F Butyl formate

The rate constants for the reactions between OH and a range of ethers and hydroxy ethers have been reported at 298 K233 as well as those for reactions between dimethyl ether and methyl f-butyl ether over the range 295-750 K.234 Data from the former study show deviations from simple structure-activity relationships which were postulated to arise due to H-bonding in the reaction transition states.233 The atmospheric lifetime of methyl ethyl ether has been determined to be approximately 2 days.235 Theoretical studies on the H-abstraction from propan-2-ol (a model for deoxyribose) by OH have been reported using ab initio methods (MP2/6-31G ).236 The temperature dependence (233-272 K) of the rate coefficients for the reaction of OH with methyl, ethyl, n-propyl, n-butyl, and f-butyl formate has been measured and structure-activity... 

Buty 1-3,3-dinitroazetidine, see /V-Dimethylethyl-3,3-dinitroazetidine, 2844 terf-Butyl diperoxyoxalate, 3350 O—(9-terf-Butyl diphenyl monoperoxophosphate, 3706 O—(9-terf-Butyl di(4-tolyl) monoperoxophosphate, 3757 f Butylethylamine, see /V-Fthyl butyl ami lie, 2563b f Butyl ethyl ether, 2535 f terf-Butyl ethyl ether, 2536 A-terf-Butylformamide, 1988 f Butyl formate, 1961... 

Attention has been given to possible adverse effects of incorporating f-butyl methyl ether into automobile fuels, and it has been shown that photolysis of f-butyl formate (that is an established product of photolysis) in the presence of NO can produce the relatively stable f-butoxyformyl peroxynitrate. This has a stability comparable to that of peroxyacetyl nitrate and may therefore increase the potential for disseminating NOx (Kirchner et al. 1997). 

Iminoboianes have been suggested as intermediates in the formation of compounds derived from the pyrolysis of azidoboranes (77). The intermediate is presumed to be a boryl-substituted nitrene, RR BN, which then rearranges to the amino iminoborane, neither of which has been isolated (78). Another approach to the synthesis of amino iminoboranes involves the dehydrohalogenation of mono- and bis(amino)halobotanes as shown in equation 21. Bulky alkah-metal amides, MNR, have been utilized successfully as the strong base,, in such a reaction scheme. Use of hthium-/i /f-butyl(ttimethylsilyl)amide yields an amine, DH, which is relatively volatile (76,79). 

A successful procedure for the formation of 2,5-di-t-butylfuran involves reaction of the parent heterocycle with f-butyl chloride in the presence of iron(III) chloride and iron(III) oxide. Iron(III) oxide acts as a hydrogen chloride scavenger and at the same time regenerates the catalyst. Concurrent polymerization normally deactivates the catalyst (82CI(L)603). 

The formation of 2,3-di-f-butyl-l-methylthiirenium chloride from fran5-3-chloro-4-methylthio-2,2,5,5-tetramethyl-3-hexene is quantitative (by NMR) in liquid sulfur dioxide (Scheme 128) (82JOC590). Similar thiirenium ions are intermediates in the reactions of -thiovinyl derivatives (79MI50600). 

Thiol esters, which are more reactive to nucleophiles than are the corresponding oxygen esters, have been prepared to activate carboxyl groups for both lactoniza-tion and peptide bond formation. For lactonization S-f-butyl and S-2-pyridyP esters are widely used. Some methods used to prepare thiol esters are shown below. The S-r-butyl ester is included in Reactivity Chart 6. 

The allylic position of olefins is subject to attack by free radicals with the consequent formation of stable allylic free radicals. This fact is utilized in many substitution reactions at the allylic position (cf. Chapter 6, Section III). The procedure given here employs f-butyl perbenzoate, which reacts with cuprous ion to liberate /-butoxy radical, the chain reaction initiator. The outcome of the reaction, which has general applicability, is the introduction of a benzoyloxy group in the allylic position. 

Subsequently, rate coefficients were determined for the zinc chloride-catalysed bromination of benzene, toluene, i-propyl-benzene, r-butylbenzene, xylenes, p-di-f-butylbenzene, mesitylene, 1,2,4-trimethyl-, sym-triethyl-, sym-tri-f-butyl-, 1,2,3,5-and 1,2,4,5-tetramethyl- and pentamethylbenzenes, all at 25.4 °C and in acetic acid, and it was shown that the reaction was inhibited by HBr.ZnCl2 which accumulates during the bromination and was considered to cause the first step of the reaction (formation of ArHBr2) to reverse320. The second-order coefficients for bromination of o-xylene at 25.0 °C were shown to be inversely dependent upon the hydrogen bromide concentration and the reversal of equilibrium (155)... 

Esters and amides may be sulfinylated. Addition of a mixture of t-butyl acetate and sulfinate ester 19 to a THF-ether solution of magnesium diisopropylamide led to the formation of (R)-(+)-f-butyl p-toluenesulfinylacetate (49) in 90% yield (equation 14)7. t-Butyl propanoate and butanoate also underwent this sulfinylation to give 50 and 51 in yields of 68 and 45%, respectively83. The diastereomeric ratio was 1 1 for 50 and 3 7 for 51. These esters may also be obtained by alkylation of 49. Similarly, treatment of a-lithio-A, A -dimethylacetamide with sulfinate ester 19 gave (R)-( + )-N, Ar-dimethyl-p-toluene-sulfinylacetamide (52) (equation 15)84. 

Oxidative cleavage of oxosulfonium ylides490 as well as of sulfoximines491 leads to sulfone formation. In the course of oxidations of dialkoxy sulfuranes(IV) by hydrogen peroxide492 or f-butyl hydroperoxide493, sulfone formation takes place (equation 99). 

A proof for the formation of alkyl radicals was found by their addition to the aci-nitromethane anion (CH2=N02 ) and by their reaction with p-benzoquinone to give the optically active nitroalkane radical-anion and the semiquinone radicals, respectively. In the case of di-r-butyl sulfoxide the f-butyl radical was observed directly by its absorption spectra. 

Di-f-butyl sulfone is different from the other dialkyl sulfones in that RH is mainly alkene and not alkane [G(isobutene) = 3.2 and G(isobutane) = 1.2]. The preference for isobutene over isobutane means that the formation of the alkene cannot be due to disproportionation of two t-butyl radicals but is due to a hydrogen atom expulsion as suggested by Bowmer and O Donnell70... 

In 2004, Alterman et al. used a microwave-assisted Ullmann-type protocol for the synthesis of N-(f-butyl)-3-[4-(lH-imidazol-l-yl)benzyl]-5-isobutylthiophene-2-sulfonamide (Scheme 106) [61]. Deprotection of the sulfonamide followed by carbamate formation via reaction with butyl chloro-formate finally gave the target compound for biological evaluation as selective angiotensin II AT2 receptor agonist. The IH-imidazole derivative, however, showed only a low affinity for the AT2 receptor (Ki value > 10 p,M). 

Enantioselective enolate formation can also be achieved by kinetic resolution through preferential reaction of one of the enantiomers of a racemic chiral ketone such as 2-(f-butyl)cyclohcxanone (see Section 2.1.8 of Part A to review the principles of kinetic resolution). 

The reaction in Entry 8 was conducted in excess refluxing vinyl f-butyl ether, using 1.1 equivalent of Hg(OAc)2 to catalyze the exchange reaction. In Entry 9 a thermal reaction leads to formation of an eight-membered ring. 

Metal-Catalyzed. Cyclopropanation. Carbene addition reactions can be catalyzed by several transition metal complexes. Most of the synthetic work has been done using copper or rhodium complexes and we focus on these. The copper-catalyzed decomposition of diazo compounds is a useful reaction for formation of substituted cyclopropanes.188 The reaction has been carried out with several copper salts,189 and both Cu(I) and Cu(II) triflate are useful.190 Several Cu(II)salen complexes, such as the (V-f-butyl derivative, which is called Cu(TBS)2, have become popular catalysts.191... 

In general, an increase in steric demand of the substituents on silicon atoms appears to lead to the formation of more stable disilenes. For example, 3, which has two f-butyl groups, is more stable than 1 while 4, which has two 1-adamantyl groups, is more stable than 3.9 Disilene 4... 

As seen earlier in this section, the energy released upon formation of the benzophenone ketyl radical is about 104 kcal/mole. This value is almost identical to that released upon formation of f-butyl alcohol from the f-butoxy radical,... 

These results suggest that the transition state which leads for example to the compound (38) is not symmetrical and completely productlike. It may well be that bond formation at the position para to the f-butyl group is more advanced in the transition state, as represented schematically in (40). 

Photolysis of dicyclopentadienyltin results in formation of the Cp- radical (again detected by ESR), along with the precipitation of some unidentified yellow solid54. In contrast, photolysis of dicyclopentadienyllead produces no Cp-, unless di-f-butyl peroxide or biacetyl are added to the reaction mixture. The trimethylstannylcyclopentadienyl radical was produced by photolysis of bis(trimethylstannyl)cyclopentadiene (reaction 35), and was detected using ESR spectroscopy57. 

Formation of the conjugate base of phosphine under the conditions of aqueous dioxane and KOH with red phosphorus allows also for the formation of C-P bonds by attack of oxiranes.33 Under these conditions, mixtures of phosphines and phosphine oxides are formed. Using red phosphorus in liquid ammonia with sodium metal and f-butyl alcohol, good yields of primary (2-hydroxyalkyl)phos-phines are obtained.34... 

Difficulties that arise using simple primary alcohols (ketal and enol-ether formation) may be avoided by using phenol or f-butyl alcohol.360... 

Diastereomeric excesses of up 56% have been claimed for the preparation of a-amino-P-hydroxy acids via the aldol condensation of aldehydes with f-butyl N-(diphenylmethylene)glycinate [63]. It might be expected that there would be thermodynamic control of the C-C bond formation influenced by the steric requirements of the substituents, but the use of cinchoninium and cinchonidinium salts lead to essentially the same diastereoselectivity. The failure of both tetra-n-butylammo-nium and benzyltriethylammonium chloride to catalyse the reaction is curious. 

Initiating a remarkable series of papers in 2008-2009, Grubbs and Whited reported the formation of an Ir(I) carbene complex, 44, from the reaction of methyl f-butyl ether (MTBE) with Ozerov s (PNP)lrH2 (PNP = [N(2-P Pr2-4-Me-C6H3)2] ) and NBE [121-127]. C-H addition to (PNP)lr presumably occurs followed by... 

Church, C.D., Pankow, J.F., and Tratnyek, P.G. Hydrolysis of ferf-butyl formate kinetics, products, and implications for the environmental impact of methyl ferf-butyl ether. Environ. Toxicol. Chem., 18(12) 2789-2796, 1999. 

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