A compound having a structure according to formula wherein R 1 is (C 1 -C 5 alkyl)O, (C 1 -C 2 alkyl)O(CH 2) 2-3 O, (C 1 -C 5 alkyl)C(=O)O, (C 1 -C 5 alkyl)NH, (C 1 -C 2 alkyl)O(CH 2) 2-3 NH, or (C 1 -C 5 alkyl)C(=O)NH; R 2 and R 3 are, independently for each occurrence thereof, H, C 1 -C 3 alkyl, halo, O(C1-C3 alkyl), CN, or NO 2, where one R 3 may be replaced by (CH 2) x R 4, where the subscript x is 1, 2, 3, or 4; R 4 is H, halo, OH, CN, NH 2, NH(C 1 -C 5 alkyl), N(C 1 -C 5 alkyl) 2, NH(C 3 -C 6 cycloalkyl), NH(C 4 -C 8 bicycloalkyl), NH(C 6 -C 10 spirocycloalkyl), N(C 3 -C 6 cycloalkyl) 2, NH(CH 2) 1-3 (aryl), N((CH 2) 1-3 (aryl)) 2, a cyclic amine moiety having the structure a 6-membered aromatic or heteroaromatic moiety or a 5-membered heteroaromatic moiety; wherein an alkyl, cycloalkyl, bicycloalkyl, spirocycloalkyl, cyclic amine, 6-membered aromatic or heteroaromatic, or 5-membered heteroaromatic moiety is optionally substituted with one or more substituents selected from OH, halo, CN, (C 1 -C 3 alkyl), O(C 1 -C 3 alkyl), C(=O)(Me), SO 2 (C 1 -C 3 alkyl), C(=O)(Et), NH 2, NH(Me), N(Me) 2, NH(Et), N(Et) 2, and N(C 1 -C 3 alkyl) 2; and a cycloalkyl, bicycloalkyl, spirocycloalkyl, or cyclic amine moiety may have a CH2 group replaced by O, S, NH, N(C 1 -C 3 alkyl), or N(Boc); R 5 is, independently for each occurrence thereof, O, S or NR 6; R 6 is H or C 1 -C 3 alkyl; X 1 is, independently for each occurrence thereof, CR 2 or N; and X 2 is, independently for each occurrence thereof, CR 3 or N. R 1 is (C 1 -C 5 alkyl)O, (C 1 -C 2 alkyl)O(CH 2) 2-3 O, (C 1 -C 5 alkyl)C(=O)O, (C 1 -C 5 alkyl)NH, (C 1 -C 2 alkyl)O(CH 2) 2-3 NH, or (C 1 -C 5 alkyl)C(=O)NH; R 2 and R 3 are, independently for each occurrence thereof, H, C 1 -C 3 alkyl, halo, O(C1-C3 alkyl), CN, or NO 2, where one R 3 may be replaced by (CH 2) x R 4, where the subscript x is 1, 2, 3, or 4; R 4 is H, halo, OH, CN, NH 2, NH(C 1 -C 5 alkyl), N(C 1 -C 5 alkyl) 2, NH(C 3 -C 6 cycloalkyl), NH(C 4 -C 8 bicycloalkyl), NH(C 6 -C 10 spirocycloalkyl), N(C 3 -C 6 cycloalkyl) 2, NH(CH 2) 1-3 (aryl), N((CH 2) 1-3 (aryl)) 2, a cyclic amine moiety having the structure a 6-membered aromatic or heteroaromatic moiety or a 5-membered heteroaromatic moiety; wherein an alkyl, cycloalkyl, bicycloalkyl, spirocycloalkyl, cyclic amine, 6-membered aromatic or heteroaromatic, or 5-membered heteroaromatic moiety is optionally substituted with one or more substituents selected from OH, halo, CN, (C 1 -C 3 alkyl), O(C 1 -C 3 alkyl), C(=O)(Me), SO 2 (C 1 -C 3 alkyl), C(=O)(Et), NH 2, NH(Me), N(Me) 2, NH(Et), N(Et) 2, and N(C 1 -C 3 alkyl) 2; and a cycloalkyl, bicycloalkyl, spirocycloalkyl, or cyclic amine moiety may have a CH2 group replaced by O, S, NH, N(C 1 -C 3 alkyl), or N(Boc); an alkyl, cycloalkyl, bicycloalkyl, spirocycloalkyl, cyclic amine, 6-membered aromatic or heteroaromatic, or 5-membered heteroaromatic moiety is optionally substituted with one or more substituents selected from OH, halo, CN, (C 1 -C 3 alkyl), O(C 1 -C 3 alkyl), C(=O)(Me), SO 2 (C 1 -C 3 alkyl), C(=O)(Et), NH 2, NH(Me), N(Me) 2, NH(Et), N(Et) 2, and N(C 1 -C 3 alkyl) 2; and a cycloalkyl, bicycloalkyl, spirocycloalkyl, or cyclic amine moiety may have a CH2 group replaced by O, S, NH, N(C 1 -C 3 alkyl), or N(Boc); R 5 is, independently for each occurrence thereof, O, S or NR 6; R 6 is H or C 1 -C 3 alkyl; X 1 is, independently for each occurrence thereof, CR 2 or N; and X 2 is, independently for each occurrence thereof, CR 3 or N.