| abstract |
The application is directed to compounds of Formula I or II: and pharmaceutically acceptable salts and solvates thereof, wherein R', R", R"' R 1 , R 2 , R 3 , R 4 , R 4a , and R 20 are defined as set forth in the specification. The invention is also directed to use of compounds of Formula I or II and the pharmaceutically acceptable salts and solvates thereof to treat disorders responsive to the modulation of one or more opioid receptors. Certain compounds of the invention are especially useful for treating pain. |