Cesium carbonate → tert-Butyl (2S)-2-benzyloxycarbonylamino-3-(4-(3-ethoxycarbonylpropyloxy)phenyl)propionate

Participants

Reaction Steps

7.42 g (0.02 mol) of N-benzyloxycarbonyl-L-tyrosine tert-butyl ester were refluxed for 6 h together with 9.77 g(0.03 mol) of cesium carbonate and 3.9 g (0.02 mol) of ethyl 4-bromo-butyrate in about 60 ml of acetone. After cooling the reaction mixture, the solvent was removed in vacuo. The residue was partitioned between ethyl acetate and water (1/1). After separation of the phases, the organic phase was washed two times each with water and saturated sodium chloride solution, dried over sodium sulfate and concentrated in vacuo. The oily crude product was purified by flash chromatography on silica gel (dichloromethane/acetonitrile 25/1). Yield: 9.4 g (97%) of viscous oil. Rf=0.36 (silica gel, dichloromethane/methanol 9911).

Provenance & Evidence