Title compound can be prepared by two different ways: 1) Reaction of 2H-[1,4]benzothiazin-3(4H)-one (I) with POCl3 in the presence of triethylamine followed by treatment with ethyl carbazate gives 3-carbethoxyhydrazinyl[1,4]benzothiazine (II), which is thermally cyclized by refluxing in o-dichlorobenzene (ODCB) to give 1-oxo-2,4-dihydro[1,2,4]triazolo[3,4-c][1,4]benzothiazin-1-one. 2) Alternatively, IDPH-791 can be prepared by converting 2H-[1,4]benzothiazin-3(4H)-one (I) to the thione (III), followed by reaction with ethyl carbazate in refluxing DMF.

Title compound can be prepared by two different ways: 1) Reaction of 2H-[1,4]benzothiazin-3(4H)-one (I) with POCl3 in the presence of triethylamine followed by treatment with ethyl carbazate gives 3-carbethoxyhydrazinyl[1,4]benzothiazine (II), which is thermally cyclized by refluxing in o-dichlorobenzene (ODCB) to give 1-oxo-2,4-dihydro[1,2,4]triazolo[3,4-c][1,4]benzothiazin-1-one. 2) Alternatively, IDPH-791 can be prepared by converting 2H-[1,4]benzothiazin-3(4H)-one (I) to the thione (III), followed by reaction with ethyl carbazate in refluxing DMF.

Title compound can be prepared by two different ways: 1) Reaction of 2H-[1,4]benzothiazin-3(4H)-one (I) with POCl3 in the presence of triethylamine followed by treatment with ethyl carbazate gives 3-carbethoxyhydrazinyl[1,4]benzothiazine (II), which is thermally cyclized by refluxing in o-dichlorobenzene (ODCB) to give 1-oxo-2,4-dihydro[1,2,4]triazolo[3,4-c][1,4]benzothiazin-1-one. 2) Alternatively, IDPH-791 can be prepared by converting 2H-[1,4]benzothiazin-3(4H)-one (I) to the thione (III), followed by reaction with ethyl carbazate in refluxing DMF.