The present invention relates to a compound of Formula (I): wherein: R1 is H or C1-2 alkyl R2 is H or C1-3 alkyl R3 and R4 are each independently H or C1-2 alkyl, where the alkyl may be substituted with one to three of the same or different substituents selected from R10 R5 is H, hydroxy, C1-2 alkyl, or OCH3 and R10 is F or CI, or a pharmaceutically acceptable salt or ester thereof.