Cyclohexyl sulphones as gamma-secretase inhibitors

1. A compound according to one of the following formulae:

wherein

R 1 represents H or C 1-4 alkyl;

R 2 and R 4 independently represent H or a hydrocarbon group of up to 10 carbon atoms, optionally substituted with CF 3 , CHF 2 , halogen, CN, OR 5 , COR 5 , CO 2 R 5 , OCOR 6 , N(R 5 ) 2 , CON(R 5 ) 2 or NR 5 COR 6 ;

R 5 represents H or C 1-4 alkyl;

R 6 represents C 1-4 alkyl; and

Ar 1 and Ar 2 independently represent phenyl or heteroaryl, either of which bears 0-3 substituents independently selected from halogen, CN, NO 2 , CF 3 , CHF 2 , OH, OCF 3 , CHO, CH═NOH, C 1-4 alkoxy, C 1-4 alkoxycarbonyl, C 2-6 acyl, C 2-6 alkenyl and C 1-4 alkyl which optionally bears a substituent selected from halogen, CN, NO 2 , CF 3 , OH and C 1-4 alkoxy;

or a pharmaceutically acceptable salt thereof.

2. A compound according to claim 1

wherein R 1 represents H;

or a pharmaceutically acceptable salt thereof.

3. A compound according to claim 1 wherein Ar 1 is selected from 6-(trifluoromethyl)-3-pyridyl and phenyl which is optionally substituted in the 4-position with halogen, CN, vinyl, allyl, acetyl, methyl or mono-, di- or trifluoromethyl;

and Ar 2 represents 2,5-difluorophenyl, 2,6-difluorophenyl or 2,3,6-trifluorophenyl.

4. A pharmaceutical composition comprising a compound according to claim 1 and a pharmaceutically acceptable carrier.