摘要：

The reaction of trans-3-penten-2-one (1) with methyllithium and with methylmagnesium has been studied to learn the effect of added copper salts on the reaction rate and the proportions of reaction products 3 and 4. These studies have led to the development of two organocopper reagents which have the stoichiometry Li+Me2Cu- and MeCuP(n-Bu)3 and which very selectively add a methyl group to the β carbon of an α,β-unsaturated ketone. Although the conjugate addition of a 0.2 M solution of the methylcopper-tri-n-butylphosphine complex to the unsaturated ketone 1 is complete in less than 0.05 sec, the same reagent does not add to the carbonyl function of saturated ketones or esters even after reaction periods of 30 min or more. Investigation of the stereochemistry of enolate anions produced by conjugate addition of these organocopper reagents provides direct experimental evidence that these reactions do not involve a cyclic six-centered transition state. Other reactions and properties of these organocopper reagents are also described.

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