(5S)-1-((2R)-2-(cyclopentylmethyl)-4-oxo-4-{[(phenylmethyl)oxy]amino}butanoyl)-N,N-dimethyl-4,5-dihydro-1H-pyrazole-5-carboxamide → (5S)-1-[(2R)-2-(cyclopentylmethyl)-4-(hydroxyamino)-4-oxobutanoyl]-N,N-dimethyl-4,5-dihydro-1H-pyrazole-5-carboxamide

To a solution of (5S)-1-((2R)-2-(cyclopentylmethyl)-4-oxo-4-{[(phenylmethyl)oxy]amino}butanoyl)-N,N-dimethyl-4,5-dihydro-1H-pyrazole-5-carboxamide (120 mg, 0.28 mmol) in methanol (10 mL) was added Pearlman's catalyst (39 mg, 0.056 mmol). The resulting mixture was stirred under 1 atm of H2 for 1 hour. After 1 hour, the mixture was filtered, concentrated, and purified by Gilson HPLC (Sunfire Column 19×50 mm, flowrate 25 mL/min, 10 min, 5-65% MeCN:H2O) to afford (5S)-1-[(2R)-2-(cyclopentylmethyl)-4-(hydroxyamino)-4-oxobutanoyl]-N,N-dimethyl-4,5-dihydro-1H-pyrazole-5-carboxamide (78 mg, 0.23 mmol, 82% yield) as a yellow solid. MS: 389 ([M+H]+). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 1.09-1.26 (m, 2H) 1.59 (br. s., 35H) 1.78-1.97 (m, 5H) 2.43-2.52 (m, 1H) 2.62-2.73 (m, 1H) 2.85-2.95 (m, 1H) 3.01 (s, 3H) 3.19 (s, 4H) 3.58-3.67 (m, 1H) 5.08-5.18 (m, 1H) 6.88-6.97 (m, 1H).