cinnamonitriles_cinnamonitrile(5)

Whenawater-solublepalladiumcatalystisused,5-hydroxymethylfurfuralisselectivelycarbonylatedtothecorrespondingacidat70°C,togetherwithreducedproduct(eq174).658

9.3.3.CarbonylationofArylHalides

Thepalladium-catalyzedcarbonylationofarylha-lidesinthepresenceofvariousnucleophilesisacon-venientmethodforsynthesizingvariousaromaticcarbonylcompounds(e.g.,acids,esters,amides,thio-esters,aldehydes,andketones).Aromaticacidsbear-ingdifferentaromaticfragmentsandhavingvarioussubstituentsonthebenzeneringhavebeenpreparedfromaryliodidesatroomtemperatureunder1atmCOinamixedsolventofH2O/DMF(1/1or1/2,v/v)andeveninwateralone,dependingonthesolubilityofthesubstrate(eq175).659Thepalladium(II)com-

plexesPd(OAc)2,K2PdCl4,PdCl2(PPh3)2,andPd(N-H3)4Cl2areusedastheprecursorsofthecatalystusingeitherK2CO3orNaOAcasthebase.Iodoxyare-nescanbecarbonylatedinwateraloneduetoitssol-ubilityinthesolvent.660Recentworkwasdoneontheuseofwater-solublecatalysts.661Undertheap-propriateconditionsofpressureandtemperature,arylmercaptans(thiophenols)csobecarbonyl-atedinaqueousmediawithcobaltcarbonylasthecatalyst.662

9.4.TheHeckCoupling

Thereactionbetweenaryl(oralkenyl)halidesandalkenesinthepresenceofacatalyticamountofapalladiumcompoundtogivesubstitutionofthehalidesbythealkenylgroupiscommonly

referred

OrganicReactionsinAqueousMediatoastheHeckreaction.663Bothinter-andintramo-lecularHeckreactionshavebeenperformedinaque-ousmedia.Palladium-catalyzedreactionsofarylhalideswithacrylicacidoracrylonitrilegavethecorrespondingcouplingproductsinhighyieldsinthepresenceofabaseinwater(eq176).664Thereaction

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