Methanol → (S)-2-[(S)-3-(4-But-3-enyloxy-phenyl)-2-tert-butoxycarbonylamino-propionylamino]-4-methyl-pentanoic acid

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Reaction Steps

Methyl ester 20 (2.30 g, 4.97 mmol) was dissolved in THF (30 mL) and NaOH (0.298 g, 7.46 mmol) dissolved in water (10 mL) was added. Methanol (10 mL) was added to obtain a homogenous solution and this was stirred at rt for 18 h. The reaction mixture was then concentrated in vacuo and the residue was partitioned between EtOAc and 1M hydrochloric acid. The aqueous phase was extracted twice more with EtOAc and the combined organic extracts were washed with brine, dried (MgSO4), filtered and concentrated in vacuo to yield a white solid, 2.14 g, 96%. m.p. 68-70° C.

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