6,7-DIHYDRO-PYRAZOLO[1,5-a]PYRAZIN-4-YLAMINE DERIVATIVES USEFUL AS INHIBITORS OF BETA-SECRETASE (BACE)

A compound of Formula (I)

• or a tautomer or a stereoisomeric form thereof, wherein
• R1 and R2 are independently selected from the group consisting of hydrogen, halo, cyano, C1-3alkyl, mono- and polyhalo-C1-3alkyl or C3-6cycloalkyl;
• R3 is selected from the group consisting of hydrogen, C1-3alkyl,
• C3-6cycloalkyl, mono- and polyhalo-C1-3alkyl, homoaryl and heteroaryl;
• X1, X2, X3, X4 are independently C(R4) or N, provided that no more than two thereof represent N;
• each R4 is selected from the group consisting of hydrogen, halo, C1-3alkyl, mono- and polyhalo-C1-3alkyl, cyano, C1-3alkyloxy, mono- and polyhalo-C1-3alkyloxy;
• L is a bond or —N(R5)CO—, wherein R5 is hydrogen or C1-3alkyl;
• Ar is homoaryl or heteroaryl;
• wherein homoaryl is phenyl or phenyl substituted with one, two or three substituents selected from the group consisting of halo, cyano, C1-3alkyl,
• C1-3alkyloxy, mono- and polyhalo-C1-3alkyl, mono- and polyhalo-C1-3alkyloxy;
• heteroaryl is selected from the group consisting of pyridyl, pyrimidyl, pyrazyl, pyridazyl, furanyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, thiazolyl, thiadiazolyl, oxazolyl, and oxadiazolyl, each optionally substituted with one, two or three substituents selected from the group consisting of halo, cyano, C1-3alkyl,
• C1-3alkyloxy, mono- and polyhalo-C1-3alkyl, mono- and polyhalo-C1-3alkyloxy;
• or an addition salt or a solvate thereof.