tert-butyl (3S)-3,4-diamino-4-oxobutanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a room temperature CH2Cl2 solution (400 mL) of 3-benzyloxy-4-chlorosulfonyl-benzoic acid methyl ester (11.43 g, 33.50 mmol) was added (S)-3-amino-succinamic acid tert-butyl ester (6.32 g, 33.50 mmol) and pyridine (10.80 mL). The reaction mixture was allowed to stir for 12 h at room temperature. The reaction was then diluted with ethyl acetate and washed with 5% citric acid and saturated NaHCO3. The organic phase was dried (MgSO4), and then the solvent was removed under vacuum. The resulting crude product was purified using silica gel flash chromatography (3% MeOH in CH2Cl2). 3-Benzyloxy-4-((S)-2-tert-butoxycarbonyl-1-carbamoyl-ethylsulfamoyl)-benzoic acid methyl ester was obtained in 45% yield (7.40 g) as an off white foam. MS m/z 491.2 (M−1). washed with 5% citric acid and saturated NaHCO3 The organic phase was dried (MgSO4) the solvent was removed under vacuum The resulting crude product was purified

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a room temperature CH2Cl2 solution (50 mL) of 2-benzyloxy-4-nitro-benzenesulfonyl chloride from Route J (2.62 g, 8.0 mmol) was added (S)-3-amino-succinamic acid tert-butyl ester (1.50 g, 8.0 mmol) and pyridine (2.60 mL). The reaction mixture was allowed to stir for 12 h at room temperature. The reaction was then diluted with ethyl acetate (200 mL) and washed with 5% citric acid and then saturated NaHCO3. The organic phase was dried (MgSO4), and then the solvent was removed under vacuum. The resulting crude product was purified using silica gel flash chromatography (40% hexanes in EtOAc). (S)-3-(2-Benzyloxy-4-nitro-benzenesulfonylamino)-succinamic acid tert-butyl ester was obtained in 43% yield (1.66 g) as an off white foam. MS (APCI) m/z 478.3 (M−1). washed with 5% citric acid The organic phase was dried (MgSO4) the solvent was removed under vacuum The resulting crude product was purified

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution 3-benzyloxycarbonylamino-succinamic acid tert-butyl ester (5.0 g, 15.50 mmol) in THF (20 mL) was added 20% Pd/C (150 mg), and the mixture was stirred for 4 h under H2 atmosphere at 50 psi. The catalyst was filtered and the solvent removed. The resulting oil solidifies upon the addition of ether. The solid was dried to give 2.90 g (98%) of (S)-3-amino-succinamic acid tert-butyl ester as an off white solid. The solid was used immediately in the next step. MS (APCI) m/z 189.1 (M+1). The catalyst was filtered the solvent removed The resulting oil solidifies upon the addition of ether The solid was dried