Copolymer p-toluenesulfonic acid: an efficient catalyst for synthesis of tetrahydrobenzo[a]xanthenes-11-one derivatives

Copolymer p-toluenesulfonic acid (CPPTSA), is an efficient catalyst for the synthesis of tetrahydrobenzo[a]xanthenes-11-one derivatives via the condensation of various aldehyde, and dimedone with 2-naphthol. Copolymer p-toluenesulfonic acid is a novel heterogeneous strong acid catalyst. Furthermore, the catalyst possesses the advantages of the high thermal stability (200 ?C) and low cost for the simple synthetic procedure. Simplicity of procedure, mild conditionhigh yields, easy workup and green process are some advantages of this protocol.