Compounds for nonsense suppression, and methods for their use

A compound of Formula 1-B or 1-D:

• wherein:
• Ra is hydrogen or a C1-C4 alkyl group;
• n is 1, 2, or 3;
• R1 is a cyano group;
• or a carbonyl group which is substituted with a hydroxy, a C1-C4 alkyl, or a C1-C4 alkoxy group;
• R is independently selected from a hydroxy group;
• a halogen;
• a C1-C4 alkyl which is optionally substituted with one or more independently selected halogen or hydroxy groups;
• a C1-C4 alkoxy which is optionally substituted with one or more independently selected halogen or phenyl groups;
• a C4-C8 cycloalkyl which is optionally substituted with one or more independently selected C1-C4 alkyl groups;
• an —Rb group;
• a —O—Rb group;
• a five to six-membered heterocycle which is optionally substituted with one or more independently selected C1-C4 alkyl, oxo, or —Rb groups;
• a nine to ten membered heterocycle having two ring structures;
• a carbonyl which is substituted with a C1-C4 alkyl, or a C1-C4 alkoxy group;
• a carbamoyl which is optionally substituted with one or two C1-C4 alkyl groups;
• a nitro group;
• a thio which is optionally substituted with a hydroxy, a C1-C4 alkyl, or —Rb group;
• a sulfonyl which is optionally substituted with a hydroxy, a C1-C4 alkyl, or —Rb group;
• an amino which is optionally substituted with one or two independently selected C1-C4 alkyl, sulfonyl, or carbonyl groups, wherein the aminosulfonyl group is optionally substituted with a hydroxy, a C1-C4 alkyl, or an —Rb group, and wherein the aminocarbonyl group is optionally substituted with a C1-C4 alkyl, a C1-C4 haloalkyl, a benzoxy, or an amino group which is optionally substituted with an —Rb group;
• or two R groups together with the phenyl ring to which they are attached form a benzo[1,3]dioxole or a 2,3-dihydro-benzo[1,4]dioxinyl group;
• wherein
• Rb is a C6-C8 aryl which is optionally substituted with one or more of the following:
• a hydroxy, a halogen, a C1-C4 alkyl group, a C1-C4 haloalkyl group, a C1-C4 alkoxy group, or an amino group which is optionally substituted with one or more C1-C4 alkyl groups;
• wherein R1 is in the meta or para position when said compound is a compound of Formula 1-B;
• or a pharmaceutically acceptable salt thereof.