Water → (S)-3-tert-Butoxycarbonylamino-2-p-tolyl-propionic acid

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Reaction Steps

The 3-tert-butoxycarbonylamino-2-p-tolyl-propionic acid methyl ester (12.3 g, 41.9 mmol) was dissolved in 200 mL 1:1 THF:water and treated with lithium hydroxide monohydrate (2.64 g, 62.9 mmol) at room temperature. The reaction was stirred at room temperature overnight to completion and concentrated in vacuo. The oily mixture was partitioned with water and washed with EtOAc (discarded). The aqueous was treated with solid KHSO4 until pH<2, then extracted with EtOAc. The combined organic was dried over Na2SO4, filtered, and concentrated in vacuo to afford the 3-tert-butoxycarbonylamino-2-p-tolyl-propionic acid as a white solid (10.95 g, 93%). 1H NMR (ca. 1:1 mixture of rotamers) (CDCl3, 400 MHz) δ 10.40-8.40 (br s, 1H), 7.16 (d, J=8.4 Hz, 2H), 7.13 (d, J=8.4 Hz, 2H), 6.80 or 4.91 (br s, 1H), 3.86 and 3.75 (m, 1H), 3.55 (m, 1H), 3.47 (m, 2H), 2.31 (s, 3H), 1.44 and 1.41 (s, 9H). LCMS (APCI−) m/z 557 [2M−H]−. HPLC R2=2.80 min.

Provenance & Evidence