OXIDATIVE ADDITION OF PY(DMGH)(2)CO-NA- AN UNUSUAL REACTION WITH THE COBALOXIME LIGAND( TO A RIBOFURANOSYL BROMIDE )

Reaction of 2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl bromide (12) with NaCo(dmgH)(2)py (dmgH = dimethylglyoxime monoanion) in CH3CN was expe cted to proceed by normal oxidative addition to the carbon-bromine bon d to form 2,3,5-tri-O-benzoyl ribofuranosyl cobaloxime (4) with a carb on-cobalt bond in place of the carbon-bromine bond. Instead, the major products, the isomeric (mixture of alpha- and beta-anomers) dimethylg lyoxime adducts lglyoximato)-2,3,5-tri-O-benzoyl-D-ribofuranosides (17 ), were the result of reaction at the oxygen of the dimethylglyoxime l igand rather than at the cobalt.