The present invention relates to compounds of formula (I), a process for the manufacture thereof, their use for the preparation of medicaments for treating CNS disorders and pharmaceutical compositions containing them: wherein A, B, X, Y, R 1 , R 2 , R 3 and R 4 are as defined in the description and claims.本發明係關於式(I)化合物,其製造方法,其用於製備藥劑以治療CNS病症之用途,及含有彼等之醫藥組合物:其中A,B,X,Y,R1,R2,R3及R4均如說明文與請求項中之定義。