乙基 4-溴-2-甲基-3-氧代戊酸乙酯

反应条件: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To ethyl 4-bromo-2-methyl-3-oxopentanoate (7.49 g, 31.6 mmol) was added cold potassium hydroxide (4.7 g, 84 mmol) in water (36 mL) at 0° C., the resulting mixture was vigorously stirred at 0° C. for 4 h. The reaction mixture was extracted with methylene chloride (2×100 mL), the alkaline phase was acidified to ph 1 by 6N hydrogen chloride followed by extraction with methylene chloride (3 times 100 mL). The combined latter organic phase was dried over sodium sulfate, and concentrated to give 4-hydroxy-3,5-dimethylfuran-2(5H)-one. LC/MS: (M+23)+: 151.10, 1HNMR (500 MHz, CDCl3), δ4.882-4.842 (dd, J=6.8 Hz, 1H), 3.744 (s, 1H), 1.759 (s, 3H). 1.526-1.513 (d, J=6.8 Hz, 3H). The reaction mixture was extracted with methylene chloride (2×100 mL) followed by extraction with methylene chloride (3 times 100 mL) The combined latter organic phase was dried over sodium sulfate concentrated

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

实验步骤: To a solution of ethyl 2-methyl-3-oxopentanoate (5.0 g, 34.7 mmol) in chloroform at 0° C. was added bromine (1.79 mL, 34.7 mmol) in chloroform (10 mL) drop-wise. The resulting solution was stirred at rt for 16 h. The solution was washed with water, dried over sodium sulfate, and concentrated to give the title compound. 1HNMR (500 MHz, CDCl3), δ4.781-4.740 (dd, J=6.6 Hz, 1H), 4.140-4.098 (dd, J=7.0 Hz, 1H), 3.770 (s, 3H), 1.797-1.783 (d, J=6.6 Hz, 3H), 1.455-1.442 (d, J=7.0 Hz, 3H). The solution was washed with water dried over sodium sulfate concentrated

反应条件: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To ethyl 4-bromo-2-methyl-3-oxopentanoate (7.49 g, 31.6 mmol) was added cold potassium hydroxide (4.7 g, 84 mmol) in water (36 mL) at 0° C., the resulting mixture was vigorously stirred at 0° C. for 4 h. The reaction mixture was extracted with methylene chloride (2×100 mL), the alkaline phase was acidified to ph 1 by 6N hydrogen chloride followed by extraction with methylene chloride (3 times 100 mL). The combined latter organic phase was dried over sodium sulfate, and concentrated to give 4-hydroxy-3,5-dimethylfuran-2(5H)-one. LCMS: (M+23)+: 151.10, 1HNMR (500 MHz, CDCl3), δ4.882-4.842 (dd, J=6.8 Hz, 1H), 3.744 (s, 1H), 1.759(s, 3H). 1.526-1.513 (d, J=6.8 Hz, 3H). The reaction mixture was extracted with methylene chloride (2×100 mL) followed by extraction with methylene chloride (3 times 100 mL) The combined latter organic phase was dried over sodium sulfate concentrated

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

实验步骤: To a solution of ethyl 2-methyl-3-oxopentanoate (5.0 g, 34.7 mmol) in chloroform at 0° C. was added bromine (1.79 mL, 34.7 mmol) in chloroform (10 mL) drop-wise. The resulting solution was stirred at rt for 16 h. The solution was washed with water, dried over sodium sulfate, and concentrated to give the title compound. 1HNMR (500 MHz, CDCl3), δ4.781-4.740 (dd, J=6.6 Hz, 1H), 4.140-4.098(dd, J=7.0 Hz, 1H), 3.770 (s, 3H), 1.797-1.783(d, J=6.6 Hz, 3H), 1.455-1.442 (d, J=7.0 Hz, 3H). The solution was washed with water dried over sodium sulfate concentrated