[2+1] Cycloaddition reaction of bis(iodozincio)methane with 1,2-diketones: face-to-face complex of bis(iodozincio)methane and 1,2-diketones as a reaction intermediate

A reaction of 1,2-diketone with bis(iodozincio)methane gave a cyclopropanediol derivative via [2+1] cycloaddition. The reaction proceeded via a sequential nucleophilic attack of the dizinc reagent to a couple of carbonyl group in the substrate. The reaction proceeded with high diastereoselectivity to give cis-isomer. Detailed mechanistic studies have been examined by ab initio calculation.