Morphan and morphinan analogues, and methods of use

A compound of Formula III:

• or a pharmaceutically acceptable salt thereof, wherein
• R1 is C1-C6 alkyl, C2-C6 alkenyl, cycloalkyl, heterocyclyl, hydroxyalkyl, or alkoxyalkyl;
• R2 and R3, together with the carbon atoms to which they are attached, form a 6-membered unsubstituted carbocyclic ring, or a 6-membered carbocyclic ring optionally substituted with a NR50R60 group, wherein R50 and R60 are each independently H, alkyl, or substituted acyl;
• R4 and R5 are each, independently, H, hydroxyl, or taken together with the carbon atom to which they are attach to, form a C═O group;
• R6 is unsubstituted or substituted C6-C10 aryl, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-membered rings and 1-4 heteroatoms selected from N, O and S;
• and
• R7 and R8 are each, independently, H or hydroxyl.