1-Hydroxybenzotriazole → t-Butyloxycarbonyl-L-methionyl-L-alanyl-L-valyl-Nepsilon-benzyloxycarbonyl-L-lysine benzyl ester

Participants

Reaction Steps

Partial deprotection of compound XXI (3.4 g, 5.3 mmole) was carried out as described in the previous paragraph. The trifluoroacetate salt (RfC, 0.75) was acylated in DMF (50 ml) with Boc-L-Met-ONp (2.18 g, 5.9 mmole, Bachem) in the presence of DIEA (1.9 ml, 12 mmole) and HOBt (0.9 g, 5.9 mmole). After 4 hr at room temperature the reaction was complete. Evaporation of most of the solvent in vacuo was followed by trituration with EtOAc. The precipitate was washed with EtOAc, with ether and dried: 3.8 g (93%); m.p. 169°-171° C., [α]D24 -21.5° (c 1.2, DMF) RfK, 0.65; RfI, 0.52.

Provenance & Evidence