Sulphones which modulate the action of gamma-secretase

1. A compound of formula I:

wherein

A is selected from: —(CH 2 ) r —O—(CH 2 ) s — and (—CH 2 ) r —NR 1 —(CH 2 ) 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 Ar 2 and Ar 1 SO 2 , 0-3 substituents independently selected from ═X, halogen, CN, NO 2 , N 3 , R 2 , CF 3 , N(R 1 ) 2 , OR 1 , COR 1 , CO 2 R 1 , CON(R 1 ) 2 , OCOR 1 , OCO 2 R 2 , OCON(R 1 ) 2 , N(R 1 )COR 2 , N(R 1 )CO 2 R 2 , OSO 2 R 2 and N(R 1 )SO 2 R 2 , except that the ring positions adjacent to the carbon bonded to the Ar 1 SO 2 group are occupied by unsubstituted methylene groups;

X represents C(R 1 ) 2 , CHCO 2 R 1 , O, S, NOR 1 , CHCON(R 1 ) 2 , NNHCOR 2 , or the atoms necessary to complete a spiro-linked 5- or 6-membered carbocyclic or heterocyclic ring;

Ar 1 represents phenyl or pyridyl either of which bears 0-3 substituents independently selected from halogen, CN, NO 2 , CF 3 , OH, OCF 3 , C 1-4 alkoxy or C 1-4 alkyl which optionally bears a substituent selected from halogen, CN, NO 2 , CF 3 , OH and C 1-4 alkoxy;

Ar 2 represents phenyl, bearing 1 or 2 substituents independently selected from halogen, CN, NO 2 , CF 3 , OH, OCF 3 , C 1-4 alkoxy or C 1-4 alkyl which optionally bears a substituent selected from halogen, CN, NO 2 , CF 3 , OH and C 1-4 alkoxy;

R 1 represents H or R 2 , or two R 1 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, ═NOR 1 , halogen, CN, NO 2 , R 2 , CF 3 , N(R 1a ) 2 , OR 1 , COR 1 , CO 2 R 1 and CON(R 1a ) 2 ;

R 1a represents H or R 2 , or two R 1a 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, C 1-4 alkyl CN, NO 2 , CF 3 , OH, C 1-4 alkoxy, C 1-4 alkoxycarbonyl, amino, C 1-4 alkylamino, di(C 1-4 alkyl)amino, carbamoyl, Ar and COAr;

R 2 represents C 1-6 alkyl, C 3-9 cycloalkyl, C 3-6 cycloalkylC 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl or C-heterocyclyl, any of which may bear up to 3 substituents independently selected from halogen, CN, NO 2 , N 3 , CF 3 , OR 2a , N(R 2a ) 2 , CO 2 R 2a , COR 2a , OCOR 2a , CON(R 2a ) 2 , OCON(R 2a ) 2 , CONR 2a (OR 2a ), CONHC(═NOH)R 2a , CON(R 2a )N(R 2a ) 2 , heterocyclyl, phenyl and heteroaryl, said heterocyclyl, phenyl and heteroaryl substituents themselves bearing 0-3 substituents selected from halogen, CN, NO 2 , CF 3 , OR 2a , N(R 2a ) 2 , CO 2 R 2a , COR 2a , CON(R 2a ) 2a and C 1-4 alkyl; or R 2 represents Ar; or 2 OR 2 groups attached to adjacent carbon atoms may complete a 1,3-dioxolane ring;

R 2a represents H, C 1-6 alkyl, C 3-6 cycloalkyl, C 3-6 cycloalkylC 1-6 alkyl, C 2-6 alkenyl, any of which optionally bears a substituent selected from halogen, CN, NO 2 , CF 3 , OR 2b , CO 2 R 2b , N(R 2b ) 2 , CON(R 2b ) 2 , Ar and COAr; or R 2a represents Ar; or two R 2a 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, C 1-4 alkyl, CN, NO 2 , CF 3 , OH, C 1-4 alkoxy, C 1-4 alkoxycarbonyl, CO 2 H, amino, C 1-4 alkylamino, di(C 1-4 alkyl)amino, carbamoyl, Ar and COAr;

R 2b represents H, C 1-6 alkyl, C 3-6 cycloalkyl, C 3-6 cycloalkylC 1-6 alkyl, C 2-6 alkenyl, any of which optionally bears a substituent selected from halogen, CN, NO 2 , CF 3 , OH, C 1-4 alkoxy, C 1-4 alkoxycarbonyl, CO 2 H, amino, C 1-4 alkylamino, di(C 1-4 alkyl)amino, carbamoyl, Ar and COAr; or R 2b represents Ar; or two R 2b 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, C 1-4 alkyl, CN, NO 2 , CF 3 , OH, C 1-4 alkoxy, C 1-4 alkoxycarbonyl, CO 2 H, amino, C 1-4 alkylamino, di(C 1-4 alkyl)amino, carbamoyl, Ar and COAr;

Ar represents phenyl or heteroaryl bearing 0-3 substituents selected from halogen, C 1-4 alkyl, CN, NO 2 , CF 3 , OH, C 1-4 alkoxy, C 1-4 alkoxycarbonyl, amino, C 1-4 alkylamino, di(C 1-4 alkyl)amino, carbamoyl, C 1-4 alkylcarbamoyl and di(C 1-4 alkyl)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.

2. A compound according to claim 1 wherein each of r and s is at least 1.

3. A compound according to claim 1 wherein r+s is 3 or 4.

4. A compound according to claim 1 of formula IV, or a pharmaceutically acceptable salt thereof:

wherein:

W represents —NR 6 —(CH 2 ) t — or —O—CHR 7 —;

R 6 represents R 1 , COR 2 or CO 2 R 2 ;

R 7 H or OR 1 ; and

t is 0 or 1.

5. A compound which is selected from the group consisting of

or a pharmaceutically acceptable salt thereof.