Доброго времени суток!
Озадачили меня вопросом, в котором я забуксовал.
Возможен ли гидролиз сульфида в метионине? До гомосерина, например.
Интуиция подсказывает, что задувка иодоводорода до упора может что-то сотворить, возможно, что-то типа комбинации солянка/хлорид меди или ртути.
Чего посоветуете?
Гидролиз метионина
Re: Гидролиз метионина
Нет. Даже S-трет-бутиловые эфиры очень стабильны в растворах HCl и требуют безводной HF или солей металлов (таллия, ртути). Наверняка и с никелем есть способы, так навскидку не вспомню. В пептидном синтезе при снятии пептида в TFA главные побочные реакции с метионином (а также цистеином) это алкилирование или окисление.
Re: Гидролиз метионина
У меня смутные воспоминания, что видел я подобный гидролиз на сайте rhodium. Через образование сульфониевой соли с метил йодидом, а потом вроде гидролиз с карбонатом натрия.
Вопрос, не путаю ли с каким-то другим субстратом.
Вопрос, не путаю ли с каким-то другим субстратом.
Последний раз редактировалось Phobos Сб сен 11, 2021 11:09 am, всего редактировалось 1 раз.
Wodka trinkt man pur und kalt, das macht hundert Jahre alt!
Re: Гидролиз метионина
General/Typical Procedure: Example 1: (2S)-Methionine methylsulfonium iodide. Methyl iodide (5.2 mL, 83.9 mmol) was added to a solution of L-methionine (5.0 g, 33.6 mmol) in water (50 mL) and the reaction mixture was stirred at 40°C for 20 h. The mixture was then concentrated on a rotary evaporator and the resulting white solid was dissolved in a minimum volume of water (10 mL) with gentle heating, and treated with ethanol (70 mL) to give a white precipitate. The suspension was allowed to stand for 12 h allowing maximum precipitation. The precipitate was collected by filtration to give (2S)-methionine methylsulfonium iodide as a white solid (9.4 g, 96%). Example 2: (2R)-Methionine methylsulfonium iodide The reaction was carried out according to the above procedure using D-methionine (9.9 g, 66.6 mmol) to give (2R)-methionine methylsulfonium (17.5 g, 91%) as a white solid. [α]D20 -16.8 (C 1.0, H2O); All other characterisation data was entirely consistent with that of the 2S-enantiomer.
Step 2
General/Typical Procedure: Example 3: (S)-2-Amino-4-hydroxybutyric acid ((2S)-9). (L-homoserine) (2S)-Methionine methylsulfonium iodide (9.4 g, 32.3 mmol) was dissolved in water (30 mL) in a three-necked round-bottom flask and heated to reflux. Sodium bicarbonate (2.71 g, 32.3 mmol) was dissolved in water (40 mL), placed in a dropping funnel and added dropwise to the reaction mixture until the pH of the solution rose to 5.0 (monitored using a VWR symphony SB20 pH meter). The reaction was allowed to proceed until the pH dropped to 2.0 (~ 15 min), whereupon base was added as previously described (addition over 6 h). The reaction mixture was then allowed to stir with heating at reflux for 12 h before being cooled, transferred to a 50 mL round-bottom flask and concentrated to give a clear oil. The oil was dissolved in water (5 mL) and ethanol (10 mL), and treated with acetone (150 mL) to produce a white precipitate that was collected by filtration. The precipitate was dissolved in water (20 mL) and freeze-dried, giving (S)-2-amino-4-hydroxybutyric acid (2S)-9 as a white solid (3.55 g, 92%).
Step 2
General/Typical Procedure: Example 3: (S)-2-Amino-4-hydroxybutyric acid ((2S)-9). (L-homoserine) (2S)-Methionine methylsulfonium iodide (9.4 g, 32.3 mmol) was dissolved in water (30 mL) in a three-necked round-bottom flask and heated to reflux. Sodium bicarbonate (2.71 g, 32.3 mmol) was dissolved in water (40 mL), placed in a dropping funnel and added dropwise to the reaction mixture until the pH of the solution rose to 5.0 (monitored using a VWR symphony SB20 pH meter). The reaction was allowed to proceed until the pH dropped to 2.0 (~ 15 min), whereupon base was added as previously described (addition over 6 h). The reaction mixture was then allowed to stir with heating at reflux for 12 h before being cooled, transferred to a 50 mL round-bottom flask and concentrated to give a clear oil. The oil was dissolved in water (5 mL) and ethanol (10 mL), and treated with acetone (150 mL) to produce a white precipitate that was collected by filtration. The precipitate was dissolved in water (20 mL) and freeze-dried, giving (S)-2-amino-4-hydroxybutyric acid (2S)-9 as a white solid (3.55 g, 92%).
Wodka trinkt man pur und kalt, das macht hundert Jahre alt!
Re: Гидролиз метионина
Спасибо! То что надо!
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