Organolithiums reaction with water

Strong nucleophiles such as organolithium or organomagnesium derivatives do not react with substituted or unsubstituted phosphabenzene or arsabenzene (39, Y = P or As) by nucleophilic substitution as in the case of pyridines, but by addition to the heteroatom forming intermediate anions 40. These can then be converted into nonaromatic compounds by reaction with water to yield 1-alkyl-1,2-dihydro-derivatives 41, or they can be alkylated by an alkyl halide with the same or a different alkyl group, when two products may result a 1,2-dialkyl-1,2-dihydro 40-derivative 42, or a -derivative 43. The former products are kinetically controlled, whereas the latter compounds are thermodynamically controlled, so that one may favor the desired product by choosing the appropriate reaction conditions. 

Write equations for the reaction of organolithium reagents with water or epoxides. 

Organolithium and Grignard reagents are prepared from alkyl (or aryl) halides. The reactions are carried out under anhydrous conditions because reaction with water leads to the formation of alkanes. 

Whereas the reactions of sulfones with nucleophiles via pathways A and B of equation 1 are most frequently observed, the nucleophilic substitution reaction by pathway D has been observed only in the cases where the leaving carbanion can be stabilized, or in the highly strained molecules. Chou and Chang3 has found recently that an organolithium reagent attacks the sulfur atom of the strained four-membered sulfone in 34. When this sulfone is treated with 1 equivalent methyllithium, followed by workup with water or Mel, 38 or 39 are formed in high yield. 

One of the most interesting reactions of this type involves the intramolecular addition of the organolithium derivative to the aryne (13) which is derived from the dilithio-compound (12) 28>. This leads to the remarkably stable organolithium compound (14) which reacts with water to form the expected heptafluorobiphenylene, and with bromine to form 1-bromoheptafluorobiphenylene. 

Y = O) or —90°C (Y = NMe, S) gave the corresponding intermediates 427 resulting from a carbon-sulfur cleavage. Further reaction of these functionalized organolithium compounds with different electrophiles at the same temperature, followed by hydrolysis with water, yielded products 428 (Scheme 120) . 

The interaction between pyridine and organolithium compounds in benzene was first reported by Ziegler and Zeiser129 and was attributed to the formation of 1 1 adducts. Indirect evidence for intermediates of this kind was based on the formation of dihydropyridines by treatment of the reaction mixture with water. More definite evidence was obtained with quinoline, isoquinoline, and acridine.130 Phenyllithium reacts quantitatively with quinoline in ether to yield an adduct as a yellow powder that can be recrystallized. In order to define the site of attachment, the adducts were hydrolyzed to dihydro derivatives and the latter dehydrogenated. Because this treatment leads mainly to 2-phenyIquinoIine and l-phenylisoquinoline from quinoline and isoquinoline, respectively, the related adducts can be assumed to have structures 80 and 81. Isolation and characterization of the dihydro derivatives have been carried out, as well as in the case of the reaction of acridine with phenyllithium. 

There has been a review of didehydropyridines, focusing on then formation from halopyridines and base.123 The reactions of tri-p-tolyloxonium salts with hydroxide in water yield a mixture of p- and m-cresols via a benzyne intermediate,124 as shown in Scheme 7. A benzyne intermediate, generated by loss of lithium fluoride, is also implicated in the reaction of organolithium reagents with fluoro-AyV-diallylanilincs leading to 3,4-disubstituted indolines.125 The reaction of benzyne with 1,8-diethynylnaphthalene has been shown to yield benzo [a]pyrene.126... 

Grignard and organolithium reagents react vigorously and irreversibly with water. Therefore, all reagents and solvents used in these reactions must be dry. 

Reactions of Esters Esters are much more stable than acid chlorides and anhydrides. For example, most esters do not react with water under neutral conditions. They hydrolyze under acidic or basic conditions, however, and an amine can displace the alkoxyl group to form an amide. Lithium aluminum hydride reduces esters to primary alcohols, and Grignard and organolithium reagents add twice to give alcohols (after hydrolysis). 

When Grignard reagents, organolithium compounds, or complex metal hydrides add to amides, the elimination step is slow at —78 °C, especially when the amine component is -N(Me)OMe (Weinreb amides). When the tetrahedral intermediate is sufficiently long lived, quenching of the reaction mixture with water at —78 °C gives the ketone or aldehyde rather than the alcohol. 

The serious disadvantage of the use of the reactions of the chlorinated silica with organometallic compounds is caused by the high sensitivity of the Grignard reagent and organolithium compounds to the action of water, side reactions with the participation of surface siloxane bonds, and problems of removing metallic impurities from the surface of modified matrices. The difficulties mentioned explain why this approach to the synthesis of surface chemical compounds with Si-C bonds finds limited application. 

Cyclic alkyl aryl ethers lead also to functionalized organolithium compounds by reductive carbon-oxygen bond cleavage in arene-catalyzed lithiation process. Thus, the treatment of 2,3-dihydrobenzofuran (47) with an excess of lithium in the presence of a catalytic amount of DTBB in THF at 0°C gives the dianion (48) which after reaction with different carbonyl compounds and final hydrolysis with water leads to... 

The initiator may be preformed or generated in situ simply by combining the organolithium compound with the amine. Despite its high reactivity, the resulting complex can be easily handled as a hydrocarbon solution. Impurities such as water, air, and carbon dioxide must be rigidly excluded because of their rapid reaction with organolithium compounds. 

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