Patent ID: 8258097

Claim:
A compound which is a substituted phenylalanine of formula (I) or formula (II), or a salt or hydrate thereof: wherein: R 1 is a carboxyl, carboxyl ester, or carboxamide group; R 2 is a group —C(═O)—NR 3 R 4 , or —S(═O) 2 —NR 3 R 4 ; R 3 and R 4 are independently selected from hydrogen, optionally substituted C 1 -C 6 alkyl, (C 1 -C 5 fluoroalkyl)-CH 2 —, -Q, and —CH 2 Q, wherein Q is an optionally substituted monocyclic carbocyclic or heterocyclic ring of 3 to 6 ring atoms; or R 3 and R 4 together with the nitrogen to which they are attached form an optionally substituted monocyclic cycloalkyl or non-aromatic heterocyclic ring of 3 to 8 ring atoms; R 5 is hydrogen, or a natural or non-natural alpha amino acid residue linked via a peptide bond; R 6 is hydrogen or a group R 7 C(═O)—; and R 7 is C 1 -C 6 alkyl, C 1 -C 6 fluoroalkyl or cyclopropyl.