A facile and efficient DBU-mediated 3 + 3 cycloaddition reaction of N-2,2,2-trifluoroethylisatin ketimines with diazo esters for the synthesis of trifluoromethyl dihydro-1,2,4-triazine-spirooxindole derivatives has been developed. The reaction proceeds under mild conditions with a broad substrate scope, tolerating various electronically and sterically diverse substituents to afford moderate to excellent yields. Furthermore, a one-pot cycloaddition/oxidation strategy is established to achieve efficient synthesis of trifluoromethyl-1,2,4-triazine-spirooxindoles. This study not only enriches the structural diversity of spirooxindoles but also provides a valuable synthetic tool for developing novel bioactive molecules in medicinal chemistry.
Chen et al. (Fri,) studied this question.