Substituted imidazo[1,2-b]pyridazines as interleukin-23 and interferon-α modulators

A compound of formula (I):

• or a pharmaceutically acceptable salt, stereoisomer, or tautomer thereof,
• wherein:
• R1 is NH2 or NHC1-C6 alkyl;
• R2 is H, C1-C6 alkyl, or C3-C10 cycloalkyl, wherein the C3-C10 cycloalkyl is monocyclic or bicyclic;
• R3 is H, C1-C6 alkyl, C1-C6 alkyl-OH, or C3-C8 cycloalkyl;
• R4 is:
• R5 is H, C1-C4 alkyl, C(O)NR6R7, C(O)OH, or OC1-C4 alkyl;
• R6 is H or C1-C4 alkyl;
• R7 is H, C1-C4 alkyl, C1-C4 alkyl-OH, heterocyclyl, or C6-C8 aryl, wherein the heterocyclyl is optionally substituted with 1 or 2 independently selected R8 substituents;
• or
• R6 and R7, taken together with the nitrogen atom to which they are attached, form a 4- to 8-membered heterocyclyl, wherein the 4- to 8-membered heterocyclyl is optionally substituted with 1 or 2 independently selected R8 substituents;
• and
• each R8 is independently H, halo, C1-C4 alkyl, or OH.