Quinazoline inhibitors of BACE 1 and methods of using

1. A compound of the formula

or a pharmaceutically acceptable salt, thereof; wherein

R a is 6-aryloxy;

R 1 is hydrogen;

R 2 is cycloalkyl or heterocyclyl, each of which is optionally substituted;

R 3 is selected from the group consisting of alkyl, alkenyl, heteroalkyl, cycloalkyl, cycloalkenyl, heterocyclyl, aryl, arylalkyl, heteroaryl, and heteroarylalkyl, each of which is optionally substituted; or R 3 and the attached nitrogen form an amino acid or an ester or amide derivative thereof;

X 1 is C 1 -C 4 alkylene; and Y 1 is N(R 4 ) or OC(O)N(R 4 );

R 4 is hydrogen, or R 4 is X 2 —Z, where X 2 is a bond or a C 1 -C 4 alkylene group; and Z is alkyl, alkenyl, heteroalkyl, cycloalkyl, cycloalkenyl, heterocyclyl aryl, or heteroaryl, each of which is optionally substituted.

2. The compound of claim 1 wherein R 4 is hydrogen, alkyl, or heteroarylalkyl.

3. The compound of claim 1 wherein R 3 is cyclohexyl and R 2 is cyclohexyl.

4. The compound of claim 1 wherein R 2 is substituted with one or more substituents selected from the group consisting of halogen, hydroxy, alkoxy, haloalkoxy, aryloxy, acyloxy, alkoxycarbonyl, acyl, alkoxycarbonyloxy, alkylsulfonyl, arylsulfonyl, alkylsulfinyl, arylsulfinyl, optionally substituted carbamoyl, optionally substituted amido, optionally substituted carbamoyloxy, amino, optionally substituted ureido, and cyano.

5. The compound of claim 1 wherein R 3 is substituted with one or more substituents selected from the group consisting of halogen, hydroxy, alkoxy, haloalkoxy, aryloxy, acyloxy, alkoxycarbonyl, acyl, alkoxycarbonyloxy, alkylsulfonyl, arylsulfonyl, alkylsulfinyl, arylsulfinyl, optionally substituted carbamoyl, optionally substituted amido, optionally substituted carbamoyloxy, amino, optionally substituted ureido, and cyano.

6. The compound of claim 1 wherein R 2 is cyclohexyl, tetrahydropyranyl or tetrahydrofuranyl.

7. The compound of claim 1 wherein R 4 is heteroarylalkyl, where the heteroaryl is selected from the group consisting of furan, pyrazole, thiazole and oxazole, each of which is optionally substituted and the alkyl is selected from CH 2 , (CH 2 ) 2 , and CH(CH 3 ).

8. The compound of claim 1 wherein R 2 is optionally substituted cyclohexyl.

9. The compound of claim 1 wherein R 2 is optionally substituted tetrahydropyranyl or tetrahydrofuranyl.

10. The compound of claim 1 wherein R 3 is cycloalkyl or heterocycloalkyl, each of which is substituted with hydroxyl.

11. The compound of claim 1 wherein R 3 is optionally substituted cyclohexyl.

12. The compound of claim 1 wherein R 3 is optionally substituted phenyl, benzyl or phenethyl.

13. The compound of claim 1 wherein R 3 is optionally substituted cyclohexylmethyl or cyclohexylethyl.

14. The compound of claim 1 wherein R 3 and the attached nitrogen form an amino acid or an ester or amide derivative thereof.

15. The compound of claim 1 wherein R 3 and the attached nitrogen form an ester or amide derivative of an amino acid, where the amino acid is selected from the group consisting of serine, threonine, and alkyl derivatives thereof.

16. The compound of claim 1 wherein X 1 —Y 1 is alkylene-N(R 4 ).

17. The compound of claim 1 wherein X 1 —Y 1 is methylene-OC(O)N(R 4 ).

18. A pharmaceutical composition comprising the compound of claim 1 in a therapeutically effective amount for treating Alzheimer's disease, and one or more carriers, diluents, or excipients, or a combination thereof.

19. The compound of claim 1 wherein R a is 6-phenoxy or 6-pyridyloxy.

20. A method for treating a patient in need of relief from Alzheimer's disease, the method comprising the step of administering to the patient a therapeutically effective amount of a compound of claim 1 , or a pharmaceutical composition thereof, where the pharmaceutical composition includes one or more carriers, diluents, or excipients, or a combination thereof.