Process for the preparation of 4-hydroxy-2-methyl-N-2-pyridyl-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide

摘要

In the preparation of 4-hydroxy-2-methyl-N-2-pyridyl-2H-benzothiazine-3-carboxamide 1,1-dioxide by reacting the corresponding 3-methoxycarbonyl compound with 2-aminopyridine, a dramatic increase in the yield is obtained if the reaction is carried out in the presence of 0.1 to 1.5 mole equivalent (based on the 3-methoxycarbonyl compound) of an alkyl- or arylsulfonic acid.