Switching between novel samarium(II)-mediated cyclizations by a simple change in alcohol cosolvent

[GRAPHICS] gamma,delta-Unsaturated ketones undergo two very different stereoselective cyclization reactions mediated by samarium(II) iodide depending upon the alcohol cosolvent used in the reaction. Switching between an unprecedented aldol spirocyclization and a novel cyclobutanol-forming process can be achieved simply by changing the alcohol cosolvent from methanol to tert-butyl alcohol.