Benzyl Bromide → di-tert-butyl (5S)-2-[4-(benzyloxy)benzyl]-2-(benzyloxycarbonyl)-5-[(tert-butoxycarbonyl)amino]hexanedioate

Participants

Reaction Steps

1.00 g (1.97 mmol) (2S)-2-Benzyloxycarbonyl-5-tert.-butoxycarbonylamino-hexane dioic acid di-tert.-butyl ester were dissolved in 25 mL dimethylformamide, 87 mg (2.2 mmol) NaH (60% in mineral oil) added and stirred at room temperature for 30 min. 601 mg (2.17 mmol) 4-benzloxy benzyl bromide 1 mL dimethylformamide were added and the reaction stirred for 1 h at 60° C. The solvent was removed i. vac. And the residue partitioned between ethyl acetate and brine. The organic phase was adsorbed on Isolute and directly chromatographed on a Biotage Isolera system (SNAP 100 g, A=n-Hexane, B=ethyl acetate. A 3 CV, A to 25% B in 10 CV, 4.7 CV 25% B, 50 mL/min, Fr. a 18 mL). Fractions 68 to 75 were collected to give 1.09 g (79%) of (2S,5SR)-5-Benzyloxycarbonyl-6-(4-benzyloxy-phenyl)-5-tert.-butoxycarbonyl-2-tert.-butoxycarbonylamino-hexanoic acid tert.-butyl ester.

Provenance & Evidence