Method of producing optically active, 4-substituted (S)-2-oxazolidinones

A method of producing optically active, 4-substituted (S)-2-oxazolidinones of general formula IV ##STR8## in which R stands for a space-filling branched alkyl group with 5-10 C atoms which contains at least one tertiary C atom, characterized in that an optically active (S)-amino alcohol of general formula III ##STR9## in which R stands for a space-filling, branched alkyl group with 5-10 C atoms which contains at least one tertiary C atom, is acylated with a chloroformic acid ethyl-or-methyl ester on the nitrogen and that the intermediate is cyclized with a catalytically active amount of a base to the corresponding (S)-2-Oxazolidinone of formula IV.