The one-pot synthesis of 14-alkyl- or aryl-14H-dibenzo[aj]xanthenes catalyzed by task-specific ionic liquid

A Bronsted-acidic task-specific ionic liquid, 1-methyl-3-propane sulfonic-imidazolium hydrosulfate ([MIMPS]HSO4), was employed as a catalyst for the synthesis of 14-alkyl- or aryl-14H-dibenzo[aj]xanthenes via the one-pot condensation of beta-naphthol with aliphatic or aromatic aldehydes. Various aliphatic and aromatic aldehydes were used in the reaction and in all cases the desired products were synthesized successfully. The novel synthesis method offers the advantages of high yields, short reaction times, simplicity and easy workup compared to the conventional method of syntheses. The catalyst could be recycled and reused five times without a noticeably decrease in its activity. (C) 2008 Elsevier Ltd. All rights reserved.