Organomanganese reagents easily react with conjugated enones to give the 1,4-addition products in excellent yields in the presence of copper salts.
The reaction compares favorably to the classical reactions involving copper-catalyzed Grignard reagents or cuprates. The difference is especially impressive with unreactive b,b-disubstituted enones such as isophorone.
Excellent results are obtained by using Grignard reagents under manganese/copper-catalysis.
Copper-catalyzed organomanganese reagents are also clearly superior in the case of conjugated ethylenic aldehydes.
On the other hand, we have shown that the copper-catalyzed alkylation of Grignard reagents led to excellent yields in the presence of NMP. Moreover the reaction is chemoselective.
Recently, we have undertaken a careful mechanistic study of this reaction and we have discovered that it is possible to obtain excellent yields without using any ligand by adding the Grignard reagents very slowly to the reaction mixture.
The copper-catalyzed reaction of Grignard reagents with 1-haloalkynes was known to give poor yields. We have reinvestigated this reaction and we have found that a slow controlled addition of the Grignard reagent allows to obtain excellent yields of substitution products.