Reactions of ozonides

The photolytic reactions of ozonides have been reviewed <74AG(E)619>. Ozonide photolysis in the gas phase has been studied for its implications on the constitution of smog . The first step is... 

Tin tetrachloride mediates the reaction of ozonides with electron-rich alkenes such as allytrimethylsilane forming 1,2-dioxolanes 50 in moderate yields (Scheme 11) <1999TL6553>. 

Table 8 Reactions of ozonides with Lewis acids and allyltrimethylsilane...

Miscellaneous Reactions. In two comprehensive publications, Taylor and co-workers detail the reactions of 1,2-dioxines with stabilised ylides as a route to diastereomerically pure cyclopropanes (Scheme 18). The reaction of ozonides with stabilised ylides produces a,p-unsaturated carbonyl compounds (Scheme 19). The E/Z isomeric ratio of the final products is affected by the identity and position of heteroatom substituents on the ozonide heterocycle. ... 

The reaction of ozonides with olefins in the presence of BFa-EtgO has been shown to give 1,2-dioxacyclopentanes (44), probably via [3 - - 2] cycloadditions of aldehyde or ketone oxides. ... 

Ozonides react with catalytic quantities of chlorosulfonic acid (0.3 equivalents) in dichloromethane at 20 °C to yield 3,6-dialkyl-1,2,4,5-tetraoxans and/or 1,4-dialkyl-2,3,5,6,ll-pentaoxabicyclo[5.3.1]undecanes. The reaction of ozonides with chlorosulfonic acid has been extensively investigated by Miura and co-work-ers. The reaction pathways appear to vary with different substituents the proposed mechanism involves heterolytic fission of the carbon-oxygen bond of the peroxide bridge. For example, methylcyclopentene ozonide 472 reacted stereo-selectively with the reagent in dichloromethane to give initially compound 473 which subsequently rearranged to form the trans tetraoxan 474 (Equation 151). 

The reaction of ozonides with carbonyl compounds and hydrogen peroxide is catalysed by the presence of chlorosulfonic acid and provides a new synthetic route to the corresponding 2,3,5,6,ll-pentaoxabicyclo[5.3.1]undecanes in 3-35% yield. As an illustration, l-phenyl-6,7,8-trioxabicyclo[3.2.1]octane 481 reacted with p-tolualdehyde, hydrogen peroxide and chlorosulfonic acid (0.03 equivalents) in acetic acid at 20 °C (2 hours) to yield a mixture of the products 482-484 (Equation 154). 

The stability of the alkali metal ozonides increases from Li to Cs alkaline-earth ozonides exhibit a similar stability pattern. Reaction of metal ozonides with water proceeds through the intermediate formation of hydroxyl radicals. 

The unstable ammonium ozonide [12161 -20-5] NH O, prepared at low temperatures by reaction of ozone withHquid ammonia, decomposes rapidly at room temperature to NH NO, oxygen, and water (51). Tetrametbylammonium ozonide [78657-29-1] also has been prepared. 

The ozonides are characterized by the presence of the ozonide ion, O - They are generally produced by the reaction of the inorganic oxide and ozone (qv). Two reviews of ozonide chemistry are available (1,117). Sodium ozonide [12058-54-7] NaO potassium ozonide [12030-89-6] 35 rubidium ozonide [12060-04-7] RbO and cesium ozonide [12053-67-7] CsO, have all been reported (1). Ammonium ozonide [12161 -20-5] NH O, and tetramethylammonium ozonide [78657-29-1/, (CH ) NO, have been prepared at low temperatures (118). 

Most ozonolysis reaction products are postulated to form by the reaction of the 1,3-zwitterion with the extmded carbonyl compound in a 1,3-dipolar cycloaddition reaction to produce stable 1,2,4-trioxanes (ozonides) (17) as shown with itself (dimerization) to form cycHc diperoxides (4) or with protic solvents, such as alcohols, carboxyUc acids, etc, to form a-substituted alkyl hydroperoxides. The latter can form other peroxidic products, depending on reactants, reaction conditions, and solvent. 

The principal organic reaction of ozone is its addition to the carbon-carbon double bond of an ethylenic compd. The resulting ozone-olefin addition compd is known as an ozonide. Decompn of the ozonide gives a mixt of oxygenated products containing carbonyl compds and acids. 

The reaction of ozone with an unsaturated organic compd was reported more than a century ago (Schonbein, JPraktChem 66, 282 (1855)), however, complete explanation of this reaction has not been made until recent times. In 1905, Harries (Ref 1) postulated that the addition of ozone to an olefin resulted in the formation of an ozonide according to the formula ... 

Gas-phase products from the reactions of ozone with the monoterpenes (-)-p-pinene and (+)-sabinene included the ketones formed by oxidative fission of the exocyclic C=C bonds as well as ozonides from the addition of ozone to this bond (Griesbaum et al. 1998). 

The suggested fragments from (54a) are a carbonyl compound (58) and a peroxy zwitterion (59), the latter then effecting a 1,3-dipolar addition on the former to yield the ozonide (57a). Alternative reactions of the zwitterion (59), including its polymerisation, lead to the formation of the abnormal products that are sometimes observed in addition to the ozonide, If ozonolysis is carried out in MeOH as solvent then (59) is trapped , as it is formed, by its conversion into the relatively stable a-hydroperoxy ether (60) ... 

Reaction of caesium or potassium ozonides with water or aqueous acids is violent, producing oxygen and flashes of light. 

It has been shown that abstraction of an a or p hydrogen from the ozonide also can occur. In fact, a-hydrogen abstraction can occur up to 2.5 times faster than Criegee fragmentation [36], As an example, the proposed mechanism for the reaction of ds-2-butene with ozone is shown in Figure 4. 

There are many ways to categorize the oxidation of double bonds as they undergo a myriad of oxidative transformations leading to many product types including epoxides, ketones, diols, endoperoxides, ozonides, allylic alcohols and many others. Rather than review the oxidation of dienes by substrate type or product obtained, we have chosen to classify the oxidation reactions of dienes and polyenes by the oxidation reagent or system used, since each have a common reactivity profile. Thus, similar reactions with each specific oxidant can be carried out on a variety of substrates and can be easily compared. 

Reaction of ozone with a double bond is not surprisingly a function of the nucleophilicity or electron density of the double bond. Therefore, in ozonolysis of octamethylsemibullvalene208 (122) as well as for hexamethylbicyclo[2.2.0]-2,5-hexadiene209 and octamethyltricyclo-octadiene210 the diozonides, e.g. 123, are formed as the major product (equation 33). On the other hand, for hexachlorobicyclopentadiene211 (124), hexachlorobicycloheptadiene212 and 2-chloro-3-methyl-l,3-butadiene213 attack takes place at the nonchlorinated double bond only to form the ozonide 125 (equation 34). 

Reactions of 07 with Alkanes and Alkenes. Ozonide ions are intermediate in reactivity between 0 and 01 (20,21). On MgO they re-... 

The formation of similar reaction products when alkanes react with either 0 or 07 suggests that the ozonide ion may first dissociate according to the reverse of reaction 2, and the alkane would then react with the 0 ion. However, the lifetime for the 07 ion under vacuum is considerably longer than the lifetime for the reaction of 07 with an alkane. In addition, each alkane reacts with 07 at a characteristic rate therefore, it seems likely that the alkane reacts directly with 07> rather than indirectly with 0 . 

The reaction gave only the rearrangement products 333 and 334, and the side product 335, as expected from the reactivity of alkylidenecyclopropane derivatives (Scheme 49). Compound 333 might arise from the 0-0 bond cleavage followed by the rearrangement of a cyclopropyloxy cation to an oxoethyl cation (Scheme 49, path a). Spiro-hexanone 334 could arise from a different fragmentation of ozonide C-O bond and further cyclopropyloxy-cyclobutanone rearrangement (Scheme 49, path b). Oxirane 335 can eventually derive from the same path b or from other side processes [13b]. 

There is some information concerning the reaction of ozone with chemicals under aqueous conditions. The information available suggests that double-bond cleavage takes place, just as it does under nonaqueous conditions, except that ozonides are not formed. Instead, the zwitterionk intermediate reacts with water, producing an aldehyde and hydrogen peroxide. In addition to double-bond cleavage, a number of other oxidations are possible. Mudd et showed that the susceptibility of amino acids is in the order cysteine, tryptophan, methionine. 

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