A novel MgI2 mediated unusual dimerization–spirocyclopropanation of bromo isomerised Morita–Baylis–Hillman adduct of isatin: a facile synthesis of 3-spirocyclopropane-2-oxindole derivatives

A novel magnesium iodide mediated unusual dimerization–spirocyclopropanation of bromo isomerised Morita–Baylis–Hillman adducts of isatin afforded highly functionalized 3-spirocyclopropane-2-oxindole derivatives as regioisomers in good combined yield. It has been observed that the regioselectivity is dependent on the nature of electron withdrawing group at the activated position. A plausible mechanism involving organomagnesium reagent has been proposed.