Lithium alkylamide

Zirconium dichiorohis(dimethylamide) [87227-57-4] ZrCl2[N(CH2)2]2 h made direcdy from methylamine and zirconium tetrachloride but all of the halogens can be substituted by treating zirconium tetrachloride with the appropriate lithium alkylamide (229). Zirconium arylamines are made from zirconium alkoxides which first are converted to aryloxides (230). 

Lithium alkylamides (in situ generated from the amine and either n-BuLi or sec-BuLi) generally give higher yields under milder conditions. Thus, n-BuLi (5%) catalyzes the addition of primary and secondary amines to styrene to afford (-phenethy-lamines in moderate to good yields (e.g., Bq. 4.32) [155]. NH, and PhNHj, however, do not add to styrene under these conditions. a-Methylstyrene and 1,1-diphenyleth-ylene can also be hydroaminated. 

Lithium alkylamides react with dimethyltin dichloride to give the cyclotristannazane, which is methylated by trimethyl-aluminum, -gallium, or -indium, giving the metal stannylamides, which are coordinatively dimerized (Equation (167)).503... 

Effective product control can be achieved by properly adjusting the basicity of the electrolyte 297 Reduction of benzene with UCl/methylamine as SSE in an undivided cell yields exclusively 1,4-cyclohexadiene, while in a divided cell cyclohexene is formed (Eq. (131) ). This difference is attributed to different basicities of the electrolytes. In the divided cell the lithium alkylamide formed isomerizes 1,4-cyclohexadiene to 1,3-cyclohexadiene, which is further reduced to cyclohexene. 

When a deficit of the lithium alkylamide is used, dimeric chloride-bridged silylamides are obtained which are useful synthetic intermediates (Figure 4.10). 

When a deficit of the lithium alkylamide is used, dimeric chloride-bridged silylamides are obtained which are useful synthetic intermediates (Figure 27) they can also be prepared by redistribution reactions between LnCb and [Ln(N(SiMc3)2)3 some bromo- and iodo- analogues have been reported. 

Amidines 14 are cyclized to quinazolines 15 in lithium alkylamide or dialkylamide mediated reactions in which the construction of the quinazoline ring system and introduction of the amino substituent occur in the same reaction. Mechanistically, each fluorine of the trifluo-romethyl substituent of the amidine is displaced by a series of internal nucleophilic processes and the resulting quinazoline contains the amino function of the lithium reagent incorporated at the C4 position. The cyclization method is suitable for the synthesis of sterically congested quinazolin-4-amines and in syntheses of derivatives for which the corresponding chloroquinaz-olines are not readily available. ... 

This review article is concerned with chemical behavior of organo-lithium, -aluminum and -zinc compounds in initiation reactions of diolefins, polar vinyls and oxirane compounds. Discussions are given with respect to the following five topics 1) lithium alkylamide as initiator for polymerizations of isoprene and 1,4-divinylbenzene 2) initiation of N-carboxy-a-aminoacid anhydride(NCA) by a primary amino group 3) activated aluminum alkyl and zinc alkyl 4) initiation of stereospecific polymerization of methyloxirane and 5) comparison of stereospecific polymerization of methyloxirane with Ziegler-Natta polymerization. A comprehensive interpretation is proposed for chemistry of reactivity and/or stereospecificity of organometallic compounds in ionic polymerizations. 

The action of lithium alkylamides, LiNR2, on TiCl4 leads to liquid or solid compounds of the type Ti[N(C2H5)2]4, which, like the alkoxides, are readily hydrolyzed by water with liberation of amine.13 Similar dialkylamides are known also for both Ti111 and Ti11.14... 

Reactions with lithium alkylamides in hexamethylphosphoramide Elimination and substitution... 

Rickborn and co-workers have published a number of papers on the base-induced rearrangement of epoxides using lithium alkylamides and lithium salts. The effect of a range of lithium alkylamides (459) on the proportion of... 

The products from reaction of cyclohexene oxide (149) with a variety of lithium alkylamides have been investigated. Major pathways are considered relevant and these involve rearrangement to allylic alcohol or ketone or direct nucleophilic substitution. With lithium monoalkylamides the reaction product is essentially partitioned between cyclohex-2-enol (150) and amino-adduct... 

Analogous products were obtained from the reaction of silylene 85 with silyl lithium compounds, with alkali metal silylamides and alkali metal alkylamides, and sodium methoxide <2000CC1427, 2004JCD3288, 2005JCD2720, 2005CC5112>. In the case of the reaction with metallated silylamides a thermally initiated rearrangement (114 — 115) to give the new silylamide 115 took place (Scheme 11). 

A major route to arynes and hetarynes proceeds by dehydrohalogenating molecules which are deactivated with respect to substitution by an SnAt mechanism. Frequently employed bases are amide and alkylamide ions, alkyl and aryl lithium reagents and tew-butoxide ion. In spite of various claims this approach has not been used successfully to generate a 5-membered hetaryne.68,7S)... 

Reaction with cyclic epoxides. The reaction of epoxides of medium-size rings with base (lithium di- -alkylamides) has been extensively studied by Cope and by Crandall (1, 610 611 2, 247). Two products are usually obtained an allylic alcohol formed by -elimination and a bicyclic alcohol derived from a carbene intermediate formed by a-elimination. Boeckman has now found that the ciirbcnc pathway is highly favored if n-butyllithium (3 equiv.) is used as base and if (he reaction is conducted at low temperatures, —78 to 25° in the case of cis-eyelooctene oxide (1) and m-cyclodecene oxide. The oxide of cyclododecene,... 

It should also be noted that copper-catalyzed Ullmann-type coupling of aryl halides with amines yields substituted products [206], and reaction with diphenylamine has been used to form triaryl-amines [207], Triarylamines may also be formed in a variation of the Meyers reaction [47] by displacement by lithium amides of fluoro- or methoxy-substituents activated by an ort/io-ester function [208], The oxidation of a-adducts is discussed in Chapter 11, but it should also be mentioned that aminated products may also be produced by the oxidation of adducts formed by the addition of amide or alkylamide ions at ring carbon atoms carrying hydrogen [209]. 

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