Halides reaction with phenyllithium

Reaction with l-chloro-2-methylcyclohexene (1). This vinyl halide reacts with phenyllithium (5 equiv.) to give the bicyclo[4.1.0]heptane (2) in 90% yield. The paper presents evidence for the intermediacy of the cyclopropene a. Other organo-lithium reagents react in the same way, but yields are lower, 47% in the case of CHjLi. 

Organolithium compounds, generally phenyl- or butyllithium, can be used, in the same way as(triphenylmethyl)sodium (see page 917), as base for C-alkyla-tion, since in certain cases they react by metal exchange with activated hydrocarbons. For instance, the 2-lithio derivative of resorcinol dimethyl ether is formed in 70% yield on reaction with phenyllithium. The organolithium compounds thus obtained react readily with alkyl halides or sulfates, forming a carbon-carbon bond 326 for example, 2,6-dimethoxytoluene is formed by... 

The results from reactions with phenyllithium and phenylsodium indicated that the phosphorus-derived organophosphides were of complex structure (6). The alkyl halide reactions demonstrated the presence of structural units having two phenyl groups bonded to phosphorus, yet only small yields of diphenylphosphine were obtained on hydrolysis. Lithium diphenylphosphide was thus ruled out as an important intermediate, since it hydrolyzes cleanly to diphenylphosphine. Moreover, hydrolysis of the organophosphide from plienylsodium and phosphorus failed to give simple phosphine products at all, but reaction of the sodium... 

FormylatioH and acylation of pyridine. Direct formylation and acylation at the )S-position of pyridine is possible by reaction with phenyllithium and then with Fe(CO)s. The reactions are formulated in scheme (I). 2-Phenylpyridine is also obtained in these reactions. Halide exchange of 3-bromopyridine with n-butyl-lithium to give 3-pyridinyllithium followed by reaction with Fe(CO)5 gives only a 5% yield of 3-pyridinectu boxaldehyde. ... 

Alkylation by allylic halides is usually a satisfactory reaction, and in this case the reaction may proceed through a cyclic mechanism.81 For example, when l-14C-allyl chloride reacts with phenyllithium, about three-fourths of the product has the labeled carbon at the terminal methylene group. 

Upon reaction with carbon monoxide, aryllithium reagents (made from the corresponding halide) react to give excellent yields of 1,2-diketones in some instances853. Surprisingly, phenyllithium gives a 94% yield of the somewhat unexpected a,a-diphenylacetophenone854. 

Syntheses of RM(CO)5 compounds by reaction of [M(CO)5] with halides or by decarbonylation of acyl derivatives have been described. A third synthesis involves treatment of the pentacarbonyl halides M(CO)5X with an organic derivative of lithium or magnesium. Examples of this reaction include the treatment of Mn(CO)5Br with benzylmagnesium chloride to give the benzyl derivative C6H5CH2Mn(CO)5 93) and the reaction of Mn(CO)sBr with phenyllithium to give the phenyl derivative CsHsMn (CO)5 156). Disadvantages of reactions of this type include the formation of much Mn2(CO)io as a by-product and a low yield of the desired product. 

Aryl halides readily undergo lithium-halogen exchange with alkyllithiums in ethereal solvents at temperatures at or below —78°C and the less expensive n-BuLi is often used for this purpose. However, the presence of the n-butyl halide product can cause complications when the aryllithium is warmed since a coupling reaction may ensue (for example, the reaction of phenyllithium with n-butyl iodide in THF at —78 °C has a half-life of 30 min). This potential problem is avoided when 2 equiv of r-BuLi are used for the generation of aryllithiums. 

The reaction of an a-bromoalkyltin halide (Scheme 13) with sodium or phenyllithium gives a transient stannene, which self-reacts to give the dimer, or gives an adduct with anthracene, which dissociates into its precursors on heating.326... 

The Grignard reagents used in the reaction may be either those derived from aryl halides or those formed from alkyl halides. Phenyllithium reacted with the tosylate to give sulfones rather than azoxy compounds. 

Exercise 16-13 a. Phosphorus ylides can be prepared by heating triphenyl phosphine, (C6H5)3P, with a primary alkyl halide, RCH2X, in a solvent such as benzene. The initial product then is mixed with an equivalent quantity of a very strong base, such as phenyllithium in ether. Write equations for the reactions and probable mechanisms involved, using ethyl bromide as the alkyl halide. 

Reactions of 2,4,6-Tri(l-butyl)phenyllithium with Phosphorus Halides... 

The reaction of tetramethylpyrazine with alkyl halides using either sodamide in liquid ammonia or phenyllithium in ether as condensing agent gives mixtures of alkyltrimethylpyrazines and 2,5-dialkyl-3,6-dimethylpyrazines. A number of carbinols were also prepared from... 

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