Stereoselective cyclizations mediated by functionalized organomagnesium reagents and catalyzed by cobalt or copper salts

The iodine–magnesium exchange reaction with i-PrMgCl allows a mild preparation of functionalized arylmagnesium compounds bearing a leaving group in the molecule. With the appropriate transition-metal catalyst (a copper or cobalt salt), cyclization reactions occur leading to five- or six-membered ring systems in good yields.