green and easy synthesis of xanthenes using formic acid as bio-based and green catalyst under solvent-free conditions

In this research study, a green synthetic route for eco-safe and solvent-free preparation of 12-aryl-tetrahydrobenzo[α]xanthene-11-ones, 1,8-dioxooctahydroxanthenes and 14-aryl-14h-dibenzo[α,j]xanthenes using formic acid as a bio-based, natural and versatile catalyst was developed. the notable advantages of this green approach are use of bio-based, natural, easy-tohandle and available readily green catalyst, absence of hazardous organic solvents, solvent-free conditions with good to high yields and short reaction times and one-pot reactions. furthermore, one of the source of environmental pollutions is the usage of organic solvents under reflux conditions and the need for column chromatography to purity the products. in this present work, the products were obtained through simple filter with no need column chromatographic separation.