text: At room temperature and below, hydroxylamine-O-sulfonic acid reacts with ketones and aldehydes as a nucleophile to the corresponding oxime-O-sulfonic acids or their salts. The oxime-O-sulfonic acids of aldehydes react above room temperature upon elimination of sulfuric acid in high yields to nitriles.
  Aliphatic ketones provide under similar conditions in very high yields oximes, arylalkyl ketones react in a Beckmann rearrangement to amides. When heated to reflux for several hours under acidic conditions (e.g., in the presence of concentrated formic acid) alicyclic ketones react to provide lactams in high yields.
  Under basic conditions in the presence of primary amines, hydroxylamine-O-sulfonic acid forms with aldehydes and ketones (e.g. cyclohexanone) diaziridines, which can easily be oxidized to the more stable diazirines.
  The reaction also provides substituted aziridines from simple aldehydes and ketones with high yield and diastereoselectivity.
  1,2-Benzisoxazole is efficiently produced by nucleophilic attack of hydroxylamine-O-sulfonic acid to the carbonyl group of 2-hydroxybenzaldehyde followed by cyclization.
  1,2-Benzisoxazole is a structural element in the antipsychotic risperidone and paliperidone, as well as the anticonvulsant zonisamide.
  In a one-pot reaction, N-aryl[3,4-d]pyrazolopyrimidines are obtained in good yields from simple 4,6-dichloropyrimidine-5-carboxaldehyde,
  which can be used as purine analogs for a wide range of diagnostic and therapeutic applications.