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With tert-butylmagnesium chloride; In tetrahydrofuran; at 65 - 70℃; for 1.5h;
In a 4-neck anhydrous flask there are introduced at 20-25C 5.0 g of (4-methylsulfonyl)phenyl acetic acid of formula (IV) (1.0 mol. equiv.), 100 mL of Anhydrous THF and the mixture is heated to 65-70C (up to reflux). Maintaining at T=65-70 C there are simultaneously dosed in the mixture in about 1 hour: a) 62.0 g of t-BuMgCl 1.0 M solution in THF (about 70.0 mL) (3.0 mol. equiv.) andb) a solution of 2.3 g of methyl ester of 6-methylpyridine-3-carboxylic acid of formula (III - R=Me) (0.65 mol. equiv.) in 7.5 mL of Anhydrous THF. After completing addition, maintain at 65-70 C for 30 minutes. The reaction is controlled through HPLC: HPLC purity 72.05% (A%) and Impurity '408' = 0.26% (A%).
1.8 kg
With tert-butylmagnesium chloride; In tetrahydrofuran; at 70 - 80℃;Large scale;
4-methanesulfonylphenylacetic acid (3.0 kg) was added tetrahydrofuran (6 L),A solution of 1 M t-butylmagnesium chloride in tetrahydrofuran (40 L) was added dropwise,Heating 70 ~ 80 ,A solution of methyl 6-methylnicotinate (1.7 kg) in tetrahydrofuran (5 L) was slowly added dropwise,About 2 to 3 hours dripping.After refluxing for 1 hour.Cooling to 20 ~ 25 ,add water,The pH of the sodium hydroxide aqueous solution (the mass concentration refers to the mass of sodium hydroxide as a percentage of the total mass of the aqueous sodium hydroxide solution) is adjusted to pH = 7 to 8,Precipitate a lot of solid.Centrifugal,The filter cake was rinsed with water and dried in vacuo at 50 C for 16 hours,About 3.6 kg of a yellow solid was obtained.Recrystallization from dichloromethane (20 L) gave 1.8 kg of etoposide intermediate II.
In an anhydrified 4-neck flask there were introduced at 20-25C 5.0 g of (4-methylsulfonyl)phenyl acetic acid of formula (IV) and 100 mL of anhydrous THF and stirring is carried out at 20-25C. 1.0 g of sodium hydride dispersion in mineral oil (60% w/w, MW: 24.00; 1.1 molar equivalents) is added in portions in about 5 minutes, ensuring that the temperature does not exceed 45-50C. After completing the addition the mixture is heated to 65-70C for 1 hr. Maintaining at T=65-70C there are rapidly added 21 g (1.0 equiv.) of t-BuMgCl 1.0 M solution in THF (PM116.87) (23 mL). The mixture is left under stirring for 1 hr at 65-70C then is rapidly added, still at 65-70C, a solution of 1.78 g (0.5 equiv.) of methyl ester of the 6-methylpyridine-3-carboxylic acid of formula (III - R=Me) in 5 ml of Anhydrous THF. After completing the addition the mixture is maintained at 65-70C for 1 hr. Maintaining at T=65-70C there are rapidly added 10.5 g (0.5 equiv.) of t-BuMgCl 1.0 M solution in THF (PM 116.87) (11.5 mL). The mixture is left under stirring for 1 hr at 65-70C then there is rapidly added, still at 65-70C, a solution of 260 mg (0.075 equiv.) of methyl ester of 6-methylpyridine-3-carboxylic acid of formula (III - R=Me) in 1 mL of anhydrous THF. After completing addition the mixture is maintained at 65-70 C for 1 hr. Maintaining at T=65-70 C there are rapidly added 10.5 g (0.5 equiv.) of t-BuMgCl 1.0 M solution in THF (PM 116.87) (11.5 mL). The mixture is left under stirring for 1 hr at 65-70 C then there is rapidly added, still at 65-70 C, a solution of 260 mg (0.075 equiv.) of methyl ester of the 6-methylpyridine-3-carboxylic acid of formula (III - R=Me) in 1 mL of Anhydrous THF. After completing addition the mixture is maintained at 65-70 C for 1 hr. Cooling is carried out to 20-25C. The yield is calculated in solution through titration: 80%. The product is isolated according to the preceding example. It is obtained a molar yield equivalent to 73% and with 94.4% HPLC purity (A%) and amount of impurity '408' = 2.02% (A%) (see figure 4).
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