Prodrugs of dithiol mucolytic agents

A compound represented by formula Ia or Ib:

• wherein
• R1 and R2 are each, independently, hydrogen, lower alkyl, halogen or triflouromethyl;
• R3 and R4 are each, independently, hydrogen, lower alkyl, hydroxyl-lower alkyl, phenyl, (phenyl)-lower alkyl, (halophenyl)-lower alkyl, ((lower-alkyl)phenyl)-lower-alkyl, ((lower-alkoxy)phenyl)-lower-alkyl, (naphthyl)-lower-alkyl, or (pyridyl)-lower-alkyl;
• each R5 is, independently, hydrogen, halogen, trifluoromethyl, lower alkyl, unsubstituted or substituted phenyl, lower alkyl-thio, phenyl-lower alkyl-thio, lower alkyl-sulfonyl, phenyl-lower alkyl-sulfonyl, OH, —(CH2)m—OR8, —O—(CH2)m—OR8, —(CH2)n—NR7R10, —(CH2)n—NR7R7, —O—(CH2)m—NR7R10, —O—(CH2)m—NR7R7, —(CH2)n(CHOR8)(CHOR8)n—CH2OR8, —O—(CH2)m(CHOR8)(CHOR8)n—CH2OR8, —(CH2CH2O)m—R8, —O—(CH2CH2O)m—R8, —(CH2CH2O)m—CH2CH2NR7R10, —O—(CH2CH2O)m—CH2CH2NR7R10, —(CH2)n—C(═O)NR7R10, —O—(CH2)m—C(═O)NR7R10, —(CH2)n—(Z)g—R7, —O—(CH2)m—(Z)g—R7, —(CH2)n—NR10—CH2(CHOR8)(CHOR8)n—CH2OR8, —O—(CH2)m—NR10—CH2(CHOR8)(CHOR8)n—CH2OR8, —(CH2)n—CO2R7, —O—(CH2)m—CO2R7, —OSO3H, —O-glucuronide, —O-glucose,
• -Link-(CH2)m-CAP, -Link-(CH2)n(CHOR8)(CHOR8)n-CAP, -Link-(CH2CH2O)m—CH2-CAP, -Link-(CH2CH2O)m—CH2CH2-CAP, -Link-(CH2)m—(Z)g-CAP, -Link-(CH2)n(Z)g—(CH2)m-CAP, -Link-(CH2)n—NR13—CH2(CHOR8)(CHOR8)n-CAP, -Link-(CH2)n—(CHOR8)mCH2—NR13—(Z)g-CAP, -Link-(CH2)nNR13—(CH2)m(CHOR8)nCH2NR13—(Z)g-CAP, -Link-(CH2)m—(Z)g—(CH2)m-CAP, -Link-NH—C(═O)—NH—(CH2)m-CAP, -Link-(CH2)m—C(═O)NR13—(CH2)m-CAP, -Link-(CH2)n—(Z)g—(CH2)m—(Z)g-CAP, or -Link-Zg—(CH2)m-Het-(CH2)m-CAP, with the proviso that at least one R5 group contains at least one basic nitrogen;
• each R7 is, independently, phenyl, substituted phenyl, lower alkyl phenyl or —CH2(CHOR8)m—CH2OR8;
• each R8 is, independently, hydrogen, lower alkyl, lower alkyl phenyl, —C(═O)—R1, glucuronide, 2-tetrahydropyranyl, or
• each R9 is, independently, —CO2R7, —CON(R7)2, —SO2CH3, —C(═O)R7, —CO2R13, —CON(R13)2, —SO2CH2R13, or —C(═O)R13;
• each R10 is, independently, —H, —SO2CH3, —CO2R7, —C(═O)NR7R9, —C(═O)R7, or —CH2—(CHOH)n—CH2OH;
• each Z is, independently, —(CHOH)—, —C(═O)—, —(CHNR7R10)—, —(C═NR10)—, —NR10—, —(CH2)n—, —(CHNR13R13)—, —(C═NR13)—, or —NR13—;
• each R11 is, independently, hydrogen, lower alkyl, phenyl lower alkyl or substituted phenyl lower alkyl;
• each R12 is, independently, —SO2CH3, —CO2R7, —C(═O)NR7R9, —C(═O)R7, —CH2(CHOH)n—CH2OH, —CO2R13, —C(═O)NR13R13, or —C(═O)R13;
• each R13 is, independently, hydrogen, lower alkyl, phenyl, substituted phenyl or —CH2(CHOR8)m—CH2OR8, —SO2CH3, —CO2R7, —C(═O)NR7R9, —C(═O)R7, —CH2—(CHOH)n—CH2OH, —(CH2)m—NR7R10, —(CH2)m—NR7R7, —(CH2)m—NR11R11, —(CH2)m—(NR11R11R11)+, —(CH2)m—(CHOR8)m—(CH2)mNR11R11, —(CH2)m—(CHOR8)m—(CH2)mNR7R10, —(CH2)m—NR10R10, —(CH2)m—(CHOR8)m—(CH2)m—(NR11R11R11)+, or —(CH2)m—(CHOR8)m—(CH2)mNR7R7;
• each R14 is, independently, —C(═O)—R7, —C(═O)-lower alkyl, or an amino acyl of the natural configuration;
• each g is, independently, an integer from 1 to 6;
• each m is, independently, an integer from 1 to 7;
• each n is, independently, an integer from 0 to 7;
• each -Het- is, independently, —N(R7)—, —N(R10)—, —S—, —SO—, —SO2—;
• —O—, —SO2NH—, —NHSO2—, —NR7CO—, —CONR7—, —N(R13)—, —SO2NR13—, —NR13CO—, or —CONR13—;
• each Link is, independently, —O—, —(CH2)n—, —O(CH2)m—, —NR13—C(═O)—NR13—, —NR13—C(═O)—(CH2)m—, —C(═O)NR13—(CH2)m−, —(CH2)n—(Z)g—(CH2)n—, —S—, —SO—, —SO2—, —SO2NR7—, —SO2NR10—, or -Het-;
• each CAP is, independently
• with the proviso that when any —CHO8— or —CH2OR8 groups are located 1,2- or 1,3- with respect to each other, the R8 groups may, optionally, be taken together to form a cyclic mono- or di-substituted 1,3-dioxane or 1,3-dioxolane;
• or racemates, enantiomers, diastereomers, tautomers, polymorphs, pseudopolymorphs or pharmaceutically acceptable salts thereof.