6-O-substituted benzoxazole and benzothiazole compounds and methods of inhibiting CSF-1R signaling

A compound of Formula (I) or a pharmaceutically acceptable salt thereof

• wherein X is O or S;
• R1 is LR1a wherein L is a covalent bond, alkylidene, or substituted alkylidene,
• and R1a is selected from tetrahydropyran-2-yl, tetrahydropyran-3-yl, tetrahydropyran-4-yl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclohexenyl, and each R1a is unsubstituted or substituted;
• R2 is hydrogen or methyl;
• R3 is —C(O)NH-L2R3a, wherein L2 is a covalent bond, alkylidene, or substituted alkylidene, and R3a is selected from the group consisting of alkyl, haloalkyl, amino, acylamino, (carboxyl ester)amino, hydroxy, alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, heterocyclyl, and substituted heterocyclyl,
• or R3 is selected from the group consisting of pyrazol-1-yl, pyrazol-3-yl, pyrazol-4-yl, pyridine-2-yl, pyridine-3-yl, pyridine-4-yl, pyrimidin-4-yl, pyrimidin-3-yl, pyrimidin-2-yl, thiazoyl, tetrazolyl, imidazol-1-yl, imidazol-2-yl, imidazol-3-yl, pyrazinyl, furanyl, oxazole, and oxadiazole, wherein each R3 is substituted or unsubstituted;
• each R6 is independently alkyl, substituted alkyl, alkoxy, substituted alkoxy, amino, substituted amino, or halo;
• n is 0, 1, or 2;
• and
• R4 is hydrogen, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, or substituted alkynyl, and
• R5 is hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aminocarbonyl, halo, heteroaryl, substituted heteroaryl, cycloalkyl, or substituted cycloalkyl.