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反应条件: temp:0.00; pressure:0.00; stir:

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a solution of 4-hydroxy-5, 5-dimethyl-5H-furan-2-one (2.1 g, 16.4 mmol) in DCE (40 mL) and DMF (1.5 mL) at 0° C. was added dropwise oxalyl bromide (3.0 mL, 32 mmol, 2 equiv). The mixture was stirred at room temperature for 4-5 h, and then put in an ice bath. Ice water (100 mL) was added slowly. The mixture was extracted with CH2Cl2 (100 mL). The organic phase was washed with 10% NaHCO3 and again with water, dried over sodium sulfate and evaporated to give the title compound 2.7 g (86% yield). put in an ice bath The mixture was extracted with CH2Cl2 (100 mL) The organic phase was washed with 10% NaHCO3 and again with water dried over sodium sulfate evaporated

反应条件: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a −78° C. stirred solution of 4-hydroxy-5,5-dimethyl-5H-furan-2-one (250 mg, 1.95 mmol) in 18 mL of anhydrous CH2Cl2, was added triethylamine (0.40 mL, 2.9 mmol) and Tf2O (0.49 mL, 2.9 mmol). The reaction was stirred at −78° C. for 30 minutes, and quenched with saturated NH4Cl solution (10 mL). The mixture was warmed up to room temperature and separated. The aqueous layer was extracted with CH2Cl2 (2×20 mL). All organic layers were combined, dried over Na2SO4 and evaporated to brown oil, which was purified by plugging through a short pad of silica gel column with EtOAc/hexanes (1/3). Evaporation of solvents gave 2,2-dimethyl-5-oxo-2,5-dihydrofuran-3-yl trifluoromethanesulfonate as a light brown oil (450 mg, 89%). quenched with saturated NH4Cl solution (10 mL) The mixture was warmed up to room temperature separated The aqueous layer was extracted with CH2Cl2 (2×20 mL) dried over Na2SO4 evaporated to brown oil, which was purified Evaporation of solvents

反应条件: temp:88.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: A suspension of 5,5-dimethyl-4-pyrrolidin-1-ylfuran-2(5H)-one (535 mg) in a mixture of MeOH (2 mL) and 5M HCl (8 mL) was heated at 88° C. for 2 hours. The mixture was cooled to room temp., extracted with CHCl3 (10×15 mL), combined, dried over Na2SO4, and evaporated to dryness to give 4-hydroxy-5,5-dimethyl-5H-furan-2-one as light brown solid. Yield: 359 mg, 95%. The mixture was cooled to room temp. extracted with CHCl3 (10×15 mL) dried over Na2SO4 evaporated to dryness

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a solution of 4-hydroxy-5,5-dimethyl-5H-furan-2-one (2.1 g, 16.4 mmol) in DCE (40 mL) and DMF (1.5 mL) at 0° C. was added dropwise oxalyl bromide (3.0 mL, 32 mmol, 2 equiv). The mixture was stirred at room temperature for 4-5 h, and then put in an ice bath. Ice water (100 mL) was added slowly. The mixture was extracted with CH2Cl2 (100 mL). The organic phase was washed with 10% NaHCO3 and again with water, dried over sodium sulfate and evaporated to give the title compound 2.7 g (86% yield). put in an ice bath The mixture was extracted with CH2Cl2 (100 mL) The organic phase was washed with 10% NaHCO3 and again with water dried over sodium sulfate evaporated

反应条件: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a −78° C. stirred solution of 4-hydroxy-5,5-dimethyl-5H-furan-2-one (250 mg, 1.95 mmol) in 18 mL of anhydrous CH2Cl2, was added triethylamine (0.40 mL, 2.9 mmol) and Tf2O (0.49 mL, 2.9 mmol). The reaction was stirred at −78° C. for 30 minutes, and quenched with saturated NH4Cl solution (10 mL). The mixture was warmed up to room temperature and separated. The aqueous layer was extracted with CH2Cl2 (2×20 mL). All organic layers were combined, dried over Na2SO4 and evaporated to brown oil, which was purified by plugging through a short pad of silica gel column with EtOAc/hexanes (1/3). Evaporation of solvents gave 2,2-dimethyl-5-oxo-2,5-dihydrofuran-3-yl trifluoromethanesulfonate as a light brown oil (450 mg, 89%). quenched with saturated NH4Cl solution (10 mL) The mixture was warmed up to room temperature separated The aqueous layer was extracted with CH2Cl2 (2×20 mL) dried over Na2SO4 evaporated to brown oil, which was purified Evaporation of solvents

反应条件: temp:88.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: A suspension of 5,5-dimethyl-4-pyrrolidin-1-ylfuran-2(5H)-one (535 mg) in a mixture of MeOH (2 mL) and 5M HCl (8 mL) was heated at 88° C. for 2 hours. The mixture was cooled to room temp., extracted with CHCl3 (10×15 mL), combined, dried over Na2SO4, and evaporated to dryness to give 4-hydroxy-5,5-dimethyl-5H-furan-2-one as light brown solid. Yield: 359 mg, 95%. The mixture was cooled to room temp. extracted with CHCl3 (10×15 mL) dried over Na2SO4 evaporated to dryness

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a solution of 4-hydroxy-5,5-dimethyl-5H-furan-2-one (2.1 g, 16.4 mmol) in DCE (40 mL) and DMF (1.5 mL) at 0° C. was added dropwise oxalyl bromide (3.0 mL, 32 mmol, 2 equiv). The mixture was stirred at room temperature for 4-5 h, and then put in an ice bath. Ice water (100 mL) was added slowly. The mixture was extracted with CH2Cl2 (100 mL). The organic phase was washed with 10% NaHCO3 and again with water, dried over sodium sulfate and evaporated to give the title compound 2.7 g (86% yield). put in an ice bath The mixture was extracted with CH2Cl2 (100 mL) The organic phase was washed with 10% NaHCO3 and again with water dried over sodium sulfate evaporated

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a solution of 4-hydroxy-5,5-dimethyl-5H-furan-2-one (2.1 g, 16.4 mmol) in DCE (40 mL) and DMF (1.5 mL) at 0° C. was added dropwise oxalyl bromide (3.0 mL, 32 mmol, 2 equiv). The mixture was stirred at room temperature for 4-5 h, and then put in an ice bath. Ice water (100 mL) was added slowly. The mixture was extracted with CH2Cl2 (100 mL). The organic phase was washed with 10% NaHCO3 and again with water, dried over sodium sulfate and evaporated to give the title compound 2.7 g (86% yield). put in an ice bath The mixture was extracted with CH2Cl2 (100 mL) The organic phase was washed with 10% NaHCO3 and again with water dried over sodium sulfate evaporated

反应条件: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a −78° C. stirred solution of 4-hydroxy-5,5-dimethyl-5H-furan-2-one (250 mg, 1.95 mmol) in 18 mL of anhydrous CH2Cl2, was added triethylamine (0.40 mL, 2.9 mmol) and Tf2O (0.49 mL, 2.9 mmol). The reaction was stirred at −78° C. for 30 minutes, and quenched with saturated NH4Cl solution (10 mL). The mixture was warmed up to room temperature and separated. The aqueous layer was extracted with CH2Cl2 (2×20 mL). All organic layers were combined, dried over Na2SO4 and evaporated to brown oil, which was purified by plugging through a short pad of silica gel column with EtOAc/hexanes (1/3). Evaporation of solvents gave 2,2-dimethyl-5-oxo-2,5-dihydrofuran-3-yl trifluoromethanesulfonate as a light brown oil (450 mg, 89%). quenched with saturated NH4Cl solution (10 mL) The mixture was warmed up to room temperature separated The aqueous layer was extracted with CH2Cl2 (2×20 mL) dried over Na2SO4 evaporated to brown oil, which was purified Evaporation of solvents

反应条件: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a −78° C. stirred solution of 4-hydroxy-5,5-dimethyl-5H-furan-2-one (250 mg, 1.95 mmol) in 18 mL of anhydrous CH2Cl2, was added triethylamine (0.40 mL, 2.9 mmol) and Tf2O (0.49 mL, 2.9 mmol). The reaction was stirred at −78° C. for 30 minutes, and quenched with saturated NH4Cl solution (10 mL). The mixture was warmed up to room temperature and separated. The aqueous layer was extracted with CH2Cl2 (2×20 mL). All organic layers were combined, dried over Na2SO4 and evaporated to brown oil, which was purified by plugging through a short pad of silica gel column with EtOAc/hexanes (1/3). Evaporation of solvents gave 2,2-dimethyl-5-oxo-2,5-dihydrofuran-3-yl trifluoromethanesulfonate as a light brown oil (450 mg, 89%). quenched with saturated NH4Cl solution (10 mL) The mixture was warmed up to room temperature separated The aqueous layer was extracted with CH2Cl2 (2×20 mL) dried over Na2SO4 evaporated to brown oil, which was purified Evaporation of solvents

反应条件: temp:88.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: A suspension of 5,5-dimethyl-4-pyrrolidin-1-ylfuran-2(5H)-one (535 mg) in a mixture of MeOH (2 mL) and 5M HCl (8 mL) was heated at 88° C. for 2 hours. The mixture was cooled to room temp., extracted with CHCl3 (10×15 mL), combined, dried over Na2SO4, and evaporated to dryness to give 4-hydroxy-5,5-dimethyl-5H-furan-2-one as light brown solid. Yield: 359 mg, 95%. The mixture was cooled to room temp. extracted with CHCl3 (10×15 mL) dried over Na2SO4 evaporated to dryness