Lithium tert-butyl

Lead tetraacetate, 55,44, 115 Lithium, 55, 103 Lithium bromide, 55, 129 Lithium butyl-,55,1 10,39,122 Lithium, tert-butyl- [Lithium, 1,1-dimethyl... 

Bromopene Propane, 2-bromo- (8) 1-Propene, 2-bromo- (9) (557-93-7) tert-Butyllithium Lithium, tert-butyl- (8) Lithium, (1,1-dimethylethy )- (19) (594-19-4)... 

An alternative method for the epoxidation of enones was developed by Jackson and coworkers in 1997 , who utilized metal peroxides that are modified by chiral ligands such as diethyl tartrate (DET), (5,5)-diphenylethanediol, (—)-ephedrine, ( )-N-methylephedrine and various simple chiral alcohols. The best results were achieved with DET as chiral inductor in toluene. In the stoichiometric version, DET and lithium tert-butyl peroxide, which was generated in situ from TBHP and n-butyllithium, were used as catalyst for the epoxidation of enones. Use of 1.1 equivalent of (-l-)-DET in toluene as solvent afforded (2/f,35 )-chalcone epoxide in 71-75% yield and 62% ee. In the substo-ichiometric method n-butyllithium was replaced by dibutylmagnesium. With this system (10 mol% Bu2Mg and 11 mol% DET), a variety of chalcone-type enones could be oxidized in moderate to good yields (36-61%) and high asymmetric induction (81-94%), giving exactly the other enantiomeric epoxide than obtained with the stoichiometric system (equation 37). 

Lithium tert-butyl amide is an air- and moisture-sensitive flammable solid that can be stored for up to 4 months in the drybox. In the solid state it has an... 

Bromo-l-(4-fluorophenyl)-l-(3-dimethylaminopropyl)-l,3-dihydroisobenzofuran Magnesium Butyl lithium tert-Butyl methyl ether Isopropylmagnesium chloride Thionyl chloride Sulfamide Dry ice... 

A similar intramolecular Wittig-Horner reaction provides a key 5,6-dihydropyran-2-one 880 intermediate during synthetic studies towards leinamycin. The choice of base, lithium tert-butylate (/-BuOLi), is vital for the high yield observed due to the importance of the lithium cation for smooth deprotonation of the phosphonoacetate, the first time this base is documented during a Wittig-Horner olefination (Equation 353) <2005T7481>. 

A novel asymmetric synthesis of a-amino acids via electrophilic amination has been demonstrated by Zheng and Armstrong and co-workers.94 No +NHBoc was observed when lithium tert-butyl-A-tosyloxycarbamate (LiBTOC) was reacted with zinc and lithium enolates of 48. Transmetallation of the lithium enolate with copper cyanide was necessary to generate a reactive amide cuprate, which then added efficiently to the electrophile. The electrophilic amination of chiral cuprates with LiBTOC provided an expedient approach to a-amino acids with predictable absolute configuration in high enantiomeric purity and good yield (Scheme 24.23). 

Stereoselective Synthesis of a-Amino Carboxylic and Phosphonic Acids via Electrophilic Amination with Lithium tert-Butyl Af-(tosyloxy) carbamate... 

Analogous properties are inherent in lithium tert- butyl peroxide used for epoxidation of electron-unsaturated olefins (86JCS(CC)1378, 88JCS(P1)2663). 

Using this methodology for systems with fluorine atoms considerably enriches our knowledge of the properties of olefinic systems. The reagent also plays an important role. Thus calcium hypochlorite is occasionally ineffective in epoxidations of fluoroolefins, whereas lithium tert-butyl peroxide is extremely effective (95JCS(CC)629, 96RCI703). 

Butyl lithium, sec-butyl lithium, tert-butyl lithium, and phenyl lithium cleave Te-phenyl and Te-alkyl bonds in tetrahydrofuran at — 78°. These reactions, in which on organic group bonded to tellurium is exchanged for the organic group associated with the organic lithium compound, are useful for the preparation of organic lithium compounds that are otherwise available only with difficulty or not at all. 

Aggarwal and co-workers have used Jackson s metal peroxide oxidants for the epoxidation of ketene thioacetals. This resulted in highly diastereoselective epoxide formation (>20 1 selectivity).136 Carmen Carreiio and colleagues showed that epoxidation of (S)-(2-p-tolylsulfonyl)-2-cyclohexan-1 -ol and its OAc and OMOM derivatives, with lithium tert-butyl hydroperoxide, proceeds with high stereoselectivity to give the syn epoxy alcohols.137... 

Figure 81 The structure of the lithium tert-butyl peroxide, Li[7j -02(Bu )] i2.

Another example of the nucleophilic chloro ligand substitution involves the reaction of the zirconium dichloride complex 468 with lithium ester enolates (Scheme 112). Its reaction with 2 equiv. of stable lithium ester enolates such as lithium tert-butyl isobutyrate in TF1F produces the bis(ester enolate) complex 499 as a crystalline solid.344 The same reaction but with the unstable lithium methyl isobutyrate leads to the isolation of the decomposition product, the bis(methoxide) complex 500, which exists as a dimer in the solid state. Treatment of the bis(ester enolate)... 

Lithium bis(l-methylpropyl)cuprate [Lithium bis(2-butyl)cuprate], 55, 112 Lithium bromide, 55,129 Lithium, butyl-, 55,1,10, 39, 122 Lithium, 1,1-dimethylethyl- [Lithium, tert-butyl-],55, 123... 

The reaction of tetrachlorothiophene 1,1-dioxide with a dienophile 87 affords the primary product 88 in a stereospecific manner. In 88, the cyclohexadiene ring protons are placed in close proximity to the double bond of the other ring. Upon dehalogenation of 88 with lithium/tert-butyl alcohol, the double bond is regenerated to give 89, accompanied by a stereospecific hydrogen atom transfer. 

The addition of lithium tert-butyl acetate to benzyl 2,3-anhydro-a-L-ery/Aro-pentopyranosid-4-ulose gave compound 15 which, on treatment with trifluoro-acetic acid, afforded bicyclic derivative 16. The 4-epimer of 15 was also formed but on reaction with acid gave only the product of de-esterification. A similar... 

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