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A. (S)-2-(tert-Butoxycarbonylamino)-3-methoxypropanoic acid A sodium methanolate (NaOMe) solution was prepared by slowly adding MeOH (50 mL) to a suspension of sodium hydride (60percent in mineral oil, 28 g, 0.71 mol) in dry THF (1.2 L) at 0° C. The resulting mixture was stirred at RT for 2 h. A portion of the NaOMe solution (320 mL) was added to (S)-2-(tert-butoxycarbonylamino)-3-hydroxypropanoic acid (36 g, 175 mmol) in dry THF (1.6 L), and the mixture was stirred at RT for 1 h. Methyl iodine (16 mL) was then added and the mixture was stirred at RT for 1 h. Another aliquot of NaOMe solution (540 mL) was added and the reaction mixture stirred at RT for 1 h. Additional methyl iodine (38 mL) in THF (200 mL) was added and the reaction mixture was stirred at RT for 36 h. Following reaction, the mixture was concentrated and the residue was dissolved in water and washed with diethyl ether (2.x.100 mL). The aqueous layer was acidified to pH 2 by the addition of solid citric acid and was extracted with EtOAc (3.x.200 mL) and dried over Na2SO4. The organic phase was concentrated, and the residue was dissolved in water and extracted with DCM (4.x.150 mL). The organic layers were combined and concentrated to give the title compound as an oil, which was used without further purification (10.9 g, 28percent).
2-(S)-amino-4-methyl-1-(5-phenyl-[1,3,4]oxadiazol-2-yl)-(R/S)-pentan-1-ol hydrochloride[ No CAS ]
[ 51293-47-1 ]
[ 660847-58-5 ]
Yield
Reaction Conditions
Operation in experiment
79%
[N-A-BOC-0-METHYL-L-SERINE] (2.19g, 10.0 mmol), HOBt (1.62g, 12.0 mmol), [1-ETHYL-3- (3APOS;-DIMETHYLAMINO-PROPYL) CARBODIIMIDE] hydrochloride (EDC, 2. [01G,] 10.5 mmol), and N-methylmorpholine (1.4 mL, 12.5 mmol) were stirred in 150 mL anhydrous dichloromethane. After 5 min, [2-AMINO-4-METHYL-L- (5-PHENYL-] [[1,] 3,4] oxadiazol-2-yl)-pentan-1-ol hydrochloride (2.61g, 10.0 mmol) dissolved in dichloromethane (50 [ML)] and more N-methylmorpholine (1.4 mL, 12.5 mmol) were added. After 3 hr, the reaction mixture was transferred to a separatory funnel and washed twice with 100 mL portions [OF 0. 5N] aqueous [HCI.] The organic phase was separated and once with water (50 mL) and twice with saturated aqueous sodium bicarbonate (100 mL). The organic phase was dried over anhydrous magnesium sulfate. Filtration and solvent evaporation gave a tan foam. This was flash chromatographed on silica gel, eluting with 5percent methanol in dichloromethane to give (1- 1- [hydroxy- (5-phenyl- [1, 3,4] oxadiazol-2-yl) methyl]-3-methyl-butylcarbamoyl}- 2-methoxyethyl) carbamic acid ter-butyl ester as a brittle, pale yellow foam, (3.65g, 79percent) as a mixture of diastereomers.
{(S)-1-[(S)-1-((1S,2S,4R)-1-Benzyl-2-hydroxy-4-{(S)-2-methyl-1-[(pyridin-4-ylmethyl)-carbamoyl]-propylcarbamoyl}-pentylcarbamoyl)-ethylcarbamoyl]-2-methoxy-ethyl}-carbamic acid tert-butyl ester[ No CAS ]