MODEL STUDIES FOR THE COENZYME-B-12-CATALYZED METHYLMALONYL-]SUCCINYLREARRANGEMENT - THE IMPORTANCE OF HYDROPHOBIC PERIPHERAL ASSOCIATIONS

The interaction between a vitamin B-12 derivative containing a periphe ral C-18 alkyl chain (see 1a) and a (methyl)thiomalonate substrate bea ring alkyl chains of various length at the thioester group (see 5) was investigated. A catalytic cycle was established for the methylmalonyl -->succinyl rearrangement by using electrochemistry and photolysis (se e Scheme 3). Increased yields of the succinate relative to the reducti on product were obtained (2:3 ratio), when the reaction was run in MeO H/H2O, and when both the substrate and the catalyst had an octadecyl s ubstituent capable of hydrophobic interactions.