4-Methylmorpholine → 2-bromopentanoyl-(L)-homophenylalanine methyl ester

Participants

Reaction Steps

Combine (L)-homophenylalanine methyl ester trifluoroacetic acid salt (3.6 g, 10 mmol), N-methylmorpholine (3.3 mL, 30 mmol), and dichloromethane (20 mL). Add 2-bromovaleric acid (2.0 mL, 15.3 mmol), hydroxybenzotriazole (2.07 g, 15.3 mmol), and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (2.93 g, 15.3 mmol). After 1 hour, partition the reaction mixture between methyl t-butyl ether and an aqueous 5% sulfuric acid solution. Separate the layers, extract the organic layer with a saturated sodium bicarbonate solution and then brine. Dry over Na2SO4, filter, and evaporate in vacuo to give a residue. Chromatograph the residue on silica gel eluting sequentially with 3/1 hexane/ethyl acetate and then 2.5/1 hexane/ethyl acetate to give the title compound: Rf=0.55 (silica gel, 1/1 ethyl acetate/hexane).

Provenance & Evidence