Compounds and their use as PDE inhibitors

A method for inhibiting the enzymatic or catalytic activity of PDE7 in mammals which comprises administering to a mammal in need thereof an effective amount of a compound of Formula 1:

• wherein,
• R1 is NRaRb where Ra and Rb are independently H or C1-6 alkyl;
• R2 is H, C1-8alkyl, C1-3alkyl-Ar, C1-3alkyl-C3-6cycloalkyl, C2-8alkenyl, C2-4alkenyl-Ar, or C2-4alkenyl-C3-6cycloalkyl;
• Ar is substituted or unsubstituted phenyl;
• R3 is NO2, halo, CN, C(O)OR7, COR1, or NRaRb where Ra and Rb are independently H or C1-6alkyl;
• R4 is H, —OC1-6alkyl, halo, C(O)NRaRb, C(O)OR7, C1-8alkyl, —OCHF2, CH2OR8, —OC1-3alkylAr or CH2NH(O)CH3;
• R5 is H, halo, or alkyl;
• R6 is C1-8alkyl, OC1-4alkyl or halo;
• R7 is hydrogen or an ester or amide-forming group;
• R8 is hydrogen or C1-6alkyl;
• or a pharmaceuticaly acceptable salt or solvate thereof.