Electron deficient alkyllithium

Aryl-A3-iodanes bearing an electron-deficient alkyl ligand such as aryl(sul-fonylmethyl)-A3-iodanes (Section 3.2.7) and aryl(perfluoroalkyl)-A3-iodanes are relatively stable. A series of (perfluoroalkyl)phenyl-A3-iodanes 96 were synthesized in good yields by treating bis(trifluoroacetoxy)-A3-iodanes with benzene in the presence of triflic acid [47]. The AModanes 96 transfer the perfluoroalkyl groups to a variety of nucleophiles with reductive elimination of iodobenzene. The nucleophiles involve Grignard reagents, alkyllithiums, enolate anions, alkenes, alkynes, trimethylsilyl enol ethers, arenes, phenols, and thiols. In these reactions, the AModane 96 serves as a source of the perfluoroalkyl cation and, in... 

Alkyllithium compounds have solubility and stability because of their ability to associate to form aggregates of definite structure. Such aggregation confers stability but is not extensive enough to cause insolubility. Methyllithium and n-butyllithium, for instance, exist in a highly associated form, typical of electron-deficient bonding, e.g., (MeLi) and (BuLi)4. 

Trialkylaluminum and alkylaluminum hydrides associate with alkyl or hydride bridges. Since there are no available lone-pair electrons with which to form bridges by standard two-center two-electron interactions, multicenter bonding is invoked in the same manner as for electron-deficient boranes (see Boron Hydrides), alkyllithium (see Alkali Metals Organometallic Chemistry), dialkylberyllium and dialkylmagnesium compounds (see Beryllium Magnesium Organometallic Chemistry). 

Anionic polymerisation employs nucleophiles such as alkyllithiums, alkoxides or hydroxide as the initiator. Hydroxide, for example, adds to an electron-deficient alkene to form the most stable carbanion (in a Michael-type reaction). The carbanion then adds to another electron-deficient alkene to build the polymer chain. The polymerisation is terminated by, for example, protonation. 

In 1991, new syntheses of C-disaccharides incorporated Lewis acid mediated couplings with allylsilanes. Additionally, alkyllithium sugar derivatives were coupled to sugar lactones and electron deficient anions were added to sugar carbonates. Finally, complimentary to the anion chemistry used, sugar cuprates were utilized. 

Organometallic compounds of small atomic number metals (Be, Mg, B and Al) tend to form an electron-deficient bond, and similarly organolithium compounds also tend to form an electron-deficient bond. In particular, alkyllithium forms mainly a tetramer or hexamer in solid, liquid and gas state [14,36-42]. 

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