Proposed are 2-oxo-1,3-dioxolane-4-carboxylic acid and derivatives thereof, according to the following formula, in which R1 represents a negative charge, hydrogen or can be preferably Me or Et or a radical having a valency of 2 to 5, which is substituted with an amount of further 2-oxo-1,3-dioxolane-4-carboxyl groups equal to the radical valency minus 1, as well as a process for their preparation by means of carboxylation of the corresponding epoxides, a process for their transesterification and their use for the preparation of hydroxyurethanes and as end groups for the blocking of amines.