Metalloporphyrin hydrogenated intermediates

Use of transition metal catalysts opens up previously unavailable mechanistic pathways. With hydrogen peroxide and catalytic amounts of methyl trioxorhe-nium (MTO), 2-methylnaphthalene can be converted to 2-methylnaphtha-l,4-qui-none (vitamin K3 or menadione) in 58 % yield and 86 % selectivity at 81 % conversion (Eq. 10) [43, 44]. Metalloporphyrin-catalyzed oxidation of 2-methylnaphtha-lene with KHSOs can also be used to prepare vitamin K3 [45]. The MTO-catalyzed process can also be applied to the synthesis of quinones from phenols [46, 47]. In particular, several benzoquinones of cardanol derivatives were prepared in this manner [48], The oxidation is thought to proceed through the formation of arene oxide intermediates [47]. 

Guo, C.C., J.X. Song, X.B. Chen, and G.R Jiang (2000). A new evidence of the high-valent oxo-metal radical cation intermediate and hydrogen radical abstract mechanism in hydrocarbon hydroxylation catalyzed by metalloporphyrins. J. Mol. Cat. A 157, 31-40. 

Carbon dioxide radical anions, C02 , are commonly used in aqueous chemistry as a reducing agent for metalloporphyrins or as intermediate in the formation of superoxide anion. COf has been reported to undergo efficient electron transfer reactions with methyl violo-gen, quinones, alkyl halides, fumarates, nitro and nitrosobenzenes and chlorinated benzaldehydes. With nitrobenzenes and chlorinated benzaldehydes, electron attachment occurs on the nitro and aldehyde groups, respectively. CO2 radicals have also been reported to add to some unsaturated compounds such as acrylamide and pyridin-3-ol. Efficient hydrogen abstraction from mercaptobenzenes have also been reported. 

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