Tcrt-butyl hydroperoxide

Osrnate esters are fairly stable but are readily cleaved in the presence of an oxidizing agent such as tcrt-butyl hydroperoxide. 

The asymmetric epoxidation of an allylic alcohol 1 to yield a 2,3-epoxy alcohol 2 with high enantiomeric excess, has been developed by Sharpless and Katsuki. This enantioselective reaction is carried out in the presence of tetraisopropoxyti-tanium and an enantiomerically pure dialkyl tartrate—e.g. (-1-)- or (-)-diethyl tartrate (DET)—using tcrt-butyl hydroperoxide as the oxidizing agent. 

In order to induce the free-radical chain reaction, a starter compound such as dibenzoyl diperoxide, azo-Zj -(isobutyronitrile) or tcrt-butyl hydroperoxide or UV-light is used. The commercially available, technical grade N-bromosuccinimide contains traces of bromine, and therefore is of slight red-brown color. Since a small amount of elemental bromine is necessary for the radical... 

All classes of primary amine (including primary, secondary, and tertiary alkyl as well as aryl) are oxidized to nitro compounds in high yields with dimethyl dioxirane." Other reagents that oxidize various types of primary amines to nitro compounds are dry ozone, various peroxyacids," MeRe03/H202,"" Oxone ," ° tcrt-butyl hydroperoxide in the presence of certain molybdenum and vanadium compounds, and sodium perborate." ... 

Scheme 28) Quantum yields of lucigenin oxidation by hydrogen peroxide in alkaline media are comparable with the values obtained in luminol oxidation (1.24 x 10 E mol ) ° . However, the use of other peroxides, such as tcrt-butyl hydroperoxide, results in a decrease of chemiluminescence quantum yields of two orders of magnitude, confuming the hypothesis that a 1,2-dioxetane is the HEI, since its formation would be impossible with alkyl peroxides . 

Fig. 14. The relationship between C and the maximum concentration of tcrt-butyl hydroperoxide.

Of considerable practical importance is the concentration of substrate. Even fairly reactive compounds do not autoxidize readily at sub-millimolar concentrations [7a]. The rate of initiation is also crucial in promoting autoxidation. Although many autoxidation reactions are auto-initiated, the use of initiators such as d -tert-butyl peroxyoxalate (DBPO) [12a] or di-tcr -butyl hyponitrite (DTBN) [12b] can be beneficial. DBPO and DTBN are convenient sources of tcrt-butoxyl radicals in the temperature ranges of 20-60 and 20-90 °C, respectively (Scheme 2). They are especially effective when used in conjunction with an excess of tcrt-butyl hydroperoxide (TBHP), whose role is to trap product peroxyl radicals as hydroperoxides, thereby preventing side-reactions [13a,c. In contrast to auto-initiated autoxidation, the autoxidation of simple alkenes (e.g. 1-methylcyclohexene, Scheme 2) by the DBPO-TBHP procedure is of comparable preparative value to the widely used singlet oxygen route [13a,b]. 

Scheme 45) [81]. After probing several initiators, it was found that a combination of DBPO (0.5 equiv) and tcrt-butyl hydroperoxide (TBHP 10 equiv) is remarkably effective for inducing cyclization of hydroperoxide 26 to diastereomeric 1,2-diox-anes 27a and 27b [81],... 

Methylselenoxy analogs are even more difficult to react and treatment of the corresponding methylseleno derivative at 80 °C with tcrt-butyl hydroperoxide/basic alumina (conditions which proved particularly efficient for the synthesis of terminal olefins from methyl selenides bearing a methylseleno group at the terminus of the alkyl chain which are more difficult to react) as expected does not... 

The authors demonstrated the catalytic properties of the resulting composite materials. Thus, rho-TMGP with encapsulated Mn porphyrin was found to be active for cyclohexane oxidation using tcrt-butyl hydroperoxide as the oxidant, cyclohexanol and cyclohexanone being the only products detected (91.5% total yield after 24 h at 65°C and with 3.8% catalysts loading). The solid was found to retain its crystallinity, no leaching of the metalloporphyrin was detected, and it was reused for 11 catalytic cycles without significant lose of activity [68]. 

The Sharpless reagent coi thi] components tcrt-butyl hydroperoxide, (CH3)3COOH a titanium and diethyl tartrate... 

Benzylic Bromination. Toluene and substituted methylben-zenes undergo benzylic bromination using CuBt2 and tcrt-butyl hydroperoxide in acetic acid or anhydride (eq 14). While the yields (43-95%) are not quite as high as those obtained using A-bromosuccinimide, the copper(II) bromide procedure allows the benzylic bromination of compounds which are insoluble in nonpolar solvents. 

Ring expansion with Tamura et al. s Beckmann reagent, followed by dechlorination with Zn-Cu couple in methanol saturated with ammonium chloride, provided key pyrrolidinone intermediate 197 in 72% overall yield from 193. The intermediate 197 was then converted by using selenium dioxide and tcrt-butyl hydroperoxide into allylic alcohol (62%), which yielded the desired 1,3-diol 198 through rhodium-catalyzed hydroboration and oxidation as a 1 1 mixture of diastereomers in 72% yield. A seven-step reaction sequence then converted the diol 198 into (-l-)-retronecine 199, which was indistinguishable from an authentic sample of the natural product obtained by hydrolysis of natural monocrotaline (Scheme 16.29). ... 

SIDA self-induced diastereomeric TBHP tcrt-butyl hydroperoxide... 

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