Five-membered heteroaryl-fused imidazole compound and application thereof

1. A compound represented by formula (III) or a pharmaceutically acceptable salt thereof,

wherein,

is selected from a single bond and a double bond;

T 1 is selected from N, C and CR 6 ;

T 2 is selected from N, C and CH;

T 3 , T 4 , T 5 and T 6 are each independently selected from N and CR 7 ;

X 1 and X 2 are N;

X 3 and X 4 are C;

X 5 is CR 8 , N, NH, O and S;

X 6 is CH;

X 7 is CH, N, NH, O and S;

X 1 , X 2 , X 3 and X 4 constitute ring A;

X 3 , X 4 , X 5 , X 6 and X 7 constitute ring B;

L 1 is selected from a single bond and —C 1-3 alkyl-;

R 1 is each independently selected from F, Cl, Br, I, OH, NH 2 and CN;

m is selected from 0, 1, 2, 3, 4 and 5;

R 2 is selected from

 and the

 are optionally substituted by 1, 2 or 3 R a ;

Y 1 and Y 2 are each independently selected from CH, CH 2 , N, NH and O;

o and p are each independently selected from 0, 1, 2 and 3;

R 3 is selected from —C(═O)—NH—R b , —C(═O)—R b , —C(═O)—NH—S(═O) 2 —R b , —S(═O) 2 —NH—R b , —S(═O) 2 —R b , —P(═O)(R b ) 2 , C 1-3 alkyl, tetrazolyl, isoxazolyl,

 the C 1-3 alkyl, tetrazolyl, isoxazolyl,

 are optionally substituted by 1, 2 or 3 R b ;

R 5 is each independently selected from F, Cl, Br, I and C 1-3 alkyl;

n is selected from 0, 1 and 2;

or, two adjacent R 5 together form C 3-5 cycloalkyl;

R 4 is selected from H, F, Cl, Br, I and CH 3 ;

R 6 is selected from H, F, Cl, Br, I and CH 3 ;

or, R 4 and R 6 combining with the bonds to which they are attached form a double bond or C 3-5 cycloalkyl;

R 7 is each independently selected from H, F, Cl and CN;

R 8 is each independently selected from H, F, Cl and CH 3 ;

R a is selected from F, Cl, Br and I;

R b is selected from OH, CN, C 1-3 alkyl, C 1-3 alkoxy, C 1-3 alkylamino and oxazolyl, and the C 1-3 alkyl, C 1-3 alkoxy and oxazolyl are optionally substituted by 1, 2 or 3 R;

R is selected from F, Cl and Br.

2. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein, R 2 is selected from

are optionally substituted by 1, 2 or 3 R a .

3. The compound as defined in claim 2 or the pharmaceutically acceptable salt thereof, wherein, R 2 is selected from

4. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein, L 1 is selected from a single bond and —CH 2 —.

5. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein, m is selected from 0, 1 and 2.

6. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein, R b , is selected from OH, CN, CH 3 , CF 3 and OCH 3 .

7. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein, R 3 is selected from —COON, —C(═O)—NH—CN, —C(═O)—NH—OH, —C(═O)—NH—OCH 3 , —C(═O)—CF 3 , —S(═O) 2 —NH—CH 3 and —S(═O) 2 —OH.

8. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein, the structural moiety

is selected from

9. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein, the structural moiety

is selected from

10. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein, the structural moiety

is selected from

11. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein the structural moiety

is selected from

12. The compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein the compound is selected from,

wherein,

is selected from a single bond and a double bond;

R 1 , R 2 , R 3 , L 1 , T 1 , T 2 , m, X 5 and X 7 are as defined in claim 1 .

13. The compound as defined in claim 12 or the pharmaceutically acceptable salt thereof, wherein the compound is selected from:

wherein, R 1 , X 5 and X 7 are as defined in claim 12 .

14. A compound represented by the following formula or a pharmaceutically acceptable salt thereof, wherein the compound is selected from:

15. The compound as defined in claim 14 or the pharmaceutically acceptable salt thereof, wherein the compound is selected from:

16. A method for activating GLP-1 receptor in a subject in need thereof, comprising administering to the subject an effective amount of the compound as defined in claim 1 or the pharmaceutically acceptable salt thereof.

17. A method for treating a disease related to GLP-1 receptor in a subject in need thereof, comprising administering to the subject an effective amount of the compound as defined in claim 1 or the pharmaceutically acceptable salt thereof, wherein the disease is type II diabetes.

18. A method for activating GLP-1 receptor in a subject in need thereof, comprising administering to the subject an effective amount of the compound as defined in claim 14 or the pharmaceutically acceptable salt thereof.

19. A method for treating a disease related to GLP-1 receptor in a subject in need thereof, comprising administering to the subject an effective amount of the compound as defined in claim 14 or the pharmaceutically acceptable salt thereof, wherein the disease is type II diabetes.