Unprecedented two-step synthesis of symmetrical diarylamines from 2-alkyl-1,3-dinitropropanes

This letter reports a new, two-step synthesis of symmetrical diarylamines from 1,3-dinitropropanes, by their reaction with acrolein under basic conditions (Al2O3, neat), followed by aromatisation of the obtained 2,4-dinitrocyclohexanols, through their treatment with four equivalents of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), in acetonitrile as a solvent, and warming overnight at 60 °C.