Neutrophil elastase inhibitor and use thereof

A compound of Formula I or a pharmaceutically acceptable salt thereof,

• wherein
• R1 is selected from R6—C(═O)—, or R1 is attached to a benzene ring to form a five-membered or six-membered ring, in which the five-membered or six-membered ring is optionally substituted with R6;
• R6 is selected from t-butyl, C3-C6 cycloalkyl, and C3-C6 heterocycloalkyl;
• ring A is selected from 5 to 10-membered cycloalkyl, heterocycloalkyl, heteroaryl, and aryl, ring A is optionally substituted with one or more R5;
• R2 and R5 are each independently selected from hydrogen, halogen, cyano, trifluoromethyl, nitro, amino, C1-C6 alkyl, C1-C6 alkoxy, C3-C6 cycloalkyl, C3-C6 heterocycloalkyl, and C3-C6 heteroaryl;
• R3 is selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C3-C6 cycloalkyl, and C1-C6 haloalkyl;
• R4 is optionally selected from —COOH, —SO3H, and —PO3H2;
• and
• m and n are independently 0, 1, 2, or 3;
• where the alkyl, alkoxy, cycloalkyl, heterocycloalkyl, and heteroaryl are unsubstituted or optionally substituted with one or more deuterium, C1-C3 alkyl, C1-C3 alkoxy, C1-C3 deuterated alkoxy, halogen, cyano, trifluoromethyl, nitro, amino, —CONH2, and —COOH.