Autophagy inhibitors useful for the treatment of cancer and other diseases are described. The autophagy inhibitors are a compound of formula: I wherein R1 is a group selected from lower alkyl, lower alkyl amide, lower alkyl ester, lower alkyl ketone, and lower alkyl ether; R2 and R3 are H or a group selected from cycloalkyl, lower alkyl, lower alkyl amide, lower alkyl ester, lower alkyl ketone, and lower alkyl ether; R4 is a heteroaryl group; and L is a —(CH2)n—X—(CH2)n— group, wherein n is 1, 2, 3, or 4, X is absent, O, S, or N—R5, wherein R5 is H or a lower alkyl group, or a pharmaceutically acceptable salt thereof.