Inhibitors of serine proteases

A compound of formula (I)

• or a pharmaceutically acceptable salt thereof wherein:
• Each A is —(CX1X2)a—;
• Each B is —(CX1X2)b—;
• Each X1 is independently hydrogen, halo, amino, sulfanyl, optionally substituted (C1-4)-aliphatic, optionally substituted aryl, or —O—X1A;
• Each X2 is independently hydrogen, halo, amino, sulfanyl, optionally substituted (C1-4)-aliphatic, optionally substituted aryl, or —O—X1B;
• X1A and X1B are each independently an optionally substituted aliphatic, an optionally substituted cycloaliphatic, an optionally substituted heterocycloaliphatic, an optionally substituted aryl, or an optionally substituted heteroaryl;
• Or, X1 and X2 together form an oxo group;
• Each R1 is -ZAR4, wherein each ZA is independently a bond or an optionally substituted branched or straight C1-12 aliphatic chain wherein up to three carbon units of ZA are optionally and independently replaced by —C(O)—, —C(S)—, —C(O)NRA—, —C(O)NRANRA—, —C(O)O—, —NRAC(O)O—, —O—, —NRAC(O)NRA—, —NRANRA—, —S—, —SO—, —SO2—, —NRA—, —SO2NRA—, or —NRASO2NRA— provided that —NRANRA—, —NRAC(O)NRA—, or —NRASO2NRA— is not directly bound to the nitrogen ring atom of formula I;
• Each R4 is independently RA, halo, —OH, —CN, —NO2, —NH2, or —OCF3;
• Each RA is independently hydrogen, an optionally substituted aliphatic, an optionally substituted cycloaliphatic, an optionally substituted heterocycloaliphatic, an optionally substituted aryl, or an optionally substituted heteroaryl;
• Each R2 is -ZBR5, wherein each ZB is independently a bond or an optionally substituted branched or straight C1-12 aliphatic chain wherein up to three carbon units of ZB are optionally and independently replaced by —C(O)—, —C(S)—, —C(O)NRB—, —C(O)NRBNRB—, —C(O)O—, —NRBC(O)O—, —NRBC(O)NRB—, —NRBNRB—, —S—, —SO—, —SO2—, —NRB—, —SO2NRB—, or —NRBSO2NRB—, provided that SO, SO2, or —SO2NRB— is not directly bound to the carbonyl of formula I;
• Each R5 is independently RB, halo, —OH, —CN, —NO2, —NH2, or —OCF3;
• Each RB is independently hydrogen, an optionally substituted aliphatic, an optionally substituted cycloaliphatic, an optionally substituted aryl, or an optionally substituted heteroaryl;
• Or R1 and R2, together with the atoms to which they are attached, form an optionally substituted heterocycloaliphatic ring;
• Each R3 is an optionally substituted aliphatic, amino, sulfonyl, sulfanyl, sulfinyl, sulfonamide, sulfamide, sulfo, —O—R3A, an optionally substituted cycloaliphatic, an optionally substituted heterocycloaliphatic, an optionally substituted aryl, or an optionally substituted heteroaryl;
• Each R3A is independently an optionally substituted aliphatic, an optionally substituted cycloaliphatic, an optionally substituted heterocycloaliphatic, an optionally substituted aryl, or an optionally substituted heteroaryl;
• Each Y and Y′ is independently -ZDR7, wherein each ZD is independently a bond or an optionally substituted straight or branched C1-6 aliphatic chain wherein up to two carbon units of ZD are optionally and independently replaced by —C(O)—, —C(S)—, —C(O)NRD—, —C(O)NRDNRD—, —C(O)O—, —NRDC(O)O—, —O—, —NRDC(O)NRD—, —NRDNRD—, —S—, —SO—, —SO2—, —NRD—, —SO2NRD—, —NRDSO2—, or —NRDSO2NRD—, or Y and Y′ together form ═O or ═S;
• Each R7 is independently RD, halo, —OH, —CN, —NO2, —NH2, or —OCF3;
• Each RD is independently hydrogen, or optionally substituted aryl;
• and
• Each of a and b is independently 0, 1, 2, or 3;
• provided that the sum of a and b is 2 or 3.