β-(Trifluoromethyl)phenylalanine is a protected amino acid used in the synthesis of pharmacologically active compounds. Phenylalanine (P319415) is an essential amino acid. L-Phenylalanine is biologically converted into L-tyrosine, another one of the DNA-encoded amino acids, which in turn is converted to L-DOPA and further converted into dopamine, norepinephrine, and epinephrine.