Completely Diastereoselective Radical Reactions Using Arenechromium Tricarbonyl Complexes.

Reaction of chromium tricarbonyl complexed aryl aldehydes and ketones with samarium(II) iodide and methyl acrylate results in formation of cyclic lactones as single diastereomers. Complete diastereoselectivity is demonstrated with aldehydes and ketones α or β to the aromatic ring with radical coupling directed anti to the chromium tricarbonyl moiety.