Allyl-tert.-butyl

Hydroxy-3-methoxy-4-methyl-E21b, 1487 (H3C-CO-CH3 + RO - CH = CH - CH2 - A1R2) Peroxid Allyl-tert.-butyl- E13/1, 346 (Br - O-OR)... 

Carbamidsaure N-Allyl- tert.-butyl-peroxyester E13/1, 278 [CO(NR2)2 + R-O-OH/ Amin]... 

Thioketen Allyl-(tert.-butyl-dimethyl-silyl)- Ell, 247... 

C7H6N204 2,5-dinitrotoluene 619-15-8 1.112E-K10 88.070 11927 1 C7H1402 allyl-tert-butyl peroxide 39972-78-6 1.140E+10 86.500... 

Allyl methyl ether292 (ethyl diazoacetate, rhodium catalysis) and allyl tert-butyl ether124 (dimethyl diazomalonate, copper catalysis) yield cyclopropanes exclusively. With y-substituted allyl methyl ethers, C-0 insertion is generally strongly favored over cyclopropanation, even with tetraacetatodirhodium as catalyst.293 In view of these findings, the cyclopropanation of ( )- ,4-dibenzyloxybut-2-ene in moderate yield, only, to give (la,2a,3/ )-31 is notable.294... 

As anticipated, by analogy with the chemistry of Barton esters, the same mixed oxalate esters can be used to prepare tertiary alkyl chlorides, simply by refluxing in carbon tetrachloride [47], and also for the creation of quaternary carbon centers through selection of either a Michael acceptor [46] or 2-(carboethoxy) allyl tert-butyl sulfide [46] as the radicophile. 

Pyridinium p-toluenesulphonate in methanol at reflux has been shown to be effective in selective removal of the isopropylldene groups of 1, 6-anhydro-2,3-0-isopropylidene-/d-D-mannopyrano3e derivatives bearing 4.-0-allyl, -tert-butyl, -trichloroacetyl, and -tert-butyldi-phenylsilyl groups. 

We have found allylic peroxides, i.e., allyl tert-butyl to be more susceptible (14). Heating 0.1-0.2 molar solutions in toluene at 130 C gives an estimated 14-15% induced decomposition, while DBPO-peroxide-toluene mixtures at 60 C yield similar results. 

The first practical method for asymmetric epoxidation of primary and secondary allylic alcohols was developed by K.B. Sharpless in 1980 (T. Katsuki, 1980 K.B. Sharpless, 1983 A, B, 1986 see also D. Hoppe, 1982). Tartaric esters, e.g., DET and DIPT" ( = diethyl and diisopropyl ( + )- or (— )-tartrates), are applied as chiral auxiliaries, titanium tetrakis(2-pro-panolate) as a catalyst and tert-butyl hydroperoxide (= TBHP, Bu OOH) as the oxidant. If the reaction mixture is kept absolutely dry, catalytic amounts of the dialkyl tartrate-titanium(IV) complex are suflicient, which largely facilitates work-up procedures (Y. Gao, 1987). Depending on the tartrate enantiomer used, either one of the 2,3-epoxy alcohols may be obtained with high enantioselectivity. The titanium probably binds to the diol grouping of one tartrate molecule and to the hydroxy groups of the bulky hydroperoxide and of the allylic alcohol... 

We noted m Section 2 13 that the common names of certain frequently encoun tered alkyl groups such as isopropyl and tert butyl are acceptable m the lUPAC sys tern Three alkenyl groups—vinyl, allyl, and isopropenyl—are treated the same way... 

The first order rate constant for ethanolysis of the allylic chloride 3 chloro 3 methyl 1 butene is over 100 times greater than that of tert butyl chloride at the same temperature... 

Both compounds react by an S l mechanism and their relative rates reflect their acti vation energies for carbocation formation Because the allylic chloride is more reactive we reason that it ionizes more rapidly because it forms a more stable carbocation Struc turally the two carbocations differ m that the allylic carbocation has a vinyl substituent on Its positively charged carbon m place of one of the methyl groups of tert butyl cation... 

Benzylic halides resemble allylic halides m the readiness with which they form carbocations On comparing the rate of S l hydrolysis m aqueous acetone of the fol lowing two tertiary chlorides we find that the benzylic chloride reacts over 600 times faster than does tert butyl chloride... 

The Sharpless-Katsuki asymmetric epoxidation reaction (most commonly referred by the discovering scientists as the AE reaction) is an efficient and highly selective method for the preparation of a wide variety of chiral epoxy alcohols. The AE reaction is comprised of four key components the substrate allylic alcohol, the titanium isopropoxide precatalyst, the chiral ligand diethyl tartrate, and the terminal oxidant tert-butyl hydroperoxide. The reaction protocol is straightforward and does not require any special handling techniques. The only requirement is that the reacting olefin contains an allylic alcohol. 

Pseudo-/ -DL-gi Zopyranose triacetate (36) was prepared by hydroxyla-tion of the enetriol triacetate (32) and converted to the corresponding pentol and pentaacetate. The intermediate 32 was obtained by Diels-Alder reaction (200°C., two days) of rans/ rans-l,4-diacetoxy-l,3-buta-diene with allyl acetate. The double bond was surprisingly inert to the usual additive reagents and not detectable by infrared spectroscopy because of near-symmetry, but it did react with tert-butyl hydroxperoxide to give 36 in about 30% yield (27). 

In light of the previous discussions, it would be instructive to compare the behavior of enantiomerically pure allylic alcohol 12 in epoxidation reactions without and with the asymmetric titanium-tartrate catalyst (see Scheme 2). When 12 is exposed to the combined action of titanium tetraisopropoxide and tert-butyl hydroperoxide in the absence of the enantiomerically pure tartrate ligand, a 2.3 1 mixture of a- and /(-epoxy alcohol diastereoisomers is produced in favor of a-13. This ratio reflects the inherent diasteieo-facial preference of 12 (substrate-control) for a-attack. In a different experiment, it was found that SAE of achiral allylic alcohol 15 with the (+)-diethyl tartrate [(+)-DET] ligand produces a 99 1 mixture of /(- and a-epoxy alcohol enantiomers in favor of / -16 (98% ee). 

The activity of the FePeCli6-S/tert-butyl hydroperoxide (TBHP) catalytic system was studied under mild reaction conditions for the synthesis of three a,p-unsaturated ketones 2-cyclohexen-l-one, carvone and veibenone by allylic oxidation of cyclohexene, hmonene, and a-pinene, respectively. Substrate conversions were higher than 80% and ketone yields decreased in the following order cyclohexen-1-one (47%), verbenone (22%), and carvone (12%). The large amount of oxidized sites of monoterpenes, especially limonene, may be the reason for the lower ketone yield obtained with this substrate. Additional tests snggested that molecular oxygen can act as co-oxidant and alcohol oxidation is an intermediate step in ketone formation. 

The heterogeneous catalytic system iron phthalocyanine (7) immobilized on silica and tert-butyl hydroperoxide, TBHP, has been proposed for allylic oxidation reactions (10). This catalytic system has shown good activity in the oxidation of 2,3,6-trimethylphenol for the production of 1,4-trimethylbenzoquinone (yield > 80%), a vitamin E precursor (11), and in the oxidation of alkynes and propargylic alcohols to a,p-acetylenic ketones (yields > 60%) (12). A 43% yield of 2-cyclohexen-l-one was obtained (10) over the p-oxo dimeric form of iron tetrasulfophthalocyanine (7a) immobilized on silica using TBHP as oxidant and CH3CN as solvent however, the catalyst deactivated under reaction conditions. 

Regio- and Stereoselectivity. For the allylation of carbonyl compounds mediated by indium and other compounds in aqueous media, usually the carbon-carbon bond forms at the more substituted carbon of the allyl halide, irrespective of the position of halogen in the starting material. However, the carbon-carbon bond forms at the less-substituted carbon when the y-substituents of allyl halides are large enough (e.g., trimethylsilyl or tert-butyl) as shown by Chan et al.139 (Scheme 8.10). The following conclusions can be drawn ... 

L4 = 4 -Ethyl-, L5 = 4 -tert-butyl, L6 = 4 -allyl-, L7 = 4 -tert-butyl-3-methyl-l, 2, 4-triazole. 

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