Synthesis of Tetrahydrobenzo[a]xanthene-11-one Derivatives Using ZrO2–SO3H as Highly Efficient Recyclable Nano-catalyst

The catalytic effect of Zirconia Sulfuric Acid (ZrSA) nanoparticle which is synthesized from thereaction of ZrO with chlorosulfonic acid has been investigated in the synthesis oftetrahydrobenzo[a]xanthene-11-ones by one-pot three-component reaction of β-naphthol,aromatic aldehydes, and dimedone. Different reaction conditions were studied in the presence ofZrSA nanoparticle as catalyst. The results showed that ZrSA exhibited high catalytic activitytowards the synthesis of tetrahydrobenzo[a]xanthene-11-ones, with the desired products beingformed in high yields. Furthermore, the catalyst was recyclable and could be reused at least threetimes without any discernible loss in its catalytic activity. Overall, this new catalytic method forthe synthesis of tetrahydrobenzo[a]xanthene-11-ones provides rapid access to the desiredcompounds under solvent-free conditions at 110 °C following a simple work‐up procedure, andavoids the use of harmful organic solvents. This method therefore represents a significantimprovement over the methods currently available for the synthesis oftetrahydrobenzo[a]xanthene-11-ones.