Aspects of the invention include 2'-protected nucleoside monomers that are protected at the 2'-site with thiocarbon protecting groups. Thiocarbon protecting groups of interest include thiocarbonate, thionocarbonate, dithiocarbonate groups, as well as thionocarbamate protecting groups. Aspects of the invention further include nucleic acids that include the protecting groups of the invention, as well as methods of synthesizing nucleic acids using the protecting groups of the invention.