Ethyl alpha-oxobenzenebutanoate → Ammonium Hydroxide

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Reaction Steps

Dissolve 1-[(S)-alanyl]azacyclooctane-2(S)-carboxylic acid (prepared in paragraph C of this example) in 100 ml of absolute ethanol. Add 1.10 g 2-oxo-4-phenylbutyric acid, ethyl ester and 20 ml of 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 0.68 g 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 200 ml of a XAD-2 (Rohm & Hass Co. ) resin. Elute the resin with 2000 ml of water and then with 2000 ml of methanol. Concentrate the methanol solution and place the residue on a column of silica gel (400 g, 60-200 mesh) and elute with chloroform:isopropanol: 7% ammonium hydroxide 1:1:1 (organic layer) to give 1 -[N-(1 -ethoxycarbonyl-3-phenylpropyl)-(S)-alanyl]azacyclooctane-2(S)-carboxylic acid.

Provenance & Evidence