Silica gel-promoted practical synthesis of oxindole–nitrones from diazooxindoles and nitrosoarenes under solvent-free conditions†
Abstract
A practical method for the synthesis of oxindole–nitrones promoted by silica gel was developed with good results. The protocol is environmentally friendly as the reaction proceeds under solvent-free conditions with broad substrate scope, and high selectivity and chemical yield, and the silica gel can be quantitatively recovered and reused multiple times.