Wikipedia
Diphenylalanine
The most common use of the word Diphenylalanine refers to two Phenylalanine molecules joined together by a Peptide bond.
Diphenylalanine is an unnatural amino acid. It is similar to the two amino acids alanine and phenylalanine. It has been used for the synthesis of pseudopeptide analogues which are capable of inhibiting certain enzymes.
A possible synthesis starts from 3,3-diphenyl- propionic acid which is stereoselective aminated to the diphenylalanine.