Terf-Alkyl tert-butyl

The reaction of arylphospholes with phosphorus tribromide was extended to di-te/f-butyl-methylphenylphosphole (17c) leading after further steps, to a mixture of 3- and 2-substituted products (43 and 45, respectively) (Scheme 10) [40], The di-tert-butyl-tolyl substituent clearly occupies an intermediate position between the triisopropylphenyl and tri-terf-butylphenyl ones regarding the steric hindrance caused by the ortho alkyl substituents. 

The classical method for tert-butyl esterification involves nnineral add catalyzed addition of the amino acid to isobutene. Both, N-protected, e.g. Z-Xaa-OH, and unprotected amino acids form tert-butyl esters with isobutene in the presence of catalytic amounts of sulfuric acid or TosOH. " Another efficient method is the transesterification of an acetic acid tert-bvXy ester catalyzed by perchloric acid. " Amide tert-butylation was recognized as a side reaction in the presence of perchloric acid, but could be completely suppressed by using sulfuric acid. Both methods, acid-catalyzed addition to isobutene and the transesterification of acetic add terf-butyl esters, result in simultaneous terf-butyl-ation of hydroxy and sulfanyl groups. A synthetic route to Z-Thr-OtBu, Z-Ser-OtBu, and Z-Hyp-OtBu without conconnitant O-alkylation involves the hydroxy protection by the acetoacetyl group, which is readily cleaved by treatment with 2 equivalents of hydrazine in EtOH for 30 minutes. ... 

One of the principal reasons for the interest in the calixarenes is their potential for serving as enzyme mimics. If they are to operate in this capacity, however, it is necessary that they carry functional groups of various types. The p-ieri-butylcalix-arenes have proved to be excellent precursors for functional group introduction, for the p-tert-butyl group is easily removed by /ram-alkylation 123). As outlined in Scheme 7, de-ieri-butylation of p-terf-butylcalix[4]arene (58) yields compound 59 which is amenable to functionalization in the p-position. For example, bromination of the tetramethyl ether of calix[4]arene (60) proceeds smoothly, affording the tetra-bromo compound 61124) which, by lithiation followed by carbonation yields the... 

Isomerization is observed with higher alkyl halides, as in Friedel-Crafts reactions isopropylphosphonic dichloride is stated to be the sole product from n-propyl chloride,190,191 and terf-pentyl chloride undergoes C-C fission, yielding the tert-butyl acid.193 On reduction by lithium tetrahydroaluminate the phosphonic chloride formed from w-butyl chloride gives a primary phosphine that is shown by 31P-nuclear magnetic resonance to consist of n- and sec-butylphosphine in the proportions 5 95 and the product from n-octyl chloride was similarly shown to contain all four position isomers.194... 

The conformational effect of the aglycon in alkyl glycopyranosides has been examined with the methyl, ethyl, isopropyl, and tert-butyl tri-0-acetyl-/3-D-ribopyranosides, and the corresponding benzoates. In each series, there was a negligible change in conformational population as between the methyl, ethyl, and isopropyl derivatives, but the terf-butyl derivatives contained somewhat less of that con-former [IC(d)] having the aglycon axially attached, presumably because there is loss of some rotational freedom about the C-1-0-1 bond in the tert-butyl derivatives as a result of steric hindrance. 

Metal catalysts such as bismuth triflate (Bi(OTf)3) and iron chloride hexa-hydrate (FeCl3 6H2O) have been shown to catalyse Ritter reaetions by Barrett and Cossy respeetively. Barrett used 20 mol% Bi(OTf)3 in the synthesis of A(-fe/t-butyl amides by coupling a range of alkyl and aryl nitriles with ferf-BuOH or tert-butyl aeetate (terf-BuOAc). Although Cossy used lower catalyst loadings of a cheaper metal, higher temperatures of 150 °C were... 

Hydroxyphenyl benzotriazoles have the structure (XV) where X is H or Cl (chlorine shifts the absorption to longer wavelengths), Rj is H or branched alkyl, and R2 is CH3 to C8H17 linear and branched alkyl (Rj and R2 increase the affinity to polymers). Some technically important materials in this class are 2-(2 -hydroxy-5 -methyl-phenyl)-benzotriazole, 2-(2 -hydroxy-3 -5 -di-tert-butyl-phenyl)-benzotriazole, and 2-(2 -hydroxy-3, 5 -di-terf-butyl-phenyl)-5-chlorobenzotriazole. In comparison with 2-hydroxybenzophenones, the 2-(2 -hydroxyphenyl) benzotriazoles have higher molar extinction coefficients and steeper absorption edges towards 400 nm. 

Alkyl radicals can be obtained by abstraction of a hydrogen atom from an alkyl group by another radical. This method was utilized for the generation of benzyl radicals from toluene with tert-butoxy radical obtained on heating di-terf-butyl peroxide.38 Benzoyl92 and carboxymethyl88 radicals have also been obtained by this method. The reaction gives rise to a complex mixture of products and therefore is of rather limited use. 

Highly acidic Al-MCM-41, U-MCM-41 and Th-MCM-41 catalysts have been used for the Friedel-Crafts alkylation of 2,4-di-tert-butylphenol with cinnamyl alcohol to give the corresponding substimted benzopyran (equation 21) °. The reaction involves an initial ort/io-alkylation, followed by an acid-catalyzed intramolecular cyclization. Loss of the 2-terf-butyl group results in minor byproducts. 

When two positions are comparably activated by alkyl groups, substitution usually occurs at the less hindered site. Nitration of p-tert-butyltoluene takes place at positions ortho to the methyl group in preference to those ortho to the larger terf-butyl group. This is an example of a steric effect. 

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

The reactivity of the aluminum-carbon bonds is greatly reduced in the 1 1 adducts, and this may be utilized in preparing particularly labile organoaluminum compounds which cannot be isolated in the free form. Thus tri-tert-alkyl alanes, such as tri-terf-butylalane, may be prepared as etherates from tertiary butyl lithium in diethylether (207) or from the corresponding magnesium tertiary alkyls (157, 159) ... 

SAMPLE SOLUTION (a) The molecule has a terf-butyl group bonded to a nine-membered cycloalkane. It is tert-butylcyclononane. Alternatively, the ferf-butyl group could be named systematically as a 1,1-dimethylethyl group, and the compound would then be named (1,1-dimethylethyl)cyclononane. (Parentheses are used when necessary to avoid ambiguity, in this case the parentheses alert the reader that the locants 1,1 refer to substituents on the alkyl group and not to ring positions.)... 

The current experiment involves the preparation of the sterically hindered amine A -ferf-butyl-3,5-dimethylaniline. Other preparations of this amine involve addition of methyllithium to lV-3,5-dimethylphenylacetone imine and the reaction of l-bromo-2,4-dimethylbenzene with terf-butylamine either via aryne formation or by palladium-catalyzed alkylation. The current method, the reaction of tert-butylamine with the 2,4,6-trimethylpyrylium cation, involves inexpensive starting materials and proceeds in high yield. The molybdenum(III) complex of the deprotonated form of this amine, Mo[N(f-Bu)(3,5-C6H3Me2)]3, splits the N=N triple bond in N2 to afford molybdenum(VI) nitrido products. This latter reaction is the key step in the recently discovered catalytic process to convert N2 to ammonia under ambient conditions. 

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