The present invention provides compounds of the general formula: ##STR1## in which R and R.sub.1, independently of one another, each represent a straight-chained or branched alkyl or alkoyl radical containing up to 6 carbon atoms or a phenyl radical or R and R.sub.1 together also form a methylene bridge, the hydrogen atoms of which, independently of one another, can each be substituted by an alkyl radical containing up to 5 carbon atoms or a phenyl radical, R.sub.2 represents an oligoglucoside residue containing 2 to 7 glucose units and X is a hydrogen atom or an optically-determinable residue.The present invention also provides a process for the preparation of these compounds.