Sodium Hydroxide → 2-{[1-({[(3S)-1-(2-tert. butoxy-2-oxoethyl)-2-oxo-2,3,4,5-tetrahydro-1H-1-benzazepin-3-yl]amino}-carbonyl)cyclopentyl]methyl}-4-(isopropylamino)-4-oxobutyric Acid

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Reaction Steps

2.6 g ethyl 2-{[(3S)-1-({[1-(2-tert. butoxy-2-oxoethyl)-2-oxo-2,3,4,5-tetrahydro-1H-1-benzazepin-3-yl]amino}carbonyl)cyclopentyl]methyl}-4-(isopropylamino)-4-oxobutyrate (for preparation see Example 1) was dissolved in 52 ml of ethanol. A solution of 710 mg solid NaOH in 52 ml water was added to this receiving solution. After 30 minutes, it was acidulated with dilute aqueous KHSO4 solution to approximately pH 2 and the aqueous phase was extracted three times with 50 ml EA each time. The combined organic phases were dried over magnesium sulfate, the solvent was largely evaporated at reduced pressure and the remaining residue was chromatographed on silica gel (mobile phase: EA/cyclohexane 2:1 v/v). Drying the product fractions in an oil pump vacuum (5×10−2 mbar) yielded 2.2 g of the title compound as white foam resin, MS: [M+H]+: 558; m/z: 502, 425, 397, 323.

Provenance & Evidence