Methyl 2-oxo-4-phenylbutanoate → Ammonium Hydroxide

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Reaction Steps

Dissolve 1-[(S)-alanyl]hexahydrofuro[3,4-b]pyrrole-2(S)-carboxylic acid (prepared in paragraph C of this example) in absolute methanol. Add 2-oxo-4-phenylbutyric acid, methyl ester and 3 Angstrom molecular sieve pellets, and stir the resulting mixture at room temperature for eighteen hours. Filter the reaction mixture and treat the filtrate with sodium cyanoborohydride at room temperature for two hours. Concentrate the mixture under nitrogen and dilute the oil with dilute hydrochloric acid and stir at room temperature for one hour. Absorb the aqueous solution on XAD-2 (Rohm & Hass Co.) resin. Elute the resin with water and then with methanol. Concentrate the methanol solution and place the residue on a column of silica gel and elute with chloroform:isopropanol: 7% ammonium hydroxide 1:1:1 (organic layer) to give 1-[N-(1-methoxycarbonyl-3-phenylpropyl)-(S)-alanyl]hexahydrofuro[3,4-b]pyrrole-2(S)carboxylic acid.

Provenance & Evidence