Organolithium reagents, addition metalation

Like other Lewis bases, Grignard reagents, organolithium reagents, and metal hydrides are also able to undergo addition to carbonyl-containing compounds. These additions lead directly to the next subject. 

Several examples of intramolecular additions to carbonyl groups by organolithium reagents generated by halogen-metal exchange have been reported, such as the examples shown below. What relative reactivity relationships must hold in order for... 

It was observed that the metallation of terminal alkynes by organomagnesium (or organolithium) reagents considerably accelerated the rate of the subsequent addition of allylzinc bromide. The products resulting from a bis-addition predominate even in the case of sterically more demanding alkynes (equation 140). 

The addition of Grignards and organolithium reagents proceeds by attack at the metal center in ir-allylpalladium complexes. The regiochemical selectivity exhibited by these hard carbon nucleophiles with ir-allyl complexes substituted at the termini with alkyl or aryl groups is comparable to the soft carbon nucleophiles (ligand attack) in most cases, with addition occurring predominantly at the less substituted terminus (equations 248 and 249).1591387... 

Finally perfluorinated alkenes, prepared according to various routes (decarboxylation of perfluorinated acids or anhydrides, action of organolithium, magnesium reagents or metallic zinc-copper couple to perfluoroalkyl iodides, oligomerisation of TFE and of HFP, addition of perfluoroalkyl iodides to per-fluoroallyl chloride [304], addition of KF to perhalogenated esters or alkanes... 

Non-enolizable amides, for example N,N-dialkyl pivalamides [212], benzamides, thiobenzamides [213], or phosphinamides (Ph2P(0)NR2[214]), can be lithiated a to the amino group by treatment with sBuLi[54, 213, 215] or tBuLi[216], without further additives, in THF at -78 °C. N,N-Dimethylbenzamides can be attacked at the carbonyl group by these organolithium reagents to yield ketones [217] or alcohols, but with sterically more demanding amides metalation is usually faster than addition. 

The addition compounds (I) are insoluble in diethyl ether, and the slurries obtained are quite stable. In more strongly solvating media, such as tetrahydrofuran or dimethoxyethane, the compounds are soluble but show rapid decomposition, with trimethylamine and polymethylene as the main products. These experiments indicate (9, 40) that when the lithium salt is trapped by donor solvent molecules, the free ylide quickly undergoes decomposition (40). No free trialkylammonium ylide has yet been prepared, even under very mild conditions (35). On the other hand, it has been shown, that the tetramethylammonium cation can even be metalated twice by organolithium reagents (102) to afford dimethyl-ammonium bismethylides ... 

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