ethyl 3-oxo-4H-1,4-benzothiazine-2-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of 3.0 g of 2-ethoxycarbonyl-2H-1,4-benzothiazin-3(4H)-one in ethanol (50 ml) was added portionwise 0.95 g of sodium borohydride with stirring at room temperature. After stirring for 2 hours, the mixture was diluted with water, made acidic with acetic acid, and extracted with ether. The ether layer was washed with water, dried (MgSO4), and then concentrated under reduced pressure. The residue was washed with hexane to obtain 1.25 g (50.8%) of 2-hydroxymethyl-2H-1,4-benzothiazin-3(4H)-one as crystals. Recrystallization from ethyl acetate gave prisms, m.p. 156°-157° C. After stirring for 2 hours extracted with ether The ether layer was washed with water dried (MgSO4) concentrated under reduced pressure The residue was washed with hexane

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of 3.0 g of 2-ethoxycarbonyl-2H-1,4-benzothiazin-3(4H)-one in ethanol (50 ml) was added portionwise 0.95 g of sodium borohydride with stirring at room temperature. After stirring for 2 hours, the mixture was diluted with water, made acidic with acetic acid, and extracted with ether. The ether layer was washed with water, dried (MgSO4), and then concentrated under reduced pressure. The residue was washed with hexane to obtain 1.25 g (50.8%) of 2-hydroxymethyl-2H-1,4-benzothiazin-3(4H)-one as crystals. Recrystallization from ethyl acetate gave prisms, m.p. 156°-157° C. After stirring for 2 hours extracted with ether The ether layer was washed with water dried (MgSO4) concentrated under reduced pressure The residue was washed with hexane

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of 3.0 g of 2-ethoxycarbonyl-2H-1,4-benzothiazin-3(4H)-one in ethanol (50 ml) was added portionwise 0.95 g of sodium borohydride with stirring at room temperature. After stirring for 2 hours, the mixture was diluted with water, made acidic with acetic acid, and extracted with ether. The ether layer was washed with water, dried (MgSO4), and then concentrated under reduced pressure. The residue was washed with hexane to obtain 1.25 g (50.8%) of 2-hydroxymethyl-2H-1,4-benzothiazin-3(4H)-one as crystals. Recrystallization from ethyl acetate gave prisms, m.p. 156°-157° C. After stirring for 2 hours extracted with ether The ether layer was washed with water dried (MgSO4) concentrated under reduced pressure The residue was washed with hexane