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 a second reaction process. The results show that the yield of product after five runs was only slightly reduced.