Synthesis of Novel bis-Spirooxindoles Using Triethylamine as a Homogeneous Base Catalyst under Mild Conditions

Abstract

We now report our investigation into the preparation of novel bis-spirooxindoles (2) under mild conditions (Scheme 1). As starting materials, we used spirooxindoles (1), themselves readily prepared from malononitrile, isatin derivatives, and cyclohexanones. In a procedure of particular interest for its convenience, the bis-spirooxindoles were generated in methanol with triethylamine as a homogeneous base catalyst at room temperature (see Experimental section).