning of His properties through the targeted introduction of substituents with various steric, lipophilic and electronic characteristics.…”

The Right Light: De Novo Design of a Robust Modular Photochemical Reactor for Optimum Batch and Flow Chemistry

“…The cross‐coupling of aryl iodides and sulfinic acid salts to generate sulfones has been reported . An initial wavelength screen in PHIL, for the coupling of 17 and 18 (Scheme ), identified 525 nm as the optimum wavelength, despite the photocatalyst having a lambda max at 450 nm.…”

“…Internal reaction temperatures of ∼60 °C were observed during the course of the reaction, whilst the LED temperature was maintained at the set temperature of 15 °C; we have noted air temperatures 10 °C lower than internal reaction temperatures suggesting the reaction is releasing heat (vibrational relaxation) . Other nickel systems infer that the nickel oxidative addition is a thermally governed process, so higher temperatures facilitate the cross‐coupling cycle in a rate‐limiting fashion, whilst the optimization of photochemical conditions facilitates radical formation . At a constant current (350 mA) the internal reaction temperature was varied by altering the set point of the thermoelectric cooling unit.…”