Acyl guanidines as beta-secretase inhibitors

A compound of Formula (I);

• or a stereoisomer thereof
• wherein
• R1 is naphthyl optionally substituted with halogen, quinolyl, thienyl, 2,3-dimethyl-1H-indol-5-yl, or phenyl in which said phenyl is optionally substituted with one or more groups selected from halogen, CN, CF3, OH, —NH2, C3-6cycloalkyl, C1-6alkoxy, OR21, C1-6alkyl optionally substituted with OH or —NH2, —(CH2)m—NHC(═O)OR17, —(CH2)m—NHC(═O)Ophenyl optionally substituted with halogen, —(CH2)m—NHC(═O)R18, —NH(C═O)R19, —CH2NH(SO2)R20, R22, R23, and —CH2morpholino;
• R2 and R3 are each independently hydrogen, methyl or hydroxymethyl;
• R4 is hydrogen, C1-6alkyl optionally substituted with C1-4alkoxy or thiomethyl;
• or phenyl optionally substituted with one or more groups selected from halogen, C1-4alkyl, C1-4alkoxy, nitro and dimethylamino;
• R5 is phenyl in which said phenyl is optionally substituted with one or more groups selected from halogen, —S(O)2methyl, C1-4alkyl and C1-4alkoxy;
• X is O, S, NH or NHCH3;
• m is 0 or 1;
• R17 is C1-6 alkyl optionally substituted with C1-4alkoxy, halogen, C2-3alkynyl, 4-nitrophenyl, benzyloxy or benzothiophene 1,1-dioxide;
• R18 is C1-6alkyl or C3-6cycloalkyl in which each is optionally substituted with a group selected from halogen, CN, CF3, —N(CH3)2, C1-4alkoxy, C3-6cycloalkyl, morpholino, thienyl, imidazolyl, pyridyl, azepinyl, benzothienyl, benzofuranyl, phenyl and methoxyphenyl;
• R19 is C1-6alkyl optionally substituted with methoxyethyloxy or methylthio;
• C1-4alkoxy optionally substituted with halogen;
• C3-6cycloalkyl, phenyl, pyridyl optionally substituted with one or two halogen and C1-4alkyl;
• benzothienyl, 1-methyl-2-pyrrolyl or furanyl;
• R20 is C1-6alkyl, 1,2-dimethyl-1H-imidazolyl, thienyl or phenyl in which said phenyl is optionally substituted with a group selected from acetyl, C1-4alkoxy, benzyloxy, halogen, NH(C═O)CH3 and nitro;
• R21 is C1-6alkyl optionally substituted with a group selected from C1-4alkoxy, halogen, phenyl, furanyl and methylamino;
• R22 is —CH═CH-phenyl or —CH═CH—C1-4alkyl optionally substituted with C1-4alkoxy or OH;
• and
• R23 is pyridyl, thienyl, C2-6alkenyl, or phenyl optionally substituted with halogen;
• or a nontoxic pharmaceutically acceptable salt thereof.