Electrophilic additions metal-containing reagents

If the point of unwanted metalation contains a strong electrophile, the later will need to be protected or modified. In some cases, it might be possible to change the reactivity of the Grignard reagent through the addition of zinc or copper salts in order to minimize the formation of secondary products [6, 7]... 

The use of transition metal catalysts, especially those containing Pd and Ni, has converted otherwise unreactive or sluggishly reactive organozincs into highly reactive reagents for their reactivity towards various common electrophiles. This includes carbonyl addition reactions of organozinc reagents, which are catalyzed by Pd complexes. 

Aldehydes (RCHO) react with 1-diazo-l-lithioacetone to give a-diazo- -hydroxyketones (48). These latter compounds can then be converted to P-diketones by the addition of rhodium(il) acetate a procedure which has been applied in the synthesis of -damascone. 1,6,6A -Trithiapentalene and a metal salt catalyse the lithiation of unactivated alkenes to alkenyl-lithiums by lithium metal, constituting a very useful method for preparing such compounds since in the past the preparation of alkenyl-lithiums from lithium metal has been confined to alkenes containing relatively acidic protons. Finally, the allenyl-lithium reagent (49) can be converted to various functionalized allenes by simple electrophiles. ... 

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