Organo(di)metal reagents for organic synthesis. Generation of carbanions by extrusion of N2 : history and applications

The first presentation develops doubly metalated organozinc reagents whose two nucleophilic sites can react sequentially. Examples include silyl- and germylzincation of alkynes, rearrangements producing metalated allenes and enantioselective activation of geminal diorganozincs. The second examines nitrogen extrusion as a driving force for carbanion formation. It surveys synthetic applications and describes decomposition of silylated diazenes to obtain group-one organometallic reagents with tertiary alkyl centres.