Investigation of efficient synthesis of 1, 8-dioxo-octahydroxanthene derivatives under solvent-free grinding method

Abstract

In these studies, we had observed polyaniline (PANI) supported p-toluene sulfonic acid (TsOH) and FeCl 3 (PANI-TsOH, PANI-FeCl 3 ) as excellent reusable solid acid catalysts for the synthesis of 1, 8-dioxo-octahydroxanthene derivatives 4(a-g) under solvent-free grinding method at mild conditions. Additionally, in the same optimized condition ferric nitrate nonahydrate also acted as (non-reusable) very reactive inexpensive Lewis acid catalyst. The ferric nitrate nonahydrate lost its activity in the form of Clayfen (Clay-supported ferric nitrate) catalyst.