Tetrabutylammonium bromide: an efficient media for dimethoxytritylation of the 5′-hydroxyl function of nucleosides

An efficient procedure for selective dimethoxytritylation of the 5′-hydroxyl function of nucleosides in the presence of DABCO in molten tetrabutylammonium bromide is described. The methodology is very practical, environmentally benign and produced the desired product in less than 5 min by grinding in a hot mortar. In addition, the effects of the room temperature ionic liquid (1-butyl-3-methylimidazolium chloride) and microwave irradiation on this system were also studied and the results showed that depurination of the nucleosides occurred under microwave irradiation.