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meso-Tetrahexylporphyrin was converted to its corresponding 7,8-dihydroxychlorin using an osmium tetroxide-mediated dihydroxylation strategy. Its diol moiety was shown to be able to undergo a number of subsequent oxidation reactions to form a chlorin dione and porpholactone, the first meso-alkylporphyrin-based porphyrinoid containing a non-pyrrolic building block. Further, the diol chlorin was shown to be susceptible to dehydration, forming the porphyrin enol that is in equilibrium with its keto-chlorin form. The meso-hexylchlorin dione could be reduced and it underwent mono- and bis-methylation reactions using methyl-Grignard reagents, and trifluoromethylation using the Ruppert-Prakash reagent. The optical and spectroscopic properties of the products are discussed and contrasted to their corresponding meso-aryl derivatives (where known). This contribution establishes meso-tetrahexyl-7,8-dihydroxychlorins as a new and versatile class of chlorins that is susceptible to a broad range of conversions to generate functionalized chlorins and a pyrrole-modified chlorin analogue. [ABSTRACT FROM AUTHOR]

Cobalt porphyrinoids find broad use as catalysts or electrode materials. Traditional solution state cobalt insertion reactions into a free base porphyrinoid to generate the corresponding cobalt complex generally require fairly harsh conditions, involving the heating of the reactants in high-boiling solvents for extended period of times. We report here an alternative method of cobalt insertion: A solvent-free (at least for the insertion step) mechanochemical method using a planetary ball mill with Co2(CO)8 as a cobalt source. The scope and limits of the reaction were investigated with respect to the porphyrinic substrate susceptible to the reaction conditions, the influences of different grinding aids, and bases added. While the mechanochemical method is, like other metal insertion methods into porphyrinoids, not universally suitable for all substrates tested, it is faster, milder, and greener for several others, when compared to established solution-based methods. [ABSTRACT FROM AUTHOR]