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Three-Component Coupling of Arenes, Ethylene, and Alkynes Catalyzed by a Cationic Bis(phosphine) Cobalt Complex: Intercepting Metallacyclopentenes for C–H Functionalization
journal contribution
posted on 2022-03-04, 18:36 authored by William
G. Whitehurst, Junho Kim, Stefan G. Koenig, Paul J. ChirikA cobalt-catalyzed
intermolecular three-component coupling of arenes,
ethylene, and alkynes was developed using the well-defined air-stable
cationic bis(phosphine) cobalt(I) complex, [(dcype)Co(η6-C7H8)][BArF4]
(dcype = 1,2-bis(dicyclohexylphosphino)ethane; BArF4 = B[(3,5-(CF3)2)C6H3]4), as the precatalyst. All three components were
required for turnover and formation of ortho-homoallylated
arene products. A range of directing groups including amide, ketone,
and 2-pyridyl substituents on the arene promoted the reaction. The
cobalt-catalyzed method exhibited broad functional group tolerance
allowing for the late-stage functionalization of two drug molecules,
fenofibrate and haloperidol. A series of control reactions, deuterium
labeling studies, resting state analysis, as well as synthesis of
substrate- and product-bound η6-arene complexes supported
a pathway involving C(sp2)–H activation from a cobalt(III) metallacycle.
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two drug moleculesresting state analysisdeuterium labeling studiesb [( 35 -( cf>< sup ><7 sub6 sub4 subcobalt ( iiicatalyzed intermolecular threesp ortho cobalt (three componentsstage functionalizationpyridyl substituentsintercepting metallacyclopentenesdeveloped usingdefined aircontrol reactionscomponent couplingcationic bisbound ηarene promotedalkynes catalyzed2