Isoindolinone derivatives useful as antiviral agents

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof wherein:
• R1 is C1-6 alkyl;
• R2 is C5-14aryl, C3-7cycloalkyl, (C3-7)cycloalkenyl, (C2-9)heterocycle, or (C2-9)heteroaryl, each of which is optionally substituted by one to four substituents selected from halo, C1-6 alkyl, C1-6 hetereoalkyl, or C1-6 alkylene or C1-6 hetereoalklylene wherein said C1-6alkylene or C1-6 hetereoalklylene are bonded to adjacent carbon atoms on said C5-14 aryl, C3-7cycloalkyl, (C3-C7)cycloalkenyl, (C2-C9)heterocycle, or (C2-C9)heteroaryl to form a ring, and wherein each heterocycle, heteroaryl, heteroalkyl, and hetereoalkylene contains one to three heteroatoms selected from S, N or O;
• L is a bond or C1-3 alkylene:
• and
• R3 is H, C1-6 alkyl, C5-14aryl, C3-7cycloalkyl, (C3-7)cycloalkenyl, (C2-9)heterocycle, or (C2-9)heteroaryl, each of which is optionally substituted by one to four substituents selected from halo, or C1-6 alkyl, and wherein each heterocycle and heteroaryl contains one to three heteroatoms selected from S, N or O.