The invention relates to novel compounds of formula (I), the compounds being capable of acting as avβ6
integrin antagonists, their use in the treatment of
disease, their methods of manufacture and compositions comprising said compounds for such purposes (I) wherein R1 is selected from: R1a, —C(O)R1a, —C(O)OR1a —C(O)NHR1a, —C(O)N(R1a)2, —SO2R1a, wherein R1a are each independently selected from:
alkyl, alkenyl, alkynyl,
aryl, heteroaryl, alkylaryl or alkylheteroaryl, each of which may be optionally substituted; R2 is selected from:
hydrogen,
halogen, optionally substituted
alkyl or optionally substituted alkoxyl; R2a are each independently selected from:
hydrogen,
halogen, optionally substituted
alkyl or optionally substituted alkoxyl; R3 is selected from:
hydrogen, optionally substituted alkyl or optionally substituted alkoxyl; R4 is hydroxyl; Ar1 is an optionally substituted heteroaryl or bicyclic heteroaryl; and L is a
linker; or a pharmaceutically acceptable salt thereof.