Patent ID: 8138215

Claim:
A compound of Formula (I) or a pharmaceutically acceptable salt thereof, wherein R 1 is selected from hydrogen, —C(O)R 6 , and R 2 and R 2a are independently selected from hydrogen, alkyl, and aryl; R 3 is cycloalkyl; R 3a is cycloalkyl; R 4 and R 5 are independently selected from hydrogen and alkyl; wherein the alkyl can optionally form a fused three- to six-membered ring with an adjacent carbon atom or optionally form a spirocyclic three- to six-membered ring with the carbon to which it is attached; and R 6 is selected from alkoxy, alkyl, arylalkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, (NR c R d )alkenyl, and (NR c R d )alkyl.