Sulphones which modulate the action of gamma-secretase

A compound of formula I:

• wherein
• A is selected from:
• —(CH2)r—O—(CH2)s— and (—CH2)r—NR1—(CH2)s—, wherein r and s are 0-5 such that r+s is an integer in the range 2-5, said ring bearing, in addition to Ar2 and Ar1SO2, 0-3 substituents independently selected from ═X, halogen, CN, NO2, N3, R2, CF3, N(R1)2, OR1, COR1, CO2R1, CON(R1)2, OCOR1, OCO2R2, OCON(R1)2, N(R1)COR2, N(R1)CO2R2, OSO2R2 and N(R1)SO2R2, except that the ring positions adjacent to the carbon bonded to the Ar1SO2 group are occupied by unsubstituted methylene groups;
• X represents C(R1)2, CHCO2R1, O, S, NOR1, CHCON(R1)2, NNHCOR2, or the atoms necessary to complete a spiro-linked 5- or 6-membered carbocyclic or heterocyclic ring;
• Ar1 represents phenyl or pyridyl either of which bears 0-3 substituents independently selected from halogen, CN, NO2, CF3, OH, OCF3, C1-4alkoxy or C1-4alkyl which optionally bears a substituent selected from halogen, CN, NO2, CF3, OH and C1-4alkoxy;
• Ar2 represents phenyl, bearing 1 or 2 substituents independently selected from halogen, CN, NO2, CF3, OH, OCF3, C1-4alkoxy or C1-4alkyl which optionally bears a substituent selected from halogen, CN, NO2, CF3, OH and C1-4alkoxy;
• R1 represents H or R2, or two R1 groups together with a nitrogen atom to which they are mutually attached may complete an N-heterocyclyl group bearing 0-3 substituents selected from ═O, ═S, ═NOR1, halogen, CN, NO2, R2, CF3, N(R1a)2, OR1, COR1, CO2R1 and CON(R1a)2;
• R1a represents H or R2, or two R1a groups together with a nitrogen atom to which they are mutually attached may complete an N-heterocyclyl group bearing 0-3 substituents selected from ═O, ═S, halogen, C1-4alkyl CN, NO2, CF3, OH, C1-4alkoxy, C1-4alkoxycarbonyl, amino, C1-4alkylamino, di(C1-4alkyl)amino, carbamoyl, Ar and COAr;
• R2 represents C1-6alkyl, C3-9cycloalkyl, C3-6cycloalkylC1-6alkyl, C2-6alkenyl, C2-6alkynyl or C-heterocyclyl, any of which may bear up to 3 substituents independently selected from halogen, CN, NO2, N3, CF3, OR2a, N(R2a)2, CO2R2a, COR2a, OCOR2a, CON(R2a)2, OCON(R2a)2, CONR2a(OR2a), CONHC(═NOH)R2a, CON(R2a)N(R2a)2, heterocyclyl, phenyl and heteroaryl, said heterocyclyl, phenyl and heteroaryl substituents themselves bearing 0-3 substituents selected from halogen, CN, NO2, CF3, OR2a, N(R2a)2, CO2R2a, COR2a, CON(R2a)2a and C1-4alkyl;
• or R2 represents Ar;
• or 2 OR2 groups attached to adjacent carbon atoms may complete a 1,3-dioxolane ring;
• R2a represents H, C1-6alkyl, C3-6cycloalkyl, C3-6cycloalkylC1-6alkyl, C2-6alkenyl, any of which optionally bears a substituent selected from halogen, CN, NO2, CF3, OR2b, CO2R2b, N(R2b)2, CON(R2b)2, Ar and COAr;
• or R2a represents Ar;
• or two R2a groups together with a nitrogen atom to which they are mutually attached may complete an N-heterocyclyl group bearing 0-4 substituents independently selected from ═O, ═S, halogen, C1-4alkyl, CN, NO2, CF3, OH, C1-4alkoxy, C1-4alkoxycarbonyl, CO2H, amino, C1-4alkylamino, di(C1-4alkyl)amino, carbamoyl, Ar and COAr;
• R2b represents H, C1-6alkyl, C3-6cycloalkyl, C3-6cycloalkylC1-6alkyl, C2-6alkenyl, any of which optionally bears a substituent selected from halogen, CN, NO2, CF3, OH, C1-4alkoxy, C1-4alkoxycarbonyl, CO2H, amino, C1-4alkylamino, di(C1-4alkyl)amino, carbamoyl, Ar and COAr;
• or R2b represents Ar;
• or two R2b groups together with a nitrogen atom to which they are mutually attached may complete an N-heterocyclyl group bearing 0-4 substituents independently selected from ═O, ═S, halogen, C1-4alkyl, CN, NO2, CF3, OH, C1-4alkoxy, C1-4alkoxycarbonyl, CO2H, amino, C1-4alkylamino, di(C1-4alkyl)amino, carbamoyl, Ar and COAr;
• Ar represents phenyl or heteroaryl bearing 0-3 substituents selected from halogen, C1-4alkyl, CN, NO2, CF3, OH, C1-4alkoxy, C1-4alkoxycarbonyl, amino, C1-4alkylamino, di(C1-4alkyl)amino, carbamoyl, C1-4alkylcarbamoyl and di(C1-4alkyl)carbamoyl;
• “heterocyclyl” at every occurrence thereof means a cyclic or polycyclic system of up to 10 ring atoms selected from C, N, O and S, wherein none of the constituent rings is aromatic and wherein at least one ring atom is other than C;
• and
• “heteroaryl” at every occurrence thereof means a cyclic or polycyclic system of up to 10 ring atoms selected from C, N, O and S, wherein at least one of the constituent rings is aromatic and wherein at least one ring atom of said aromatic ring is other than C;
• or a pharmaceutically acceptable salt thereof.