Synthesis of [14C]-N-[(trimethylamineboryl)carbonyl]-phenylalanine-methyl ester

Reported is the synthesis of [14C]-L-N-[(trimethylamine-boryl) carbonyl]-phenylalanine methyl ester, a boron containing α-amino acid dipeptide analog with antineoplastic, anti-inflammatory, and hypolipidemic activities. The 14C label is universally distributed among all carbon positions of the phenylalanine portion of the molecule. Briefly, the dipeptide is prepared by reacting the phenylalanine methyl ester hydrochloride salt with trimethylamine-carboxyborane, triphenylphospine (TPP), CCl4, and triethylamine (TEA) in acetonitrile, for 24 hours. The final product afforded a specific activity of 5.71 mCi/mmol. (author)