Selective Hofmann alkylation of aromatic-aliphatic diamines in the presence of carbon dioxide

Selective Hofmann alkylation at arylamino group in carbon dioxide medium was demonstrated on model diamines containing aliphatic and aromatic primary amino groups, namely, 2-H₂NC₆H₄CH₂NH₂, 3-H₂NC₆H₄CH(Me)NH₂, and 4-H₂NC₆H₄CH₂CH₂NH₂. Depending on the spatial factors, di- or trialkylarylammonium derivatives are selectively formed in amide solvents (DMF, DMA) without additional base.