Lithium tert-butoxide

Because of their ease of crystallization, alkylzinc alkoxides are often isolated as decomposition products in reactions involving organozinc compounds. The methylzinc lithium tert- butoxide heterocubes [ (THF)LiOBut 2-(MeZnOBu1 ]182 (Figure 58, 123) and [(LiOBu MeZnOBu1 ]183 124 were isolated as hydrolysis products from reactions involving amines, amidines, /< //-butyllithium, and dimethylzinc. 

CH3)3C0H + LiH (CH3)3COLi + H2 (tert-butanol) (lithium tert-butoxide)... 

We have further examined the effect of initiators and solvents on the equilibrium product distribution. The use of lithium tert-butoxide instead of potassium tert-butoxide and the change of solvent from THF to toluene showed no effect on the product distribution of e-caprolactone oligomers.4 Also we are examining the equilibrium oligomer distribution in cationic system such as trifluoromethane sulfonic acid catalyst.z... 

Applying this equation to the depolymerization experiment (Figure 5) of the polymer with lithium tert-butoxide, kp,x can be obtained. ly>x was calculated by using the value of kx. 

Two methodologies for the direct C-2 arylation of thiazoles have been reported. The first one is mediated by both palladium and copper <07T1970>. Thus, the C-2 arylation of thiazole and benzothiazole with aryl iodides is carried out using copper iodide (2 equiv.) and a catalytic amount of palladium acetate under base-free conditions. The other method involves copper-catalyzed arylation with aryl iodides in the presence of lithium t-butoxide <07JA12404>. In general, reactions with lithium tert-butoxide provide better yields than those with potassium fert-butoxide. In addition, arylation with phenyl bromide, chloride or tosylate fails to provide any desired arylation products. 

The rate of chloral polymerization was studied by estimating the monomer disappearance by NMR. Figure 26 shows a comparison of the rate of polymerization of chloral initiated by lithium tert-butoxide, a quaternary ammonium chloride and triphenyl phosphine. The rate of chloral polymerization initiated with lithium lert-butoxide was much faster than the chloride initiated polymerization. This may be explained by the much more efficient and essentially quantitative initiation with the butoxide and consequently the greater number of growing polychloral chains. 

Diphenylmethyl Carbanions The carbanions based on diphenylmethane (p/fj, = 32) [2] are useful initiators for vinyl and heterocyclic monomers, especially alkyl methacrylates at low temperatures [78]. 1,1-Diphenylalkyllithiums can also efficiently initiate the polymerization of styrene and diene monomers that form less stable carbanions. Diphenylmethyllithium can be prepared by the metallation reaction of diphenylmethane with butyllithium or by the addition of butyllithium to DPE as shown in Equation 7.13. This reaction can also be utilized to prepare functionalized initiators by reacting butyllithium with a substituted DPE derivative [78]. Addition of lithium salts such as lithium chloride, lithium tert-butoxide, or lithium 2-(2-methoxyethoxy)ethoxide with... 

Ketone Cleavage Reactions. f-BuOK in ether containing water is the medium of choice for the cleavage of nonenolizable ketones such as nortricyclanone (eq 33). Optically active tertiary a-phenyl phenyl ketones are cleaved in fair yields with high retention of configuration with the base in f-BuOH or PhH (eq 34). f-BuOK is more effective than f-BuONa or Lithium tert-Butoxide in these reactions. 

Lithium tertiary alkoxide such as lithium tert-butoxide or l,l poly(methyl methacrylate) even in toluene. The polymer obtained was highly isotactic. Addition of pipmdine increased the initial rate of... 

In practice, there have been many other modifications of the RBR conditions, mostly differing in the choice of base used. The most popular base for the RBR is potassium tert-butoxide, either added directly or generated in situ from tert-BuOH and KOH (powdered or supported on alumina). Nonetheless, numerous other bases have been employed for the RBR, including lithium tert-butoxide, l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), lithium bis(trimethylsilyl)amide (LiHMDS), and butyllithium(n-BuLi). ° The stronger bases tend to favor formation of (E)-alkenes (see Section 8.4). 

The same group reported an extension of the direct alkylation of (benz)oxazoles with various alkyl bromides and chlorides by using the stronger base lithium tert-butoxide (Scheme 19.23) [38]. 5-Aryloxazoles containing electronically diverse substituents such as CFj and OMe were also alkylated successfully. Various linear alkyl chains were introduced, such as phenylpropyl, citronellyl, or octyl, affording interesting lipophilic molecules. The optimized reaction conditions failed to apply to benzothiazoles, and the authors had to turn their attention to nickel catalysis to achieve the corresponding alkylation (Section 19.2.3). Experiments were run to understand the reaction mechanism that presumably involves Sj 2-type oxidative addition of the alkyl halide to palladium(O) followed by transmetallation by the in situ-lithiated (benz)oxazole (Scheme 19.24). 

Kasperczyk, J. E. Micro structure analysis of polyflactic acid) obtained by lithium tert-butoxide as initiator. Macromolecules 1995, 28, 3937-3939. 

Amongst the alkali metals, the lithium derivatives would be expected to be the least ionic as is shown by their solubility in organic solvents and volatility of lithium tert-butoxide (110°/0.1 mm) alkoxides of other alkali metals tend to be nonvolatile and decompose on being heated to higher temperatures even under reduced pressure. 

Also obtained from p-acetoxybenzoyl chloride by treatment with lithium tert-butoxide and tert-butyUithium in a mixture pentane/tetrahydrofurane in the presence of cuprous iodide, followed by hydrolysis (80%) [6683]. 

Janata, M., Lochmann, L., Vlcek, P. etal (1992)Mechanismandkineticsoftheanionicpolymerization of acrylates, 2. Polymerization of tert-butyl acrylate in a flow tube reactor and effect of Uthium chloride and lithium tert-butoxide. 

It is worth noting that ROP of rac-LA initiated with lithium tert-butoxide, as it was reported by Kasperczyk and co-work-ers, gives syndiotactic PLA, thus also with retention of configuration. 

In another example, [Zn(tcpb)(L )] reacts with lithium tert-butoxide to lithiate the hydroxyl groups on the A,A-ditopic pillaring ligand. Lithium-containing MOFs are of interest as calculations have shown they have enhanced H2 storage potential. 

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