2-ethoxy-2H-furan-5-one

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: This procedure may be carried out in a manner similar to that described by C. Escobar, et al., Ann. Quim. (1971), 67, 43-57.). To a solution of 5-ethoxy-5H-furan-2-one (II, R1=Et) (10.0 g, 78.0 mmol) in carbon tetrachloride (50 mL) at 0° C. is added over 0.5 h a solution of bromine (4.05 mL, 78.2 mmol) in carbon tetrachloride (25 mL). The reaction is stirred 1 h at 0° C., then 2 h at room temperature. The solvents are removed under reduced pressure and the residue was short-path distilled at pump vacuum (about 0.5 mm). The fraction collected at 100° C.-120° C. provided 4-bromo-5-ethoxy-5H-furan-2-one (13.2 g, 82% yield) as a yellow oil. 1H-NMR (500 MHz, CDCl3) δ 6.24 (s, 1H), 5.63 (s, 1H), 3.71 (m, 1H), 3.63 (m, 1H), 1.14 (t, J=7.1 Hz, 3H) ppm. 2 h at room temperature The solvents are removed under reduced pressure the residue was short-path distilled at pump vacuum (about 0.5 mm) The fraction collected at 100° C.-120° C.

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: This procedure may be carried out in a manner similar to that described by C. Escobar, et al., Ann. Quim. (1971), 67, 43-57.). To a solution of 5-ethoxy-5H-furan-2-one (II, R1=Et) (10.0 g, 78.0 mmol) in carbon tetrachloride (50 mL) at 0° C. is added over 0.5 h a solution of bromine (4.05 mL, 78.2 mmol) in carbon tetrachloride (25 mL). The reaction is stirred 1 h at 0° C., then 2 h at room temperature. The solvents are removed under reduced pressure and the residue was short-path distilled at pump vacuum (about 0.5 mm). The fraction collected at 100° C.-120° C. provided 4-bromo-5-ethoxy-5H-furan-2-one (13.2 g, 82% yield) as a yellow oil. 1H-NMR (500 MHz, CDCl3) δ 6.24 (s, 1H), 5.63 (s, 1H), 3.71 (m, 1H), 3.63 (m, 1H), 1.14 (t, J=7.1 Hz, 3H) ppm. 2 h at room temperature The solvents are removed under reduced pressure the residue was short-path distilled at pump vacuum (about 0.5 mm) The fraction collected at 100° C.-120° C.

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

Procedure: This procedure was carried out in a manner similar to that described by D. J. Guerin, et al., Org. Lett (1999), 1, 1107-1109. To a solution of azidotrimethylsilane (25.8 mL, 0.32 mol) in dichloromethane (400 mL) at room temperature under nitrogen was added acetic acid (18.1 mL, 0.32 mol), and the reaction was stirred for 20 min. 5-Ethoxy-5H-furan-2-one (II, R1=Et) (8.10 g, 0.063 mol) was added dropwise, followed by 1,8-diazabicyclo[5.4.0]undec-7-ene (1.9 mL, 0.013 mol). The reaction was stirred for 24 h, washed with sodium bicarbonate, dried over sodium sulfate and evaporated. Purification by flash chromatography (SiO2) eluted with 1:9 ethyl acetate:hexanes afforded 4-azido-5-ethoxy-dihydrofuran-2-one (7.85 g, 73% yield) as a colorless oil. The reaction was stirred for 24 h washed with sodium bicarbonate dried over sodium sulfate evaporated Purification by flash chromatography (SiO2) eluted with 1:9 ethyl acetate

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

Procedure: This procedure was carried out in a manner similar to that described by D. J. Guerin, et al., Org. Lett (1999), 1, 1107-1109. To a solution of azidotrimethylsilane (25.8 mL, 0.32 mol) in dichloromethane (400 mL) at room temperature under nitrogen was added acetic acid (18.1 mL, 0.32 mol), and the reaction was stirred for 20 min. 5-Ethoxy-5H-furan-2-one (II, R1=Et) (8.10 g, 0.063 mol) was added dropwise, followed by 1,8-diazabicyclo[5.4.0]undec-7-ene (1.9 mL, 0.013 mol). The reaction was stirred for 24 h, washed with sodium bicarbonate, dried over sodium sulfate and evaporated. Purification by flash chromatography (SiO2) eluted with 1:9 ethyl acetate:hexanes afforded 4-azido-5-ethoxy-dihydrofuran-2-one (7.85 g, 73% yield) as a colorless oil. The reaction was stirred for 24 h washed with sodium bicarbonate dried over sodium sulfate evaporated Purification by flash chromatography (SiO2) eluted with 1:9 ethyl acetate

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

Procedure: This procedure was carried out in a manner similar to that described by D. J. Guerin, et al., Org. Lett (1999), 1, 1107-1109. To a solution of azidotrimethylsilane (25.8 mL, 0.32 mol) in dichloromethane (400 mL) at room temperature under nitrogen was added acetic acid (18.1 mL, 0.32 mol), and the reaction was stirred for 20 min. 5-Ethoxy-5H-furan-2-one (II, R1=Et) (8.10 g, 0.063 mol) was added dropwise, followed by 1,8-diazabicyclo[5.4.0]undec-7-ene (1.9 mL, 0.013 mol). The reaction was stirred for 24 h, washed with sodium bicarbonate, dried over sodium sulfate and evaporated. Purification by flash chromatography (SiO2) eluted with 1:9 ethyl acetate:hexanes afforded 4-azido-5-ethoxy-dihydrofuran-2-one (7.85 g, 73% yield) as a colorless oil. The reaction was stirred for 24 h washed with sodium bicarbonate dried over sodium sulfate evaporated Purification by flash chromatography (SiO2) eluted with 1:9 ethyl acetate

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: This procedure may be carried out in a manner similar to that described by C. Escobar, et al., Ann. Quim. (1971), 67, 43-57.). To a solution of 5-ethoxy-5H-furan-2-one (II, R1=Et) (10.0 g, 78.0 mmol) in carbon tetrachloride (50 mL) at 0° C. is added over 0.5 h a solution of bromine (4.05 mL, 78.2 mmol) in carbon tetrachloride (25 mL). The reaction is stirred 1 h at 0° C., then 2 h at room temperature. The solvents are removed under reduced pressure and the residue was short-path distilled at pump vacuum (about 0.5 mm). The fraction collected at 100° C.-120° C. provided 4-bromo-5-ethoxy-5H-furan-2-one (13.2 g, 82% yield) as a yellow oil. 1H-NMR (500 MHz, CDCl3) δ 6.24 (s, 1H), 5.63 (s, 1H), 3.71 (m, 1H), 3.63 (m, 1H), 1.14 (t, J=7.1 Hz, 3H) ppm. 2 h at room temperature The solvents are removed under reduced pressure the residue was short-path distilled at pump vacuum (about 0.5 mm) The fraction collected at 100° C.-120° C.

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: This procedure may be carried out in a manner similar to that described by C. Escobar, et al., Ann. Quim. (1971), 67, 43-57.). To a solution of 5-ethoxy-5H-furan-2-one (II, R1=Et) (10.0 g, 78.0 mmol) in carbon tetrachloride (50 mL) at 0° C. is added over 0.5 h a solution of bromine (4.05 mL, 78.2 mmol) in carbon tetrachloride (25 mL). The reaction is stirred 1 h at 0° C., then 2 h at room temperature. The solvents are removed under reduced pressure and the residue was short-path distilled at pump vacuum (about 0.5 mm). The fraction collected at 100° C.-120° C. provided 4-bromo-5-ethoxy-5H-furan-2-one (13.2 g, 82% yield) as a yellow oil. 1H-NMR (500 MHz, CDCl3) δ 6.24 (s, 1H), 5.63 (s, 1H), 3.71 (m, 1H), 3.63 (m, 1H), 1.14 (t, J=7.1 Hz, 3H) ppm. 2 h at room temperature The solvents are removed under reduced pressure the residue was short-path distilled at pump vacuum (about 0.5 mm) The fraction collected at 100° C.-120° C.

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: This procedure may be carried out in a manner similar to that described by C. Escobar, et al., Ann. Quim. (1971), 67, 43-57.). To a solution of 5-ethoxy-5H-furan-2-one (II, R1=Et) (10.0 g, 78.0 mmol) in carbon tetrachloride (50 mL) at 0° C. is added over 0.5 h a solution of bromine (4.05 mL, 78.2 mmol) in carbon tetrachloride (25 mL). The reaction is stirred 1 h at 0° C., then 2 h at room temperature. The solvents are removed under reduced pressure and the residue was short-path distilled at pump vacuum (about 0.5 mm). The fraction collected at 100° C.-120° C. provided 4-bromo-5-ethoxy-5H-furan-2-one (13.2 g, 82% yield) as a yellow oil. 1H-NMR (500 MHz, CDCl3) δ 6.24 (s, 1H), 5.63 (s, 1H), 3.71 (m, 1H), 3.63 (m, 1H), 1.14 (t, J=7.1 Hz, 3H) ppm. 2 h at room temperature The solvents are removed under reduced pressure the residue was short-path distilled at pump vacuum (about 0.5 mm) The fraction collected at 100° C.-120° C.