Single-electron Transfer Theorem

SET processes do not occur among moderately electrophilic olefinic acceptors, but are likely to be involved in highly electrophilic substrates. Some recent examples are the polyadditions of cuprate to fullerenes (Sect. 10.1.1). Fluorenone ketyl radical has been detected in a cuprate reaction of fluorenone [20]. Doubly activated olefins [67-69] and bromonaphthoquinone [70] also probably react through SET. 

Conjugate additions lo a,/ -unsalutaled kelones and eslets ate die most Impotlanl ctiptale reactions. Kinetic studies by Ktauss and Sniidi on MezCuIi and a variety of ketones teveaied die following kinetic cliatacterislics lEq. 10.5), fitsl otdet bodi in cuprate dimer and in die etione [60]. 

Tliis rate expression is conslstenl widi die reaction sclieme shown in Eq. 10.6, fot-niLilaled on die basis of die Ktauss-Smidi paper. Tlius, die inilially formed cuptate diniet/enone complex widi lidiium/catbonyl and coppet/olefin cootdinalions [71, 72] Itansfbrms inlo die product via an intermediate ot inlermediales. A lidiium/ carbonyl complex also forms, bul diis is a dead-end intermediate. Tliougli detailed 

An intetniediate foi been examined by L tiiougli a Cu/olelin rt-c tiie / -carbon. Eurdier otiier fC) is prop  

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House pioneered synthetic and mechanistic studies of cuprate reactions in the 1970s. His papers proposed a mechanism (Scheme 10.4) that assumes a single-electron transfer (SET) from the dimer producing a Cu intermediate [56 57]. The SKT/Cu theorem had a strong following for many years. However most of the experimental facts listed below once considered to support the SET process are now no longer accepted as evidence of SET. Only the Cu hypothesis has survived fbe test of time. 

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