Dry ozonation. Method for stereoselective hydroxylation of saturated compounds on silica gel

Cohen, Zvi; Keinan, Ehud; Mazur, Yehuda; Varkony, Tomas H.

doi:10.1021/jo00902a035

Cited by 123 publications

(33 citation statements)

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“…These results are in accordance with RHF/6-31G calculations reported early by Koller et al 25 ). 26 Obviously, at low temperature hydrotrioxides preferably exist as cyclic dimers (9). With increasing temperature, the molecular mobility increases leading to other associated forms (10-12), which results, as for hydroperoxides, 26 in an upfield shift of the hydrotrioxide proton signal.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, lowtemperature ozonation of hydrocarbons on a silica surface proceeds selectively and affords the tertiary alcohols as predominant (b98%) products. 9 We presume that this additional intermediate is formed by the reaction of hydrotrioxide with the solvent acetone.…”

Section: Chemiluminescence Kinetics On Thermal Decomposition Of Hydromentioning

confidence: 99%

“…Hydrotrioxide ROOOH (form B) decomposes according to reaction (9). The radical pair [RO Á Á OOH] either disproportionates in the solvent cage giving molecular singlet oxygen with efficiency 9 3 or escapes the cage [reaction (10) One can consider that singlet oxygen is generated more efficiently in the cage than from peroxyls which escaped the cage, 9 3 ) 9 1 , 9 1 '.…”

Section: Mechanism Of Decomposition Of Hydrotrioxidesmentioning

confidence: 99%

“…5,6 However, the formation of hydrotrioxides on ozonation of hydrocarbons has been proved experimentally only for cumene 7 and for some cyclopropyl-substituted alkanes. 8 In the mid-1970s, Cohen et al 9 first demonstrated that ozonation of hydrocarbons with tertiary C-H bonds on a silica gel surface (dry ozonation) selectively yields tertiary alcohols. It was proposed that hydrotrioxides are intermediates in this reaction.…”

Section: Introductionmentioning

confidence: 99%

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Formation of hydrotrioxides during ozonation of hydrocarbons on silica gel. Decomposition of hydrotrioxides

Avzyanova

Timerghazin

Khalizov

et al. 2000

J. Phys. Org. Chem.

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Hydrotrioxides (HT), ROOOH, from isopentane, 1,4-dimethylcyclohexane, 1,3-dimethylcyclohexane, decalin and triphenylmethane were synthesized for the first time by low-temperature ozonation of the corresponding hydrocarbons on a silica surface. Thermal decomposition of hydrotrioxides is accompanied by the formation of radicals and by infrared and visible chemiluminescence (CL). In solution the HTs form self-associates and react reversibly with the solvent (acetone) producing Bayer-Villiger type intermediates (unsymmetrical dialkyl trioxides). These reactions cause a complex character of the decomposition kinetics of HTs, as evidenced by monitoring the dependence of CL intensity on time. Activation parameters of thermal decomposition of HTs show a compensation effect (logA vs E A ) which describes well the available experimental and theoretical data for the homolysis of organic trioxides.

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Section: Resultsmentioning

confidence: 99%

Section: Chemiluminescence Kinetics On Thermal Decomposition Of Hydromentioning

confidence: 99%

Section: Mechanism Of Decomposition Of Hydrotrioxidesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Formation of hydrotrioxides during ozonation of hydrocarbons on silica gel. Decomposition of hydrotrioxides

Avzyanova

Timerghazin

Khalizov

et al. 2000

J. Phys. Org. Chem.

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“…A recent and interesting sidelight to the study of the ozonation of alkanes has involved the realization that silica can act as a hetero geneous catalyst for these reactions (121)(122)(123)(124). When an ozone/oxygen gas stream is passed through a bed of silica gel on which the alkane is adsorbed, the alkane is oxidized selectively to an alcohol or ketone in high yield.…”

Section: • L-j --C-ooohmentioning

confidence: 99%

Comparison of the ozonolysis products of the methylnaphthalenes and dimethylnaphthalenes in hexane, methanol, and water

Gaul

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Rearrangements of Spirocyclobutane-Substituted 2-Norbornyl Cations

Kirmse¹,

Landscheidt²,

Siegfried³

1998

Eur. J. Org. Chem.

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2‐Norbornyl cations with spiroannellated cyclobutane rings were generated for comparison with the previously studied cyclopropane analogues. Starting with the Diels‐Alder reaction of cyclopentadiene with methylenecyclobutane, spiro‐ [bicyclo[2.2.1]heptane‐2,1′‐cyclobutan]‐6‐one (11) was prepared. The tosylhydrazone 12 of 11 was photolyzed in NaOD/D2O to give the analogous alcohol 13 with a ca. 1:1 distribution of deuterium. Ring expansion was not observed, in contrast to the cyclopropane analogue. − The tosylhydrazone 22 of spiro[bicyclo[2.2.1]heptane‐2,1′‐cyclobutan]‐3‐one (21) and the related tosylates (28, 32) rearranged, in part, to afford derivatives of spiro[bicyclo[2.2.1]heptane‐7,1′‐cyclobutane] (29, 33, 34). In both series, ring expansion of the spiroannellated cyclobutane, by exo‐3,2‐C shift, was the major reaction, giving rise to a uniquely endo‐selective tertiary cation (36). Analogously positioned cyclopropane rings remain intact, due to stabilizing interactions with the neighboring positive charge which are lacking in the cyclobutane systems. − In CDCl3 solution, the tosylate 32 produced mixtures of isomeric tosylates by way of ion pair recombination. We observed that exo → exo shifts of the counterion proceed with little scrambling of 18O whereas complete equilibration of the tosylate oxygens is attained in exo → endo shifts.

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Dry ozonation. Method for stereoselective hydroxylation of saturated compounds on silica gel

Cited by 123 publications

References 0 publications

Formation of hydrotrioxides during ozonation of hydrocarbons on silica gel. Decomposition of hydrotrioxides

Formation of hydrotrioxides during ozonation of hydrocarbons on silica gel. Decomposition of hydrotrioxides

Comparison of the ozonolysis products of the methylnaphthalenes and dimethylnaphthalenes in hexane, methanol, and water

Rearrangements of Spirocyclobutane-Substituted 2-Norbornyl Cations

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