SulfurChemistrySulfurin Waste-FreeSustainableSynthesis:AdvancingCarbon–CarbonCouplingTechniquesNikitaS. Shlapakov,AndreyD. Kobelev,Julia V. Burykina,Yuan-ZhengCheng,Shu-LiYou,* and ValentineP. Ananikov*AngewandteChemieMinireviewswww.angewandte.orgHowto cite:Angew. Chem.Int. Ed.2024,63, e202402109doi.org/10.1002/anie.202402109Angew. Chem.Int. Ed.2024,63, e202402109(1 of 16)© 2024Wiley-VCHGmbHAngewandteChemie
Abstract:This reviewexploresthe pivotalrole of sulfur in advancingsustainablecarbon-carbon(CC) couplingreactions.The uniqueelectronicpropertiesof sulfur, as a soft Lewis base with significantmesomericeffect make it anexcellentcandidatefor initiatingradicaltransformations,directingCH-activation,and facilitatingcycloadditionandCS bond dissociationreactions.These attributesare crucialfor developingwaste-freemethodologiesin greenchemistry.Our mini-reviewis focusedon existingsulfur-directedCC couplingtechniques,emphasizingtheirsustainabilityand comparingstate-of-the-artmethodswith traditionalapproaches.The review highlightsthe importanceof this researchin addressingcurrentchallengesin organicsynthesisand catalysis.The innovativeuse of sulfur inphotocatalytic,electrochemicaland metal-catalyzedprocessesnot only exemplifiessignificantadvancementsin the fieldbut also opens new avenuesfor environmentallyfriendlychemicalprocesses.By focusingon atom economyand wasteminimization,the analysisprovidesbroad appeal and potentialfor future developmentsin sustainableorganicchemistry.1. IntroductionOne of the key objectivesof modernchemistryis to reducematerialand energyloss in technologicalprocesses.Thisgoal is often interpretedas an effort to minimizetechno-logical risks, energy consumption,and materialwaste in theproductionof goods.[1]Preciselyestimatingthese losses inthe supply chain of matter from naturalenvironmentsto theanthroposphereis a formidable,if not impossible,task.Nonetheless,it is essentialto have guidelinessteeringsyntheticsciencetowardoptimizingthese metrics.Thebiohazardof a reactioncan be assessedusing toxicityprofiles.[2,3]Moreover,the optimizationof energy consump-tion and materialwaste can be approachedthroughconceptssuch as pot and step efficiency,[4]atom economy[5,6]andenvironmentalfactors.[7–9]Recently,the field of organosulfurcompoundshasundergonea renaissance,empoweredby advancementsinphotoredoxcatalysis,organicelectrochemistry,and catalysisby transitionmetal complexes.In additionto traditionalsynthetictransformationsof sulfur-containingcompoundsfor CC bond construction(such as the Corey–Chaykovsky,Julia–Lythgoe,and Corey–Seebachreactions),new reactionshave emerged.These includecross-couplingswith CSelectrophiles,[10–15]radicalchains and photocatalyticproc-esses involvingsulfonylradicals.[16–20]Despitethe generationof equivalentamountsof waste by-products,these reactionsare openingthe way for new methodologies,showcasingthepotentialof organosulfurchemistryin waste-freereactions.To developa waste-freeCC couplingreaction,threemain principlesmust be adheredto (Scheme1). First, theactivationmethodfor an organosulfurcompoundshould notproducestoichiometricwaste. Currently,four main strat-egies are identified:direct catalyticCH activation,activa-tion of π-bondsconnectedto the sulfur atom, activationofthe CS bond, and substrateactivationvia the formationofreactiveS-containingadducts.The second principleinvolvesusing a couplingpartnerthat does not cause waste formation(exceptH2or H2O) duringthe CC couplingreaction.Suitablereactionsincludeadditionand cycloadditioninvolv-ing alkynes,alkenes,carbonylcompounds,or aromaticcompoundswith potentialfor dearomatization,direct CH/CH couplingwith C(sp2)-containingcompounds,or cou-pling reactionswhere alcoholsserve as electrophiles.Finally,the third principleis to avoid the use of stoichiometricquantitiesof oxidizingagents (other than oxygen),reducingagents,and strong acids or bases, as well as any additivesthat inevitablyalter their compositionand generatewasteduring the reaction.The use of catalyticamountsof acids/bases or stoichiometricquantitiesof auxiliarybases/acidsthat remainunchangedin the reactionis consideredaccept-able.In this brief review,we explorethe remarkablecapa-bilitiesof sulfur-containingcompoundsfor advancingsus-tainablecarbon-carboncouplingtechniques.Our focus is onapproachesto addresscontemporarychallenges,therebysignificantlyminimizingwaste and promotingsustainablechemicalpractices.This explorationnot only highlightstheuniquepotentialof sulfur but also suggeststhe need for anew standardfor addressingthe goal of eco-friendlyandefficientchemicalsynthesis.This mini-reviewis based on theconsiderationof selectedrepresentativestudiesto addressthe formulatedaims, while the discussionsthat have already[*] N. S. Shlapakov, A. D. Kobelev, Dr. J. V. Burykina,Prof. Dr. V. P. AnanikovZelinskyInstituteof OrganicChemistryRussianAcademyof SciencesLeninskyProspect,47, 119991Moscow(Russia)E-mail:val@ioc.ac.ruDr. Y.-Z. Cheng,Prof. Dr. S.-L. YouStateKey Laboratoryof OrganometallicChemistry, ShanghaiInstituteof OrganicChemistryChineseAcademyof Sciences345 LinglingLu, 200032Shanghai(China)E-mail:slyou@sioc.ac.cnScheme1.The mainprerequisitesof S-directedwaste-freereactions.AngewandteChemieMinireviewsAngew. Chem.Int. Ed.2024,63, e202402109(2 of 16)© 2024Wiley-VCHGmbH