SARS-COV2 MAIN PROTEASE INHIBITORS

1 . A compound of formula (I):

or a pharmaceutically acceptable salt thereof, wherein

ring

 is C 6-10 aryl or 5- to 10-membered heteroaryl;

each L 1 is independently a bond, —O—, —(C 1-6 alkyl)O—, —O(C 1-6 alkyl)-, —C 1-6 alkyl-O(C 1-6 alkyl)-, —C(O)—, —N(R L )C(O)—, —C(O)N(R L )—, —(C 1-6 alkyl)(R L )NC(O)—, —(C 1-6 alkyl)C(O)N(R L )—, —N(R L )C(O)(C 1-6 alkyl)-, —C(O)N(R L )(C 1-6 alkyl)-, —(C 1-6 alkyl)N(R L )C(O)(C 1-6 alkyl)-, —(C 1-6 alkyl)C(O)N(R L )(C 1-6 alkyl)-, —S(O) 2 —, —S(O) 2 N(R L )—, —N(R L )—S(O) 2 —, —(C 1-6 alkyl)S(O) 2 N(R L )—, —(C 1-6 alkyl)N(R L )S(O) 2 —, —S(O) 2 N(R L )(C 1-6 alkyl)-, —N(R L )S(O) 2 (C 1-6 alkyl)-, —(C 1-6 alkyl)S(O) 2 N(R L )(C 1-6 alkyl)-, or —(C 1-6 alkyl)N(R L )S(O) 2 (C 1-6 alkyl)-;

each R 1 is independently halogen, —OH, —CN, C 1-6 alkyl, —CN, —C(O)NH 2 , C 2-6 alkenyl, C 2 -6 alkynyl, C 1-6 alkoxy, C 3-8 cycloalkyl, C 6 aryl, 5- to 12-membered heteroaryl, or 4- to 10-membered heterocyclyl,

wherein each alkyl, alkenyl, alkynyl, alkoxy, cycloalkyl, aryl, heteroaryl, and heterocyclyl is optionally substituted with one to four R 1a ;

alternatively, two R 1 taken together with the atoms of ring

 to which they are attached form 5- to 10-membered heterocyclyl;

each R 1a is independently C 1-6 alkyl, C 1-6 alkoxy, halogen, C 3-8 cycloalkyl, 4- to 10-membered heterocyclyl, C 6 aryl, 5- to 10-membered heteroaryl, oxo, —OH, —CN, —NH 2 , —O(C 1-6 alkyl), —O(C 3-8 cycloalkyl), —O(5- to 10-membered heterocyclyl), —O(C 6 aryl), —O(5- to 10-membered heteroaryl), —NH(C 1-6 alkyl), —NH(C 3-8 cycloalkyl), —NH(5- to 10-membered heterocyclyl), —NH(C 6 aryl), —NH(5- to 10-membered heteroaryl), —N(C 1-6 alkyl) 2 , —N(C 3-8 cycloalkyl) 2 , —N(5- to 10-membered heterocyclyl) 2 , —N(C 6 aryl) 2 , —N(5- to 10-membered heteroaryl) 2 , —N(C 1-6 alkyl)(C 3-8 cycloalkyl), —N(C 1-6 alkyl)(5- to 10-membered heterocyclyl), —N(C 1-6 alkyl)(C 6 aryl), —N(C 1-6 alkyl)(5- to 10-membered heteroaryl), —C(O)(5- to 10-membered heterocyclyl), —C(O)(5- to 10-membered heteroaryl), —C(O)O(C 1-6 alkyl), —C(O)O(C 3-8 cycloalkyl), —C(O)O(5- to 10-membered heterocyclyl), —C(O)O(C 6 aryl), —C(O)O(5- to 10-membered heteroaryl), —C(O)NH 2 , —C(O)NH(C 1-6 alkyl), —C(O)NH(C 3-8 cycloalkyl), —C(O)NH(5- to 10-membered heterocyclyl), —C(O)NH(C 6 aryl), —C(O)NH(5- to 10-membered heteroaryl), —C(O)N(C 1-6 alkyl) 2 , —C(O)N(C 3-8 cycloalkyl) 2 , —C(O)N(5- to 10-membered heterocyclyl) 2 , —C(O)N(C 6 aryl) 2 , —C(O)N(5- to 10-membered heteroaryl) 2 , —NHC(O)(C 1-6 alkyl), —NHC(O)(C 3-8 cycloalkyl), —NHC(O)(5- to 10-membered heterocyclyl), —NHC(O)(C 6 aryl), —NHC(O)(5- to 10-membered heteroaryl), —NHC(O)O(C 1-6 alkyl), —NHC(O)O(C 3-8 cycloalkyl), —NHC(O)O(5- to 10-membered heterocyclyl), —NHC(O)O(C 6 aryl), —NHC(O)O(5- to 10-membered heteroaryl), —NHC(O)NH(C 1-6 alkyl), —NHC(O)NH(C 3-8 cycloalkyl), —NHC(O)NH(5- to 10-membered heterocyclyl), —NHC(O)NH(C 6 aryl), —NHC(O)NH(5- to 10-membered heteroaryl), —NHS(O)(C 1-6 alkyl), —N(C 1-6 alkyl)(S(O)(C 1-6 alkyl), —S(O) 2 (C 1-6 alkyl), —S(O) 2 (C 3-8 cycloalkyl), —S(O) 2 (5- to 10-membered heterocyclyl), —S(O) 2 (C 6 aryl), —S(O) 2 (5- to 10-membered heteroaryl), —S(O)(NH)(C 1-6 alkyl), —S(O) 2 NH(C 1-6 alkyl), or —S(O) 2 N(C 1-6 alkyl) 2 ,

wherein each alkyl, cycloalkyl, heterocyclyl, aryl, and heteroaryl is optionally substituted with one to three R 1b ;

each R 1b is independently C 1-6 alkyl, C 1-6 haloalkyl, halogen, oxo, —OH, —NH 2 , CO 2 H, —O(C 1-6 alkyl), —O(C 1-6 haloalkyl), —O(C 3-8 cycloalkyl), —O(5- to 10-membered heterocyclyl), —O(C 6 aryl), —O(5- to 10-membered heteroaryl), —NH(Ci-6 alkyl), —NH(C 1-6 haloalkyl), —NH(C 3-8 cycloalkyl), —NH(5- to 10-membered heterocyclyl), —NH(C 6 aryl), —NH(5- to 10-membered heteroaryl), —N(C 1-6 alkyl) 2 , —N(C 3-8 cycloalkyl) 2 , —NHC(O)(C 1-6 alkyl), —NHC(O)(C 1-6 haloalkyl), —NHC(O)(C 3-8 cycloalkyl), —NHC(O)(5- to 10-membered heterocyclyl), —NHC(O)(C 6 aryl), —NHC(O)(5- to 10-membered heteroaryl), —NHC(O)O(C 1-6 alkyl), —NHC(O)O(C 1-6 haloalkyl), —NHC(O)O(C 2-6 alkynyl), —NHC(O)O(C 3-8 cycloalkyl), —NHC(O)O(5- to 10-membered heterocyclyl), —NHC(O)O(C 6 -aryl), —NHC(O)O(5- to 10-membered heteroaryl), —NHC(O)NH(C 1-6 alkyl), S(O) 2 (C 1-6 alkyl), —S(O) 2 (C 1-6 haloalkyl), —S(O) 2 (C 3-8 cycloalkyl), —S(O) 2 (5- to 10-membered heterocyclyl), —S(O) 2 (C 6 aryl), —S(O) 2 (5- to 10-membered heteroaryl), —S(O)(NH)(C 1-6 alkyl), —S(O) 2 NH(C 1-6 alkyl), or —S(O) 2 N(C 1-6 alkyl) 2 ;

m is an integer from 0 to 3;

R 2 is hydrogen, C 1-3 alkyl, C 1-3 haloalkyl, cyclopropyl, C 1-3 alkoxy, —O(C 1-3 haloalkyl), —O(cyclopropyl), halogen, or —CN;

X 1 is S, N, or C(R x1 );

X 2 is S, N, or C(R x2 );

X 3 is N or C(R x3 ), provided that X 1 and X 2 are not S;

alternatively, X 3 is a bond, wherein one of X 1 and X 2 is S;

each R x1 , R x2 , and R x3 is independently hydrogen, halogen, C 1-3 alkyl, C 1-3 haloalkyl, O C 1-3 haloalkyl, C 1-3 alkoxy, cyclopropyl, or O-cyclopropyl;

ring

 taken together with X 4 and X 5 is C 6 aryl, 5- to 6-membered heteroaryl, C 5-10 cycloalkyl, or 5- to 10-membered heterocyclyl,

wherein each X 4 and X 5 is independently N or C;

alternatively, ring

 is absent, wherein X 4 is N or C-L x4 -R x4 , and X 5 is N or C-L x5 -R x5 ;

each L x4 and L x5 is independently a bond, —(C 1-6 alkyl)O—, —(C 1-6 alkyl)N(R L )C(O)—, —(C 1-6 alkyl)C(O)N(R L )—, —(C 1-6 alkyl)N(R L )C(O)(C 1-6 alkyl)-, —(C 1-6 alkyl)C(O)N(R L )(C 1-6 alkyl)-, —(C 1-6 alkyl), —(C 1-6 alkyl)N(R L )S(O) 2 —, —N(R L )S(O) 2 —, —C(O)—, —(C 1-6 alkyl)C(O)—, or —N(R L )C(O)—;

each R x4 and R x5 is independently hydrogen, halogen, hydroxy, —CN, C 1-6 alkyl, C 2-6 alkynyl, C 1-6 alkoxy, C 3-8 cycloalkyl, 4- to 10-membered heterocyclyl, 5- to 10-membered heteroaryl, —NH 2 , —NH(C 1-6 alkyl), —N(C 1-6 alkyl) 2 , —O(C 1-6 alkyl), or —OC 3-8 cycloalkyl;

wherein each alkyl, alkynyl, alkoxy, cycloalkyl, and heterocyclyl is optionally substituted with one to four R 4a ;

each R 4a is independently C 1-6 alkyl, C 1-6 haloalkyl, halogen, C 3-8 cycloalkyl, 4- to 10-membered heterocyclyl, C 6 aryl, 5- to 10-membered heteroaryl, oxo, —OH, —CN, —NH 2 , —O(C 1-6 alkyl), —O(C 1-6 haloalkyl), —O(C 3-8 cycloalkyl), —O(5- to 10-membered heterocyclyl), —O(C 6-10 aryl), —O(5- to 10-membered heteroaryl), —NH(C 1-6 alkyl), —NH(C 1-6 haloalkyl), —NH(C 3-8 cycloalkyl), —NH(5- to 10-membered heterocyclyl), —NH(C 6 aryl), —NH(5- to 10-membered heteroaryl), —N(C 1-6 alkyl) 2 , —N(C 1-6 haloalkyl) 2 , —N(C 3-8 cycloalkyl) 2 , —N(C 1-6 alkyl)(C 1-6 haloalkyl), —N(C 1-6 alkyl)(C 3-8 cycloalkyl), —N(C 1-6 alkyl)(5- to 10-membered heterocyclyl), —N(C 1-6 alkyl)(C 6 aryl), —N(C 1-6 alkyl)(5- to 10-membered heteroaryl), —C(O)(5- to 10-membered heterocyclyl), —C(O)(5- to 10-membered heteroaryl), —C(O)NH 2 , —C(O)NH(C 1-6 alkyl), —C(O)NH(C 1-6 haloalkyl), —C(O)NH(C 3-8 cycloalkyl), —C(O)NH(5- to 10-membered heterocyclyl), —C(O)NH(C 6 aryl), —C(O)NH(5- to 10-membered heteroaryl), —C(O)N(C 1-6 alkyl) 2 , —C(O)N(C 1-6 haloalkyl) 2 , —C(O)N(C 3-8 cycloalkyl) 2 , —NHC(O)(C 1-6 alkyl), —NHC(O)(C 1-6 haloalkyl), —NHC(O)(C 3-8 cycloalkyl), —NHC(O)(5- to 10-membered heterocyclyl), —NHC(O)(C 6 aryl), —NHC(O)(5- to 10-membered heteroaryl), —NHC(O)O(C 1-6 alkyl), —NHC(O)O(C 1-6 haloalkyl), —NHC(O)O(C 3-8 cycloalkyl), —NHC(O)O(5- to 10-membered heterocyclyl), —NHC(O)O(C 6 aryl), —NHC(O)O(5- to 10-membered heteroaryl), —NHC(O)NH(C 1-6 alkyl), —NHC(O)NH(C 1-6 haloalkyl), —NHC(O)NH(C 3-8 cycloalkyl), —NHC(O)NH(5- to 10-membered heterocyclyl), —NHC(O)NH(C 6 aryl), —NHC(O)NH(5- to 10-membered heteroaryl), —S(O) 2 (C 1-6 alkyl), —S(O) 2 (C 1-6 haloalkyl), —S(O) 2 (C 3-8 cycloalkyl), —S(O)(NH)(C 1-6 alkyl), —S(O) 2 NH(C 1-6 alkyl), or —S(O) 2 N(C 1-6 alkyl) 2 ,

wherein each alkyl, cycloalkyl, heterocyclyl, aryl, and heteroaryl is optionally substituted with one to three R 4b ;

each R 4b is independently C 1-6 alkyl, C 1-6 haloalkyl, C 3-6 cycloalkyl, halogen, oxo, —OH, —NH 2 , CO 2 H, —O(C 1-6 alkyl), —O(C 1-6 haloalkyl), —O(C 3-8 cycloalkyl), —O(5- to 10-membered heterocyclyl), —O(C 6 aryl), —O(5- to 10-membered heteroaryl), —NH(C 1-6 alkyl), —NH(C 1-6 haloalkyl), —NH(C 3-8 cycloalkyl), —NH(5- to 10-membered heterocyclyl), —NH(5- to 10-membered heteroaryl), —N(C 1-6 alkyl) 2 , —N(C 3-8 cycloalkyl) 2 , —NHC(O)(C 1-6 alkyl), —NHC(O)(C 1-6 haloalkyl), —NHC(O)(C 3-8 cycloalkyl), —NHC(O)(5- to 10-membered heterocyclyl), —NHC(O)(5- to 10-membered heteroaryl), —NHC(O)O(C 1-6 alkyl), —NHC(O)O(C 1-6 haloalkyl), —NHC(O)O(C 3-8 cycloalkyl), —NHC(O)O(5- to 10-membered heterocyclyl), —NHC(O)O(5- to 10-membered heteroaryl), —NHC(O)NH(C 1-6 alkyl), S(O) 2 (C 1-6 alkyl), —S(O) 2 (C 1-6 haloalkyl), —S(O) 2 (C 3-8 cycloalkyl), —S(O)(NH)(C 1-6 alkyl), —S(O) 2 NH(C 1-6 alkyl), or —S(O) 2 N(C 1-6 alkyl) 2 ;

each L 3 is independently a bond, —(C 1-6 alkyl)O—, —(C 1-6 alkyl)N(R L )C(O)—, —(C 1-6 alkyl)C(O)N(R L )—, —(C 1-6 alkyl)N(R L )C(O)(C 1-6 alkyl)-, —(C 1-6 alkyl)C(O)N(R L )(C 1-6 alkyl)-, —(C 1-6 alkyl), —(C 1-6 alkyl)N(R L )S(O) 2 —, —N(R L )S(O) 2 —, —C(O)—, —(C 1-6 alkyl)C(O)—, or —N(R L )C(O)—;

each R 3 is independently halogen, hydroxy, —CN, C 1-6 alkyl, C 2-6 alkynyl, C 1-6 alkoxy, C 3-8 cycloalkyl, 4- to 10-membered heterocyclyl, C 6 aryl, 5- to 10-membered heteroaryl, —NH 2 , —NH(C 1-6 alkyl), —N(C 1-6 alkyl) 2 , or —OC 3-8 cycloalkyl;

wherein each alkyl, alkynyl, alkoxy, cycloalkyl, heterocyclyl, aryl, and heteroaryl, is optionally substituted with one to four R 3a ;

each R 3a is independently C 1-6 alkyl, C 1-6 haloalkyl, halogen, —C(O)(C 1 -C 6 alkyl), C 3-8 cycloalkyl, 4- to 10-membered heterocyclyl, C 6 aryl, 5- to 10-membered heteroaryl, oxo, —OH, —CN, —NH 2 , —O(C 1-6 alkyl), —O(C 1-6 haloalkyl), —O(C 3-8 cycloalkyl), —O(5- to 10-membered heterocyclyl), —O(C 6-10 aryl), —O(5- to 10-membered heteroaryl), —NH(C 1-6 alkyl), —NH(C 1-6 haloalkyl), —NH(C 3-8 cycloalkyl), —NH(5- to 10-membered heterocyclyl), —NH(C 6 aryl), —NH(5- to 10-membered heteroaryl), —N(C 1-6 alkyl) 2 , —N(C 1-6 haloalkyl) 2 , —N(C 3-8 cycloalkyl) 2 , —N(C 1-6 alkyl)(C 1-6 haloalkyl), —N(C 1-6 alkyl)(C 3-8 cycloalkyl), —N(C 1-6 alkyl)(5- to 10-membered heterocyclyl), —N(C 1-6 alkyl)(C 6 aryl), —N(C 1-6 alkyl)(5- to 10-membered heteroaryl), —C(O)(5- to 10-membered heterocyclyl), —C(O)(5- to 10-membered heteroaryl), —C(O)NH 2 , —C(O)NH(C 1-6 alkyl), —C(O)NH(C 1-6 haloalkyl), —C(O)NH(C 3-8 cycloalkyl), —C(O)NH(5- to 10-membered heterocyclyl), —C(O)NH(C 6 aryl), —C(O)NH(5- to 10-membered heteroaryl), —C(O)N(C 1-6 alkyl) 2 , —C(O)N(C 1-6 haloalkyl) 2 , —C(O)N(C 3-8 cycloalkyl) 2 , —NHC(O)(C 1-6 alkyl), —NHC(O)(C 1-6 haloalkyl), —NHC(O)(C 3-8 cycloalkyl), —NHC(O)(5- to 10-membered heterocyclyl), —NHC(O)(C 6 aryl), —NHC(O)(5- to 10-membered heteroaryl), —NHC(O)O(C 1-6 alkyl), —NHC(O)O(C 1-6 haloalkyl), —NHC(O)O(C 3-8 cycloalkyl), —NHC(O)O(5- to 10-membered heterocyclyl), —NHC(O)O(C 6 aryl), —NHC(O)O(5- to 10-membered heteroaryl), —NHC(O)NH(C 1-6 alkyl), —NHC(O)NH(C 1-6 haloalkyl), —NHC(O)NH(C 3-8 cycloalkyl), —NHC(O)NH(5- to 10-membered heterocyclyl), —NHC(O)NH(C 6 aryl), —NHC(O)NH(5- to 10-membered heteroaryl), —S(O) 2 (C 1-6 alkyl), —S(O) 2 (C 1-6 haloalkyl), —S(O) 2 (C 3-8 cycloalkyl), —S(O)(NH)(C 1-6 alkyl), —S(O) 2 NH(C 1-6 alkyl), or —S(O) 2 N(C 1-6 alkyl) 2 ,

wherein each alkyl, cycloalkyl, heterocyclyl, aryl, and heteroaryl is optionally substituted with one to three R 3b ;

each R 3b is independently C 1-6 alkyl, C 1-6 haloalkyl, C 3-6 cycloalkyl, halogen, oxo, —OH, —NH 2 , CO 2 H, —O(C 1-6 alkyl), —O(C 1-6 haloalkyl), —O(C 3-8 cycloalkyl), —O(5- to 10-membered heterocyclyl), —O(C 6-10 aryl), —O(5- to 10-membered heteroaryl), —NH(C 1-6 alkyl), —NH(C 1-6 haloalkyl), —NH(C 3-8 cycloalkyl), —NH(5- to 10-membered heterocyclyl), —NH(5- to 10-membered heteroaryl), —N(C 1-6 alkyl) 2 , —N(C 3-8 cycloalkyl) 2 , —NHC(O)(C 1-6 alkyl), —NHC(O)(C 1-6 haloalkyl), —NHC(O)(C 3-8 cycloalkyl), —NHC(O)(5- to 10-membered heterocyclyl), —NHC(O)(5- to 10-membered heteroaryl), —NHC(O)O(C 1-6 alkyl), —NHC(O)O(C 1-6 haloalkyl), —NHC(O)O(C 3-8 cycloalkyl), —NHC(O)O(5- to 10-membered heterocyclyl), —NHC(O)O(5- to 10-membered heteroaryl), —NHC(O)NH(C 1-6 alkyl), S(O) 2 (C 1-6 alkyl), —S(O) 2 (C 1-6 haloalkyl), —S(O) 2 (C 3-8 cycloalkyl), —S(O)(NH)(C 1-6 alkyl), —S(O) 2 NH(C 1-6 alkyl), or —S(O) 2 N(C 1-6 alkyl) 2 ;

each R L is independently hydrogen, C 1-6 alkyl, C 1-6 haloalkyl, or C 3-8 cycloalkyl;

n is an integer from 0 to 3;

each X 6 and X 7 is independently N, CH, or CF,

wherein no more than two of X 4 , X 5 , X 6 , and X 7 are N;

L 2 is a bond, C 1 -C 6 alkyl, —(C 1-6 alkyl)O—, —(C 1-6 alkyl)O(C 1-6 alkyl)-, —(C 1-6 alkyl) (R L2 )NC(O)—, —(C 1-6 alkyl)C(O)N(R L2 )—, —(C 1-6 alkyl)S(O) 2 N(R L2 )—, —(C 1-6 alkyl)N(R L2 )S(O) 2 —, —(C 1-6 alkyl)S(O) 2 N(R L2 ) (C 1-6 alkyl)-, or —(C 1-6 alkyl)S(O) 2 —(C 1-6 alkyl)-;

R L2 is hydrogen or C 1-6 alkyl;

R 5 is hydrogen, —CN, —OR 5a , —C(O)NR 5a 2 , —NR 5a C(O)R 5a , —NR 5a 2 , C 1-6 alkyl, C 3-8 cycloalkyl, C 6 aryl, 4- to 10-membered heterocyclyl, or 5- to 10-membered heteroaryl, wherein each alkyl, cycloalkyl, aryl, heterocyclyl, and heteroaryl is optionally substituted with one or two R 5b ;

each R 5a is independently hydrogen or C 1-6 alkyl;

each R 5b is independently halogen, cyclopropyl, hydroxy, —CN, C 1-3 alkyl, C 1-3 alkoxy, —OCF 3 , or —OCF 2 H; and

Z is O or S.

2 - 4 . (canceled)

3 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the structure of formula (II):

4 - 16 . (canceled)

5 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein ring

is C 6 aryl.

6 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the structure of formula (IV):

7 - 36 . (canceled)

8 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein n is 0.

9 . (canceled)

10 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein ring

is absent.

11 - 50 . (canceled)

12 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein ring

is C 6 aryl.

13 . (canceled)

14 . (canceled)

15 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein ring

is 5- to 10-membered heteroaryl.

16 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein L 1 is a bond.

17 . (canceled)

18 . (canceled)

19 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein each R 1 is independently halogen, —CN, —C(O)NH 2 , C 1-6 alkyl, C 2-6 alkynyl, C 1-6 alkoxy, C 3-8 cycloalkyl, C 6 aryl, or 5- to 10-membered heteroaryl, wherein each alkyl, alkynyl, alkoxy, cycloalkyl, aryl, and heteroaryl is optionally substituted with one to three R 1a .

20 - 66 . (canceled)

21 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein m is 1 or 2.

22 - 70 . (canceled)

23 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 2 is hydrogen, halogen, C 1-3 alkyl, or C 1-3 alkoxy.

24 - 78 . (canceled)

25 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein L 2 is a bond or C 1 -C 3 alkyl.

26 . (canceled)

27 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 5 is hydrogen or —CN.

28 - 86 . (canceled)

29 . The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein Z is O.

30 . A compound selected from

or a pharmaceutically acceptable salt thereof.

31 - 102 . (canceled)

32 . A pharmaceutical composition comprising the compound of claim 1 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient.

33 . A method of treating or preventing a viral infection in a human in need thereof, wherein the method comprises administering to the human the compound of claim 1 .

34 . The method of claim 104 , wherein the viral infection is a coronavirus infection.

35 - 109 . (canceled)

36 . The method of claim 104 , wherein the viral infection is SARS-CoV-2 infection (COVID-19).

37 - 113 . (canceled)