Regioselective 2,7-dimethyl-9-phenyl xanthen-9-yl protection and deprotection of nucleosides under mild conditions

Abstract

A simple and efficient protocol is developed for regioselective protection of primary hydroxyl group of nucleosides using 2,7-dimethylpixyliumtrifluoroacetate, prepared in-situ from 2,7-dimethyl-9-phenylxanthen-9-ol (DMPx-OH) and trifluoroacetic anhydride (TFAA). Furthermore deprotection of DMPx group is accomplished with TFAA in shorter reaction times with excellent yields in DCM:Methanol solvent system. Both procedures are successfully implemented on gram scale for synthesis of natural as well as other modified nucleosides. Various functional groups such as benzoyl, benzyl, tetrahydropyranyl, TBDPS, and formamidine groups are intact during protection with DMPx-group.