Ketones, aromatic oxidation

In 2003, Velusamy and Punniyamurthy reported on a copper(II)-catalyzed C—H oxidation of alkylbenzenes and cyclohexane to the corresponding ketones with 30% hydrogen peroxide (Scheme 131). The reaction was catalyzed by the copper complex 192a depicted in Scheme 131 and yields were high in the case of alkylbenzenes (82-89%) whereas cyclohexanone was obtained with a low yield of 18%. Chemoselectivity was very high in every case neither aromatic oxidation nor oxidation at another position of the alkyl chain was observed. 

Permanganate ion is a strong oxidant and tends to cleave aromatic side chains. However, when used under phase-transfer conditions,109,849 it converts benzylic methine groups into alcohols, and benzylic methylene compounds to ketones. Convenient oxidations can be carried out when KMn04 is applied in Et3N, an organic solvent (CHC13), and traces of water at room temperature.850... 

In addition, manganese oxide oxidizes benzylic methyl or methylene to carbonyl [814] and cleaves the carbon bonds of vicinal diols [577, 522]. It converts amines into imines [577, 525] tertiary amines into secondary amines [572], formamides [526, 527, 525], or ketones aromatic primary amines [575, 525] and hydrazo compounds [525] into azo compounds hy-droxylamines into nitroso [576] or nitro compounds [525] hydrazones into diazo compounds [520] phosphines into phosphine oxides [575] thiols into disulfides [576] and sulfides into sulfoxides [541]. 

Secondary benzylic chlorides and bromides give aromatic ketones on oxidation with chromium trioxide [5<5f>] or with tetrabutylammonium hypochlorite [690] (equations 198 and 199). 

More than 800 chemicals have been identified as being toxic to the skin. These include aliphatic, aromatic and chlorinated hydrocarbons, alcohols, esters, ethers, glycols, aldehydes, ketones, inorganic oxidizers, heavy metals, acids, alkalis, pesticides, plasticizers, polynuclear aromatic compounds, POPs, and surfactants J1-3 A partial list of these is contained in Table 27.1. A more complete list is available on the Scorecard web site.I3 ... 

Hydrogenation of CO. COj (Fischer-Tropsch), olefins, oximes, nitriles, phenols, ben7)4 alcohols, aryl amines, aromatic heterocycles, cyclopentane. aliphatic ketones, nitrobenzenes, oxidation of hydrocarbons Ammonia synthesis... 

This method is well suited to the formation of symmetrical pyrazines, " but if both diketone and diamine are unsymmetrical, two isomeric pyrazines are formed. The dihydro-pyrazines can be dehydrogenated and they will also react with aldehydes and ketones, with introduction of another alkyl group at the same time as achieving the aromatic oxidation level. ... 

This synthesis uses the approach of starting from a pyrrole the cyclic ketone intermediate is in general a useful intermediate for the synthesis of 4-substituted indoles - in this case a sulfur substituent - it is already at the aromatic oxidation level needing only the loss of the 4-chlorophenylthiol. 

In general, better results are obtained with Raney nickel catalysts, especially in large-scale reactions. The preferential formation of the thermodynamically most stable product can be used, e.g., in the synthesis of steroids from aromatic precursors such as 1324. Here hydrogenation yields the tram-fused product with a nearly equimolar mixture of the two isomeric alcohols, which can be converted into the corresponding ketone by oxidation with chromium trioxide24. 

Ketone, aromatic nitrate, tertiary amine, pyridine, sulfone, trialkyl phosphate or phosphine oxide + 0 + + 0 + +... 

---