This compound has been obtained by two related ways: 1) The sulfonation of 3,5-dichloroaniline (I) with chlorosulfonic acid gives 2-amino-4,6-dichlorobenzenesulfonyl chloride (II), which is condensed with 3-bromobenzylamine (III) by means of TEA yielding the corresponding sulfonamide (IV). The cyclization of (IV) with glyoxylic acid (A) in ethanol/sulfuric acid affords the esterified benzothiadiazine-3-carboxylate (V), which is finally hydrolyzed with aqueous NaOH. 2) The reaction of sulfonyl chloride (II) with liquid ammonia gives the corresponding sulfonamide (VI), which is cyclized with glyoxylic acid (A) as before yielding the benzothiadiazine (VII). Finally the alkylation of (VII) with 3-bromobenzyl bromide (VIII) by means of NaH affords the already reported benzothiadiazine-3-carboxylate (V). 3) The enantiomers of the title compound have been obtained in optically pure form by preparative liquid chromatography on a Pirkle-type chiral phase column.