Model experiments pertaining to the mechanism of action of vitamin B12-dependent α-methyleneglutarate mutase

Abstract

Photolysis of di-t-butyl 1-bromomethylcyclopropane-1,2-dicarboxylate (1a) in cyclopropane containing triethylsilane and di-t-butyl peroxide gave the 4-methylenepent-2-yl-1,5-dioic acid radical (3c), which was also produced from treatment of (1a), its cis-isomer (2b), di-t-butyl-2-bromo-4-methyleneglutarate (3a), or di-t-butyl 2-bromo-methyl-3-methylenesuccinate (4b), with triphenyltin hydride; these experiments support a mechanism via protein-bound free radicals for the B₁₂-dependent enzyme α-methyleneglutarate mutase.