KRAS G12C inhibitors and methods of using the same

A compound of Formula (Ia):

• or a pharmaceutically acceptable salt thereof;
• wherein
• R2 is aryl, wherein the aryl is substituted with one or more groups independently selected from halo, C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, —CF3, —OCF3, —NO2, —CN, —NC, —OH, alkoxy, amino, —CO2H, —CO2C1-C6alkyl, —OCOC1-C6alkyl, C3-C10cycloalkyl, C3-C10heterocycloalkyl, C5-C10aryl, and C5-C10heteroaryl;
• R3 is halo;
• R4 is
• and
• R8 is