Phosphorus-containing rucaparib as PARP inhibitor

Abstract

A novel class of phosphorus-containing Rucaparib analogues were synthesized and evaluated as poly(ADP-ribose) polymerase (PARP) inhibitors. Two distinct series were designed: one incorporating a spacer and the other without a spacer. Pharmacokinetic evaluation of representative compounds demonstrated favorable oral bioavailability and improved metabolic stability relative to Rucaparib. Oral administration of compound 9 (20 mg / kg, twice weekly) resulted in significant tumor growth inhibition (71%) compared to vehicle control and showed superior efficacy over Rucaparib (100 mg / kg, 52% inhibition). Importantly, compound 9 exhibited no mortality or significant body weight loss, while Rucaparib-treated animals displayed slight weight reduction and mortality in the final week of treatment. Collectively, these results highlight phosphorus-containing Rucaparib analogues as a promising new class of PARP inhibitors with favorable pharmacological properties and therapeutic potential for the treatment of BRCA-mutant and homologous recombination–deficient cancers, particularly breast and ovarian malignancies.

Description

[0001] PHOSPHORUS-CONTAINING RUCAPARIB AS PARP INHIBITOR

[0002] FIELD OF THE INVENTION

[0003] The present invention provides phosphorus-containing rucaparib as parp inhibitor used in cancer treatment. These compounds are modified to include phosphorus-containing groups, which are designed to enhance their effectiveness and address specific challenges in current therapies.

[0004] BACKGROUND OF THE INVENTION

[0005] Poly (ADP-ribose) polymerase (PARP) inhibitors represent a crucial advancement in cancer therapeutics. These inhibitors work by targeting PARP enzymes, particularly PARP-1 and PARP-2, which are essential for DNA repair. Inhibiting these enzymes leads to the accumulation of DNA damage in cancer cells, eventually causing cell death. This mechanism is particularly beneficial in cancers such as ovarian cancer, especially in patients with BRCA1 or BRCA2 mutations, where PARP inhibitors like Rucaparib have shown promise in improving patient outcomes and extending survival.

[0006] Despite its therapeutic potential, Rucaparib faces significant challenges with selectivity. While its primary targets are PARP-1 and PARP-2, Rucaparib also interacts with other PARP isoforms, leading to off-target effects that disrupt essential cellular processes. These unintended interactions can cause side effects such as bone marrow suppression, gastrointestinal disturbances, and fatigue, which diminish the quality of life for patients. Moreover, this lack of selectivity complicates defining an optimal therapeutic window — the dosage range where the drug is both effective and safe. Rucaparib's non-selective nature makes it difficult to balance therapeutic efficacy with patient safety, limiting its clinical utility.

[0007] In response to these challenges, research efforts have focused on improving the selectivity of PARP inhibitors like Rucaparib to minimize off-target effects and enhance overall safety and efficacy. This research is critical for refining the clinical potential of PARP inhibitors.

[0008] OBJECTIVES OF THE INVENTION

[0009] The main objectives of the present invention is to provide a phosphorus-containing rucaparib having Formula I for PARP-l / PARP-2 Inhibition; Formula I

[0010] R is:

[0011] Hydrogen, Fluorine; an optionally Substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl group (e.g., unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally substituted amino and ether groups (such as O-aryl)); or -C(O)-R.

[0012] And where:

[0013] RI:R2 is: OMe, OEt, O-zPr, O-Cyp, O-4-C1 butyl and RI:R2 is OEt, OPh and Ri:R2is NHR': OMe, OEt (R'= Me, Et); and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl group (e.g., unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, amino, and alkyl and aryl groups unsubstituted or Substituted with one or more substituents selected from halo, hydroxy, nitro, and amino or heteroaryl group (e.g., unsubstituted or substituted with one or more substituents selected from alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, amino, and alkyl and aryl groups unsubstituted or Substituted with one or more substituents selected from halogen, hydroxy, nitro, and optionally substituted amino groups).

[0014] Another objective of this invention is the development of a novel synthesis process: To establish a detailed and efficient process for synthesizing compounds of Formula I that are phosphorous-derivatized with various functional groups.

[0015] Another objective of this invention is to develop a method for synthesizing the phosphorus- containing compounds, including:

[0016] • A multistep synthetic protocol for spacer-containing compounds.

[0017] • A shorter and more efficient synthesis for non-spacer compounds.

[0018] Another objective of this invention is Afunctional HRD assay to evaluate the capability of cancer cells to repair DNA damage through the homologous recombination repair (HRR) pathway. In the context of PARP inhibitors, this assay is crucial because cancer cells with HRD — such as those with BRCA1 or BRCA2 mutations — are more sensitive to PARP inhibition. PARP inhibitors block the repair of single-strand DNA breaks, leading to doublestrand breaks that HRR-deficient cells cannot effectively repair, resulting in cell death. The HRD assay helps identify patients whose tumors have this deficiency, making them more likely to respond to PARP inhibitor therapy.

[0019] Another objective of the present invention is to validate the effectiveness of the synthesized phosphorus-containing inhibitors in inhibiting poly (ADP -ribose) polymerases (PARPs) through Cell free PARPi (PARP 1) screening and Cell Based Studies. Yet another objective of the present invention is to evaluate and confirm the efficacy of the phosphorus-containing compounds in inhibiting poly(ADP-ribosyl)ation (PARylation), utilizing immunocytochemistry and immunoblotting analyses as analytical methods for assessment.

[0020] Yet another objective of the present invention is to evaluate the capability of cancer cells to repair DNA damage through the homologous recombination repair (HRR) pathway.

[0021] Yet another objective of the present invention is to demonstrate the use of the phosphorus- containing compounds for trapping the PARP enzyme, as validated through immunoblotting analyses and fluorescence microscopy, wherein cells are stained for PAR (red) and DAPI (blue) to visualize enzyme interaction and localization.

[0022] Another objective of this invention is to provide novel rucaparib analogues with improved pharmacokinetic characteristics, including rapid systemic exposure, moderate distribution, and optimized clearance, thereby enabling sustained therapeutic efficacy in the treatment of cancers.

[0023] Another objective of the present invention is to provide a novel compound (Example 9) with potent anti-tumor activity that demonstrates superior efficacy and safety compared to standard PARP inhibitor therapy (Rucaparib) in OVCAR-8 xenograft models.

[0024] SUMMARY OF THE INVENTION

[0025] Accordingly, the present invention provides a phosphorus-containing rucaparib of formula I for PARP- 1 / PARP -2 inhibition;

[0026] Formula I wherein, R is selected from the group consisting of hydrogen, fluorine, and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, unsubstituted or substituted aryl, or heteroaryl group; wherein the substituted aryl, or heteroaryl group is selected from the group consisting of one or more halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally Substituted amino and ether groups; wherein, R1 and R2 are independently selected from the consisting of OMe, OEt, O- / Pr, O-Cyp, O-- / -C1 butyl, OPh, NHR’ and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, unsubstituted or substituted aryl, or heteroaryl group; wherein the substituted aryl, or heteroaryl group is selected from the group consisting of one or more halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally substituted amino groups; wherein R' is selected from Me, or Et; wherein spacer in formula I may be absent or present; wherein the spacer is selected from the group consisting of phenyl, fluorophenyl alkyl, fluorophenyl substituted alkyl, benzyl, substituted benzyl, thiophenyl alkyl, or furyl alkyl.

[0027] In one of the embodiment of the present invention discloses the compounds of the Formula I selected from:

[0028] (i) Dimethyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5-yl)phosphonate (compound 1);

[0029] (ii) Diisopropyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 2);

[0030] (iii) Dicyclopentyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 3);

[0031] (iv) Diethyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5-yl)phosphonate (compound 4);

[0032] (v) Bis(4-chlorobutyl) (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 5);

[0033] (vi) Ethyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)(phenyl)phosphinate (compound 6);

[0034] (vii) Dimethyl ((butylamino)(4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol- 5-yl)phenyl)methyl)phosphonate (compound 7);

[0035] (viii) Ethyl (8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)(phenyl)phosphinate (compound 8);

[0036] (ix) Dimethyl (8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 9);

[0037] (x) Dimethyl (hydroxy(3-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phenyl)methyl)phosphonate (compound 10);

[0038] (xi) Dimethyl (hydroxy(4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phenyl)methyl)phosphonate (compound 11); (xii) Dimethyl ((3-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phenyl)(hydroxy)methyl)phosphonate (compound 12);

[0039] (xiii) Diethyl ((3-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phenyl)(hydroxy)methyl)phosphonate (compound 13);

[0040] (xiv) Dimethyl (3-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 14);

[0041] (xv) Dimethyl (4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 15);

[0042] (xvi) Dimethyl (3-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 16);

[0043] (xvii) Dimethyl (2-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 17);

[0044] (xviii) Dimethyl (2-fluoro-3-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 18);

[0045] (xix) Dimethyl (3-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 19);

[0046] (xx) Dimethyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 20);

[0047] (xxi) Dimethyl (2-fluoro-4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd]indol-5-yl)benzyl)phosphonate (compound 21);

[0048] (xxii) Dimethyl (3-fluoro-4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 22);

[0049] (xxiii) Dimethyl ((5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)thiophen-2-yl)methyl)phosphonate (compound 23);

[0050] (xxiv) Dimethyl ((5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5-yl)furan- 2-yl)methyl)phosphonate (compound 24);

[0051] (xxv) Dimethyl ((5-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)furan-2-yl)methyl)phosphonate (compound 25);

[0052] (xxvi) Dimethyl (2-fluoro-3-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd]indol-5-yl)benzyl)phosphonate (compound 26);

[0053] (xxvii) Diethyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 27);

[0054] (xxviii) Dibenzyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 28); (xxix) Ethyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)(phenyl)phosphinate (compound 29);

[0055] (xxx) Diethyl (4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 30);

[0056] (xxxi) 5-(dimethylphosphoryl)-8-fluoro-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd]indol-l-one (compound 31);

[0057] (xxxii) 5-(4-((dimethylphosphoryl)methyl)phenyl)-8-fluoro-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-l-one (compound 32)

[0058] In another embodiment of the present invention discloses a method for synthesizing the phosphorus-containing compound of Formula I, wherein the method comprises the steps of:

[0059] (a) coupling 2,3,4,6-tetrahydro-U / -azepino[5,4,3-cd] indol-l-one with dialkyl / alkylarylphosphite and silver acetate in dry acetonitrile under inert atmosphere at a temperature range of 100X2 for 8-12 hours to obtain a phosphonate derivate;

[0060] (b) cooling the phosphonate derivative as obtained in step (a) followed by extracting and purifying to obtain the compound of Formula I.

[0061] In yet another embodiment of the present invention discloses a method for synthesizing the phosphorus-containing compound of Formula I, wherein the method comprises the steps of:

[0062] (a) coupling (l-oxo-2,3,4,6-tetrahydro-U / -azepino[5,4,3-cd] indol-5-yl) benzaldehyde and dialkyl phosphite with copper iodide and potassium carbonate in dry dimethoxy ethane under inert atmosphere to obtain a phosphonate derivate;

[0063] (b) cooling the phosphonate derivative as obtained in step (a) followed by extracting and purifying to obtain the compound of Formula I.

[0064] In other embodiment of the present invention discloses a method for treating cancer comprising administering therapeutically effective amount of of phosphorus-containing compound of Formula I.

[0065] In yet other embodiment of the present invention discloses the method wherein the cancer is breast cancer or ovarian cancer.

[0066] In one of the embodiment of the present invention discloses the phosphorus-containing compound, for use in the inhibition of poly(ADP-ribosyl)ation (PARylation) (PARP) enzyme activity.

[0067] In another embodiment of the present invention discloses the compound, wherein the compound inhibiting PARP enzyme activity are selected from the group consisting of:

[0068] (i) Ethyl (8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5 yl)(phenyl)phosphinate (compound 8); (ii) Dimethyl (8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 9);

[0069] (iii) Dimethyl (3-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 16);

[0070] (iv) Dimethyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 20);

[0071] (v) 5-(dimethylphosphoryl)-8-fluoro-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-l-one (compound 31);

[0072] (vi) 5-(4-((dimethylphosphoryl)methyl)phenyl)-8-fluoro-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-l-one (compound 32).

[0073] In another embodiment, the present invention provides novel PARP1 inhibitors, particularly Example 9 and Example 20 with potent enzymatic and cellular activity comparable to Rucaparib. These compounds were screened using a cell-free ELISA-based colorimetric assay, wherein both Example 9 and example 20 demonstrated significant PARP1 inhibition, confirming their potential as effective therapeutic agents.

[0074] Still another embodiment of the present invention provides Example 9 and example 20 as potent PARP1 inhibitors with cytotoxic effects comparable to Rucaparib. The cytotoxicity of these compounds was evaluated in the UWB1.289-BRCA1 cell line using an MTT assay, wherein ICso values demonstrated equivalent cytotoxic activity to Rucaparib. This result indicates that Example 9 and example 20 possess significant therapeutic potential as alternative agents for the treatment of BRC Al -deficient cancers. This embodiment further encompasses pharmaceutical compositions and treatment methods utilizing Example 9 and example 20 as monotherapy or in combination with other therapeutic agents.

[0075] Yet another embodiment of the present invention is the superior dose-dependent PARP1 trapping inhibition exhibited by example 20, which demonstrates significantly higher potency compared to Rucaparib. Notably, example 20 effectively inhibits PARP1 trapping even at sub-micromolar concentrations (0.1 pM), where Rucaparib shows limited activity.

[0076] Yet another embodiment of the present invention provides example 9 and example 20 as PARP1 inhibitors with PARylation inhibition confirmed via immunocytochemistry and immunoblotting, showing efficacy comparable to Rucaparib. Additionally, example 20 demonstrated equivalent PARP1 trapping efficiency upon hydrogen peroxide-induced activation, as confirmed by fluorescence microscopy. These findings support their therapeutic potential in BRCA-deficient cancers and other PARP1 -associated diseases.

[0077] BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1. Interactions of Rucaparib with PARP Protein.

[0079] Figure 2. Graphical representation of PARP 1 inhibitory activity of Phosphorus Containing Rucaparib and its analogues. Figure 3. PARylation inhibition activity of compound 9. PARylation inhibition activity was assessed using immunocytochemistry on Ovcar8 cells treated with Rucaparib (IpM) and Test compound 9 for 24 hours. The cells were stained for PAR (red) and DAPI (blue), and the images were merged under a fluorescent microscope. H2O2 at lOmM / L was used as a positive control (I). Additionally, immunoblotting analysis was performed to evaluate the PARylation inhibition activity of compound 9.

[0080] Figure 4. PARylation inhibition activity of compound 20. PARylation Inhibition Activity: Immunocytochemical analysis of Ovcar8 cells treated with Rucaparib (IpM) and Test compound 20 for 24 hours. Cells were stained for PAR (red) and DAPI (blue), and the images were merged using a fluorescence microscope. Hydrogen peroxide (H2O2) at a concentration of lOmM / L was used as a positive control (I).

[0081] Figure 5. PARP1 Trapping Assay for compound-20. PARP1 trapping activity: Immunocytochemistry of Ovcar8 cells treated with Rucaparib (IpM) and Test compound 20 (Example-20) for 24 hours, stained for PARP1 (red) and DAPI (blue). Images were merged using fluorescence microscopy, with H2O2 (lOmM / L) as a positive control (I).

[0082] Figure 6. Mean plasma concentration vs. time profde of compound 9 after intravenous administration at 5 mg / kg in BALB / c mice.

[0083] Figure 7. Mean plasma concentration vs. time profde of compound 20 after intravenous administration at 5 mg / kg in BALB / c mice.

[0084] DETAIL DESCRIPTION OF THE INVENTION

[0085] The present invention relates to the development of Rucaparib derivatives by incorporating phosphonate, phosphine oxides and phosphinate groups, inspired by earlier work (G. Nemeth et al., J. Med. Chem., 2014; 2002). These phosphorus-containing modifications were designed to investigate the biological behaviour and efficacy of Rucaparib against PARP-1 and PARP-2.

[0086] The synthesis of these novel compounds, followed by their evaluation in enzymatic assays, showed that the incorporation of phosphorus-based moieties enabled the compounds to effectively penetrate and inhibit PARP-1 / PARP-2.

[0087] Structurally, phosphorus-containing groups like phosphonamidates, phosphonates, and phosphinates closely resemble amides, sulphonamides, and sulfonyl derivatives, sharing similar shapes and electron densities (N. Meanwell, J. Med. Chem., 2011; W. J. Moree, Tetrahedron, 1993). Despite offering greater variability in substituents, these phosphorus- containing groups have been underutilized in medicinal chemistry. By leveraging their isosteric relationship with amides, we anticipate that these phosphorus-containing Rucaparib analogs will significantly advance the development of PARP-1 and PARP-2 inhibitors. A diverse array of these analogs has been carefully designed, based on the intricate interactions between Rucaparib and PARP proteins, as illustrated in Figure 1. This research opens exciting possibilities for developing PARP inhibitors with significantly advancement, having potential benefits for cancer treatment and beyond.

[0088] Although PARP is a well-established target for cancer therapy, evidence from in vivo models suggests additional potential benefits of PARP inhibitors. Overactivation of PARP- 1 due to oxidative stress and genomic damage results in excessive consumption of NAD+, which leads to increased intracellular Ca2+levels. This disruption impairs mitochondrial ATP production, causing energy failure and subsequent cell death.

[0089] Moreover, nuclear PARP-1 and mitochondrial PARP-1 (mtPARP-1) play contrasting roles in maintaining cellular integrity. Nuclear PARP-1 is crucial for activating and recruiting proteins involved in DNA repair, thereby supporting genomic stability. In contrast, mtPARP-1 inhibits the repair of mitochondrial DNA (mt DNA) damage, adversely affecting mitochondrial biogenesis and function. This dichotomy highlights the complex roles of PARP-1 in cellular processes and underscores the need to consider both nuclear and mitochondrial PARP activities in therapeutic strategies.

[0090] Aspects of the Invention

[0091] Incorporation of Rucaparib Analogs: The primary objective of this invention is to integrate newly developed Rucaparib analogs, which feature, phosphonate, phosphine oxides and phosphinate moieties, into the existing Rucaparib framework.

[0092] PARP-1 Role and Importance: PARP-1 (Poly (ADP -ribose) Polymerase 1) is a crucial enzyme involved in DNA repair. It detects DNA damage and adds poly (ADP-ribose) chains to itself and other proteins, facilitating the repair of single-strand breaks. PARP-1 plays a key role in maintaining genomic stability and is a target for cancer therapies, especially in cancers with defective DNA repair mechanisms.

[0093] Inhibition with Phosphorus-Containing Rucaparib: The invention demonstrates that Rucaparib analogs containing phosphorus moieties can inhibit new generation PARP-1 inhibitors.

[0094] Rucaparib Pharmacophore: The Rucaparib analogs featuring phosphorus moieties are designed within a ‘Rucaparib pharmacophore,’ indicating that these compounds maintain structural similarities to Rucaparib. This structural analogy highlights their potential relevance and utility in drug development, especially for enhancing PARP inhibition.

[0095] In order to further investigate and optimize these effects, we prepared the new generation PARP-1 inhibitor candidates (formula I) characterized by a variation of the spacer and linker.

[0096] In another aspect of the invention in the drug design, a spacer is a molecular component that separates different pharmacophore or functional groups within a drug molecule. It can be a flexible linker or a specific chemical structure that optimizes the spatial arrangement of these groups for optimal interaction with biological targets.

[0097] A linker in the context of drug design refers to a chemical moiety that connects two distinct pharmacophores or functional groups within a drug molecule. The linker is designed to provide flexibility and maintain the structural integrity of the drug, allowing it to interact effectively with its target.

[0098] Another aspect of this invention is that these inhibitors hold substantial promise across diverse applications, notably within the realm of diseases such as cancer, where PARP inhibition is a subject of active research.

[0099] PARP stands for Poly (ADP-ribose): Poly: Refers to the polymerization of multiple units. ADP -ribose: ADP (Adenosine Diphosphate) is a molecule that can form chains with ribose, a type of sugar. In the context of PARP, ADP-ribose units are linked together to create a polymer. Poly (ADP-ribose) Polymerase (PARP): Polymerase: This term is commonly associated with enzymes that facilitate the polymerization of molecules. In the case of PARP, it catalyzes the polymerization of ADP-ribose units.

[0100] The aim of this invention is to establish an isosteric relationship between amides and various phosphorus-containing compounds, encompassing phosphonates, phosphonamidates, and phosphinates. This pursuit involves creating analogs designed to efficaciously inhibit both PARP1 and PARP2 enzymes.

[0101] In another aspect of the invention is isosteric relationship which refers to the substitution of atoms or groups in a molecule with others that have similar size and shape but may differ in electronic properties. This replacement maintains the overall three-dimensional structure of the molecule while potentially improving its properties, such as bioavailability or pharmacological activity. Isosteric modifications are strategically used to optimize lead compounds during drug design.

[0102] In another aspect of the invention, phosphonamidate is a term derived from its structure, and its full form does not involve an acronym. It is a chemical moiety where a phosphonate group is attached to an amide nitrogen atom.

[0103] In another aspect of the invention Phosphonate is derived from the term "phosphonic acid," and its full form involves the replacement of the "-ic acid" with "-ate. "Phosphonates are chemical moieties containing a phosphorus atom bonded to three oxygen atoms and a carbon atom. They are often used in various applications, including as components in certain pesticides and pharmaceuticals.

[0104] BRCA1 : stands for Breast Cancer gene 1

[0105] BRCA2 : stands for Breast Cancer gene 2.

[0106] Both BRCA1 and BRCA2 are human genes that produce proteins involved in the regulation and repair of DNA.

[0107] In another aspect of this invention, PARP isoform is a family of enzymes that includes several isoforms. Isoforms are variations of a gene that can produce slightly different forms of a protein. In the case of PARP, different isoforms have specific roles in cellular processes, particularly in DNA repair and maintenance of genomic stability. Two well-known isoforms within the PARP family are PARP-1 and PARP-2. Apart from PARP-1 and PARP -2, there are additional isoforms within the PARP family, such as PARP-3, PARP-4, PARP-5a, PARP-5b, and so on.

[0108] Rucaparib Analogue: Rucaparib is a recognized drug that inhibits PARP enzymes involved in DNA repair. This inhibition is crucial in cancer treatment because certain tumors, especially those with defective DNA repair pathways like BRC A-mutant cancers, rely heavily on PARP for survival.

[0109] Phosphorus Modification: By adding phosphorus groups to the Rucaparib structure, the new analogues are designed to improve properties such as drug stability, specificity for PARP enzymes, and overall potency. These changes aim to make the drug more effective in targeting cancer cells.

[0110] Targeting PARP-1 and PARP-2: The new compounds specifically inhibit PARP-1 and PARP -2, which are key players in DNA repair mechanisms. Blocking these enzymes prevents the repair of damaged DNA in cancer cells, leading to cell death, particularly in tumors that are dependent on PARP activity.

[0111] In another aspect of the invention representative structure for PARP-l / PARP-2 Inhibition, Formula I;

[0112] Formula I wherein, R is selected from the group consisting of hydrogen, fluorine, and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, unsubstituted or substituted aryl, or heteroaryl group; wherein the substituted aryl, or heteroaryl group is selected from the group consisting of one or more halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally Substituted amino and ether groups; wherein, R1 and R2 are independently selected from the consisting of OMe, OEt, O- / Pr, O-Cyp, O-- / -C1 butyl, OPh, NHR’ and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, unsubstituted or substituted aryl, or heteroaryl group; wherein the substituted aryl, or heteroaryl group is selected from the group consisting of one or more halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally substituted amino groups; wherein R' is selected from Me, or Et; wherein spacer in formula I may be absent or present; wherein the spacer is selected from the group consisting of phenyl, fluorophenyl alkyl, fluorophenyl substituted alkyl, benzyl, substituted benzyl, thiophenyl alkyl, or furyl alkyl.

[0113] As used herein, the term “alkyl means a branched- or Straight-chained (linear) paraffinic hydrocarbon group (Saturated aliphatic group) having from 1 to 10 carbon atoms in its chain, which may be generally represented by the formula CH. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, n-pentyl, isopentyl, neopentyl, and hexyl, and the Simple aliphatic isomers thereof.

[0114] The term “carbocycle” refers to a saturated, partially Saturated, unsaturated, or aromatic, monocyclic or fused or non-fused polycyclic, ring Structure having only carbon ring atoms (no heteroatoms, i.e., non-carbon ring atoms). Exemplary carbocycles include cycloalkyl, aryl, and cycloalkyl aryl groups.

[0115] The term “heterocycle” refers to a saturated, partially Saturated, unsaturated, or aromatic, monocyclic or fused or non-fused polycyclic, ring structure having one or more heteroatoms selected from N, O, and S. Exemplary hetero cycles include heterocycloalkyl, hetero aryl, and heterocycloalkyl -heteroaryl groups .

[0116] A “cycloalkyl group' is intended to mean a non-aromatic monovalent, monocyclic or fused polycyclic, ring structure, heteroatoms). Exemplary cycloalkyls include cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cycloheptyl, adamantyl, phenanthrenyl, and like groups. A "heterocycloalkyl group' is intended to mean a nonaromatic monovalent, monocyclic or fused polycyclic, ring illustrative examples of heterocycloalkyl groups include pyrrollidinyl, tetrahydrofuryl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, aziridinyl, and like groups.

[0117] The term “aryf means an aromatic monocyclic or fused polycyclic ring exemplary aryl groups include phenyl, naphthyl, anthracenyl, and the like. A "heteroaryl group” is intended to mean an aromatic monovalent, monocyclic or fused polycyclic, ring structure. Illustrative examples of heteroaryl groups include pyrrolyl, thienyl, oxazolyl, pyrazolyl, thiazolyl, furyl, pyridinyl, pyrazinyl, triazolyl, tetrazolyl, indolyl, quinolinyl, quinoxalinyl, and the like. The term “optionally substituted” is intended to indicate that the Specified group is unsubstituted or substituted by one or more Suitable Substituents, unless the optional substituents are expressly specified, in which case the term indicates that the group is unsubstituted or Substituted with the Specified substituents. Unless indicated otherwise (e.g., by indicating that a specified group is unsubstituted), the various groups defined above may be generally unsubstituted or substituted (i.e., they are optionally Substituted) with one or more Suitable substituents. The term “Substituent” or "suitable Substituent” is intended to mean any substituent for a group that may be recognized or readily selected by the artisan, such as through routine testing, as being pharmaceutically Suitable. Illustrative examples of Suitable Substituents include hydroxy, halogen (F, Cl, I, or Br), Oxo, alkyl, acyl, Sulfonyl, mercapto, nitro, alkylthio, alkoxy, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, carboxy, amino (primary, Secondary, or tertiary), carbamoyl, aryloxy, heteroaryl oxy, arylthio, heteroaryl thio, and the like (e.g., as illustrated by the exemplary compounds described herein). Suitable substituents are seen from the exemplary compounds that follow. Preferred optional substituents for alkyl and aryl groups in the compounds of the invention include halogens and aryl groups. Especially preferred for Substituted alkyl groups are perfluoro- Substituted alkyls. Especially preferred optional substituents for aryl moieties include halogen, lower alkyl, -OH, -NO, -CN, -COH, O-lower alkyl, aryl, -O-aryl, aryl-lower alkyl, -COCH, -CONH2, -OCHCONH, -NH, -SONH, -OCHF, -CF, -OCF, and the like. Aryl moieties may also be optionally Substituted by two substituents forming a bridge, for example -O-(CH2)-O-.

[0118] In an aspect of the invention the Pharmacophore is a three-dimensional arrangement of chemical features within a molecule that is recognized at a receptor site and is responsible for a biological response. Essentially, it represents the spatial arrangement of atoms or functional groups critical for a molecule to interact with a specific biological target and elicit a desired pharmacological effect.

[0119] In an aspect of the invention PARP inhibitors are a class of drugs that block the activity of poly (ADP -ribose) polymerase (PARP) enzymes. These inhibitors have gained prominence in cancer treatment, particularly in cancers with defects in DNA repair mechanisms. By inhibiting PARP, these drugs prevent the repair of DNA damage, leading to further damage accumulation and cell death, especially in cancer cells with compromised DNA repair pathways.

[0120] This crucial validation process is instrumental in establishing the inhibitory properties of the synthesized compounds and ascertaining their efficacy in disrupting the catalytic activity of PARPs.

[0121] These objectives collectively represent a pioneering approach to the development of PARP inhibitors, centered on the strategic integration of phosphorus-containing moieties, elevated selectivity, and robust experimental assessments to substantiate their efficacy. The overall summary of these compounds having designations as series I and series II are shown above.

[0122] According to another aspect of the present invention there is direct phosphorylation of tricyclic indole, provided a compound for inhibiting the activity of PARP having compound A compound A wherein:

[0123] R is Hydrogen, Fluorine; an optionally alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl group wherein R is unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally Substituted amino and ether groups (such as O-aryl)); or -C(O)-R; and wherein the spacer is selected from phenyl, fluoro phenyl alkyl chain wherein spacer is either absent or present. and wherein:

[0124] Ri and R2 both are independently selected from OMe, OEt, O-zPr, O-Cyp, O-4-C1 butyl and OPh, NHR' (R'= Me, Et); and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl group (e.g., unsubstituted or Substituted with one or more substituents selected from halogen, hydroxy, amino, and alkyl and aryl groups unsubstituted or substituted with one or more substituents selected from halo, hydroxy, nitro, and amino or heteroaryl group (e.g., unsubstituted or Substituted with one or more Substituents selected from alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, amino, and alkyl and aryl groups unsubstituted or Substituted with one or more substituents selected from halogen, hydroxy, nitro, and optionally substituted amino groups).

[0125] According to another aspect of the present invention there is direct phosphorylation of tricyclic indole, provided a compound for inhibiting the activity of PARP having compound B Compound B wherein:

[0126] R is hydrogen, fluorine; an optionally alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl group wherein R is unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally Substituted amino and ether groups (such as O-aryl)); or -C(O)-R; and wherein:

[0127] Ri and R2 both are independently selected from OMe, OEt, O-zPr, O-Cyp, O-4-C1 butyl and OPh, NHR' (R'= Me, Et); and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl group (e.g., unsubstituted or Substituted with one or more substituents selected from halogen, hydroxy, amino, and alkyl and aryl groups unsubstituted or substituted with one or more substituents selected from halo, hydroxy, nitro, and amino or heteroaryl group (e.g., unsubstituted or Substituted with one or more Substituents selected from alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, amino, and alkyl and aryl groups unsubstituted or Substituted with one or more substituents selected from halogen, hydroxy, nitro, and optionally substituted amino groups).

[0128] According to another aspect of the present invention there is Hydrophosphonylation and alkyl / aryl / alpha amino phosphonates of tricyclic indole, provided compounds for inhibiting the activity of PARP having compound C:

[0129] Compound C wherein:

[0130] R is: hydrogen; and where R’” is: hydrogen, hydroxy, keto, butylamine, 4-fluoroanniline; an optionally Substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl group (e.g., unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally Substituted amino and ether groups; and wherein

[0131] R” is: Hydrogen and Halogens;

[0132] An optionally Substituted alkyl, alkenyl, alkynyl, heteroaryl group (e.g., unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups un substituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally Substituted amino groups.

[0133] This invention asserts the introduction of original products, distinguishing not only in terms of their synthetic methods but also in their potential biological activities. The novelty inherent in these compounds holds considerable significance for patent claims.

[0134] SYNTHETIC METHODS

[0135] The compounds and processes described in the present invention will be further clarified with reference to the following synthetic schemes, which illustrate the methods for preparing these compounds. These schemes are provided for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art will recognize that various changes and modifications to the disclosed embodiments are possible. Such modifications may include alterations to chemical structures, substituents, derivatives, and methods of the invention, and can be made without departing from the core principles and scope of the appended claims.

[0136] Compound 1-6 and compound 9 was prepared as shown below according to the procedure of Demerson et al., J. Med Chem. (1974), 17: 1140, starting from methyl indole-4-carboxylate.

[0137] Synthesis of intermediate 2

[0138] Compound 1 (170.9 mol) was added to aqueous hydrochloric acid (1 M, 4.45 L / kg) and heated at 70-75 °C for 1 h. Water (5 L / kg) was then added, and the reaction was cooled to 20 °C and stirred for 12 h. Dichloromethane (10 L / kg) was added to the reaction, and the phases were separated. The aqueous layer was extracted with a further portion of dichloromethane (2.5 L / kg), and the layers were separated. The dichloromethane layers were then combined. The solvent was removed by distillation and replaced with toluene to give a final solvent level of 5 L / kg, and the resulting slurry was stirred at 20 °C for 8 h. The product was filtered under pressure, washed with toluene (45 L, 1 L / kg), and dried under vacuum at 50 °C to give 15 as a white solid (107 mol, 62% yield); mp (toluene) 116°C.

[0139] Synthesis of intermediate 4

[0140] To a solution of 2 (106 mol) and 3 (81.3 mol) in dichloromethane (10 L / kg) was added tri ethylsilane (325.2 mol, 4 equiv). A solution of trifluoroacetic acid (2 equiv.) in dichloromethane (2 L / kg) was then added over 30 min, maintaining the temperature below 30 °C. The reaction was then stirred for 28 h at 20 °C, and the resultant slurry was filtered under pressure. The filter cake was washed with di chloromethane (0.5 L / kg) and then dried under vacuum at 40 °C to give 16 as a pale-yellow solid (3.51 mol, 43% yield); mp (dichloromethane) 216 °C.

[0141] Synthesis of intermediate 6

[0142] Compound 4 (35.1 mol) was added to methylamine (40% solution in water, 7 L / kg), and the slurry was stirred at 20 °C for 16 h. Water (7 L / kg) was charged to the reaction, and the mixture was stirred for 1 h. The solid was then filtered under pressure and washed with water (2 L / kg). The solid was then reslurried in water (10 L / kg), filtered, washed with water, and dried under vacuum at 70 °C to give the product (6) as a tan-brown solid (31.4 mol, 89%yield); mp (water) 187 °C;

[0143] Synthesis of intermediate 7 Dichloromethane (15 L / kg) and THF (15 L / kg) were mixed together, and 6 (31.4 mol) was added. After stirring for 20 min, the slurry was cooled to 0-5 °C. Pyridinium tribromide (34.5 mol, 1.1 equiv) was then added, and the solution was stirred at 0-5 °C for 1 h. Water (10 L / kg) was then charged, and the organic solvents were removed by distillation. THF was added (10 L / kg), and the reaction mixture was added slowly to a solution of saturated aqueous sodium carbonate (75 L / kg). The resultant slurry was then stirred overnight at 20 °C. The product was filtered under pressure, washed with water (10 L / kg), and dried under vacuum at 55 °C to give 9 as a beige solid (26.2 mol, 83% yield); mp (water) 215 °C;

[0144] Synthesis of intermediate 9 , q.2 3ii) Methanol reslurry 9

[0145] ’ 92%

[0146] 1 , 1 - B i s -(diphenylphosphino)ferrocene palladium(II) dichloride di chloromethane (0.66 mol, 2.5 mol %) was added to a mixture of degassed dimethylacetamide (16 L / kg) and 7 (26.2 mol) and stirred for 1 h at 20 °C. The mixture was then heated to 95 °C and stirred for 1 h. In a separate vessel, 4 -formylbenzene boronic acid 8 (31.4 mol, 1.2 equiv) was dissolved in dimethylacetamide (4 L / kg) before being added to an aqueous solution of sodium carbonate (2 equiv) and was then stirred for 3 h at 20 °C. The boronic acid solution was then added to the catalyst and substrate solution whilst maintaining the temperature above 90 °C. After stirring for 2 h the reaction was cooled to room temperature and stirred for 4 h. Water (40 L / kg) was added, and the slurry was stirred for 1 h before the solid was filtered under pressure and washed with water (10 L / kg) to give crude 9. The product 9 was further purified by resuspending in methanol (8 L / kg) and stirring at 60 °C for 1 h. The slurry was cooled to 20 °C and stirred for 1 h. The product was then filtered, washed with methanol (2 L / kg), and dried under vacuum to give 11 as an olive-green solid (24.1 mol, 92% yield); mp (methanol) 219 °C.

[0147] General procedure for Phosphorylation of Tricyclic Indoles (Compound 1-6, 8, 9):

[0148] 10 Example 1-6, 8, 9 (65-85%) To a 50 ml two neck round bottom flask were added 2,3,4,6-tetrahydro-l / / -azepino[5,4,3-cd] indol-l-one (6) (l.Ommol, lequiv.) and dialkyl / alkyl-arylphosphite (10) (2.0 mmol, 2.0 equiv.) and silver acetate (10 mol%) in dry acetonitrile ACN (15 ml) strictly under argon atmosphere. The reaction mixture was refluxed to 100° C in an oil bath for 8-12 hours to afford the corresponding phosphonate derivatives (example 1-8). After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSC , concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a viscous liquid.

[0149] General procedure for a-Amino Phosphonation of compound (compound 7):

[0150] To a 100 ml one neck round bottom flask were added 4-(l-oxo-2,3,4,6-tetrahydro-l / 7- azepino[5,4,3-cd] indol-5-yl) benzaldehyde (9) (l.Ommol, 1 equiv.) and dialkyl / alkyl- arylphosphite (10) (2.0 mmol, 2.0 equiv.) and Amine 11 (1.2 mmol, 1.2 equiv.) in toluene (25 ml) in open atmosphere. The reaction mixture was heated to 100 °C in an oil bath for 12 hours to afford the corresponding diethyl ((alkyl amino)(4-(l -oxo-2, 3,4, 6-tetrahydro-l / / - azepino[5,4,3-cd] indol-5-yl) phenyl) methyl) phosphonate derivatives (Example 7). After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSCU, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a brown solid.

[0151] General procedure for Hydrophosphonylation of compound 9 (Compound 10-13):

[0152] To a 50 ml Schlenk tube were added 4-(l-oxo-2,3,4,6-tetrahydro-l / / -azepino[5,4,3-cd] indol- 5-yl) benzaldehyde (9) (1.0 mmol, lequiv.) and dialkyl phosphite (10) (2.0 mmol, 2.0 equiv.) and potassium Fluoride (5 mmol) in DCM and Methanol in 1 : 1 ratio (15ml). The reaction mixture was stirred at room temperature for 30 minutes to one hour to afford the corresponding phosphonate derivatives (example 10-13). After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSCU, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) to afford the desired product.

[0153] General procedure for synthesis of Alkylphosphonates (Compound 14-31, 32):

[0154] To a 50 ml Schlenk tube were added 4-(l-oxo-2,3,4,6-tetrahydro-U / -azepino[5,4,3-cd] indol- 5-yl) benzaldehyde (9) (l.Ommol, lequiv.) and dialkyl phosphite (10) (2.0 mmol, 2.0 equiv.), Copper iodide (30 mOl %) and potassium Carbonate (2 mmol) in dry dimethoxy ethane (DME) strictly under argon atmosphere. The reaction mixture was stirred at 60 °C for four hours to afford the corresponding phosphonate derivatives (example 14-30, 32). After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSCU, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) to give the desired product.

[0155] General procedure for synthesis of Compound 31

[0156] Me2POH (1.1 ) Pd2(dba)3(3 mol%) Xanthphos (3 mol%)

[0157] K3PO4(1.1 eq.) dioxane, 100 °C 12h,

[0158] 78%

[0159] A solution of Pd2(dba)3 (0.03 equiv.) and Xantphos (0.06 equiv.) in dioxane (40 mL) was stirred at room temperature for 10 min. 5-bromo-8-fluoro-2,3,4,6-tetrahydro-lJT- azepino[5,4,3-cd]indol-l-one 6 (1.0 equiv.), K3PO4 (1.1 equiv.), and Me2POH (1.1 equiv.) were added to the mixture. The mixture was heated in an oil bath at 100 °C for 12 h under nitrogen atmosphere. The conversion was followed by TLC. The mixture was cooled to room temperature. The precipitate was filtered, and the resulting filtrate was concentrated under reduced pressure. The residue was worked up by dissolving in EtOAc and filtered through a short pad of SiCh. The crude compound was purified by column chromatography (DCM- MeOH 10: 1-10:3). Yield: 78%, white solid. Table 1: The following compounds were prepared employing similar protocol as described above.

[0160] High throughput screening against PARP1 : To evaluate the PARP-1 inhibitory activity compounds, an ELISA based colorimetric assay kit (R&D Systems (Cat# 4677-096-K-104)) was used. It detects biotinylated poly (ADP-ribose) deposited by PARP-1 onto immobilized histones. The addition of Strep-HRP (Biotin-binding protein) and a colorimetric HRP substrate yields relative absorbance that correlates with PARP-1 activity.

[0161] Methodology: To initiate the ribosylation reaction, histones were rehydrated using IX PARP buffer at room temperature. Following rehydration, test compounds were introduced along with PARP enzyme and activated DNAinto the prepared wells. Detection of the reaction employed an HRP substrate, subsequently visualized using TACS -sapphire. Absorbance readings were taken at 450nm. Negative control consisted of PARP buffer alone, while positive control included activated DNA with PARP1 enzyme.

[0162] Results:

[0163] Cell-based screening: The cell viability was determined by standard MTT dye uptake method. Briefly, UWB 1.289 (ATCC) (3^ 103 cells / well) were plated into a 96 well tissue culture plate and treated with different concentration of test compounds in triplicate so that the final concentration of DMSO solvent was 0.2%. After 72h incubation, media and treatment was changed and cells were incubated for further 72 hrs. Same day when incubation period was completed MTT solution was added and cells were cultured for another 4 h at 37 °C in 5.0% CO2 incubator. The amount of coloured formazan derivative was determined by measuring optical density (OD) using TEC AN microplate reader (Infinite M200 PRO) at 570 nm.

[0164] Table 2: Cell based screening of Rucaparib and its analogues for their cytotoxic potential in BRCA1 null cells P_W0 100747

[0165] Cell-Based Studies of Example 9

[0166] • In one embodiment, the inhibitory activity of Example 9 on poly (ADP-ribose) polymerase (PARP) was evaluated in Ovcar8 cell lines by immunocytochemistry. Poly (ADP-ribose) (PAR) was visualized using fluorescence microscopy, wherein red fluorescence corresponded to PAR staining and was indicative of the extent of PARylation, blue fluorescence (DAPI) marked nuclear staining, and merged images demonstrated the spatial overlap between PAR staining and nuclear localization. Ovcar8 cells treated with Example 9 at a concentration of 1 pM for 24 hours exhibited minimal red fluorescence, indicating a substantial reduction in PARylation. The merged images revealed pronounced nuclear staining with negligible PAR signal, thereby demonstrating that Example 9 produced marked PARP inhibition under the tested conditions. In comparison, Ovcar8 cells treated with Rucaparib at 1 pM for 24 hours exhibited very faint red fluorescence, indicating robust PARP inhibition. The merged images confirmed near-complete abrogation of PAR signals, with Rucaparib serving as a reference control for high-efficacy PARP inhibition. Cells exposed to hydrogen peroxide (H2O2) at 10 mM / L as a positive control displayed intense red fluorescence, indicative of elevated PARylation, and the merged images revealed significant overlap between PAR and nuclear staining. This confirmed that oxidative stress induced by H2O2 activated PARP enzymes and validated the responsiveness of the assay system.

[0167] • The inhibitory potential of Example 9 was further assessed by immunoblotting. In the upper blot, corresponding to PAR detection, the untreated control exhibited a low basal PAR signal, while the EECL-treated sample displayed a strong PAR band, consistent with oxidative stress-mediated PARylation. Samples treated with Rucaparib showed a faint PAR band, confirming potent inhibition, whereas samples treated with Example 9 (IIIM-DCF-265F) displayed a very faint PAR band comparable in intensity to Rucaparib. The lower blot, corresponding to the protein loading control (e.g., GAPDH or P-actin), exhibited uniform band intensity across all samples, confirming consistent protein loading.

[0168] • The foregoing results demonstrate that Example 9 exhibits potent PARP inhibitory activity in Ovcar8 cells, comparable to Rucaparib, as evidenced by both immunocytochemistry and immunoblotting analyses. The H2O2 positive control induced significant PARylation, thereby validating the assay conditions. Accordingly, Example 9 constitutes a promising PARP inhibitor candidate for further development, with potential applicability in overcoming tumor resistance and mitigating toxicity.

[0169] PARylation inhibition assay for Example-20

[0170] PARylation, also referred to as poly(ADP-ribosyl)ation, is a post-translational protein modification catalyzed by the enzyme poly(ADP-ribose) polymerase (PARP). This enzymatic process involves the covalent addition of poly(ADP -ribose) (PAR) chains to target proteins and plays a critical role in the cellular response to DNA damage and other stress signals. PARylation facilitates DNA repair by recruiting repair-associated proteins to sites of DNA damage. Inhibition of PARylation has emerged as a therapeutic strategy in oncology, particularly for cancers deficient in homologous recombination repair, such as BRCA- mutated tumors. In such cancers, inhibition of PARP activity leads to synthetic lethality by preventing efficient DNA repair, thereby inducing tumor cell death.

[0171] In the present study, the effect of Example 20 on PARylation levels was evaluated in a cellbased assay. The fluorescence microscopy data were organized into three panels. In the top row, red fluorescence corresponded to PAR staining, reflecting the level of PARylation in the cells. The middle row, consisting of blue fluorescence, represented DAPI staining, which binds to DNA and marks the nuclei, serving as a counterstain to normalize for cell number and nuclear integrity. The DAPI staining remained consistent across all treatment groups, indicating that neither the number of cells nor nuclear morphology was altered by the treatments. The bottom row contained merged images combining the red PAR signal and blue nuclear stain to visualize co-localization and to qualitatively assess treatment effects.

[0172] The experimental setup included the following treatments: vehicle control, hydrogen peroxide (H2O2) at 10 mM / L as a positive control, Rucaparib at 1 pM as a reference PARP inhibitor, and Example 20 at concentrations of 10 pM, 1 pM, and 0.1 pM. Quantification of PARylation levels was performed, with the Y-axis representing the mean intensity of the PAR fluorescence signal and the X-axis indicating the treatment conditions. Cells treated with vehicle control exhibited the lowest PARylation intensity, establishing the baseline level. Exposure to H2O2 resulted in the highest PARylation intensity, consistent with oxidative stress-mediated activation of PARP enzymes. Treatment with Rucaparib significantly reduced PARylation compared to H2O2 treatment, although the levels did not return completely to baseline. Example 20 produced a dose-dependent reduction in PARylation, with the 10 pM concentration achieving inhibition slightly superior to Rucaparib. At 1 pM and 0.1 pM, Example 20 maintained inhibitory activity comparable to Rucaparib, demonstrating substantial potency even at sub-micromolar concentrations.

[0173] These results indicate that Example 20 exhibits potent, dose-dependent inhibition of PARylation, performing on par with or superior to Rucaparib at equivalent or lower concentrations. The maintenance of substantial inhibitory activity at 0.1 pM underscores its potential as a highly potent PARP inhibitor with prospective advantages in efficacy and safety over existing reference compounds. Figure 4 illustrates the comparative PARylation inhibition profiles for the tested treatments under the described experimental conditions.

[0174] PARP1 trapping assay for Example-20

[0175] In another embodiment PARP1 trapping refers to the phenomenon in which inhibitors of poly(ADP-ribose) polymerase 1 (PARP1) not only block the enzyme’s catalytic activity but also immobilize PARP1 on DNA at sites of damage. This immobilization prevents the dissociation of PARP 1 from damaged DNA, thereby obstructing DNA repair and replication processes, ultimately leading to cell death. This mechanism is considered a critical determinant of PARP inhibitor efficacy in oncology, particularly for cancers deficient in homologous recombination repair.

[0176] In the present study, the effect of Example 20 on PARP1 trapping was assessed and compared with Rucaparib using a fluorescence-based assay. The results were represented graphically, with the Y-axis denoting the mean fluorescence intensity corresponding to PARP1, indicative of its trapping on DNA, and the X-axis representing the treatment groups. Cells treated with the vehicle control exhibited the lowest PARP1 trapping, establishing the baseline. Treatment with hydrogen peroxide (H2O2) at 10 mM / L produced the highest PARP1 trapping intensity, reflecting oxidative stress-induced PARP1 activation and immobilization on DNA. Rucaparib at 1 pM significantly reduced PARP1 trapping relative to H2O2 treatment, consistent with its known activity as a PARP1 trap inhibitor.

[0177] Example 20 demonstrated a clear dose-dependent inhibition of PARP 1 trapping. At a concentration of 10 pM, Example 20 produced an inhibitory effect slightly superior to that of Rucaparib. At 1 pM, the inhibitory activity of Example 20 was comparable to Rucaparib, whereas at 0.1 pM, Example 20 achieved near-baseline levels of PARP 1 trapping, indicating stronger inhibition than Rucaparib at this lower concentration.

[0178] These results indicate that Example 20 exhibits superior dose-dependent inhibition of PARP 1 trapping and maintains significant inhibitory activity even at sub-micromolar concentrations. The ability to achieve potent trapping inhibition at lower doses suggests potential therapeutic advantages, including the possibility of reducing off-target toxicity while maintaining high efficacy. Accordingly, Example 20 represents a promising candidate for further development as a PARP inhibitor with enhanced trapping inhibition properties. Figure 5 illustrates the comparative PARP1 trapping inhibition profiles under the tested conditions.

[0179] Pharmacokinetic study report of compound 9

[0180] The pharmacokinetic evaluation of compound 9 in BALB / c mice following intravenous administration revealed an initial plasma concentration (Co) of 9558 ng / mL, confirming rapid systemic exposure without first-pass metabolism. The compound exhibited a short elimination half-life (T’ ) of 0.72 hours, consistent with efficient systemic clearance (Cl) of 1.0 L / h / kg, thereby indicating rapid elimination via metabolic and / or excretory pathways. The area under the plasma concentration-time curve from time zero to the last measurable concentration (AUCo-t) was 4945 ng h / mL, and the extrapolated total exposure (AUCo-co) was 5007 ng h / mL, with minimal difference between the two, suggesting that most of the compound was eliminated within the sampling period.

[0181] Table 3. Main pharmacokinetic parameters of compound 9 after intravenous administration at 5 mg / kg in BALB / c mice

[0182] The calculated volume of distribution (Vd) of 1.0 L / kg indicates moderate tissue distribution beyond plasma, approximating total body water distribution, and supporting the inference of partitioning into both extracellular and intracellular compartments without extensive tissue binding. Collectively, these pharmacokinetic parameters demonstrate that Example 9 undergoes rapid clearance with moderate distribution, necessitating consideration of frequent dosing or modified formulations to maintain therapeutic plasma concentrations, thereby providing critical insights for further preclinical development and potential clinical translation.

[0183] Pharmacokinetic study report of compound 20 The pharmacokinetic analysis of SAP-20 following intravenous administration demonstrates a rapid onset of action, with a high initial plasma concentration (Co = 8444 ng / mL) confirming quick systemic exposure and attainment of therapeutic levels. The plasma concentration declines sharply thereafter, consistent with the short elimination half-life (T’A = 1.3 hours) and high systemic clearance (Cl = 1.9 L / h / kg), indicating that the compound is rapidly distributed and eliminated from circulation.

[0184] By 6 hours post-administration, SAP-20 levels are nearly undetectable, further underscoring its fast elimination profile. The moderate volume of distribution (Vd = 2.1 L / kg) suggests partitioning into extracellular and intracellular fluids with limited long-term tissue retention. Collectively, these pharmacokinetic characteristics highlight Compound-20 with rapid systemic availability but short duration of plasma exposure, necessitating multiple dosing strategies or formulation modifications, such as controlled-release systems, to sustain therapeutic plasma concentrations and ensure optimal pharmacological efficacy.

[0185] Table 4. Main pharmacokinetic parameters of compound 20 after intravenous administration at 5 mg / kg in BALB / c mice

[0186] Anti-tumor activity of compound 9 in the OVCAR-8 xenograft model of Athymic Nude mice

[0187] The in-vivo anti-tumor activity of compound 9 was evaluated in athymic nude mice (NU / J Foxnlnuhttps / / axggg / gtrgm / p02019) maintained at the Animal House Facility of CSIR-Indian Institute of Integrative Medicine, Jammu, India. The mice were housed in IVCs (Individually ventilated cages) under controlled environmental conditions with a temperature of 25 ± 2°C, Relative Humidity of 50-60%, and a light cycle of 12h light / dark. Gamma irradiated feed and autoclaved RO water were provided ad libitum to all experimental animals. The experiment was conducted with prior approval of the Institutional Animal Ethics Committee (IAEC) of CSIR-IIIM and performed adhering to the guidelines of CCSEA (Committee for Control and Supervision of Experiments on Animals, h ftps / / ccsea . gov . in) .

[0188] The OVCAR-8 cells were cultured in RPMI-1640 media with 10% FBS (Fetal Bovine Serum) and harvested by trypsinization. The cell pellets were resuspended in sterile PBS at 5 x 106cells / 100 pL. To develop a xenograft model in athymic nude mice, the cell suspension was mixed with Matrigel at a 1 : 1 ratio and injected subcutaneously in the right flank region of each mouse. The tumor volume was calculated using the formula: TV (mm3) = (L x W2) / 2, where L is the length (largest reading) and W is the Width (shortest reading). When the tumor volume reached around 150-200 mm3, the mice were randomized to three groups (n=5 mice / group). The groups are as follows: Control (Vehicle), Rucaparib (100 mg / kg), and compound 9 (20 mg / kg).

[0189] The control group animals received vehicle @ 10 mL / Kg b.w. via oral route. Meanwhile, Rucaparib and compound 9 were administered orally twice a week for 21 days. The tumor volume was measured using a digital vernier caliper once every three days. The body weight was recorded twice a week and on the last day of termination. The animals were humanely euthanized by CO2 asphyxiation, and tumors were excised and weighed using a calibrated analytic balance. The experimental data were analyzed by one-way ANO VA using GraphPad Prism 8.0. Dunnett’s t-test was used as post hoc to measure the significance between the control and other groups at P<0.05.

[0190] Results

[0191] The tumor volume was measured before the start of dosing (day 0) and then measured once every three days till day 21. A significant difference in mean tumor volume was observed from day 8 and so on in the compound 9 group, compared to the vehicle control.

[0192] At day 24, the percentage inhibition of tumor growth in OVCAR-8 cells was 71% in compound 9, whereas it was 52% in Rucaparib administered animals (Fig. 1 C). No significant loss in body weight and mortality was observed in compound 9. However, on the other hand, the Rucaparib group showed a slight reduction in mean body weight, and the mortality of two mice was observed in the last week of treatment with clinical signs.

[0193] Conclusion: Based on the findings, it can be inferred that compound 9 exerts a more significant reduction in tumor volume and tumor weight with no adverse effect on body weight in the OVCAR-8 xenograft athymic nude mice model.

[0194] Examples:

[0195] Following examples are given by way of illustration:

[0196] Example-1: Preparation of dimethyl(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd] indol-5-yl)phosphonate: To a 50 ml two neck round bottom flask were added 2,3,4,6-tetrahydro-U / -azepino[5,4,3- cd]indol-l-one 6 (l.Ommol, lequiv.) and dimethyl phosphite (Ha) (2.0 mmol, 2.0 equiv.) and silver acetate (10 mol%)in dry acetonitrile ACN (15 ml) strictly under argon atmosphere. The reaction mixture was refluxed to 1000C in an oil bath for 12 hours to afford the corresponding phosphonate derivative example 1. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous Na2SO4, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a brown solid.

[0197] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 98:02); (251 mg, 79%) as a brown solid. 'H NMR (400 MHz, MeOD) 5 7.77 (d, 7 = 7.4 Hz, 1H), 7.57 (d, 7 = 8.2 Hz, 1H), 7.30 (t, 7 = 7.8 Hz, 1H), 3.70 (d, 7 = 11.5 Hz, 6H), 3.58 (d, 7 = 11.0 Hz, 1H), 3.52 - 3.45 (m, 2H), 3.17 (s, 1H).13C NMR (101 MHz, MeOD) 5 171.44 (s), 138.46 (d, 7 = 13.2 Hz), 125.92 (d, 7 = 20.1 Hz), 125.25 (s), 124.42 (s), 123.85 (s), 119.64 (s), 117.44 (s), 116.28 (s), 52.29 (d, 7 = 5.4 Hz), 41.99 (s), 27.84 (s).31P NMR (162 MHz, MeOD) 5 7.98 (s).

[0198] Example-2: Preparation of diisopropyl(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd] indol-5-yl)phosphonate :

[0199] To a 50 ml two neck round bottom flask were added 2,3,4,6-tetrahydro-U / -azepino[5,4,3- cd]indol-l-one (6) (l.Ommol, lequiv.) and di-isopropyl phosphite (11c) (2.0 mmol, 2.0 equiv.) and silver acetate (10 mol%)in dry acetonitrile ACN (15 ml) strictly under argon atmosphere. The reaction mixture was refluxed to 100 °C in an oil bath for 9 hours to afford the corresponding phosphonate derivative. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSC , concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a brown solid.

[0200] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 98:02); (271 mg, 71%) as a colourless oil. 'H NMR (400 MHz, MeOD) 5 7.77 (d, J = 7.4 Hz, 4H), 7.58 (d, J = 8.2 Hz, 4H), 7.26 (t, J = 7.8 Hz, 4H), 4.57 (qd, J = 12.1, 5.9 Hz, 10H), 3.54 - 3.43 (m, 9H), 3.21 (s, 8H), 1.26 (d, J = 6.2 Hz, 24H), 1.12 (d, J = 6.2 Hz, 24H).13C NMR (101 MHz, MeOD) 5 171.53 (s), 138.22 (d, J = 13.0 Hz), 125.17 (s), 124.59 (dd, 7 = 24.9, 17.9 Hz), 123.85 (d, J = 14.2 Hz), 122.46 (s), 120.27 (s), 116.30 (s), 71.87 (d, 7 = 5.4 Hz), 42.02 (s), 28.11 (s), 23.00 (d, J = 4.1 Hz), 22.74 (d, J = 4.6 Hz).31P NMR (162 MHz, MeOD) 5 7.98 (s).

[0201] Example-3: Preparation of dicyclopentyl(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd]indol-5-yl)phosphonate(compound 3d):

[0202] To a 50 ml two neck round bottom flask were added 2,3,4,6-tetrahydro-U / -azepino[5,4,3- cd]indol-l-one (6) (l.Ommol, lequiv.) and dicylopentyl phosphite (lid) (2.0 mmol, 2.0 equiv.) and silver acetate (10 mol%)in dry acetonitrile ACN (15 ml) strictly under argon atmosphere. The reaction mixture was refluxed to 100 °C in an oil bath for 11 hours to afford the corresponding phosphonate derivatives. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSC , concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a brown solid.

[0203] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (241 mg, 56%) asbrown solid. 'H NMR (400 MHz, DMSO) 5 11.72 (s, 1H), 8.20 (d, J = 5.2 Hz, 1H), 7.80 (d, J = 7.3 Hz, 1H), 7.67 (d, J = 8.2 Hz, 1H), 7.38 (t, J = 7.8 Hz, 1H), 4.85 (s, 2H), 3.47 (s, 2H), 3.39 (s, 1H), 3.16 (s, 1H), 1.87 - 1.54 (m, 15H).13C NMR (101 MHz, DMSO) 5 169.44 (s), 138.27 (d, J = 13.0 Hz), 126.57 (s), 124.75 - 123.82 (m), 123.61 (s), 123.33 (s), 121.20 (s), 116.37 (s), 79.62 (d, J = 5.3 Hz), 41.94 (s), 34.11 (d, J = 4.3 Hz), 33.72 (d, J = 4.9 Hz), 28.66 (s), 23.04 (d, J = 4.0 Hz).31P NMR (162 MHz, DMSO) 5 10.56 (s).

[0204] Example-4: Preparation of diethyl(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol- 5 -yl)phosphonate :

[0205] To a 50 ml two neck round bottom flask were added 2,3,4,6-tetrahydro-U / -azepino[5,4,3- cd]indol-l-one (6) (l.Ommol, lequiv.) and diethyl phosphite (11b) (2.0 mmol, 2.0 equiv.) and silver acetate (10 mol%)in dry acetonitrile ACN (15 ml) strictly under argon atmosphere. The reaction mixture was refluxed to 100 °C in an oil bath for 9 hours to afford the corresponding phosphonate derivatives. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous Na2SO4, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a brown solid

[0206] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (246 mg, 71%) as a brown solid. 'H NMR (400 MHz, MeOD) 5 7.77 (d, J= 7.4 Hz, 1H), 7.58 (d, J= 7.8 Hz, 1H), 7.30 (t, J= 7.8 Hz, 1H), 4.05 (dd, J= 15.1, 7.7 Hz, 4H), 3.49 (d, J= 4.1 Hz, 2H), 3.21 (d, J = 1.2 Hz, 3H), 1.24 (t, J= 7.1 Hz, 6H).13C NMR (101 MHz, MeOD) 5 171.52 (s), 138.42 (s), 125.56 - 125.07 (m), 124.05 (s), 123.75 (s), 120.99 (s), 116.22 (s), 62.65 (d, J= 5.4 Hz), 41.97 (s), 27.93 (s), 15.20 (d, J= 6.2 Hz)31PNMR (162 MHz, MeOD) 5 7.80 (s).

[0207] Example-5: Preparation of bis(4-chlorobutyl)(l-oxo-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-5-yl)phosphonate:

[0208] Example 5

[0209] To a 50 ml two neck round bottom flask were added 2,3,4,6-tetrahydro-U / -azepino[5,4,3- cd]indol-l-one (6) (l.Ommol, lequiv.) and dialkyl / alkyl-arylphosphite (lie) (2.0 mmol, 2.0 equiv.) and silver acetate (10 mol%)in dry acetonitrile ACN (15 ml) strictly under argon atmosphere. The reaction mixture was refluxed to 100 °C in an oil bath for 8-12 hours to afford the corresponding phosphonate derivative. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSC , concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a brown solid.

[0210] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (130 mg, 54%) as a brown solid.1!! NMR (400 MHz, DMSO) 5 11.77 (s, 2H), 8.19 (s, 2H), 7.77 (d, J = 6.9 Hz, 2H), 7.64 (d, 7 = 8.1 Hz, 2H), 7.36 (t, J = 7.8 Hz, 2H), 4.15 - 3.95 (m, 9H), 3.63 (t, J = 6.2 Hz, 8H), 3.45 (d, J = 4.1 Hz, 4H), 3.15 (s, 3H), 1.86 - 1.67 (m, 18H).13C NMR (101 MHz, DMSO) 5 169.38 (s), 138.43 (d, J = 13.2 Hz), 126.67 (s), 125.06 (d, J = 19.3 Hz), 124.80 - 124.15 (m), 123.72 (s), 121.71 (s), 119.57 (s), 116.40 (s), 65.58 (d, J = 5.0 Hz), 45.34 (s), 41.97 (s), 28.90 - 28.85 (m), 28.69 (d, J = 21.6 Hz), 27.79 (d, J = 6.3 Hz).31P NMR (162 MHz, DMSO) 5 10.56 (s). Example-6: Preparation of ethyl(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)(phenyl)phosphinate :

[0211] To a 50 ml two neck round bottom flask were added 2,3,4,6-tetrahydro-17 / -azepino[5,4,3- cd]indol-l-one (6) (0.5 mmol, lequiv.) and ethyl phosphite (Ilf) (1.0 mmol, 1.0 equiv.) and silver acetate (10 mol%)in dry acetonitrile ACN (15 ml) strictly under argon atmosphere. The reaction mixture was refluxed to 100 °C in an oil bath for 10 hours to afford the corresponding phosphonate derivative. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous Na2SO4, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a brown solid.

[0212] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (101 mg, 53%) as a brown solid. 'H NMR (400 MHz, DMSO) 5 11.80 (s, 2H), 8.19 (s, 2H), 7.83 - 7.76 (m, 5H), 7.67 (d, J = 8.0 Hz, 2H), 7.58 (d, J = 7.0 Hz, 2H), 7.54 (dd, J = 6.8, 2.5 Hz, 3H), 7.35 (t, J = 7.7 Hz, 2H), 4.20 - 4.02 (m, 4H), 3.45 (s, 4H), 3.14 (s, 4H), 1.34 (t, J = 7.0 Hz, 6H).13C NMR (101 MHz, DMSO) 5 169.45 (s), 138.62 (d, J = 10.8 Hz), 133.21 (s), 132.90 (s), 131.78 (s), 131.13 (d, J = 10.7 Hz), 129.29 (d, J = 13.4 Hz), 126.64 (s), 125.27 - 124.50 (m), 124.20 (s), 123.75 (s), 123.05 (s), 116.43 (s), 61.69 (d, J = 5.7 Hz), 41.95 (s), 28.63 (s), 16.80 (d, 7 = 6.1 Hz).31P NMR (162 MHz, DMSO) 5 10.54 (s).

[0213] Example-7: Preparation of dimethyl((butylamino)(4-(l-oxo-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-5-yl)phenyl)methyl)phosphonate:

[0214] Example 7

[0215] To a 100 ml one neck round bottom flask were added 4-(l-oxo-2,3,4,6-tetrahydro-177- azepino[5,4,3-cd]indol-5-yl)benzaldehyde(9a) (l.Ommol, lequiv.) and dimethyl phosphite (Ila) (2.0 mmol, 2.0 equiv.) and n-butyl amine 12a (1.2 mmol , 1.2 equiv.) in toluene (25 ml) in open atmosphere. The reaction mixture was heated to 100 °C in an oil bath for 12 hours to afford the corresponding diethyl ((alkylamino)(4-(l-oxo-2,3,4,6-tetrahydro-177- azepino[5,4,3-cd]indol-5-yl)phenyl)methyl)phosphonate derivative. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSC , concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a brown solid.

[0216] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 98:02); (222 mg, 71%) as a brown solid. 'H NMR (400 MHz, MeOD) 5 7.69 (d, J = 7.5 Hz, 3H), 7.51 (dt, J = 24.1, 8.0 Hz, 16H), 7.15 (t, J = 7.8 Hz, 3H), 4.52 (s, 10H), 4.16 - 3.98 (m, 12H), 3.86 (ddd, J = 17.3, 10.1, 2.3 Hz, 8H), 3.44 (s, 6H), 3.21 (s, 4H), 3.06 (s, 6H), 2.53 - 2.33 (m, 8H), 1.22 (t, J = 7.0 Hz, 15H), 1.08 (t, J = 7.1 Hz, 10H), 0.79 (t, J = 7.3 Hz, 10H).13C NMR (101 MHz, MeOD) 5 172.73 (s), 136.86 (s), 135.33 (s), 135.01 (s), 131.98 (s), 128.87 (d, J = 6.4 Hz), 127.84 (s), 126.52 (s), 123.36 (s), 122.65 (s), 121.13 (s), 115.00 (s), 111.83 (s), 63.12 (dd, J = 15.4, 7.4 Hz), 60.73 (s), 59.20 (s), 42.54 (s), 31.30 (s), 28.88 (s), 19.97 (s), 15.34 (dd, J = 14.5, 5.6 Hz), 12.92 (s).31P NMR (162 MHz, MeOD) 5 23.67 (s).

[0217] Example-10: Preparation of Dimethyl(hydroxy(4-(l-oxo-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-5-yl)phenyl)methyl)phosphonate:

[0218] To a 50 ml Schlenk tube were added 4-(l-oxo-2,3,4,6-tetrahydro-l / / -azepino[5,4,3-cd]indol- 5-yl)benzaldehyde(9b) (l.Ommol, lequiv.) and dimethyl phosphite (Ha) (2.0 mmol, 2.0 equiv.) and potassium Fluoride (5mmol) in DCM and Methanol in 1 : 1 ratio (15 ml). The reaction mixture was stirred at room temperature for 30 minutes to afford the corresponding Compound. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous Na2SO4, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a off white solid.

[0219] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (33 mg, 81%) as a colourless oil. 'H NMR (400 MHz, MeOD) 5 7.73 (d, J = 7.5 Hz, 1H), 7.56 - 7.47 (m, 5H), 7.17 (t, J = 7.8 Hz, 1H), 5.29 (s, 1H), 5.05 (t, J = 12.7 Hz, 1H), 3.67 (dd, J = 10.3, 8.7 Hz, 6H), 3.50 (dd, J = 19.6, 6.7 Hz, 2H), 3.11 (d, J = 17.8 Hz, 2H).13C NMR (101 MHz, MeOD) 5 172.92 (s), 136.78 (s), 136.33 (s), 135.15 (s), 132.12 (s), 127.86 (s), 127.45 (d, 7 = 6.0 Hz), 126.57 (s), 123.17 (s), 122.92 (s), 121.36 (s), 115.33 (s), 111.84 (s), 70.49 (s), 68.85 (s), 53.77 (d, J = 7.5 Hz), 53.32 (d, J = 7.2 Hz), 42.82 (s), 28.97 (s).31P NMR (162 MHz, MeOD) 5 24.01 (s).

[0220] Example-11: Preparation of dimethyl(hydroxy(4-(l-oxo-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-5-yl)phenyl)methyl)phosphonate:

[0221] To a 50 ml Schlenk tube were added 4-(l-oxo-2,3,4,6-tetrahydro-U / -azepino[5,4,3-cd]indol- 5-yl)benzaldehyde(9a) (l.Ommol, lequiv.) and dimethyl phosphite (Ila) (2.0 mmol, 2.0 equiv.) and potassium Fluoride (5mmol) in DCM and Methanol in 1 : 1 ratio (15 ml). The reaction mixture was stirred at room temperature for 30 minutes to afford the corresponding Compound. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSCU, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a off white solid.

[0222] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (35 mg, 82%) as a colourless oil. 'H NMR (400 MHz, MeOD) 5 7.73 (d, J= 7.5 Hz, 1H), 7.53 (s, 5H), 7.16 (d, J= 6.6 Hz, 1H), 5.29 (s, 1H), 5.03 (d, J= 12.9 Hz, 1H), 3.66 (t, J= 4.5 Hz, 6H), 3.48 (d, J= 5.0 Hz, 2H), 3.25 - 3.24 (m, 1H), 3.08 (s, 2H).13C NMR (101 MHz, MeOD) 5 172.92 (s), 136.78 (s), 136.33 (s), 135.15 (s), 132.12 (s), 127.86 (s), 127.45 (d, J = 6.0 Hz), 126.57 (s), 123.17 (s), 122.92 (s), 121.36 (s), 115.33 (s), 111.84 (s), 70.49 (s), 68.85 (s), 53.77 (d, J= 7.5 Hz), 53.32 (d, J= 7.2 Hz), 42.82 (s), 28.97 (s).31P NMR (162 MHz, MeOD) 5 24.01 (s).

[0223] Example-12: Preparation of dimethyl((3-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-5-yl)phenyl)(hydroxy)methyl)phosphonate:

[0224] To a 50 ml Schlenk tube were added 4-(l-oxo-2,3,4,6-tetrahydro-U / -azepino[5,4,3-cd]indol- 5-yl)benzaldehyde(9c) (l.Ommol, lequiv.) and dimethyl phosphite (Ila) (2.0 mmol, 2.0 equiv.) and potassium Fluoride (5mmol) in DCM and Methanol in 1 : 1 ratio (15 ml). The reaction mixture was stirred at room temperature for 30 minutes to afford the corresponding Compound 5c. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSC , concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a off white solid. The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (33.45 mg, 80%) as a colourless oil. 'H NMR (400 MHz, MeOD) 5 7.81 (s, 1H), 7.66 (d, J = 7.0 Hz, 1H), 7.45 (d, J = 7.0 Hz, 2H), 7.20 - 7.01 (m, 2H), 5.35 (d, 7 = 13.1 Hz, 1H), 3.74 (d, J = 9.2 Hz, 3H), 3.66 - 3.56 (m, 3H), 3.36 (s, 2H), 2.96 (s, 2H).13C NMR (101 MHz, MeOD) 5 172.66 (s), 160.28 (s), 157.81 (s), 136.77 (s), 134.28 (s), 129.35 (d, J= 8.5 Hz), 128.83 (d, J = 23.5 Hz), 128.69 - 128.41 (m), 126.40 (s), 125.15 (d, 7 = 14.4 Hz), 123.28 (s), 122.68 (s), 121.15 (s), 115.34 (s), 115.08 (d, 7 = 10.8 Hz), 111.76 (s), 63.18 (s), 61.49 (s), 53.50 (d, 7 = 7.1 Hz), 52.94 (d, 7 = 7.3 Hz), 42.48 (s), 28.67 (s).19F NMR (377 MHz, MeOD) 5 -120.27 (s).31P NMR (162 MHz, MeOD) 523.47 (s).

[0225] Example-13: Preparation of diethyl((3-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-5-yl)phenyl)(hydroxy)methyl)phosphonate:

[0226] To a 50 ml Schlenk tube were added 4-(l-oxo-2,3,4,6-tetrahydro-U / -azepino[5,4,3-cd]indol- 5-yl)benzaldehyde(9c) (l.Ommol, lequiv.) and dimethyl phosphite (11b) (2.0 mmol, 2.0 equiv.) and potassium Fluoride (5mmol) in DCM and Methanol in 1 : 1 ratio (15 ml). The reaction mixture was stirred at room temperature for 30 minutes to afford the corresponding Compound. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous ISfeSC , concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as a off white solid.

[0227] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (37 mg, 84%) as a colourless oil. *11 NMR (400 MHz, MeOD) 5 7.87 - 7.78 (m, 1H), 7.67 (d, J= 7.5 Hz, 1H), 7.48 (d, J= 7.8 Hz, 2H), 7.18 - 7.05 (m, 2H), 5.30 (d, J= 13.5 Hz, 1H), 4.17 - 4.06 (m, 2H), 3.94 (qt, J= 16.8, 8.3 Hz, 2H), 3.40 (s, 2H), 3.01 (s, 2H), 1.28 - 1.17 (m, 3H), 1.16 - 1.07 (m, 3H).13C NMR (101 MHz, MeOD) 5 172.69 (s), 160.30 (s), 157.86 (d, J= 6.9 Hz), 136.80 (s), 134.37 (s), 129.28 (d, J= 8.4 Hz), 129.02 (s), 128.68 (s), 126.42 (s), 125.43 (d, J= 14.6 Hz), 123.34 (s), 122.67 (s), 121.15 (s), 115.51 - 115.41 (m), 115.41 - 114.89 (m), 111.71 (s), 63.69 - 63.03 (m), 42.50 (s), 28.75 (s), 15.38 (dd, J= 13.5, 5.5 Hz).19F NMR (377 MHz, MeOD) 5 -120.04 (d, J= 91.4 Hz).31P NMR (162 MHz, MeOD) 5 21.23 (s).

[0228] Example-14: Preparation of dimethyl(3-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd]indol-5-yl)benzyl)phosphonate (compound 8a):

[0229] EXAMPLE 14

[0230] To a 50 ml Schlenk tube were added 4-(l-oxo-2,3,4,6-tetrahydro-U / -azepino[5,4,3-cd]indol- 5-yl)benzaldehyde(9b) (l.Ommol, lequiv.) and dimethyl phosphite (Ila) (2.0 mmol, 2.0 equiv.), Copper iodide (30mol %) and potassium Carbonate (2mmol) in dry dimethoxy ethane (DME) strictly under argon atmosphere. The reaction mixture was stirred at 60 °Cfor four hours to afford the compound 8a. After the completion of the reaction as monitored by TLC, the reaction mixture was cooled down to room temperature, extracted with ethyl acetate (25 mix 2) and washed with H2O (50 ml x 2). The organic layer was dried over anhydrous Na2SO4, concentrated via rotary evaporation, and purified by column chromatography on silica gel (petroleum ether: ethyl acetate) as yellow solid.

[0231] The title compound was purified by column chromatography with the eluent (DCM / MeOH = 94:06); (38 mg, 87%) as a yellowsolid.1!! NMR (400 MHz, DMSO) 5 11.59 (s, 1H), 8.09 (t, J = 5.5 Hz, 1H), 7.69 (t, J = 10.7 Hz, 1H), 7.64 - 7.52 (m, 3H), 7.48 (t, J = 7.6 Hz, 1H), 7.32 (d, J = 7.4 Hz, 1H), 7.23 (t, J = 7.7 Hz, 1H), 3.65 (d, J = 10.8 Hz, 6H), 3.40 (d, J = 9.4 Hz, 3H), 3.36 (s, 2H), 3.07 (s, 2H).13C NMR (101 MHz, DMSO) 5 170.21 (s), 136.92 (s), 134.88 (s), 133.11 (d, J = 8.9 Hz), 132.43 (d, J = 2.8 Hz), 129.85 (d, J = 6.6 Hz), 129.44 (d, J = 6.5 Hz), 129.22 (s), 126.61 (s), 126.47 (s), 125.24 (s), 122.84 (s), 121.64 (s), 115.05 (s), 112.44 (s), 52.91 (d, J = 6.7 Hz), 42.46 (s), 31.50 (d, J = 134.5 Hz), 29.58 (s).31P NMR (162 MHz, DMSO) 5 28.94 (s).

Claims

We Claim,1. A phosphorus-containing rucaparib as parp inhibitor of Formula I;Formula I wherein, R is selected from the group consisting of hydrogen, fluorine, and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, unsubstituted or substituted aryl, or heteroaryl group; wherein the substituted aryl, or heteroaryl group is selected from the group consisting of one or more halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally Substituted amino and ether groups; wherein, R1 and R2 are independently selected from the consisting of OMe, OEt, O- / Pr, O-Cyp, O-- / -C1 butyl, OPh, NHR’ and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, unsubstituted or substituted aryl, or heteroaryl group; wherein the substituted aryl, or heteroaryl group is selected from the group consisting of one or more halogen, hydroxy, and amino, alkoxy, alkyl, and aryl groups unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, carboxy, and optionally substituted amino groups; wherein R' is selected from Me, or Et; optionally with or without spacer; wherein the spacer is selected from the group consisting of phenyl, fluorophenyl alkyl, fluorophenyl substituted alkyl, benzyl, substituted benzyl, thiophenyl alkyl, or furyl alkyl.

2. The compound as claimed in claim 1, wherein the compound of Formula I is selected from the group consisting of:(i) Dimethyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5-yl)phosphonate (compound 1);(ii) Diisopropyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 2);(iii) Dicyclopentyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 3);(iv) Diethyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5-yl)phosphonate (compound 4);(v) Bis(4-chlorobutyl) (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 5);(vi) Ethyl (l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)(phenyl)phosphinate (compound 6);(vii) Dimethyl ((butylamino)(4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol- 5-yl)phenyl)methyl)phosphonate (compound 7);(viii) Ethyl (8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)(phenyl)phosphinate (compound 8);(ix) Dimethyl (8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 9);(x) Dimethyl (hydroxy(3-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phenyl)methyl)phosphonate (compound 10);(xi) Dimethyl (hydroxy(4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phenyl)methyl)phosphonate (compound 11);(xii) Dimethyl ((3-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phenyl)(hydroxy)methyl)phosphonate (compound 12);(xiii) Diethyl ((3-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phenyl)(hydroxy)methyl)phosphonate (compound 13);(xiv) Dimethyl (3-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 14);(xv) Dimethyl (4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 15);(xvi) Dimethyl (3-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 16);(xvii) Dimethyl (2-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 17);(xviii) Dimethyl (2-fluoro-3-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 18);(xix) Dimethyl (3-fluoro-5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 19);(xx) Dimethyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 20);(xxi) Dimethyl (2-fluoro-4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd]indol-5-yl)benzyl)phosphonate (compound 21);(xxii) Dimethyl (3-fluoro-4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 22);(xxiii) Dimethyl ((5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)thiophen-2-yl)methyl)phosphonate (compound 23);(xxiv) Dimethyl ((5-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5-yl)furan- 2-yl)methyl)phosphonate (compound 24);(xxv) Dimethyl ((5-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)furan-2-yl)methyl)phosphonate (compound 25);(xxvi) Dimethyl (2-fluoro-3-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd]indol-5-yl)benzyl)phosphonate (compound 26);(xxvii) Diethyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 27);(xxviii) Dibenzyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 28);(xxix) Ethyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)(phenyl)phosphinate (compound 29);(xxx) Diethyl (4-(l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 30);(xxxi) 5-(dimethylphosphoryl)-8-fluoro-2,3,4,6-tetrahydro-lH-azepino[5,4,3- cd]indol-l-one (compound 31);(xxxii) 5-(4-((dimethylphosphoryl)methyl)phenyl)-8-fluoro-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-l-one (compound 32)3. The compound as claimed in claim 1, wherein the compound inhibiting PARP enzyme activity are selected from the group consisting of:(i) Ethyl (8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5 yl)(phenyl)phosphinate (compound 8);(ii) Dimethyl (8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)phosphonate (compound 9);(iii) Dimethyl (3-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 16);(iv) Dimethyl (4-(8-fluoro-l-oxo-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-5- yl)benzyl)phosphonate (compound 20);(v) 5-(dimethylphosphoryl)-8-fluoro-2,3,4,6-tetrahydro-lH-azepino[5,4,3-cd]indol-l-one (compound 31);(vi) 5-(4-((dimethylphosphoryl)methyl)phenyl)-8-fluoro-2,3,4,6-tetrahydro-lH- azepino[5,4,3-cd]indol-l-one (compound 32).

4. The compound as claimed in claim 1, for use in the inhibition of poly(ADP-ribosyl)ation (PARylation) (PARP) enzyme activity.

5. A method for synthesizing the phosphorus-containing compound of Formula I having no spacer as claimed in claim 1, wherein the method comprises the steps of:(a) coupling 2,3,4,6-tetrahydro-17 / -azepino[5,4,3-cd] indol-l-one with dialkyl / alkylarylphosphite and silver acetate in dry acetonitrile under inert atmosphere at a temperature range of 100X2 for 8-12 hours to obtain a phosphonate derivate;(b) cooling the phosphonate derivative as obtained in step (a) followed by extracting and purifying to obtain the compound of Formula I without spacer.

6. A method for synthesizing the phosphorus-containing compound of Formula I having spacer as claimed in claim 1, wherein the method comprises the steps of:(a) coupling 4(l-oxo-2,3,4,6-tetrahydro-17 / -azepino[5,4,3-cd] indol-5-yl) benzaldehyde and dialkyl phosphite with copper iodide and potassium carbonate in dry dimethoxy ethane under inert atmosphere to obtain a phosphonate derivate;(b) cooling the phosphonate derivative as obtained in step (a) followed by extracting and purifying to obtain the compound of Formula I with spacer.

7. A pharmaceutical composition comprising a therapeutically effective amount of the phosphorus-containing compound of Formula I as claimed in claim 1 in a pharmaceutically acceptable carrier.

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