Terf-Butyl

On autoxidation by aeration in tertiary butyl alcohol containing potassium tert-butyl oxide, quininone yields quininic acid (98 per cent.) and meroquinenine terf-butyl ester, CgHi N. CO. O. C4H9, b.b. 127°/20 mm., dj 0-9832, [a]o° -(- 50-0° (EtOH), identified by hydrolysis to meroquinenine (meroquinene) and eonversion of this to the better-known ethyl ester (p. 438). (Doering and Chanley.)... 

Tnflic acid is a useful reagent for the removal of protecting groups (deblocking) in synthetic proteins [67] At the same time, it is an excellent catalyst for the protection of a variety of phenols in the form of their terf-butyl ethers [5(5] (equation 37)... 

FIGURE 4.11 Combination of terf-butyl cation and chloride anion to give fert-butyl chloride. In-phase overlap between a vacant p orbital of (CHbIbC" and a filled p orbital of Cr gives a C—Cl CT bond. 

Similarly, sodium methoxide (NaOCHj) is a suitable base and is used in methyl alcohol. Potassium hydroxide in ethyl alcohol is another base-solvent combination often employed in the dehydrohalogenation of alkyl halides. Potassium ferf-butoxide [K0C(CH3)3] is the prefened base when the alkyl halide is primary it is used in either terf-butyl alcohol or dimethyl sulfoxide as solvent. 

Electrostatic potential map for terf-butyl diazonium ion shows most positively-charged regions (in blue) and less positively-charged regions (in red). 

Pivorarenko and Khilya investigated a series of organic bases including tribenzyl amine, sodium methylate, sodium terf-butylate, n-methylmorpholine,... 

Lithium 1,2,4-triazolate with [Rh2( j,-Ph2PCH2PPh2)(CO)2( j.-Cl)]PFj. gives the A-framed complex 177 (L=L = CO) (86IC4597). With one equivalent of terf-butyl isocyanide, substitution of one carbon monoxide ligand takes place to yield 177 (L = CO, L = r-BuNC), whereas two equivalents of rerr-butyl isocyanide lead to the product of complete substitution, 177 (L = L = r-BuNC). The starting complex (L = L = CO) oxidatively adds molecular iodine to give the rhodium(II)-rhodium(II) cationic species 178. 

The UV and IR spectra eliminate structures with a CN double bond. The isomerism of nitrones and oxaziranes thus cannot be a result of CIS or traris arrangement of substituents about a double bond. The carbon atoms of an oxazirane are still at the oxidation level of the carbonyl compound used in its syntheses. By acid hydrolysis, for example, 2-terf-butyl-3-phenyloxazirane (9) can be split into benzaldehyde and tert-butylhydroxylamine fEq. (8)]. ... 

To hydrogenate an aromatic ring, it s necessary either to use a platinum catalyst with hydrogen gas at several hundred atmospheres pressure or to use a more effective catalyst such as rhodium on carbon. Under these conditions, aromatic rings are converted into cyclohexanes. For example, o-xylene yields 1,2-dimethylcvclohexane, and 4-terf-butylphenol gives 4-terf-butyl-cyclohexanol. 

Because the Williamson synthesis is an S 2 reaction, it is subject to all the usual constraints, as discussed in Section 11.2. Primary halides and tosylates work best because competitive E2 elimination can occur with more hindered substrates. Unsymmetrical ethers should therefore be synthesized by reaction between the more hindered alkoxide partner and less hindered halide partner rather than vice versa. For example, terf-butyl methyl ether, a substance used in the 1990s as an octane booster in gasoline, is best prepared by reaction of tert-butoxide ion. with iodomethane rather than by reaction of methoxide ion with 2-chloro-2-methylpropane. 

How would you prepare the following compounds from 1-phenylethanoJ (a) Methyl 1-phenylethyl ether (b) Phenylepoxyethane (c) terf-Butyl 1-phenylethyl ether (d) 1-Phenylethanethiol... 

Exposure of compound 16, a substance that can be obtained in a straightforward manner from glycine, to sodium tert-butoxide furnishes an enolate that undergoes conversion to 8 upon treatment with terf-butyl formate. It was anticipated that the phthalimido and tert-butyl ester protecting groups in 8 could be removed easily and selectively under anhydrous conditions at a later stage in the synthesis. 

The synthesis of the trisubstituted cyclohexane sector 160 commences with the preparation of optically active (/ )-2-cyclohexen-l-ol (199) (see Scheme 49). To accomplish this objective, the decision was made to utilize the powerful catalytic asymmetric reduction process developed by Corey and his colleagues at Harvard.83 Treatment of 2-bromocyclohexenone (196) with BH3 SMe2 in the presence of 5 mol % of oxazaborolidine 197 provides enantiomeri-cally enriched allylic alcohol 198 (99% yield, 96% ee). Reductive cleavage of the C-Br bond in 198 with lithium metal in terf-butyl alcohol and THF then provides optically active (/ )-2-cyclo-hexen-l-ol (199). When the latter substance is treated with wCPBA, a hydroxyl-directed Henbest epoxidation84 takes place to give an epoxy alcohol which can subsequently be protected in the form of a benzyl ether (see 175) under standard conditions. 

Various nucleophiles undergo addition to oxepins to give functionalized cyclohexadienols. Thus, terf-butyl oxepin-4-carboxylate when treated with a methanolic solution of lithium hydroxide gives /ert-butyl ow .v-5-hydroxy-6-methoxycyclohexa-l,3-diene-1-carboxylate (3a) in 56% yield.156 When dioxane is used as solvent, the respective dihydroxy derivative 3b is obtained in 30 % yield. Sodium azide reacts with oxepin to give mws-6-azidocyclohexa-2,4-dien-l-ol (3c) in 55% yield.212... 

Bromination of 7-ter/-butyl, 2-mcthyl 5-methyl-4//-azepine-2,7-dicarboxylate (7) with 1 equivalent of jV-bromosuccinimide yields 2-terf-butyl,7-methyl 4-(bromomethylene)-4,5-dihvdro-l//-azepinc-2,7-dicarboxylate (8) as a 1 2 mixture of the E- and Z-isomers.113 With an excess of reagent the dibromomethylene compound 9 results. 

Aldol Addition of 2-terf-Butyl-6-methyl-l,3-dioxan-4-one to Propanal Single Procedure117 ... 

To a stirred solution of (1.5 mmol) of LDA in 3.5 mL of THF/hcxane (60 40) at — 78 C under a nitrogen atmosphere is added 198 mg (1.5 mmol) terf-butyl propanoate in 1.5 mL of HMPA. After 30 min 169 mg (1.5 mmol) of potassium rm-butoxide are added and the mixture is stirred for 10 min. Then 133 mg (0.5 mmol) of ethyl 6-iodo-2-hcxcnoatc in 1.5 mL of TI1F arc added and the mixture is stirred for an additional 0.5 h at — 78 C. The reaction is quenched by adding sat. aq NH4C1. Extraction with ethyl acetate, drying over Na,S04 followed by evaporation of the solvent and short-path distillation gives the adduct yield 135 mg (100%). 

Tetrahydrofuran or glyme work equally well in place of terf-butyl alcohol as a cosolvent, but they should be distilled under dry nitrogen... 

Most of the subsequent work on this reagent was concerned with the formation of aryl radicals (see review by Cadogan, 1971). However, 2-terf-butyl-A-nitrosoacet-anilide was found to decompose in benzene to give, instead of 2-tert-butylbiphenyl, as expected for a substitution of benzene by a 2-tert-butylphenyl radical, a mixture of isomeric tert-butylphenyl acetates. A careful reexamination (Cadogan and Hib-bert, 1964) suggested that the ratio of 2- and 3-tert-butylphenyl acetates was consistent with the involvement of 2-tert-butylbenzyne, i.e., the product of an ionic dediazoniation, as an intermediate. This was later confirmed by trapping experiments designed to detect aryne intermediates. 

Rate law and activation energy. The oxidation of nitrosobenzene by terf-butyl hydroperoxide is catalyzed by di-terf-butyl peroxyoxalate (TBO) and by a cobalt(II) chelate complex. 

Owing to the reactions of the initial primary radiolysis products among themselves, as in Eqs. (11-58)—(11-62), it is usually necessary to add another reagent to remove the unwanted ones. For example, to study reactions of e alone, one must work in neutral or basic solution to avoid its destruction by HsO+ (see Problem 11-12). Also, hydroxyl radicals and hydrogen atoms are removed from the system by prior addition of terf-butyl alcohol to give noninterfering products,... 

L-Pkenylalanine, reaction with phthalic anhydride to yield N-phthalyl-L-phenylalanine, 40,82 Phenyl terf-BUTYL ether, 41, 91 a-Phenylethylamine, N-chlorination of, 41,82... 

Initiators that have been used for these free radical reactions are di-terf-butyl peroxide and 2,2-bis-ferr-butylperoxybutane [166-168]. 

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