A compound of formula Ia, Ib, or a mixture thereof: wherein: X is O, S, or -NR 5; R 1 is -(C 1 -C 6)alkyl, -CF 3, -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 14)aryl, -(5 to 11-membered)heteroaryl, or ferrocenyl; wherein said -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 14)aryl and -(5 to 11-membered)heteroaryl of said R 1 is optionally substituted with 1 to 3 substituents independently selected from -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, and -CF 3; R 2 is H, -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 14)aryl, -(5 to 11-membered)heteroaryl, -NR 5 R 6, or -SR 5; wherein said -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 14)aryl, and -(5 to 11-membered)heteroaryl of said R 2 is optionally substituted with 1 to 3 substituents independently selected from -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, and -CF 3; R 3 is -(C 1 -C 6)alkyl substituted with 1 to 3 (5- to 6-membered)heteroaryl; wherein the (5-to 6-membered)heteroaryl ring is optionally substituted with 1 to 3 R 4 substituents independently selected from -O(C 1 -C 6)alkyl, -N-(C 1 -C 6 alkyl) 2, -(C 1 -C 6)alkyl, phenyl, (5-to 11-membered)heteroaryl and -CF 3; or R 3 is ortho -substituted pyridine, oxazoline, and chiral oxazoline, optionally substituted with 1 to 3 R 4 substituents independently selected from -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, phenyl, and -CF 3; R 5 and R 6 are each independently H, -(C 1 -C 6)alkyl, -CF 3, -(C 3 -C 10 carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 10)aryl, or -(5 to 11-membered)heteroaryl; wherein each -(C 1 -C 6)alkyl, -CF 3, -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 10)aryl, and -(5 to 11-membered)heteroaryl of said R 5 and R 6 is optionally independently substituted with 1 to 3 substituents independently selected from halo, -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, and -CF 3 wherein the term "(5 to 11-membered)heteroaryl" refers to an aromatic 5 to 6-membered monocyclic heteroaryl or an aromatic 7 to 11-membered heteroaryl bicyclic ring where at least one of the rings is aromatic, wherein the heteroaryl ring contains 1-4 heteroatoms such as N, O, P and S, wherein the term "alkyl" refers to both branched and unbranched alkyl groups being optionally partially or fully halogenated, wherein in all alkyl groups one or more carbon atoms can be optionally replaced by heteroatoms. X is O, S, or -NR 5; R 1 is -(C 1 -C 6)alkyl, -CF 3, -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 14)aryl, -(5 to 11-membered)heteroaryl, or ferrocenyl; wherein said -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 14)aryl and -(5 to 11-membered)heteroaryl of said R 1 is optionally substituted with 1 to 3 substituents independently selected from -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, and -CF 3; R 2 is H, -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 14)aryl, -(5 to 11-membered)heteroaryl, -NR 5 R 6, or -SR 5; wherein said -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 14)aryl, and -(5 to 11-membered)heteroaryl of said R 2 is optionally substituted with 1 to 3 substituents independently selected from -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, and -CF 3; R 3 is -(C 1 -C 6)alkyl substituted with 1 to 3 (5- to 6-membered)heteroaryl; wherein the (5-to 6-membered)heteroaryl ring is optionally substituted with 1 to 3 R 4 substituents independently selected from -O(C 1 -C 6)alkyl, -N-(C 1 -C 6 alkyl) 2, -(C 1 -C 6)alkyl, phenyl, (5-to 11-membered)heteroaryl and -CF 3; or R 3 is ortho -substituted pyridine, oxazoline, and chiral oxazoline, optionally substituted with 1 to 3 R 4 substituents independently selected from -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, phenyl, and -CF 3; R 5 and R 6 are each independently H, -(C 1 -C 6)alkyl, -CF 3, -(C 3 -C 10 carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 10)aryl, or -(5 to 11-membered)heteroaryl; wherein each -(C 1 -C 6)alkyl, -CF 3, -(C 3 -C 10)carbocyclyl, -(5- to 11-membered)heterocarbocyclyl, -(C 6 -C 10)aryl, and -(5 to 11-membered)heteroaryl of said R 5 and R 6 is optionally independently substituted with 1 to 3 substituents independently selected from halo, -O(C 1 -C 6)alkyl, -(C 1 -C 6)alkyl, and -CF 3 wherein the term "(5 to 11-membered)heteroaryl" refers to an aromatic 5 to 6-membered monocyclic heteroaryl or an aromatic 7 to 11-membered heteroaryl bicyclic ring where at least one of the rings is aromatic, wherein the heteroaryl ring contains 1-4 heteroatoms such as N, O, P and S, wherein the term "alkyl" refers to both branched and unbranched alkyl groups being optionally partially or fully halogenated, wherein in all alkyl groups one or more carbon atoms can be optionally replaced by heteroatoms.