Triethylamine → Z-Lys(Boc)-Lys(Boc)-OMe

Participants

Reaction Steps

To an ice-cold solution of Nε -t-butyloxycarbonyl-L-lysine methyl ester hydrochloride (H-Lys(Boc)-OMe.HCl) (0.89 g, 3 mmoles) and triethylamine (0.46 ml, 3.3 mmoles) in dimethyl-formamide (8 ml) is added Nα -benzyloxycarbonyl-Nε -t-butyloxy-carbonyl-L-lysine N-hydroxysuccinimide ester (Z-Lys(Boc)-OSu) (1.43 g, 3 mmoles) (Bull. Chem. Soc. Japan 39, 882 (1966)) and the mixture is allowed to stand at 4° C overnight followed by evaporation in vacuo at a bath temperature of 40° C. The residue is dissolved in ethyl acetate and the solution is washed successively with ice-cold M hydrochloric acid, water, and M sodium bicarbonate, dried over magensium sulfate and evaporated in vacuo to give a residue, which is precipitated from ethyl acetate-petroleum ether. Reprecipitation from the same solvent yields the desired product in pure form; yield 1.80 g (96.5%), [α]D22.5 -11.7°±0.5° (c 1.0, methanol). Thin-layer chromatography (silica gel): homogeneous (to ninhydrin after pretreatment with hydrobromic acid) in chloroform-methanol-acetic acid (90:10:3, v/v).

Provenance & Evidence