Trifluoroacetic acid → L-alanyl-L-valinamide

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Reaction Steps

N-(tert-butoxycarbonyl)-L-alanyl-L-valinamide (0.5 g, 1.74 mmol) is stirred with 3 mL of TFA in 6 mL of dichloromethane for 1 h. It is then concentrated, neutralized with 3.5 mL of 1N NaHCO3 and 3.5 mL of 1N Na2CO3, and extracted into 60 mL of ethyl ether containing several mL of methanol. The aqueous phase is extracted with 100 mL of dichloromethane and 10 mL of methanol. The aqueous layer is evaporated and the solids are extracted with methanol. This is concentrated to 180 mg (0.96 mmol, 55%) of an 85:15 mixture of the title compound and a minor diastereomer. The combined organic phases are concentrated to afford 74 mg (0.4 mmol, 23%) of the title compound as a white solid. HRMS (ESI) calcd for C8H17N3O2+H1 188.1399, found 188.1408.

Provenance & Evidence