Trifluoroacetic acid → 2,6-Dimethyl-L-tyrosyl-N-[(2S)-2-amino-3-phenylpropyl]-D-alaninamide

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Reaction Steps

N-(tert-butoxycarbonyl)-2,6-dimethyl-L-tyrosyl-N-{(2S)-2-[(tert-butoxycarbonyl)amino]-3-phenylpropyl}-D-alaninamide (6.1 g, 9.1 mmol) was dissolved in 25 mL dichloromethane and 25 mL TFA and stirred at room temperature for 3 h under a nitrogen atmosphere. The mixture was evaporated under reduced pressure to give a yellow gum. The gum was dissolved in 20 mL methanol and split into 4 equal portions. Each was loaded onto a separate 10 g SCX-2 cartridge, pre-wetted with methanol. Each cartridge was flushed with 50 mL of methanol to remove non-basic impurities, and then with 80 mL of 2N ammonia solution in methanol to elute the desired product. Fractions containing product were concentrated in vacuo to give a pale yellow gum. This was heated with a hot air gun and placed under vacuum (15 mm Hg) overnight to give 3.7 g (100%) of the title compound as a stiff white foam.

Provenance & Evidence