Unusual alkylation reactions in the biosynthesis of natural products and elucidation of their reaction mechanisms

Methylcorrinoids as methylation coenzymes in radical C-methylations: Unusual alkylation reactions at nonactivated carbon atoms of natural products can be explained for the first time by a unique reaction of methylcobalamin (1). According to the mechanistic course of the reaction the corrin part of the vitamin B12 derivative 1 undergoes substitution at the methyl group by carbon radicals with inversion of configuration.