2-Iodoethanols from aldehydes, diiodomethane and isopropylmagnesium chloride

Diiodomethane and iodoform react with i-PrMgCl by halogen–metal exchange. The resulting magnesium reagents tolerate several functional groups, but aldehydes are converted selectively into iodoethanols in good to high yields. These mild reagents preserve racemization prone centres. The substrate controlled diastereoselectivity provides straightforward access to important intermediates of peptidomimetics.