Photoredox-Mediated Desulfonylative Radical Reactions: An Excellent Approach Towards C–C and C–Heteroatom Bond Formation

Abstract

In recent times, desulfonylative radical-cross-coupling (RCC) has come to the forefront in synthetic organic, bio, and material chemistry as a powerful strategy to forge C-C and C-heteroatom bonds. Diverse functionalization through metal and photoredox-catalyzed desulfonylation reactions has attracted the scientific community due to the mild reaction conditions, wide functional group tolerance and excellent synthetic efficacy. In this review, we have highlighted the photoredox-mediated desulfonylation reactions developed in the last two decades. The current review will summarize the newly reported methodologies, with particular emphasis on their mechanistic aspects and selectivity issues which have paved a new way towards sustainable CC and CX (X= H or, heteroatom) bond formation.

Iron-catalyzed fluoroalkylative alkylsulfonylation of alkenes via radical-anion relay

“…Eventually, the Fe III is reduced by another half of Na 2 S 2 O 4 to regenerate Fe II , furnishing the iron electron-shuttle catalytic cycle. Notably, the conversion of carbon radical B to sulfone radical C is reversible 47 , 48 . Intermediate B would accumulate if the efficient reductant was absent for the reduction of sulfone radical C , which results in the formation of by-product 1b .…”

Visible-Light-Induced Reductive Coupling of Arylacetylenes with Benzothiazole Sulfones

“…More recently, reactions using carbon radicals generated from sulfones under visible-light irradiation have garnered considerable attention. Fluoroalkyl, β-keto, benzyl, and alkyl derivatives have emerged as radical sources in photoredox catalysis. In this context, we have been interested in developing visible-light-induced desulfonylative carbon–carbon bond formation and have reported transition-metal- and photocatalyst-free Giese-type reaction .…”

[2.2]Paracyclophane-based coumarins: effective organo-photocatalysts for light-induced desulfonylation processes

“…12 Recently, photocatalytic processes have unlocked new possibilities for performing light-driven desulfonylation reactions under milder conditions, and few examples have been reported. 13 These include, for instance, the use of extremely potent acridine radical photoreductants. 14 Methods involving different organophotocatalysts in the presence of hydride donors 15 or expensive transition metal complexes in combination with Hantzsch esters (HE) have also been developed.…”