A compound of formula: wherein Ar is wherein X is a bond, CH 2, O, S y, or NR 10; ring A is optionally substituted with one to three groups selected from F, Cl, Br, I, OR 21, OR 25, NR 23 R 24, NHOH, NO 2, CN, CF 3, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 7 cycloalkyl, 3-7 membered heterocycloalkyl, phenyl, 5 or 6 membered heteroaryl, arylalkyl, C(=O)R 22, CO 2 R 21, OC(=O)R 22, C(=O)NR 23 R 24, NR 21 C(=O)R 22, NR 21 CO 2 R 22, OC(=O)NR 23 R 24, NR 21 C(=S)R 22, and S y R 22; ring B is optionally substituted with one to three groups selected from C 1 -C 6 alkyl, phenyl, and 5-6 membered heteroaryl; Y is (C 1 -C 6 alkylene)-R 1; or (C 1 -C 4 alkylene) m -Z-(C 1 -C 4 alkylene) n -R 1; wherein said alkylene groups are optionally substituted with one to three R 20 groups; Z is O, NR 10A, S y, CR 21 =CR 21, C=C(R 21) 2, C=C, C 6 -C 10 arylene, 5-10 membered heteroarylene, C 3 -C 6 cycloalkylene, or 3-6 membered heterocycloalkylene; wherein said arylene, heteroarylene, cycloalkylene, and heterocycloalkylene groups are optionally substituted with one to three R 20 groups; R 1 is NR 12 R 13, NR 21 C(=O)R 14, C(=O)R 15, COOH, CO 2 R 14, OC(=O)R 11, C(=O)NR 12 R 13, C(=N)NR 12 R 13, OC(=O)NR 12 R 13, NR 21 S 2 R 11, S 2 NR 12 R 13, NR 21 C(=O)NR 12 R 13, NR 21 S 2 NR 12 R 13, or PO(OR 21) 2; R 10 and R 10A are each independently selected from H, C 1 -C 6 alkyl, C 6 -C 10 aryl, C(=O)R 15, and S y R 14; wherein said alkyl and aryl groups are optionally substituted with one to three R 20 groups; R 11 at each occurrence is independently selected from H, C 1 -C 6 alkyl, and C 6 -C 10 aryl; wherein said alkyl and aryl groups are optionally substituted with one to three R 20 groups; R 12 and R 13 at each occurrence are each independently selected from H, C 1 -C 6 alkyl, and C 6 -C 10 aryl, or R 12 and R 13, together with the nitrogen to which they are attached, form a 3-7 membered heterocycloalkyl ring; wherein said alkyl and aryl groups and heterocycloalkyl ring are optionally substituted with one to three R 20 groups; R 14 at each occurrence is independently selected from C 1 -C 6 alkyl, C 6 -C 10 aryl, and arylalkyl; wherein said alkyl, aryl and arylalkyl groups are optionally substituted with one to three R 20 groups; R 15 at each occurrence is independently selected from C 1 -C 6 alkyl, C 6 -C 10 aryl, arylalkyl, and heteroaryl; wherein said alkyl, aryl, arylalkyl, and heteroaryl groups are optionally substituted with one to three R 20 groups; R 20 at each occurrence is independently selected from F, Cl, Br, I, OR 21, OR 25, O(C 1 -C 4 alkylene)OR 21, NR 23 R 24, NHOH, NO 2, CN, CF 3, C 1 -C 6 alkyl, C 3 -C 6 spirocycloalkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 7 cycloalkyl, 3-7 membered heterocycloalkyl, phenyl, 5 or 6 membered heteroaryl, arylalkyl, =O, C(=O)R 22, CO 2 R 21, OC(=O)R 22, C(=O)NR 23 R 24, NR 21 C(=O)R 22, NR 21 CO 2 R 22, OC(=O)NR 23 R 24, NR 21 C(=O)R 22, NR 21 C(=S)R 22, and S y R 22; R 21 at each occurrence is independently selected from H and C 1 -C 6 alkyl; R 22 at each occurrence is independently selected from C 1 -C 6 alkyl, and unsubstituted C 6 -C 10 aryl; R 23 and R 24 at each occurrence are each independently selected from H, C 1 -C 6 alkyl, and unsubstituted C 6 -C 10 aryl, or R 23 and R 24, together with the nitrogen to which they are attached, form a 3-7 membered heterocycloalkyl ring; R 25 at each occurrence is independently the residue of an α-amino acid after the hydroxyl group of the carboxyl group is removed, in which the side chain of the α-amino acid is independently selected from: H CH 3 CH(CH 3) 2 CH 2 CH(CH 3) 2 CH(CH 3)CH 2 CH 3 CH 2 OH CH 2 SH CH CH 3 CH 2 CH 2 SCH 3 CH 2 C 6 H 5 (CH 2) 4 NH 2 (CH 2) 3 NHC(=NH)NH 2 CH 2 COOH CH 2 CH 2 COOH CH 2 CONH 2 CH 2 CH 2 CONH 2 CH 2 CH 3 CH 2 CH 2 CH 3 CH 2 CH 2 CH 2 CH 3 CH 2 CH 2 SH CH 2 CH 2 OH CH 2 CH 2 SCH 3 (CH 2) 3 NH 2 (CH 2) 2 CH CH 2 NH 2 (CH 2) 3 NHC(=O)NH 2 (CH 2) 2 ONHC(=NH)NH 2 CH 2 C(=O)NHCH 2 COOH wherein the α-amino acid side chain substituents are each, independently, optionally substituted with benzyloxycarbonyl or t-butoxycarbonyl protecting groups; m is 1; n is 0 or 1; q is 1 or 2; y is 0, 1, or 2; wherein any lactams are each, independently, optionally substituted with silyl, dimethoxybenzhydryl, acyl, benzyl, or methoxybenzyl protecting groups; wherein any hydroxy groups are each, independently, optionally substituted with TBS, acyl, benzyl, benzyloxycarbonyl, t-butyloxycarbonyl, and methoxymethyl protecting groups; wherein the term "cycloalkyl" refers to a saturated or partially saturated mono-or bicyclic alkyl ring system containing, unless otherwise specified, 3 to 10 carbon atoms; and the stereoisomeric forms, mixtures of stereoisomeric forms or pharmaceutically acceptable salts forms thereof.