* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
Stage #1: With chloro-trimethyl-silane In methanol at 20℃; for 12 h; Stage #2: With sodium ethanolate In methanol; ethanol at 0 - 20℃; for 0.583333 h;
Trimethylchlorosilane (2.8 mL, 23 mmol, 4 equiv) was added to L-ornithine·HCl (1.0 g,6.0 mmol, 1 equiv) followed by the addition of anhydrous methanol (20 mL). The mixturestirred at rt for 12 h. The solution was then cooled to 0 °C and a 21percent (w/w) solution ofsodium ethoxide in ethanol (42 mmol, 17 mL) was added; after 5 min the solution wasallowed to warm to rt and stirred for another 30 min. The solution was neutralized to pH7 with 6 N aq HCl. The resulting solution was filtered and conc. in vacuo. Salts wereremoved by dissolution in isopropanol, filtered, and conc. in vacuo. The crude residuewas purified by flash column chromatography on silica gel (30percent methanol indichloromethane) to afford lactam hydrochloride 4 as a hygroscopic, pale yellow solid.
Reference：
[1] Beilstein Journal of Organic Chemistry, 2017, vol. 13, p. 247 - 250
[2] Enantiomer, 2001, vol. 6, # 5, p. 275 - 279
[3] Chemistry Letters, 1981, p. 1691 - 1694
[4] Organic Process Research and Development, 2005, vol. 9, # 5, p. 570 - 576
3
[ 24424-99-5 ]
[ 3184-13-2 ]
[ 92235-39-7 ]
Yield
Reaction Conditions
Operation in experiment
78%
Stage #1: With hydrogenchloride In methanol at 20℃; for 4.75 h; Stage #2: With sodium methylate In methanol at 20℃; for 4 h; Stage #3: With triethylamine In dichloromethane at 20 - 25℃; for 60 h;
A slow stream of HCl (gas) was bubbled through a solution of (L)-omithine hydrochloride (20.2 g, 120 mmol; Aldrich) in methanol (400 mL) for 45 minutes at ambient temperature. After stirring for an additional 4 hours, the mixture was concentrated under reduced pressure to leave a brown oil. The brown oil was dissolved in methanol (300 mL) and treated with a solution of NaOCH3 (prepared from 6.9 g Na and 100 mL of methanol). After stirring at ambient temperature for 4 hours, the mixture was concentrated under reduced pressure to provide a brown semisolid. The semisolid was dissolved in dichloromethane (300 mL) and treated with triethylamine (50.1 g, 360 mmol) and di-tert-butyl dicarbonate (38.7 g, 180 mmol; Aldrich). After stirring for 60 hours at 20-25 °C, the mixture was concentrated under reduced pressure. The residue was taken up in dichloromethane (200 mL), washed successively with water (100 mL) and brine (100 mL), dried (MgSO4), and concentrated. The residue was purified by chromatography on silica gel (dichloromethane:methanol:NH4OH, 95:5:0.5) to provide the title compound as a white solid (20.1 g, 78percent). MS (CI/NH3) m/z 215 (M+H)+.
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