Sodium dithionitc

Diazoalkanes are u.seful is precursors to ruthenium and osmium alkylidene porphyrin complexes, and have also been investigated in iron porphyrin chemistry. In an attempt to prepare iron porphyrin carbene complexes containing an oxygen atom on the /(-carbon atom of the carbene, the reaction of the diazoketone PhC(0)C(Ni)CH3 with Fe(TpCIPP) was undertaken. A low spin, diamagnetic carbene complex formulated as Fe(TpCIPP)(=C(CH3)C(0)Ph) was identified by U V-visible and fI NMR spectroscopy and elemental analysis. Addition of CF3CO2H to this rapidly produced the protonated N-alkyl porphyrin, and Bit oxidation in the presence of sodium dithionitc gave the iron(II) N-alkyl porphyrin, both reactions evidence for Fe-to-N migration processes. ... 

When the required 1,2-diaminoarencs are not readily available it is often possible to utilize o-nitroanilines as substitutes. They can be successively reduced or hydrogenated and then cyclized [82, 91, 133], or the cyclization and reduction processes can be combined. Suitable reducing agents are triethyl phosphite, iron pentacarbonyl, titanium(III) chloride, Raney nickel-hydrazine, palladium-carbon, bisulfite or dithionitc, and metal-acid [54, 134,135]. Thus, 4,5-dimethyl 2-nitroaniline heated at 90"C (1 h) with formic acid and sodium dithionitc gives 5,6-dimethyIbenzimidazolc in 92% yield [136]. 

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