Ring cleavage oxidative

Sufficiently strong oxidants are able to cleave the carbon—carbon bonds in aromatic rings. Ozone, although less reactive toward arenes than alkenes, is effective in such 

Arenes can also be cleaved with peroxyacetic acid831 and permanganate.636,832 Ru04 effectively oxidizes arenes to cleavage products with the use of a cooxidant such as NaT04. Violent reaction with benzene and immediate oxidation of several other aromatics such as triphenylmethane and tetralin834 take place, but oxidation products could not be isolated. Since alkanes are resistant to Ru04, 

By far the most important aromatic cleavage reactions are the conversion on vanadia of benzene to maleic anhydride and that of naphthalene to phthalic anhydride. These oxdiations are treated in Section 9.5.4. 

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Entries 7 to 9 in Scheme 12.18 are illustrative of these oxidative ring cleavages. 

The synthesis in Scheme 13.41 is also built on the desymmetrization concept but uses a very different intermediate. cA-5,7-Dimethylcycloheptadiene was acetoxylated with Pd(OAc)2 and the resulting all-cA-diacetate intermediate was enantioselectively hydrolyzed with a lipase to give a monoacetate that was protected as the TBDMS ether. An anti Sw2 displacement by dimethyl cuprate established the correct configuration of the C(2) methyl substituent. Oxidative ring cleavage and lactonization gave the final product. 

The oxidative ring cleavage undergone by purpurogallin quinone 14 is assumed to provide the excitation energy necessary to cause the tropolones to act as fluorescers. Perhaps dioxetane derivatives are key intermediates, as in the anthracene derivatives discussed in (IV. D.). 

The sydnone TTMS 73 (Section 5.03.12) has been shown to undergo oxidative ring cleavage by cytochrome P450 <1998MI739>. 

Another example is the asymmetric synthesis of ( )-pinidine 208 and its isomers. These syntheses are achieved via asymmetric enolization, stereoselective cyclopropanation, and oxidative ring cleavage of the resulting cyclopropanol system (Scheme 5-68).123... 

On the other hand, aromatic nitro compounds having either lowest (n,7t )-or (7r,7i )-triplets are able to induce oxidative ring cleavage of aromatic methoxy compounds 65-67) a. typical example is given below. 

Oxidative ring cleavage of cyclohexanones is achieved in ethanol at a platinum anode. Cleavage of the carbon-carbonyl bond occurs and the carbonyl centee is trapped as the carboxylic acid. The radical centre formed after bond cleavage is oxidised to the carbocation. This rearranges to the most stable centre and is then trapped by the carboxyl group to form a lactone [4, 5], An identical process is... 

A-Tosyl-4,5-dicyano-l,3,2-dithiazole (8) when treated with CI2 or SOCI2 undergoes a decomposition to 4,5-dicyano-l,3,2-dithiazolium chloride (51), but not with extrusion of tosyl chloride 3,4-dichloro-5-cyanoisothiazole (52) as a product of oxidative ring cleavage was discovered in the reaction mixture <90CB881>. 

In conclusion, it should be noted that XO, NADPH oxidase, NO synthase, and peroxidases are major but not only free radical-generating enzymes. For example, superoxide participates in the oxidative ring cleavage of various indoleamine derivatives by indoleamine... 

ID) By hydrogen peroxide. Oxidative ring cleavage of propylene euJfide with 30% hydrogen peroxide baa afforded 2-hydroxy I-pr paiK>-sulfonic acid and sulfuric add as the only identified products 11 ... 

N-sulfonation N-Glucuronidation, hydroxylation, N-oxidation, ring cleavage, oxidation... 

Analogously with the reaction depicted in equation (37), a-N-morpholino oxime (59) underwent oxidative ring cleavage under standard Beckmann conditions (equation 39). Azide nitrogen assisted cleavage of the steroidal azido oxime (60) gave a dinitrile (equation 40). ... 

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