ethyl 2-(3-oxo-4H-1,4-benzothiazin-2-yl)acetate

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

Procedure: To a solution of LDA (2M) in THF (3.26 mmol) in 2 mL of anhydrous THF at 0° C. and under nitrogen, a solution of (3-oxo-3,4-dihydro-2H-benzo[1,4]thiazin-2-yl)-acetic acid ethyl ester (1.62 mmol) in 4 mL of dry THF is added dropwise. The temperature of the reaction mixture is held at room temperature for 2 hours and then dropped to −78° C. A solution of 2-bromo acetic acid (1.64 mmol) in 2 mL of anhydrous THF is added and the temperature of the reaction is slowly let to rise to room temperature. HCl (1M) is added to reach pH=1. Ethyl ether is added and the phases are separated. The organic phase is dried on Na2SO4, the drying agent is filtered and the solvent evaporated. The crude product is purified by automated column chromatography (hexane/EtOAc) to give the product ethyl 2-(3,4-dihydro-4-(carboxymetyl)-3-oxo-2H-benzo[b][1,4]thiazin-2-yl)acetate. Yield: 50%. 1H NMR (400 MHz, CDCl3): δ 9.07 (bs, 1H), 7.38 (d, J=7.6 Hz, 1H), 7.27 (t, J=7.6 Hz, 1H), 7.07 (t, J=7.6 Hz, 1H), 6.93 (d, J=7.6 Hz, 1H), 4.69 (dd, 2H), 4.18 (dd, 2H), 3.99 (t, J=6.4 Hz, 1H), 3.04 (dd, J1=6.4 Hz, J2=16.8 Hz, 1H), 2.58 (dd, 1H), 1.26 (m, 3H). dropped to −78° C to rise to room temperature the phases are separated The organic phase is dried on Na2SO4 the drying agent is filtered the solvent evaporated The crude product is purified by automated column chromatography (hexane/EtOAc)

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

Procedure: To a solution of LDA (2M) in THF (3.26 mmol) in 2 mL of anhydrous THF at 0° C. and under nitrogen, a solution of (3-oxo-3,4-dihydro-2H-benzo[1,4]thiazin-2-yl)-acetic acid ethyl ester (1.62 mmol) in 4 mL of dry THF is added dropwise. The temperature of the reaction mixture is held at room temperature for 2 hours and then dropped to −78° C. A solution of 2-bromo acetic acid (1.64 mmol) in 2 mL of anhydrous THF is added and the temperature of the reaction is slowly let to rise to room temperature. HCl (1M) is added to reach pH=1. Ethyl ether is added and the phases are separated. The organic phase is dried on Na2SO4, the drying agent is filtered and the solvent evaporated. The crude product is purified by automated column chromatography (hexane/EtOAc) to give the product ethyl 2-(3,4-dihydro-4-(carboxymetyl)-3-oxo-2H-benzo[b][1,4]thiazin-2-yl)acetate. Yield: 50%. 1H NMR (400 MHz, CDCl3): δ 9.07 (bs, 1H), 7.38 (d, J=7.6 Hz, 1H), 7.27 (t, J=7.6 Hz, 1H), 7.07 (t, J=7.6 Hz, 1H), 6.93 (d, J=7.6 Hz, 1H), 4.69 (dd, 2H), 4.18 (dd, 2H), 3.99 (t, J=6.4 Hz, 1H), 3.04 (dd, J1=6.4 Hz, J2=16.8 Hz, 1H), 2.58 (dd, 1H), 1.26 (m, 3H). dropped to −78° C to rise to room temperature the phases are separated The organic phase is dried on Na2SO4 the drying agent is filtered the solvent evaporated The crude product is purified by automated column chromatography (hexane/EtOAc)

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

Procedure: Under ice cooling, 1.01 g of ethyl 2-(3,4-dihydro-3-oxo-2H-1,4-benzothiazin-2-yl)acetate was added to a suspension of 176 mg of sodium hydride (60% in mineral oil) in 7 ml of N,N-dimethylformamide. The mixture was stirred for 30 minutes. After a solution of 1.08 g of 2-bromomethyl-5-fluorobenzothiazole in 3 ml of N,N-dimethylformamide was added dropwise to the mixture, the mixture was stirred at room temperature overnight. Thereafter the reaction mixture was poured onto ice water, and then extracted with ethyl acetate. The ethyl acetate layer was washed with water. After the drying of the organic layer over anhydrous magnesium sulfate, the solvent was distilled off. The resulting oily residue was purified by silica gel chromatography to give 1.11 g of the title compound. The structural formula and physical data of this compound are shown in Table 7. the mixture was stirred at room temperature overnight Thereafter the reaction mixture was poured onto ice water extracted with ethyl acetate The ethyl acetate layer was washed with water After the drying of the organic layer over anhydrous magnesium sulfate the solvent was distilled off The resulting oily residue was purified by silica gel chromatography

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

Procedure: After 1.82 g of ethyl 2-(3,4-dihydro-3-oxo-2H-1,4-benzothiazin-2-yl)acetate, 1.31 g of bromoacetonitrile and 146 mg of potassium iodide were dissolved in dimethylsulfoxide (18 ml), 1.50 g of potassium carbonate was added to the solution. The mixture was stirred at room temperature for 40 hours. After saturated ammonium chloride aqueous solution was added to the reaction mixture, the mixture was extracted with ethyl acetate. After the organic phase was washed with saturated sodium chloride aqueous solution, the organic layer was dried over anhydrous magnesium sulfate and the solvent was distilled off. The resulting semicrystalline residue was dissolved in benzene. After insoluble matters were filtered off, the solvent was distilled off. Isopropyl ether was added to the residue for crystallization to give 1.74 g of the title compound. The structural formula and physical data of this compound are shown in Table 5. the mixture was extracted with ethyl acetate After the organic phase was washed with saturated sodium chloride aqueous solution the organic layer was dried over anhydrous magnesium sulfate the solvent was distilled off The resulting semicrystalline residue was dissolved in benzene After insoluble matters were filtered off the solvent was distilled off Isopropyl ether was added to the residue for crystallization

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

Procedure: To a solution of LDA (2M) in THF (3.26 mmol) in 2 mL of anhydrous THF at 0° C. and under nitrogen, a solution of (3-oxo-3,4-dihydro-2H-benzo[1,4]thiazin-2-yl)-acetic acid ethyl ester (1.62 mmol) in 4 mL of dry THF is added dropwise. The temperature of the reaction mixture is held at room temperature for 2 hours and then dropped to −78° C. A solution of 2-bromo acetic acid (1.64 mmol) in 2 mL of anhydrous THF is added and the temperature of the reaction is slowly let to rise to room temperature. HCl (1M) is added to reach pH=1. Ethyl ether is added and the phases are separated. The organic phase is dried on Na2SO4, the drying agent is filtered and the solvent evaporated. The crude product is purified by automated column chromatography (hexane/EtOAc) to give the product ethyl 2-(3,4-dihydro-4-(carboxymetyl)-3-oxo-2H-benzo[b][1,4]thiazin-2-yl)acetate. Yield: 50%. 1H NMR (400 MHz, CDCl3): δ 9.07 (bs, 1H), 7.38 (d, J=7.6 Hz, 1H), 7.27 (t, J=7.6 Hz, 1H), 7.07 (t, J=7.6 Hz, 1H), 6.93 (d, J=7.6 Hz, 1H), 4.69 (dd, 2H), 4.18 (dd, 2H), 3.99 (t, J=6.4 Hz, 1H), 3.04 (dd, J1=6.4 Hz, J2=16.8 Hz, 1H), 2.58 (dd, 1H), 1.26 (m, 3H). dropped to −78° C to rise to room temperature the phases are separated The organic phase is dried on Na2SO4 the drying agent is filtered the solvent evaporated The crude product is purified by automated column chromatography (hexane/EtOAc)