Hydroperoxy rearrangement

H-Indole, 3,3-dichloro-synthesis, 4, 369 3H-Indole, 3,3-dimethyl-synthesis, 4, 224 3H-Indole, 3-hydroperoxy-autoxidation, 4, 247 rearrangement, 4, 249 3H-Indole, 3-oximino-synthesis, 4, 209, 210 3H-Indole, 3-oximino-2-phenyl Beckmann rearrangement, 4, 210 Indoleacetic acid synthesis, 4, 337 Indole-3-acetic acid as growth regulator, 4, 372 synthesis, 4, 346 Indole alkaloids, 4, 373 synthesis, 4, 276... 

It has been proposed that oxygen adds to the excited keto group [- (112)]. The rearrangement of the resulting hydroxyhydroperoxy diradical (112) could then proceed by intramolecular hydrogen abstraction involving a six-membered cyclic transition state, followed by fission of the former C —CO bond to form the unsaturated peracid (113) as the precursor of the final product. Such a reaction sequence demands a hydrogen atom in the J -position sterically accessible to the intermediate hydroperoxy radical. 

The cooxidation of thiophenol with indene by air in hydrocarbon solvents provides l-hydroperoxy-2-phenylthioindane 84 in 77% yield. Subsequent rearrangement afforded a mixture of trans and cis 2-phenylsulphinyl-l-indanols 85148 149 (equation 47). 

Rapi, G. et al., J. Chem. Soc., Chem. Comm., 1982, 1339-1340 Oxidative rearrangement of the oxazole to 4-hydroperoxy-5-hydroxy-4-methylimidazolidin-2-one in presence of iron(II) catalysts at ambient temperature may become explosive if not controlled effectively. 

A closer examination by ex situ analysis using NMR or gas chromatography illustrates that intrazeolite reaction mixtures can get complex. For example photooxygenation of 1-pentene leads to three major carbonyl products plus a mixture of saturated aldehydes (valeraldehyde, propionaldehyde, butyraldehyde, acetaldehyde)38 (Fig. 33). Ethyl vinyl ketone and 2-pentenal arise from addition of the hydroperoxy radical to the two different ends of the allylic radical (Fig. 33). The ketone, /i-3-penten-2-one, is formed by intrazeolite isomerization of 1-pentene followed by CT mediated photooxygenation of the 2-pentene isomer. Dioxetane cleavage, epoxide rearrangement, or presumably even Floch cleavage130,131 of the allylic hydroperoxides can lead to the mixture of saturated aldehydes. 

Complexation of sodium to the persulfoxide A (Fig. 13B) appears to inhibit intramolecular hydrogen abstraction to form the hydroperoxy sulfonium ylide (B in Fig. 13A) and allows a direct reaction of 12 with the sodium-complexed persulfoxide, (A in Fig. 13B) to compete. Consistent with this suggestion is the observation that the formation of 13CHO that emanates from the hydroperoxy sulfonium ylide by Pummerer rearrangement and subsequent cleavage is completely suppressed during photo-oxidations of thiolane, 13, in NaMBY ... 

In contrast to earlier literature reports, photo-oxygenation of 17/3-hydroxyoestr-5(10)-en-3-one has been shown not to be stereospecific, since a mixture of 10a- and 10/3-hydroperoxy-3-oxo-A -compounds was obtained. Thermal rearrangement of these products gave the 10a- and 10/3-hydroxy-3-oxo-A -compounds. Photo-oxygenation of 5a-cholesta-1,3-diene led only to cholesta-1,4-... 

Finally, a series of novel hydroperoxy-l,2-dioxanes 233a, b (Scheme 65) were synthesized by hydroperoxide rearrangement and ozonolysis <2006EJ02174> all the products showed weak antimalarial acitivity. Also the epoxy-endoperoxides 234a,b were designed which proved to have inhibitory acitivity against Candida albicans (Scheme 65) <2007BMC36>. 

Here Q denotes an alkyl radical with two unpaired electrons (in QOOH and QO) which may rearrange to form a stable alkene. The compound QO is a cyclic ether3 (which may break down to form an aldehyde4 and a smaller alkene). The sequence of reactions (R64) to (R67) is chain propagating, in that the initial alkyl radical has produced one HO2 or OH radical in addition to one or more stable components. However, it is also possible that a second oxygen molecule may add to QOOH to form a peroxy alkyl hydroperoxy radical,... 

Bauer G (2000) Reactive oxygen and nitrogen species efficient, selective and interactive signals during intercellular induction of apoptosis. Anticancer Res 20 4115-4140 Beckwith AU, Davies AG, Davison IGE, Maccoll A, Mruzek MH (1989) The mechanisms of the rearrangements of allylic hydroperoxides 5a-hydroperoxy-3p-hydrocholest-6-ene and 7a-hydro-peroxy-3(1-hydroxycholest-5-ene. J Chem Soc Perkin Trans 2 815-824 Behar D, Czapski G, Rabani J, Dorfman LM, Schwarz HA (1970) The acid dissociation constant and decay kinetics of the perhydroxyl radical. J Phys Chem 74 3209-3213 Benjan EV, Font-Sanchis E, Scaiano JC (2001) Lactone-derived carbon-centered radicals formation and reactivity with oxygen. Org Lett 3 4059-4062 Bennett JE, Summers R (1974) Product studies of the mutual termination reactions of sec- alkylper-oxy radicals Evidence for non-cyclic termination. Can J Chem 52 1377-1379 Bennett JE, Brown DM, Mile B (1970) Studies by electron spin resonance of the reactions of alkyl-peroxy radicals, part 2. Equilibrium between alkylperoxy radicals and tetroxide molecules. Trans Faraday Soc 66 397-405... 

Initially we chose to test elements of this approach to artemisinin in an abbreviated version of 4 that lacked the 2P-(3-oxobutyl) and 3a-methyl groups. Hence, on low-temperature ozonolysis of the vinyl silane 5 in methanol, transient and stereoexclusive formation of dioxetane 6 was observed upon immediate analysis by NMR (Eq. 3). On standing, the dioxetane 6 underwent rearrangement and cyclization to furnish hydroperoxy-lactone 7 in 54% isolated yield on a scale sufficient for X-ray structural study.44... 

Hydroperoxy-2-methylchroman results from a hydrogen peroxide mediated rearrangement of l-methyl-2,3-dihydroinden-l-ol (Equation 211) <2000JOC1873>. Further reports regarding this rearrangement are available... 

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