| abstract |
Compound of formula (I) ** Formula ** or a stereoisomeric form thereof, wherein R1, R2 are hydrogen; R3, R4 are independently methyl or ethyl; X1 and X3 are CH or CF; X2 and X4 are CH; L is a bond or -N (R6) CO- where R6 is hydrogen; Ar is heteroaryl; Heteroaryl is selected from the group consisting of pyridyl, pyrimidinyl, and pyrazyl, each optionally substituted with chloro, cyano, methyl, methoxy, or trifluoromethyl. |