Organolithium compounds conversion

Next to the formation of Grignard reagents, the most important application of this reaction is the conversion of alkyl and aryl halides to organolithium compounds, but it has also been carried out with many other metals, (e.g., Na, Be, Zn, Hg, As, Sb, and Sn). With sodium, the Wurtz reaction (10-93) is an important side reaction. In some cases, where the reaction between a halide and a metal is too slow, an alloy of the metal with potassium or sodium can be used instead. The most important example is the preparation of tetraethyl lead from ethyl bromide and a Pb—Na alloy. 

Conversion of Sulfides to Organolithium Compounds Lithio-de-phenylthio-substitution... 

Halides have been carbonylated via conversion to organolithium compounds. In the presence of chlorotrimethylsilane (TMSC1), alkyl lithium reagents give alkanoyl trimethyl-silanes (equation 165) which are useful synthetic sources of the alkanoyl synthon924. 

The conversion of oxiranes containing various functional groups has been studied with organolithium compounds. /3-Substituted allyl alcohols are formed stereoselectively with -butyl-lithium from 1,2-epoxyalkyl phosphonates (Eq. 

In another method for the conversion RM —> RCONR, Grignard reagents, and organolithium compounds are treated with a formamide (HCONR2 ) to give the intermediate RCH(0M)NR2, which is not isolated, but treated with PhCHO or Ph2CO... 

Recently, the conversion of an organolithium compound to an organotitanium or an organocerium reagent in situ has been utilized to avoid deprotonation since such reagents are less basic than organolithiums, yet retain sufficient nucleophilicity [21]. 

The rate of RLi additions to methyl isothiocyanate seems to be strongly dependent upon the basicity of RLi [9]. Whereas phenyllithium reacts rapidly at — 90 °C, the addition of the much more weakly basic 2-thiazolyllithium (pK of 1,3-thiazole is about 29) has to be carried out at —30 to —50 °C and the reaction with lithium acetylides RC=CLi (pK acetylenes is 26 or lower) requires 0 to 20 °C (all reactions were carried out at the same 0.5 to 1 mol/1 concentrations). These temperatures indicate the conditions for other organolithium compounds and also the chance of success for other reactions. A rough estimation of the pK values of RH has to be made first, taking into account stabilizing effects of substituents. Side reactions have not yet been observed in the conversions of isothiocyanates with lithium compounds. 

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