A study for the synthesis of dibenzo [a,j] xanthenes and 1-amidoalkyl 2-naphthols catalyzed by [Hmim][HSO4] as a green, efficient and reusable catalyst under solventfree conditions

A convenient and efficient procedure for the synthesis of 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes by condensation of 2-naphthol and aldehydes in the presence of Methylimidazolium hydrogensulfate, as a Brönsted acidic ionic liquid ([Hmim]HSO4), is described. Both aromatic and aliphatic aldehydes reacted easily to afford the corresponding 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes in good yields under solvent-free conditions. Moreover, the synthesis of 1-amidoalkyl 2-naphthols is studied by condensation of aromatic aldehydes with amides or urea and 2-naphthol in the presence of [Hmim]HSO4. Using solventfree conditions, non-toxic and inexpensive materials, simple and clean work-up, short reaction times and high yields of the products are the advantages of this method.