Vinyl group, oxidation carboxyl

Potassium permanganate oxidation of a vinyl group to a carboxyl group can be used to prepare fluormated carboxyhc acids with aliphatic [3/ ] (equanon 30) or alicychc 39] (equation 31) skeletons... 

Oxidation of chlorin e6 and isochlorin e6 with permanganate gives purpurin-5 (116) and purpurin-3 (117), respectively. If pheophorbide b is oxidized, the corresponding 7-carboxylic acid (118 pheophorbide by) results saturation of the vinyl group and dehydrogenation gives pheoporphyrin by (119) which can be converted into demethyldeoxyphylloerythrin... 

The standard methods of oxidation of pyridines and other heteroaromatic nitrogen compounds make use of peroxy acids or hydrogen peroxide in carboxylic acid solution. Peracetic acid, peroxymono-phthalic acid and MCPBA can all convert simple pyridines to the N-oxides. For example, the pyridine (45) was oxidized at nitrogen by MCPBA without attack on the vinyl group. Peroxymaleic acid has... 

Oxidation sometimes gives the carboxylic acid, but the use of hydrogen peroxide (as with other free radical initiators) causes polymerization. Under the influence of radical initiators it is possible to induce thiols to add in an anti-Markownikov manner across an -vinyl group (Scheme 139), while ionic catalysts promote normal electrophilic addition <75CHE1416). 

Dehydrogenation of the lactone acid (XVII) with palladium-charcoal yielded 2-ethylnaphthalene and under the same conditions the acid X afforded 2-ethyl-3-methylnaphthalene. The formation of these two hydrocarbons disproved the earlier hypotheses that the carbonyl group of himbacine was attached to a tertiary carbon atom and that the ethyl groups of 2-ethyl-6-methylpyridine and 2-ethyl-3-methylnaphthalene, isolated from the selenium dehydrogenation of himbacine, were derived from the same structure in the alkaloid. Moreover, since the results of the Hofmann degradation and the oxidation experiments had shown that the 6-(l,2-dimethylpiperidyl)-vinyl group was attached to a decalin residue by reason of the formation of the C-13 ketones, it only remained to establish the point of attachment. For this purpose the carboxyl group... 

Osmium tetroxide can be used in substoichiometric amounts because the periodate oxidizes the osmium back to the tetroxide. The periodate therefore plays two roles, one to cleave the diol and the other to re-oxidize the osmium(VI), although it does not itself react with alkenes or aldehydes. Reaction often occurs at the least-hindered alkene and therefore provides a selective method for the oxidative cleavage of, for example, a vinyl group in the presence of a di- or trisubstituted alkene. If potassium permanganate is used in place of osmium tetroxide, then any aldehyde products are usually oxidized to give the corresponding carboxylic acids. 

The main process that occurs in silicones that contain vinyl groups is photo-scission. Also, the vinyl groups are photo-oxidized into silanols, carboxylic acids, and esters. Part of the silanols are condensed into high molecular weight silicones [585]. 

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