Bicyclic pyridinones

1. A compound having the structure of Formula I:

wherein:

X is a 5- to 14-membered heteroaryl containing 1-3 heteroatoms;

R 1 is hydrogen, halogen, or C 1-6 alkyl; wherein said alkyl may be optionally and independently substituted with one to three of fluoro, cyano, —CF 3 , hydroxyl, or C 1-6 alkoxy groups;

R 2a and R 2b for each occurrence are each independently hydrogen, fluoro, cyano, —CF 3 , or C 1-6 alkyl; wherein said alkyl may be optionally and independently substituted with cyano, C 1-3 alkyl or one to three fluoro;

R 3 is —(C(R 11 ) 2 ) t —(C 6-10 aryl); wherein said aryl may be optionally and independently substituted with one to five R 10 ;

R 4a and R 4b are each independently hydrogen, —CF 3 , or C 1-6 alkyl, wherein said alkyl is optionally substituted with one to three —CF 3 , cyano or fluoro;

R 5a and R 5b for each occurrence are each independently hydrogen, —CF 3 , or C 1-6 alkyl, wherein said alkyl is optionally substituted with one to three —CF 3 , cyano or fluoro;

R 6 and R 7 are each independently hydrogen, —CF 3 , cyano, halogen, C 1-6 alkyl or —OR 9 ; provided that R 6 and R 7 cannot both be —OH;

R 9 is hydrogen, or C 1-6 alkyl, wherein said alkyl may be optionally and independently substituted with cyano, or one to three fluoro;

each R 10 is independently hydrogen, halogen, cyano, —CF 3 , C 1-6 alkyl, —(C(R 11 ) 2 ) m —OR 12 , —C(O)R 13 , —SF 5 or —Si(CH 3 ) 3 ; wherein said alkyl, may be optionally and independently substituted with one to three R 14 ;

each R 11 is independently hydrogen, C 1-6 alkyl, fluoro, —CF 3 , —CHF 2 or —OR 12 ; wherein said alkyl may be optionally independently substituted with one to three fluoro or cyano;

each R 12 is independently hydrogen, C 1-6 alkyl, or —CF 3 ; wherein said alkyl may be optionally independently substituted with one to three R 16 ;

each R 13 is independently C 1-6 alkyl; wherein said alkyl may be optionally and independently substituted with one to three R 16 ;

each R 14 is independently hydrogen, C 1-6 alkyl, halogen, cyano, —CF 3 , —CHF 2 , —OR 9 or —OCF 3 ;

R 16 is independently hydrogen, —CF 3 , cyano, halogen, C 1-6 alkyl or —OR 9 and t and m are each an integer independently selected from 0, 1, 2, 3 and 4;

z is the integer 1;

y is an integer selected from 1, 2, 3 and 4;

or a pharmaceutically acceptable salts thereof.

2. The compound according to claim 1 wherein X is imidazolyl, pyrazolyl, isothiazolyl, thiazolyl, isoxazolyl, oxazolyl or pyridyl.

3. The compound according to claim 2 wherein X is imidazolyl.

4. The compound according to claim 3 wherein R 1 is C 1-6 alkyl.

5. The compound according to claim 4 wherein R 1 is methyl optionally substituted with one hydroxyl or C 1-6 alkoxy or one to three fluoro; and y is two or three.

6. The compound according to claim 5 wherein R 10 is independently hydrogen, halogen, cyano, —CF 3 , C 1-6 alkyl, —(C(R 11 ) 2 ) m —OR 12 or —C(O)R 13 ; wherein the alkyl may be independently substituted with one to three R 14 .

7. The compound according to claim 5 wherein R 3 is phenyl.

8. The compound according to claim 7 wherein R 10 is hydrogen, chloro, fluoro, bromo, cyano, —CF 3 , —OCF 3 , methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, hydroxyl, or methoxy.

9. The compound according to claim 8 wherein R 2a and R 2b are hydrogen or C 1-6 alkyl.

10. A compound selected from the group consisting of:

2-{(1S)-2-[4-fluoro-2-(trifluoromethyl)phenoxy]-1-methylethyl}-7-(4-methyl-1H-imidazol-1-yl)-3,4-dihydro-2H-pyrido[1,2-a]pyrazine-1,6-dione;

2-{2-[4-fluoro-2-(1,1,1-trifluoro-2-methylpropan-2-yl)phenoxy]ethyl}-7-(4-methyl-1H-imidazol-1-yl)-3,4-dihydro-2H-pyrido[1,2-a]pyrazine-1,6-dione;

2-{(2S)-1-[4-chloro-2-(trifluoromethyl)phenoxy]propan-2-yl}-7-(4-methyl-1H-imidazol-1-yl)-3,4-dihydro-2H-pyrido[1,2-a]pyrazine-1,6-dione; or a pharmaceutically acceptable salt of any of the above.

11. A method for treating a mammal having Alzheimer's Disease comprising administering to the mammal a therapeutically effective amount of the compound of claim 1 or a pharmaceutically acceptable salt thereof.

12. A pharmaceutical composition comprising a compound of claim 1 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable vehicle, diluent or carrier.