Unsaturated carbonyl compounds Organocopper reagents

CONJUGATE ADDITION OF ORGANOCOPPER REAGENTS TO a,p-UNSATURATED CARBONYL COMPOUNDS... 

You met organocopper reagents in Chapter 10 where you saw that they did conjugate additions to a,p-unsaturated carbonyl compounds. Other metals, such as cadmium or manganese, can also be used to make ketones from acid chlorides. 

Mechanistic aspects of copper-catalyzed Grignard addition to a,/ -unsaturated carbonyl compounds have not attracted much attention, probably because of the complex nature of the reagent system [11], but it would resemble that of the 1,4-addition of stoichiometric or higher-order organocopper reagents that have been investigated extensively [15,18,223]. 

In reactions with a,(3-unsaturated carbonyl compounds, the organocopper reagents prefer 1,4-over 1,2-addition. 

Regioselectivity in Addition of RLi, RMgX, and Organocopper Reagents to a, p-Unsaturated Carbonyl Compounds... 

Conjugate addition to an a,3-unsaturated carbonyl compound is achieved routinely by using a lithium organocopper reagent or a copper-catalyzed Grignard reaction. " It should be noted that in many of these examples, and in particular in the case of lithium diorganocuprates, the resultant enolate has... 

Conjugate Addition of Organocopper Reagents to a,p-Unsaturated Carbonyl Compounds 912... 

Organocopper reagents are widely used to carry out addition to the P carbon atom of a,P-unsaturated carbonyl compounds. For a discussion, see Posner, G. H. Org. React. 1972,19,1. The nature of the organocopper compound is a significant factor in these reactions. See, for example, Lipshutz, B. H. Wilhelm, R. S. Kozlowski, J. A. /. Org. Chem. 1984, 49, 3938. 

Addition to a, -unsaturated carbonyl compounds is characteristic of organocopper and cuprate compounds, as alkyllithium and Grignard reagents react only with the carbonyl group of enones to give the 1,2-addition products. This synthetically useful reaction has been reviewed by Posner (1972). 

Hahdes of transition metals react with methyllithium to give methyl compounds. This reaction is alternatively afforded by organocopper compounds hke hthiumdialkylcuprates which are also known as Gilman reagents. These reagents are widely used for nucleophilic substitutions of epoxides, alkyl hahdes and for conjugate additions to a,p-unsaturated carbonyl compounds by methyl anion. 

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