Substituted 3,4-dihydropyrrolo[1,2-A]pyrazines as beta-secretase (BACE) inhibitors

A compound of Formula (I)

• or a tautomer or a stereoisomeric form thereof, wherein
• R1, R2, and R3 are independently selected from the group consisting of hydrogen, halo, cyano, C1-3alkyl, monohalo-C1-3alkyl, polyhalo-C1-3alkyl, and C3-6cycloalkyl;
• R4 is selected from the group consisting of hydrogen, C1-3alkyl, methoxymethyl, C3-6 cycloalkyl, monohalo-C1-3alkyl, polyhalo-C1-3alkyl, homoaryl, and heteroaryl;
• X1, X2, X3, and X4 are independently C(R5) or N, provided that no more than two thereof represent N;
• R5 is selected from the group consisting of hydrogen, halo, cyano, C1-3alkyl, monohalo-C1-3alkyl, polyhalo-C1-3alkyl, and C3-6cycloalkyl;
• L is a bond or —NHCO—;
• 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, monohalo-C1-3alkyl, polyhalo-C1-3 alkyl, monohalo-C1-3alkyloxy, and polyhalo-C1-3alkyloxy;
• heteroaryl is selected from the group consisting of pyridyl, pyrimidyl, pyrazinyl, 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, monohalo-C1-3alkyl, polyhalo-C1-3alkyl, monohalo-C1-3alkyloxy, and polyhalo-C1-3alkyloxy;
• or a pharmaceutically acceptable salt thereof.