Vitamin B_(12)model complex catalyzed methyl transfer reaction to alkylthiolunder electrochemical conditions with sacrificial electrodet

摘要

Catalytic methyl transfer reactions from methyl tosylate to 1-octanethiol catalyzed by heptamethylcobyrinate perchlorate, [Cob(II)7C_1 esterjClO_4, were investigated under electrochemical conditions. Asa model study for the cobalamin-dependent methyl transfer reaction from methyltetrahydrofolate tohomocysteine, controlled-potential electrolyses were carried out at –1.0 V vs. Ag/AgCl using a zincplate as the sacrificial anode at 50 °C in the dark. A turnover behaviour for the methyl transfer reactionwas observed for the first time under non-enzymatic reaction conditions. Co(I) species, which isgenerated from the continuous electrolysis of [Cob(II)7C_1ester]ClO_4, and its methylated CH_3-Cocomplex were found to be important intermediates. The mechanism for such a methyl transfer reactionwas investigated by product analysis, electronic spectroscopy and ESR spin-trapping experiments. Asimple vitamin B_(12)model complex was also utilized as the catalyst for the methyl transfer reaction.