1,2,5-Oxadiazoles as Inhibitors of Indoleamine 2,3-Dioxygenase

A method of suppressing immunosuppression or treating cancer, viral infection, depression, a neurodegenerative disorder, trauma, age-related cataracts, organ transplant rejection, or an autoimmune disease in a patient, comprising administering to said patient a therapeutically effective amount of a compound selected from compounds of Formula I and compounds of Formula F28:

• or a pharmaceutically acceptable salt thereof;
• wherein:
• R1 is NH2 or CH3;
• R2 is Cl, Br, CF3, CH3, or CN;
• R3 is H or F;
• R4 is F, Cl, Br, or I;
• and
• n is 1 or 2.

A method of inhibiting activity of indoleamine 2,3-dioxygenase comprising contacting said indoleamine 2,3-dioxygenase with a compound selected from compounds of Formula I and compounds of Formula F28:

• or a pharmaceutically acceptable salt thereof;
• wherein:
• R1 is NH2 or CH3;
• R2 is Cl, Br, CF3, CH3, or CN;
• R3 is H or F;
• R4 is F, Cl, Br, or I;
• and
• n is 1 or 2.

A process for preparing a compound of Formula F15:

• or a salt thereof, wherein R2 is Cl, Br, CF3, CH3, or CN;
• R3 is H or F;
• and n is 1 or 2, comprising:
• a) reacting a compound of Formula F12:
• or a salt thereof, with sulfamide and an organic base to afford a compound of Formula F14:
• or a salt thereof, and
• b) reacting said compound of Formula F14, or a salt thereof, with a base to afford said compound of Formula F15.

A process for preparing a compound of Formula F15:

• or a salt thereof, wherein R2 is Cl, Br, CF3, CH3, or CN;
• R3 is H or F;
• and n is 1 or 2, comprising:
• a) reacting a compound of Formula F13:
• or a salt thereof, wherein Pg1 is an amino protecting group, with an amino deprotecting agent to afford a compound of Formula F14:
• or a salt thereof;
• and
• b) reacting said compound of Formula F14 with a base to afford said compound of Formula F15.