B2(OH)4-mediated one-pot synthesis of tetrahydroquinoxalines from 2-amino(nitro)anilines and 1,2-dicarbonyl compounds in water

A practical one-pot synthesis of tetrahydroquinoxalines from readily available 2-amino(nitro) anilines and 1,2-dicarbonyl compounds mediated by diboronic acid with water as both a solvent and a hydrogen donor under metal-free conditions has been discovered. The deuterium labeling experiments with D2O were also performed to demonstrate that water acts as the hydrogen donor.