PDE9 inhibitors with imidazo triazinone backbone

A compound having the structure (I):

• wherein R2 is cyclized with either R1 or R3,
• wherein R1, R2 and R3 are:
• R1, when cyclized with R2, is:
• wherein R6 is selected from the group consisting of H, —CH3, —C2H5, and —C3H7,
• wherein * denotes the cyclization point, and
• R1, when not cyclized, is selected from the group consisting of:
• H and
• wherein R6 is selected from the group consisting of H, —CH3, —C2H5, and —C3H7 ;
• R2 is selected from the group consisting of:
• wherein R7 and R11 independently are selected from the group consisting of H, —CH3, —C2H5, and —C3H7;
• wherein * denotes the cyclization point;
• and
• R3, when cyclized with R2, is:
• wherein * denotes the cyclization point, and
• wherein R8 is selected from the group consisting of H, C1-C6 alkyl, branched C3-C6 alkyl, C3-C6 cycloalkyl, C6-C10 aryl, substituted C6-C10 aryl, C3-C9 heteroaryl, substituted C3-C9 heteroaryl, C1-C6 alkoxy, branched C3-C6 alkoxy, C3-C6 cycloalkoxy, C6-C10 aryloxy, substituted C6-C10 aryloxy, C3-C9 heteroaryloxy, and substituted C3-C9 heteroaryloxy;
• and
• R3, when not cyclized, is:
• wherein:
• R9 is selected from the group consisting of H, —CH3, and —C2H5;
• and
• R10 is selected from the group consisting of C6-C10 aryl, substituted C6-C10 aryl, C3-C9 heteroaryl, and substituted C3-C9 heteroaryl;
• R4 is selected from the group consisting of C6-C10 aryl, substituted C6-C10 aryl, C3-C9 heteroaryl, substituted C3-C9 heteroaryl, C3-C6 heterocyclyl, substituted C3-C6 heterocyclyl, C3-C6 cycloalkyl, and substituted C3-C6 cycloalkyl;
• R5 is selected from the group consisting of hydrogen, F, Cl, CN, —CH3, —C2H5, —C3 H7, and —CF3;
• A is absent,
• and tautomers and pharmaceutically acceptable acid addition salts thereof.