Photoredox Catalysis in C-S Bond Construction: Recent Progress in Photo-Catalyzed Formation of Sulfones and Sulfoxides

An unexpected reaction of aryldiazonium tetrafluoroborates, sodium metabisulfite, and thiourea under photoinduced conditions

A photoinduced synthesis of S-aryl thiosulfonates through a three-component reaction of aryldiazonium tetrafluoroborates, sodium metabisulfite, and thiourea is achieved. In this transformation, a radical coupling pathway is proposed.

Switchable regioselection of C–H thiolation of indoles using different TMS counterions

Simply swapping the counteranions of TMS leads to a switchable regioselectivity in C2– and C3–H thiolation of indoles.

Organic photoredox catalysis enabled cross-coupling of arenediazonium and sulfinate salts: synthesis of (un)symmetrical diaryl/alkyl aryl sulfones

Transition-metal- and oxidant/reductant-free visible-light-mediated synthesis of (un)symmetrical diaryl/alkyl aryl sulfones from aryl diazonium and sulfinate salts employing eosin Y as an organo-photoredox catalyst is reported.

Metal-free sulfonyl radical-initiated cascade cyclization to access sulfonated indolo[1,2-a]quinolines

A metal-free cascade reaction was developed for the synthesis of indolo[1,2-a]quinoline derivatives from arylsulfonyl hydrazides and 1-(2-(arylethynyl)phenyl)indoles in the presence of TBAI/TBHP.

Visible-light promoted one-pot synthesis of sulfonated spiro[4,5]trienones from propiolamides, anilines and sulfur dioxide under transition metal-free conditions

A novel visible-light promoted sulfonylation/ipso-cyclization of N-arylpropiolamides with aromatic amines and DABCO·(SO₂)₂ to synthesize various sulfonated spiro[4,5]trienones is reported.

Photoredox-catalyzed sulfonylation of alkenylcyclobutanols with the insertion of sulfur dioxide through semipinacol rearrangement

A photoredox-catalyzed sulfonylation of alkenylcyclobutanols with the insertion of sulfur dioxide through semipinacol rearrangement under visible light irradiation is developed.

A visible-light-induced oxidative cyclization of N-propargylanilines with sulfinic acids to 3-sulfonated quinoline derivatives without external photocatalysts

A visible-light-induced oxidative cyclization of N-propargyl anilines with sulfinic acids to 3-sulfonated quinoline derivatives was developed under external photocatalyst-free conditions.

Nitration and Cyclization of Arene-Alkynes: An Access to 9-Nitrophenathrenes

A nitration and cyclization of arene-alkynes has been developed, affording 9-nitrophenathrenes efficiently. This reaction probably proceeds via addition of the nitrogen dioxide to the alkyne moiety, intramolecular radical addition of vinyl radical to one aryl ring, oxidation of radical intermediate into carbocation species, and elimination of a proton. In this transformation, Fe(NO₃)₃ was used as both nitro source and oxidant.

A chiral nickel DBFOX complex as a bifunctional catalyst for visible-light-promoted asymmetric photoredox reactions

The enantioselective photoredox reaction of α,β-unsaturated carbonyl compounds and tertiary/secondary α-silylamines was enabled by a readily available single NiII-DBFOX catalyst (DBFOX = 4,6-bis((R)-4-phenyl-4,5-dihydrooxazol-2-yl)dibenzo[b,d]furan) under visible light conditions. The non-precious chiral catalyst is involved in the photochemical process to initiate single electron transfer and at the same time provides a well-organized chiral environment for the subsequent radical transformations. Good to excellent enantioselectivities (80-99% ee) were obtained for the formation of chiral γ-amino carboxylic acid derivatives and γ-lactams.

Copper-catalyzed radical Heck type cyclization: a three-component reaction of DABCO·(SO2)2, aryldiazonium tetrafluoroborates and dienes toward sulfonated benzo- seven-membered nitrogen heterocycles

A three-component reaction of the sulfur dioxide surrogate of DABCO·(SO₂)₂, aryldiazonium tetrafluoroborates and dienes has been developed, affording a series of sulfonated nitrogen heterocycles.

Visible-light-induced methylsulfonylation/bicyclization of C(sp3)-tethered 1,7-enynes using a DMSO/H2O system

A visible light photocatalytic methylsulfonylation/bicyclization of C(sp³)-tethered 1,7-enynes has been established using a dimethyl sulfoxide (DMSO)/H₂O system as the methylsulfonyl source.

Aerial dioxygen activation vs. thiol–ene click reaction within a system

By choosing appropriate reaction systems using solvents with additives or solvent free neat conditions, any one of the Markovnikov or anti-Markovnikov selective thiol–ene click (TEC) reactions and the synthesis of β-hydroxysulfides via aerial dioxygen activation could be achieved exclusively in excellent yields.