Synthesis of xanthenes using 1,3 cyclohexadione and aldehydes in supercritical ether

Nowadays supercritical fluid is an importance for organic synthesis studies. In supercritical conditions solvents allow using as synthesis area owing to increasing solving power and decreasing viscosity that are connecting with temperature and pressure. But using of CO2 is limited because of inadequate solving power of CO2[1]. On the other hand, there are many studies in the subcritical and supercritical water. There are rare studies about organic synthesis studies in supercritical diethyl ether in articles. In this study, Xanthene derivatives 3 were synthesized using 1,3- cyclohexadione 1 and several aldehydes 2 in supercritical diethyl ether. This reaction takes 60 min at 200 oC and 40-50 atm. There is no need any purification of the reaction product. So, this study suits to green chemistry for synthesis of xanthenes which is a new method.