Diisopropylethylamine → (3S)-2-[(2R)-3-cyclopentyl-2-({formyl[(phenylmethyl)oxy]amino}methyl)propanoyl]-1-{[(phenylmethyl)oxy]carbonyl}-3-pyrazolidinecarboxylic acid

Participants

Reaction Conditions

Reaction Steps

(2R)-3-Cyclopentyl-2-({formyl[(phenylmethyl)oxy]amino}methyl)propanoyl fluoride (11.37 g, 37 mmol) in 50 mL of DMF was added into the solution of 1-(benzyloxy carbonyl)pyrazolidine-3-carboxylic acid (12.04 g, 48.1 mmol) and Hunig's base (25.8 ml, 148 mmol) in 70 ml of DMF. The reaction was stirred at 25° C. for 5 hrs. The reaction was diluted with ethyl acetate, and the resulting solution was washed with aqueous NH4Cl (2×200 ml). The aqueous solution was extracted with ethyl acetate (5×100 ml). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated to give a residue. The residue was purified by silica Gel chromatography and then recrystallization from ethyl acetate and hexane to yield (3S)-2-[(2R)-3-cyclopentyl-2-({formyl[(phenylmethyl)oxy]amino}methyl)propanoyl]-1-{[(phenylmethyl)oxy]carbonyl}-3-pyrazolidinecarboxylic acid (2.834 g, 5.27 mmol, 14% yield). MS (ES+) m/z 538.1 (MH+).

Provenance & Evidence