Novel prodrugs

A compound of formula-I, or a pharmaceutically acceptable salt thereof:

• wherein the groups R, R′, R″ and R′″ are independently selected from hydrogen, linear alkyl, branched alkyl, cyclic alkyl, alkylaryl, aralkyl, aryl, or heterocyclic ring;
• wherein the alkyl group is independently saturated or unsaturated, and is independently optionally substituted with 1 to 5 groups selected from hydroxy, cyano, oxo, carboxylic acid, phosphoric acid, sulfonic acid, alkyl sulfonate, aryl sulfonate, aralkyl sulfonate, alkylaryl sulfonate, phosphoric acid, alkyl phosphonate, aryl phosphonate, aralkyl phosphonate, alkyl aryl phosphonate, CONR12R13 wherein R12 and R13 are independently selected from hydrogen, alkyl, or aryl;
• wherein the aryl group is unsubstituted or substituted with one or more alkyl;
• COORz, wherein Rz is selected from hydrogen, alkyl, aryl, alkylaryl, aralkyl, a cyclic ring, or a heterocyclic ring;
• wherein each aryl and heterocyclic ring is independently optionally substituted with 1 to 5 groups selected from alkyl, alkoxy, halo, perhaloalkyl, perhaloalkoxy, haloalkoxy, hydroxy, oxo, cyano, carboxy, acyl, —NRPRQ, wherein RP and RQ are independently selected from hydrogen, alkyl, arylalkyl, alkylaryl, cyclic or heterocyclic ring, and —CONRMRN, wherein RM and RN are each independently selected from hydrogen, alkyl, or aryl;
• wherein each aryl of RM and RN is optionally substituted with alkyl;
• or any two of R, R′, R″ or R′″ are joined together to form a cyclic moiety which is optionally substituted with alkyl, perhaloalkyl, alkoxy, halogen, amino, alkylamino, dialkylamino, cyano, carboxy, alkoxycarbonyl, alkanoyl or a group L, wherein L is a compound of formula-P:
• wherein m is 0 or 1;
• RE, RF and RG are selected from one of the following groups:
• i) RF represents a C1 to C3 alkoxy group, one of the groups RE and RG represents a C1 to C3 alkoxy group and the other represents a hydrogen atom and a C1 to C3 alkyl radical;
• or
• ii) RE and RG represents hydrogen or methyl;
• RF represents a group of the formula OCH2RI, wherein RI represents a fluorinated alkyl radical;
• or
• iii) RE and RG are independently represent hydrogen, methyl, methoxy, ethoxy, methoxyethoxy or ethoxyethoxy;
• and RF is selected from methoxy, ethoxy, methoxyethoxy or ethoxyethoxy;
• or
• iv) RG is hydrogen, RE represents methyl, and RF represents methoxy substituted by —O-n-propyl;
• Z is an atom selected from N, O or S;
• X is an atom selected from O or S;
• A is selected from hydrogen, C1 to C10 linear alkyl, C1 to C10 linear branched alkyl, C3 to C7 cyclic alkyl, aryl or heterocyclic ring;
• wherein the alkyl group is completely saturated or contains unsaturation, and is either unsubstituted or substituted with 1 to 5 groups selected from hydroxy, halogen, cyano, carboxy, and acyl, wherein the aryl and the heterocyclic ring are each independently unsubstituted or substituted with 1 to 5 groups selected from alkyl, alkoxy, halo, perhaloalkyl, perhaloalkoxy, haloalkoxy, hydroxy, cyano, amino, monoalkylamino and dialkylamino groups;
• B is selected from hydrogen, cyano, C1 to C10 alkyl, a group of the formula —COORa, wherein Ra is selected from hydrogen, C1-10alkyl, aryl or heteroaryl moiety;
• or a group of the formula —CONRxRy, wherein Rx and Ry are independently selected from hydrogen, C1 to C7 linear alkyl, C1 to C7 branched alkyl, C3 to C7 cyclic alkyl, aryl or heterocyclic ring, wherein the alkyl group is completely saturated or contains unsaturation and is unsubstituted or substituted with 1 to 5 groups selected from hydroxy, halogen, cyano, carboxy, and acyl;
• or B is a group of formula-II:
• wherein R, R′, R″, R′″, Z have the meanings as defined above;
• a is selected from 0 or 1;
• b is selected from 0 or 1;
• with a proviso that,
• i) when a is 0, b is 0;
• R′ and R″ are absent and R is directly attached to Z;
• ii) when Z is an atom selected from O or S;
• R′″ is absent;
• iii) the compound of formula-I is converted to a compound of formula-III:
• wherein R, R′, R″, R′″, a, b and Z are as defined above;
• iv) the compound of formula-III is a biologically active molecule or is a diagnostic agent.