合成路线1

This compound can be prepared by two similar ways: 1) The monoacylation of ethylene glycol (I) with chloroacetyl chloride (II) and triethylamine gives 2-hydroxyethyl chloroacetate (III), which is condensed with saccharine (IV) by means of NaOH in ethylene glycol yielding 2-hydroxyethyl 3-oxo-1,2-benzisothiazoline-2-acetate 1,1-dioxide (V). Isomerization of (V) by means of potassium tert-butoxide in DMSO affords2-hydroxyethyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide (VI), which is methylated with NaOH and methyl iodide in aqueous ethanol giving the corresponding N-methyl derivative (VII). Hydrolysis of (VII) with NaOH in ethanol - water yields the corresponding free acid (VIII), which is acylated with cinnamoyl chloride (IX) by means of triethylamine in dichloromethane to afford the biscinnamoyl derivative (X). Finally, this compound is treated with 2-aminopyridine (XI) in dichloromethane. 2) The preceding sequence can also be carried out with cyclohexanol (XII) instead of ethylene glycol (I), then producing compounds (XIII), (XIV), (XV) and (XVI), which by hydrolysis affords the free acid (VIII).