A new model for coenzyme B₁₂ based on a Costa‐type ligand

Abstract

Abstract The synthesis of a new Costa‐type ligand (H 2 mdo), in which the propylene bridge has been replaced by a methylenedioxy bridge has been accomplished: two molecules of butanedione monoxime are coupled via a CH 2 group by reaction with CH 2 Cl 2 and 50% aqueous NaOH in the presence of a phase‐transfer reagent. Dihalidocobalt and alkyl(halido)cobalt complexes of the deprotonated ligand have been prepared and structurally characterized by NMR spectroscopy.