Patent ID: 8912198

Claim:
A compound of Formula I: or a pharmaceutically acceptable salt thereof, wherein: R 1 is independently selected from a C 1-6 aliphatic, a C 3-6 cycloaliphatic, or a 3-6 membered heterocyclyl having 1-2 heteroatoms selected from O, N, or S; R 2 is independently selected from H, C 1-3 aliphatic or a C 3-6 cycloaliphatic; R 3 is independently selected from H, C 1-6 aliphatic, C 3-6 cycloaliphatic, or a 3-6 membered heterocyclyl having 1-2 heteroatoms selected from O, N, or S; R 4 is independently selected from H, C 1-6 aliphatic, C 3-6 cycloaliphatic, or a 3-6 membered heterocyclyl having 1-2 heteroatoms selected from O, N, or S; or R 2 and R 3 , together with the atoms to which they are attached, form an optionally substituted 4-7 membered heterocyclic ring having 1-2 heteroatoms independently selected from O, N, or S; or R 3 and R 4 , together with the nitrogen atom to which they are attached, form an optionally substituted 4-7 membered heterocyclic ring independently selected from O, N, or S.