AlCl3‑Promoted Intramolecular Indolinone-Quinolone Rearrangement of Spiro[indoline-3,2′-quinoxaline]-2,3′-diones: Easy Access to Quinolino[3,4‑b]quinoxalin-6-ones

A facile and direct intramolecular indolinone-quinolone rearrangement was developed for the synthesis of quinolino­[3,4-b]­quinoxalin-6-ones from spiro­[indoline-3,2′-quinoxaline]-2,3′-diones, which are readily available with use of isatines, malononitrile, and 1,2-phenylenediamines under quite mild conditions. This efficient approach provides excellent yields and could potentially be used for the construction of a diverse library of quinolino­[3,4-b]­quinoxalin-6-ones for high-throughput screening in medicinal chemistry. The reaction mechanism is explored by extensive DFT calculations.