A chemical scale for evaluating the electron transfer ability of alkylcopper reagents

In order to evaluate the electron transfer ability of organocopper reagents, the reactions of appropriate Michael acceptors with methyl and butylcopper reagents were investigated. The ratio of the conjugate adduct and reduction product was used as a chemical scale for evaluating the electron transfer ability of the alkylcopper reagents. Consequently, the electron transfer ability of methyl and butylcopper reagents is in the following order; Me₃CuLi₂ > Me₂CuLi >> Me₂Cu(CN)Li₂ > MeCu > MeCu(CN)Li; Bu₂CuLi > BuCu(CN)Li - Bu₂Cu(CN)Li₂ > BuCu.