Abstract: A process for preparing a 1-deoxynojirimycin of the formula ##STR1## in which R is hydrogen, optionally substituted alkyl or aralkyl, which comprises converting D-glucose to an aminosorbitol ##STR2## protecting the amino group of the aminosorbitol with an alkalinically detachable group to form the protected compound of the formula ##STR3## in which X is an alkalinically detachable protective group, microbiologically oxidizing the protected compound to an oxidation product of the formula ##STR4## alkalinically splitting off the protective group X to form an aminosorbose of the formula ##STR5## and reducing the aminosorbose.

Abstract: A process for the preparation of a 4-acyloxy-3-oxo-butyric acid ester of the formula ##STR1## in which R.sup.1 is alkyl with up to 4 C atoms, andR.sup.2 is alkyl with up to 4 C atoms and optionally substituted by halogen, hydroxyl, alkoxy or phenyl, or is aryl,which comprises reacting a 4-halogenobutyric acid ester of the formula ##STR2## in which X is chlorine or bromine, with a carboxylic acid of the formula ##STR3## in the presence of acid-trapping agent in an organic solvent at a temperature of between 0.degree. and 170.degree. C.