| abstract |
The invention provides compounds of formula I: n n nor pharmaceutically salts thereof where R 1 , R 2 , and the A, B, and C-rings are as defined herein. Compounds of formula I are useful in treating or preventing cognitive disorders, such as Alzheimer's disease. The invention also encompasses pharmaceutical compositions comprising compounds or salts of formula I, methods of preparing the desired compounds, and methods of treating cognitive disorders, such as Alzheimer's disease, using the compounds or salts of formula I. |