Derivatives of 3- (5-chloro-2-oxobenzo [d] oxazole-3 (2H) -yl) propanoic acid as KMO inhibitors

A compound of formula (I) or a salt thereof ** ** Formula wherein: X is a bond and R1 is -H, -halo, or -CN; or X is -CH2- and R1 is -H or C1-3 alkyl; or X is -O- and R1 is alkyl C1-4, - (CH2) mCF3, -CHR2CH2OMe, - (CH2) n-C3-4 cycloalkyl, - (CH2) noxetano, -benzyl or -CHR2heteroarilo; wherein the heteroaryl may be further substituted by halo, methyl, ethyl or O; m> = 1 or 2; n> = 0 or 1; R2> = -H, -methyl or -ethyl; and R3> = H or -methyl, provided that the compound of formula (I) or a salt thereof is not 3- (5-chloro-2-oxobenzo [d] oxazole-3 (2H) - yl) propanoic acid or 3- (5-chloro-2-oxobenzo [d] oxazole-3 (2H) -yl) -2-methylpropanoic acid