Sulfamic acid supported on cellulose as a biodegradable and recyclable heterogeneous catalyst for the synthesis of tetrahydrobenzo xanthene derivatives

Cellulose bonded N-propyl diethylene tetra sulfamic acid (CBPDETSA) was successfully applied as a green and recyclable acidic catalyst for the synthesis of tetrahydrobenzo [a] xanthene-11-one as an important class of potentially bioactive compounds. The products are obtained by the coupling of 2-naphtol, cyclohexadione and aldehyde derivatives in good to high yields (70- 92%) under solvent-free conditions. The reactivity of different aromatic aldehydes was influenced by the nature and position of the substituents on the aromatic ring. The benzaldehyde derivatives having an electron-withdrawing substituent were highly reactive and gave the products in excellent yields. Also, the catalyst could be recovered by filtration and subjected to further reaction processes. The results show that the yield of product after five runs was only slightly reduced.