Diisopropylethylamine → (S)-tert-butyl 4-(5-(tert-butyldimethylsilyloxy)-4-(3-(2-chloro-3-fluorobenzyl)-1-methylureido)pentanoyl)piperazine-1-carboxylate

Participants

Reaction Steps

To a solution of (S)-5-(tert-butyldimethylsilyloxy)-4-(3-(2-chloro-3-fluorobenzyl)-1-methylureido)pentanoic acid (4.46 g, 10 mmol, 1.0 equiv.) in DMF (50 mL), was added HBTU (5.69 g, 15 mmol, 1.5 equiv.), 1-N-Boc-piperazine (2.79 g, 15 mmol, 1.5 equiv.) and DIEA (5.21 mL, 30 mmol, 3.0 equiv.) in sequence. The reaction was completed in 15 min. Ether (100 mL) and brine (100 mL) were added to the reaction mixture. The organic layer was dried and concentrated. The residue was purified on silica gel column using a mixture of hexane and EtOAc to give (S)-tert-butyl 4-(5-(tert-butyldimethylsilyloxy)-4-(3-(2-chloro-3-fluorobenzyl)-1-methylureido)pentanoyl)piperazine-1-carboxylate (4.2 g, 68%). LRMS (M+H+) m/z 615.2.

Provenance & Evidence