Lithium, ferf-butyl

Diorgano tellurium compounds exchange organic groups when treated with one or two molar equivalents of butyl lithium, 2-methylpropyl lithium, ferf.-butyl lithium, or phenyl... 

Pradilla et al. have shown that simple p-tolyl vinyl sulfoxides undergo nucleophilic epoxidation with metal alkyl peroxides to give enantiopure sulfinyl oxiranes.138 This process takes place with fair to excellent diastereoselectivities. The same group recently reported the epoxidation of diastereomeric hydroxy vinyl sulfoxides, bearing an additional stereocenter adjacent to the reactive carbon-carbon double bond. Hydroxy vinyl sulfoxides 256 and 258 underwent epoxidation with lithium ferf-butyl peroxide with high anti selectivity. However, when potassium ferf-butyl peroxide was used, only hydroxy vinyl sulfoxide 256 showed anti... 

Neopentyl alcohol has been made by lithium aluminum hydride reduction of trimethylacetic acid and by treating ferf-butyl-magnesium chloride with methyl formate. ... 

Lithium dispersion can be safely destroyed by carefully adding it in small portions to a large excess of technical tert-butyl alcohol in a metal pan. If too much lithium is added at one time, the reaction with the ferf-butyl alcohol can become very vigorous. Under these circumstances, a fire can be avoided by covering the pan with a second, larger metal pan or with an asbestos sheet. 

In the presence of a strong base, the ot carbon of a carboxylic ester can condense with the carbonyl carbon of an aldehyde or ketone to give a P-hydroxy ester, which may or may not be dehydrated to the a,P-unsaturated ester. This reaction is sometimes called the Claisen reaction,an unfortunate usage since that name is more firmly connected to 10-118. In a modem example of how the reaction is used, addition of tert-butyl acetate to LDA in hexane at -78°C gives the lithium salt of ferf-butyl acetate, " (12-21) an enolate anion. Subsequent reaction a ketone provides a simple rapid alternative to the Reformatsky reaction (16-31) as a means of preparing P-hydroxy erf-butyl esters. It is also possible for the a carbon of an aldehyde or ketone to add to the carbonyl carbon of a carboxylic ester, but this is a different reaction (10-119) involving nucleophilic substitution and not addition to a C=0 bond. It can, however, be a side reaction if the aldehyde or ketone has an a hydrogen. 

Structural data of phospholide ions themselves are scarce. The lithium salt of the tetramethylphospho-lide ion, which is in fact an y -complex, and the K salt of the 2,4,5-tri-terf-butyl-l,3-diphospholide an-ion have been reported. Also the structure of the Li salt of the 2,5-bis(ferf-butyl)-l,3,4-triphospholide ion has been obtained In all these structures the bond lengths are equalized (CC, 1.396—1.424 A CP, 1.690-1.752 A). 

Arnett and Moe studied the protodelithiation of organolithiums with isopropyl alcohol in hexane/ether mixtures. These authors found protodelithiation enthalpies for n- and iec-butyl lithium of —209.2 4.2 and —220.9 2.9, respectively. The difference between their enthalpies of reaction, and so of the enthalpies of formation of the two organolithiums, is 11.7 5.1 kJmor, about half the difference between these species as found in Table 1. The protodelithiation enthalpy of terf-butyl lithium is —237.7 7.5 kJmoP. From equation 10 with n-butyl lithium as the benchmark species, and the butane hydrocarbons in their liquid reference states, the derived enthalpy of formation of ferf-butyl lithium is —87.5 kJmoP, in good agreement with that found before by Hohn . 

Benzamides 565 without any substituent at the para position reacted with lithium and a catalytic amount of naphthalene under Barbier-type reaction conditions (in the presence of a carbonyl compound) in THF at —78 °C to give, after hydrolysis, the corresponding dearomatized products 566 (Scheme 151). When 567 was used as starting material with a 4-ferf-butyl group in p-position, and using 3-pentanone as electrophile and under the same reaction conditions, the fraw -product 568 was the only one isolated . 

Another type of adducts [8, Eq. (3)] was formed by the reaction of di(fert-butyl)aluminum chloride with dilithium bis(trimethylsilyl)hydrazide in low yields below 30% [19]. The structure of 8 consists of a distorted heterocubane with four vertices occupied by nitrogen atoms, two of which are connected by an intact N—N bond across one face of the cube. The cation positions are occupied by two aluminum and two lithium atoms, of which the last ones bridge the N—bond. Part of the hydrazide molecules was cleaved, and the aluminum atoms are bonded to one ferf-butyl group only. On the basis of the NMR spectroscopic characterization many unknown by-products were formed in the course of that reaction, and no information is available concerning the reaction mechanism. Compound 8 may be described as an adduct of dilithium bis(trimethylsilyl)hydrazide to a dimeric iminoalane containing a four-membered AI2N2 heterocycle. Further... 

The reaction of ethyl A-arylcarbamates 3 with l-bromo-3,3-dimethyl-2-buta-none or l-bromo-3-ethyl-3-methyl-2-pentanone 4 in the presence of lithium bis(trimethylsilyl)amide (LiHMDS) results in the one-step synthesis of 3-aryl-5-ferf-butyl-2(3/T)-oxazolones 7 in fair to good yields (Fig. 5.2 Table 5.1, Fig. 5.3). This method is efficient for the preparation of bulky 5-substimted-2(37f)-oxazo-lones. 

This model would predict higher selectvities for bulkier lithium reagents. Experimental data (Table 8.27 Scheme 8.146) supports this prediction. An unexpectedly lower selectivity was obtained when ferf-butyllithium was used to metalate ferf-butyl-substituted oxazolinylferrocene. In this particular case, the authors suggested that the reaction may proceed via oxygen directed or a nondirected pathway. 

SAMPLE SOLUTION (a) The metal lithium provides the base name for (CH3)3CLi. The alkyl group to which lithium is bonded is ferf-butyl, and so the name of this organometallic compound is fe/t-butyllithium. An alternative, equally correct name is 1,1-dimethylethyllithium. ... 

The large sulfur atom is a preferred reaction site in synthetic intermediates to introduce chirality into a carbon compound. Thermal equilibrations of chiral sulfoxides are slow, and parbanions with lithium or sodium as counterions on a chiral carbon atom adjacent to a sulfoxide group maintain their chirality. The benzylic proton of chiral sulfoxides is removed stereoselectively by strong bases. The largest groups prefer the anti conformation, e.g. phenyl and oxygen in the first example, phenyl and ferf-butyl in the second. Deprotonation occurs at the methylene group on the least hindered site adjacent to the unshared electron pair of the sulfur atom (R.R. Fraser, 1972 F. Montanan, 1975). 

The reaction of tetrachlorodisilane with chalcogenation reagents is one of the synthetic methods to bis-nor-adamantane or double-decker type compounds. When a solution of di-terf-butyltetrachlorodisilane 66 in THF is refluxed together with one equivalent of lithium sulfide or stirred with lithium selenide at room temperature, the tetra(ferf-butylsilicon)pentachalcogenides 67 and 68, respectively, are formed (Scheme 18)6. Each pentachalcogenide exhibits one resonance of a ferf-butyl group in the H and 13C NMR spectra. Most likely, the bis-nor-adamantane derivatives 69 and 70 are initially formed. Insertion of a sulfur or selenium atom into one of the two strained Si—Si bonds would then lead to the observed products. 

Be this as it may, hthium attempts to bind to several bonding partners, and the structural consequences for the enolates of a ketone, an ester, and an amide are shown in Figure 10.2 In contrast to the usual notation, these enolates are not monomers at all The heteroatom that carries the negative charge in the enolate resonance form is an excellent bonding partner, such that several such heteroatoms are connected to every hthium atom. Lithium enolates often result in tetramers if they are crystallized in the absence of other hthium salts and in the absence of other suitable neutral donors. The hthium enolate of ferf-butyl methyl ketone, for example, crystallizes from THF in the form shown in Figure 10.3. 

Several new catalytic asymmetric protonations of metal enolates under basic conditions have been published to date. In those processes, reactive metal enolates such as lithium enolates are usually protonated by a catalytic amount of chiral proton source and a stoichiometric amount of achiral proton source. Vedejs et al. reported a catalytic enantioselective protonation of amide enolates [35]. For example, when lithium enolate 43, generated from racemic amide 42 and s-BuLi, was treated with 0.1 equivalents of chiral aniline 31 followed by slow addition of 2 equivalents of ferf-butyl phenylacetate, (K)-enriched amide 42 was obtained with 94% ee (Scheme 2). In this reaction, various achiral acids were... 

This is a direct SN2 displacement of the bromide anion of ferf-butyl bromoacetate by a methyl acetoacetate anion. Lithium bromide (LiBr), the salt by-product, is not shown in the reaction below. 

Phenanthrene (7), the smallest member of the helicene series, is planar in its neutral state and shows aromatic character. Reducing the compound with lithium affords a highly paratropic dianion34 (72 ) that, according to calculations, is not planar35. It is possible to twist the sp2 framework of phenanthrene by its alkylation at the 4- and 5-positions36, i.e. in 4,5-dimethylphenanthrene (8), 2,4,5,7-tetramethylphenanthrene (9) and 2,4-di-ferf-butyl-5,7-dimethylphenanthrene (10). When these systems are reduced with lithium metal, three... 

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