8-substituted diaryl xanthines as dual a2a-a2b antagonists

A compound of Formula I or a stereoisomer or pharmaceutically acceptable salt thereof:

• wherein:
• Ring A is phenyl or a 5-6 membered heteroaryl having 1-3 heteroatoms selected from O, S, or N;
• Ring B is phenyl or a 5-6 membered heteroaryl having 1-2 heteroatoms selected from O, S, or N;
• R1 is selected from:
• C1-5 alkyl, —CH2—C2-4 alkenyl, —CH2—C2-4 alkynyl, C3-6 cycloalkyl, and —C2-5 alkylene-O—C1-5 alkyl;
• R2 is selected from:
• C1-5 alkyl, —CH2—C2-4 alkenyl, —CH2—C2-4 alkynyl, C3-6 cycloalkyl, and —C2-5 alkylene-O—C1-5 alkyl;
• R3 is selected from:
• H, C1-5 alkyl, C3-6 cycloalkyl, and —C2-5 alkylene-O—C1-5 alkyl;
• R4 is —(CH2)1-6—;
• R5 is —(CH2)1-6—;
• R6 is selected from:
• H, C1-5 alkyl, C3-6 cycloalkyl, and —C2-5 alkylene-O—C1-5 alkyl;
• R7 is absent or is selected from:
• C1-5 alkyl, O, S, N—C1-5 alkyl, and NH;
• R8 is selected from:
• C1-5 alkyl, —CH2—C2-4 alkenyl, —CH2—C2-4 alkynyl, C3-6 cycloalkyl, —C1-5 alkylene-O—C1-5 alkyl, phenyl, 5-6 membered heterocycle, and 5-6 membered heteroaryl;
• the phenyl and heteroaryl groups of R8 are optionally substituted with 1-3 groups independently selected from:
• C1-4 alkyl, C3-6 cycloalkyl, —C1-3 alkylene-C3-6 cycloalkyl, F, Cl, Br, I, —CN, ORa, SRa, NRaRb, CF3, OCF3, CORa, CO2Ra, C(O)NRaRb, OC(O)Ra, OCO2Ra, OC(O)NRaRb, NRbCORa, NRbCO2Ra, NRbC(O)NRaRb, and S(O)pNRaRb;
• each Ra is independently selected from:
• H, C1-8 alkyl, C3-6 cycloalkyl, and —C1-3 alkylene-C3-6 cycloalkyl;
• each Rb is independently selected from:
• H, C1-8 alkyl, C3-6 cycloalkyl, and —C1-3 alkylene-C3-6 cycloalkyl;
• alternatively, each NRaRb group is optionally selected from a 3-6 membered cyclic amine;
• and,
• p is independently selected from:
• 0, 1, and 2.