Trifluoroacetic acid → Boc-Ala-Ala-Ala-NH-(CH2)3-Br

Participants

Reaction Steps

To a cold (−15° C.) solution of Boc-Ala-OH (118 mg, 0.63 mmol) and NMM (103 μl, 1.03 mmol) in THF (8 mL) was added ECF (61 μl, 0.64 mmol) and stirred vigorously. After 2 min. a solution of the TFA salt of Ala-Ala-NH(CH2)3—Br (270 mg, 0.69 mmol) in a mixture of THF:DMF (4 mL: 2 mL) was added to it followed by NMM (170 μL, 1.7 mmol) and stirred for further 30 minutes. The mixture was warmed to r.t. and stirred for 6 h. The solvent was removed under reduced pressure to give a residue which was diluted with EtOAc and washed with saturated citric acid, saturated NaHCO3 and the organic layer was dried over Na2SO4 and concentrated under vacuum to give a residue, which was purified by silica gel flash column chromatography (EtOAc:Hexanes—9:1) to give the desired product as a solid (m.p.—decomposed at 192° C.) in moderate yields (137 mg, 54%). TLC (MeOH:DCM—1:9; Rf—0.44).

Provenance & Evidence