A procedure for using thermolabile groups to protect a hydroxyl function, above all in nucleosides, nucleotides, oligomers, nucleic acids during the reactions of organic synthesis. Various new compounds that can be used to implement the procedure. The way of using thermolabile groups to protect hydroxyl functions consists in a primary, secondary and tertiary hydroxyl group converting into a groups during the reaction between a compound and a compound whose hydroxyl group is to be blocked. The blocking reaction is carried out by means of widely known methods appropriate for that purpose in the presence of a chemically basic catalyst. The obtained product has its hydroxyl group blocked. Then the compound with the group blocked can be used for the purposes of various chemical processes. After their completion, the hydroxyl group is unblocked by dissolving it in a solvent at a temperature of 50-95° C.