Contraceptive agents

A compound of formula I, II, III, or IV:

• wherein:
• R1 is H, (C1-C6)alkyl, or Rc, wherein the (C1-C6)alkyl is optionally substituted with one or more halo or (C1-C6)alkoxy;
• R2 is H or (C1-C6)alkyl, wherein the (C1-C6)alkyl is optionally substituted with one or more halo or (C1-C6)alkoxy;
• R3 is H or (C1-C6)alkyl, wherein the (C1-C6)alkyl is optionally substituted with one or more halo or (C1-C6)alkoxy;
• R4 is Ra, cyano, carboxy, hydroximinomethyl, (C1-C4)alkyl, (C2-C4)alkenyl, (C2-C4)alkynyl, aryl, heteroaryl, or (C1-C4)alkanoyl, wherein the (C1-C4)alkyl, (C2-C4)alkenyl, (C2-C4)alkynyl, and (C1-C4)alkanoyl is optionally substituted with one or more groups selected from hydroxy, halo, aryl, and heteroaryl;
• wherein any aryl and heteroaryl of R4 is optionally substituted with one or more Rb;
• R5 is H or (C1-C6)alkyl, wherein the (C1-C6)alkyl is optionally substituted with one or more halo or (C1-C6)alkoxy;
• R6 is H or (C1-C6)alkyl, wherein the (C1-C6)alkyl is optionally substituted with one or more halo or (C1-C6)alkoxy;
• and R7 is H or (C1-C6)alkyl, wherein the (C1-C6)alkyl is optionally substituted with one or more halo or (C1-C6)alkoxy;
• or R6 and R7 taken together form a (C1-C6)alkylene;
• R8 is —CH═N—N═C(NH2)2 or heteroaryl, which heteroaryl is optionally substituted with one or more Rg;
• R9 is —CH═N—N═C(NH2)2 or heteroaryl, which heteroaryl is optionally substituted with one or more Rh;
• X is O, or ═N—N═C(NH2)2;
• Y is O, or ═N—N═C(NH2)2;
• R10 is —OH, morpholino, or —O—C(═O)CH(NH2)Rk,
• R11 is Rm, aryl, or heteroaryl, wherein the aryl and heteroaryl of R11 is optionally substituted with one or more Rn;
• Ra, is a 4, 5, or 6 membered saturated or partially unsaturated heterocyclic ring comprising at least one carbon atom and at least one heteroatom selected from O, S, or NH in the ring, which ring is optionally substituted with one or more oxo (═O);
• Rb, is aryl or aryl(C1-C6)alkyl, wherein the aryl or aryl(C1-C6)alkyl is optionally substituted with one or more (C1-C6)alkoxy or halo;
• Rc, is a C-linked amino acid, a C-linked dipeptide, —C(═O)CH2CH2COOH, —P(═O)(OH)2, or:
• Rd is H, (C1-C6)alkanoyl, or (C1-C6)alkyl, wherein the (C1-C6)alkanoyl and the (C1-C6)alkyl are each optionally substituted with one or more halo or (C1-C6)alkoxy;
• and Re is H, (C1-C6)alkanoyl, or (C1-C6)alkyl, wherein the (C1-C6)alkanoyl and the (C1-C6)alkyl are each optionally substituted with one or more halo or (C1-C6)alkoxy;
• or Rd and Re taken together form a (C1-C6)alkylene;
• and
• Rf is H, (C1-C6)alkanoyl, or (C1-C6)alkyl, wherein the (C1-C6)alkanoyl and the (C1-C6)alkyl are each optionally substituted with one or more halo or (C1-C6)alkoxy;
• each Rg, is independently aryl or aryl(C1-C6)alkyl, wherein the aryl or aryl(C1-C6)alkyl is optionally substituted with one or more halo;
• each Rh, is independently aryl or aryl(C1-C6)alkyl, wherein the aryl or aryl(C1-C6)alkyl is optionally substituted with one or more halo;
• Rk is H or (C1-C6)alkyl, wherein the (C1-C6)alkyl is optionally substituted with one or more halo, (C1-C6)alkoxy, benzyl, or amino;
• Rm, is a 4, 5, or 6 membered saturated or partially unsaturated heterocyclic ring comprising at least one carbon atom and at least one heteroatom selected from O, S, or NH in the ring, which ring is optionally substituted with one or more oxo (═O);
• and
• Rn, is (C1-C6)alkyl, aryl, or aryl(C1-C6)alkyl, wherein the (C1-C6)alkyl is optionally substituted with one or more halo, (C1-C6)alkoxycarbonyl, or (C1-C6)alkoxy;
• and wherein the aryl or aryl(C1-C6)alkyl is optionally substituted with one or more halo;
• or a salt thereof.