Solvent- and transition metal-free synthesis of spiro [cyclopropane-1,3-oxindoles] from cyclic diazoamides

A highly efficient method to synthesize spiro[cyclopropane-1,3-oxindoles] from cyclic diazoamides and mono-substituted or 1,2-disubstituted alkenes under solvent- and transition metal-free conditions is reported. The reaction offers proficient access to synthetically useful and biologically important spiro[cyclopropane-1,3-oxindoles]. The advantageous features of this sustainable method are being metal-free, shorter reaction time, cost-effectiveness, eco-friendliness and excellent yields. The selectivity and yield are comparable with transition metal-catalyzed cyclopropanation reactions. (C) 2014 Elsevier Ltd. All rights reserved.