申请人:ELAN PHARM INC
                            
                            
                                公开号:WO2002098849A2
                            
                            
                                公开(公告)日:2002-12-12
                            
                            Disclosed are compounds of formula X, where Rn, R20, R1, R2, R3, and Rc are defined herein. These compounds are useful in treating Alzheimer's disease and other similar diseases. Pharmaceutical compositions comprising compounds of formula X and methods of preparing the compounds of formula X are also disclosed.