By condensation of 3-carbethoxy-4-hydroxy-2-methyl-2H-1,2 benzothiazine 1,1-dioxide (III) vvith 2 pyridylisocyanate (II) obtained in situ by decom position of 2-phenoxycarbonylaminopyridine (I).
By chlorination of acid (I) and subsequent esterification with the aminoalcohol (II).