Diastereoselective Preparation of Spiro[2,3‐dihydrofuran‐3,3’‐oxindole] Derivatives by an Atom‐Economic Tandem Reaction in Water

Abstract A catalyst‐free tandem reaction was developed for the clean synthesis of spiro[2,3‐dihydrofuran‐3,3’‐oxindole] derivatives from 2‐(2‐oxoindolin‐3‐yl)malononitriles and aldehydes in water. This method has an extensive substrate scope. The targeted products were easily isolated by filtration in high yields and excellent diastereoselectivities. The reaction also features numerous advantages, including step/atom economy, both catalyst and additive‐free, no organic solvents, simple work‐up, short reaction times, and environmentally friendly conditions. The present strategy utilizes simple conditions, demonstrating the potential application in the synthesis of pharmaceuticals and biologically active compounds.