Preparation and Properties of Organometallic Nucleophiles

Carbon nucleophiles are very useful species because their reactions with carbon electrophiles result in the formation of carbon—carbon bonds. Section 10.8 introduced acetylide anions as nucleophiles that could be used in Sm2 reactions. These nucleophiles are prepared by reacting 1-alkynes with a strong base such as sodium amide. The relatively acidic hydrogen on the. vp-hybridized carbon is removed in this acid-base reaction  

The structure of the R group of RX can vary widely as long as no other reactive functional group is present. The halogen of RX can be iodine (most reactive), bromine, or chlorine (least reactive) fluorine is not commonly used. Several examples are provided 

All of these reagents are quite reactive and are commonly used immediately after they are prepared. However, solutions of some of them, including methyllithium, butyl-lithium, phenyllithium, and a number of simple Grignard reagents, are now commercially available. 

Let s now turn our attention to the chemical behavior of these organometallic reagents. As mentioned previously, even though the carbon-metal bonds in these compounds are predominantly covalent, they often react as would be predicted for the corresponding carbanion, although the identity of the metal certainly modifies their behavior somewhat. As expected for carbanions whose pATa s would be in the 

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