Nano titania-supported sulfonic acid (n-TSA) as an efficient, inexpensive, and reusable catalyst for one-pot synthesis of 1, 8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives

Abstract

This paper explains how with the help of nano titania-supported sulfonic acid (n-TSA), new 1,8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives can be produced. To do this, at first n-TSA, which is relatively cheap, easy separable and reusable was made. Next, using this nano catalyst,1,8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives were synthesized from di-ketones and various aromatic aldehydes/or malononitrile without using solvent. Appropriate one-pot operation using different aromatic aldehydes with both electron donating and withdrawing groups have resulted in the best yields. Reusability of the nano catalyst, environmental friendliness, reduced reaction time, non-toxic reaction medium and catalyst high activity are substantial advantages of this work. Nowadays, it is really important that the catalyst can be recovered easily and reused five times while maintaining catalytic activity.