C5-C6-fused tricyclic iminothiadiazine dioxide compounds as BACE inhibitors, compositions, and their use

1. A compound, or a pharmaceutically acceptable salt thereof, said compound having the structural Formula (I):

or a tautomer thereof having the structural Formula (I′):

or pharmaceutically acceptable salt thereof, wherein:

-L 1 - is a divalent moiety selected from the group consisting of —C(O)NH—, —CH 2 C(O)NH—, —NH—, —CH(CH 3 )NH— and —CH 2 NH—;

R 1 is selected from the group consisting of H, alkyl, cycloalkyl, and -alkyl-cycloalkyl,

wherein each said alkyl, cycloalkyl, and -alkyl-cycloalkyl, is optionally substituted with one or more halogen, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —;

R 2 is selected from the group consisting of H, alkyl, cycloalkyl, -alkyl-cycloalkyl, heterocycloalkyl, and -alkyl-heterocycloalkyl,

wherein each said alkyl, cycloalkyl, -alkyl-cycloalkyl, heterocycloalkyl, and -alkyl-heterocycloalkyl is optionally substituted with one or more halogen, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —;

R 3 is selected from the group consisting of H, halogen, alkyl, cycloalkyl, and -alkyl-cycloalkyl,

wherein said alkyl, cycloalkyl, and -alkyl-cycloalkyl are optionally substituted with one or more fluorine, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, or —N(alkyl)-;

X is selected from the group consisting of —C(R 4X ) 2 —, —O—, —S—, —S(O)—, and —S(O) 2 —, and Y is C(R 4Y ) 2 —,

or, alternatively, X is C(R 4X ) 2 — and Y is selected from the group consisting of —C(R 4Y ) 2 —, —O—, —S—, —S(O)—, and —S(O) 2 —;

each R 4X , when present, is independently selected from the group consisting of H, halogen, alkyl, and cycloalkyl,

wherein said alkyl and cycloalkyl are each optionally independently unsubstituted or substituted with one or more halogen, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —;

each R 4Y , when present, is independently selected from the group consisting of H, halogen, alkyl, and cycloalkyl,

wherein said alkyl and cycloalkyl are each optionally independently unsubstituted or substituted with one or more halogen, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —;

ring A is selected from the group consisting of aryl and heteroaryl;

m is 0 or more, with the proviso that the value of m does not exceed the number of available substitutable hydrogen atoms on ring A;

each R A , when present, is independently selected from the group consisting of halogen, oxo, —OH, —CN, alkyl, —O-alkyl, and cycloalkyl,

wherein said alkyl, —O-alkyl, and cycloalkyl of R A are each optionally independently unsubstituted or substituted with one or more fluorine, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —;

R L is selected from the group consisting of H and alkyl,

wherein said alkyl of R L are each optionally unsubstituted or substituted with one or more halogen, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —;

or, alternatively, R L is a moiety having the formula

wherein

ring B is selected from the group consisting of aryl, heteroaryl, cycloalkyl, and heterocycloalkyl;

n is 0 or more, with the proviso that the value of n does not exceed the number of available substitutable hydrogen atoms on ring B; and

each R B , when present, is independently selected from the group consisting of halogen, oxo, —OH, —CN, —SF 5 , —OSF 5 , —OR 5B , —SR 5B , alkyl, alkenyl, alkynyl, cycloalkyl, -alkyl-cycloalkyl, heterocycloalkyl, -alkyl-heterocycloalkyl, aryl, and heteroaryl,

wherein said alkyl, alkenyl, alkynyl, cycloalkyl, -alkyl-cycloalkyl, heterocycloalkyl, -alkyl-heterocycloalkyl, aryl, and heteroaryl of R B are each optionally independently unsubstituted or substituted with one or more groups independently selected from R 6 , and;

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —

each R 5B , when present, is independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, -alkyl-cycloalkyl, heterocycloalkyl, -alkyl-heterocycloalkyl,

wherein each said alkyl, alkenyl, alkynyl, cycloalkyl, -alkyl-cycloalkyl, heterocycloalkyl, -alkyl-heterocycloalkyl of R 5B is unsubstituted or optionally substituted with one or more fluorine, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —; and

each R 6 , when present, is independently selected from the group consisting of halogen, —OH, —CN, alkyl, alkoxy, cycloalkyl, -alkyl-cycloalkyl, —O-cycloalkyl, heterocycloalkyl, and -alkyl-heterocycloalkyl,

wherein each said alkyl, alkoxy, cycloalkyl, -alkyl-cycloalkyl, —O-cycloalkyl, heterocycloalkyl, and -alkyl-heterocycloalkyl are optionally substituted with one or more fluorine, and

wherein 1 to 2 non-adjacent, non-terminal carbon atoms in said alkyl are optionally independently replaced with —O—, —NH—, —N(alkyl)-, —S—, —S(O)—, or —S(O) 2 —.

2. A compound of claim 1 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, wherein:

R 1 is selected from the group consisting of H, methyl, ethyl, cyclopropyl, —CH 2 -cyclopropyl, and —CH 2 CH 2 OCH 3 ;

R 2 is selected from the group consisting of H, methyl, ethyl, cyclopropyl, —CH 2 -cyclopropyl, —CH 2 F, —CHF 2 , —CF 3 , and —CH 2 OCH 3 ; and

R 3 is selected from the group consisting of H, fluoro, chloro, methyl, ethyl, cyclopropyl, —CH 2 -cyclopropyl, —CH 2 OCH 3 .

3. A compound of claim 2 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, wherein:

X is —C(R 4X ) 2 —; and

Y is —C(R 4Y ) 2 —.

4. A compound of claim 2 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, wherein:

X is —O—; and

Y is —C(R 4Y ) 2 —.

5. A compound according to claim 1 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, wherein:

ring A is selected from the group consisting of phenyl, pyridazinyl, pyridyl, pyrimidinyl, pyrazinyl, pyrazolyl, triazinyl, thiazolyl, and thienyl;

m is 0 or more, with the proviso that the value of m does not exceed the number of available substitutable hydrogen atoms on ring A;

and each R A group, when present, is independently selected from the group consisting of fluoro, chloro, bromo, —CN, —OCH 3 , —CH 2 OCH 3 , methyl, ethyl,

cyclopropyl, —CF 3 , —CHF 2 , —CH 2 F, —OCF 3 , and —OCHF 2 .

6. A compound of claim 5 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, wherein:

L 1 is —C(O)NH—; and

R L is a moiety having the formula

wherein:

ring B is selected from the group consisting of indolyl, isothiazolyl, isoxazolyl, oxadiazolyl, oxazolyl, phenyl, pyrazinyl, pyrazolyl, pyridazinyl, pyridyl, pyrimidinyl, pyrrolyl, thiadiazolyl, thiazolyl, and thienyl;

n is 0, 1, or 2; and

each R B group, when present, is independently selected from the group consisting of fluoro, chloro, bromo, —CN, —OCH 3 , —O—CH 2 -cyclopropyl, —OCH 2 —C≡C—H, —OCH 2 —C≡C—CH 3 , methyl, ethyl, propyl, cyclopropyl, —CH 2 -cyclopropyl, —CH 2 OCH 3 , —C≡CH, —C≡C—CH 3 , —CF 3 , —CHF 2 , —OCF 3 , and —OCHF 2 .

7. A compound of claim 5 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, wherein:

L 1 is —NH—; and

R L is a moiety having the formula

wherein:

ring B is selected from the group consisting of cyclopentyl, phenyl, pyridinyl, pyrimidinyl, naphthyridinyl, pyridopyrimidinyl, pyridopyrazinyl, and pteridinyl;

n is 0, 1, or 2; and

each R B group, when present, is independently selected from the group consisting of fluoro, chloro, —CN, —OCH 3 , —O—CH 2 -cyclopropyl, —OCH 2 —C≡C—H, —OCH 2 —C≡C—CH 3 , methyl, ethyl, propyl, cyclopropyl, —CH 2 -cyclopropyl, —CH 2 OCH 3 , —C≡CH, —C≡C—CH 3 , —CF 3 , —CHF 2 , —OCF 3 , and —OCHF 2 .

8. A compound of claim 5 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, wherein:

L 1 is —CH 2 NH—; and

R L is a moiety having the formula

wherein:

ring B is selected from the group consisting of cyclobutyl, cyclopropyl, phenyl, pyrazinyl, and pyridyl;

n is 0, 1, or 2; and

each R B group, when present, is independently selected from the group consisting of fluoro, chloro, bromo, —CN, —OCH 3 , —O—CH 2 -cyclopropyl, —OCH 2 —C≡C—H, —OCH 2 —C≡C—CH 3 , methyl, ethyl, propyl, cyclopropyl, —CH 2 -cyclopropyl, —CH 2 OCH 3 , —C≡CH, —C≡C—CH 3 , —CF 3 , —CHF 2 , —OCF 3 , and —OCHF 2 .

9. A compound of claim 1 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, said compound selected from the group consisting of:

10. A pharmaceutical composition comprising a compound according to claim 1 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, and a pharmaceutically acceptable carrier or diluent.

11. A method of treating Alzheimer's disease, said method comprising administering an effective amount of a compound according to claim 1 , or a tautomer thereof, or a pharmaceutically acceptable salt of said compound or said tautomer, to a patient in need thereof.