Catalysts for selective alkylation of arenes and a method of preparing the same thereof

Abstract

The present invention relates to recyclable metal-fluorenyl catalysts to perform sustainable and selective method for C-H alkylation and C-H editing of aromatic compounds using recyclable metal-fluorenyl catalysts. These catalysts are based on inexpensive and air-stable metals like cobalt, iron, and manganese, operate under mild conditions using green solvents such as methanol and THF. The process avoids the need for directing groups, post-reaction hydrogenation, and hazardous waste generation, while achieving mono-alkylated products with high selectivity (93-98%). Furthermore, the catalysts enable stepwise C-H editing, allowing for precise, controlled substitution of multiple hydrogen atoms on an aromatic ring. The recyclable nature of the catalysts and the reduced environmental impact make this method highly suitable for industrial-scale applications.

Description

CATALYSTS FOR SELECTIVE ALKYLATION OF ARENES AND A METHOD OF PREPARING THE SAME THEREOFFIELD OF THE INVENTION

[0001] The present invention relates to the organic chemistry and catalysts synthesis. More particularly, the present invention relates to the synthesis of catalysts for selective alkylation of arenes and a method of preparing the same thereof.BACKGROUND OF THE INVENTION

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] Aromatic alkylation is a cornerstone reaction in industrial chemistry, especially in the production of essential chemicals like ethylbenzene (used in making styrene) and cumene (used to make phenol and acetone). Traditional methods for alkylating arenes, such as Friedel-Crafts alkylation, use Lewis’s acids like aluminum chloride (AlCh) as catalysts. Although effective, this method has several limitations, including stoichiometric catalyst use where large amounts of the catalyst are needed, making the process expensive. Also, the process requires strict reaction conditions with dry and specific solvents, often halogenated, which are environmentally harmful. It has also been reported that the process leads to excessive metal hydroxide waste, leading to disposal and environmental issues. Nevertheless, Friedel-Crafts reactions can lead to unwanted by-products like polyalkylated products, reducing the efficiency of the process.

[0004] Another commonly used approach is Friedel-Crafts acylation, followed by the reduction of the acyl group to an alkyl group. While this process offers more control over alkylation, it involves multiple steps, increasing both time and cost. The production of byproducts and the need for post-reaction hydrogenation further increase the environmental impact.

[0005] Additionally, Suzuki-Miyaura, Heck, and Negishi coupling reactions provide powerful alternatives for aryl alkylation. However, they all suffer from drawbacks such as the use of expensive palladium catalysts, air and moisture sensitivity of reagents, complicating reaction conditions. Also, the process needs a post-reaction hydrogenation, adding extrasteps. It is also reported that said method suffers from functional group sensitivity, limiting substrate scope and introducing undesired side reactions.

[0006] In view of the above, it is observed that many C-H activation methods in the literature rely on expensive metal catalysts, and they often lead to alkenylation, requiring further steps to achieve alkylation. None of these methods allow for precise C-H editing, which limits their utility for introducing multiple functional groups in a controlled, stepwise manner.

[0007] Hence, there is a need for an environmentally friendly, selective, and cost-effective process that can directly alkylate aromatic compounds without requiring pre -functionalization or hazardous reagents.OBJECTIVE OF THE INVENTION

[0008] An objective of the present invention is to develop a new class of catalysts based on metal-fluorenyl complexes (such as cobalt, iron, and manganese) that allow for selective C-H alkylation of aromatic compounds.

[0009] An objective of the present invention is to achieve high selectivity and yield in the alkylation of arenes, eliminating polysubstitution or polyalkylation issues common with Friedel-Crafts alkylation.

[0010] An objective of the present invention is to eliminate the need for expensive palladium catalysts and environmentally harmful solvents, using instead inexpensive and greener alternatives like methanol and THF.

[0011] An objective of the present invention is to enable C-H editing by developing the catalysts which allow controlled, stepwise substitution of multiple hydrogens in an aromatic ring, making it possible to attach different alkyl groups with precision.

[0012] An objective of the present invention is to reduce environmental impact by using recyclable catalysts and minimizing waste production.

[0013] An objective of the present invention is to enable industrial-scale production through catalyst recyclability and operational simplicity under mild conditions, making the process scalable and cost-effective.SUMMARY OF THE INVENTION

[0014] The major aspect of the present invention, is to provide a novel method for C-H alkylation and C-H editing of arenes, using catalysts based on metals like cobalt, iron, ormanganese coordinated with fluorenyl ligands. These catalysts offer several benefits over conventional methods

[0015] In an aspect of the present invention, it discloses a method for preparing a [Co(r|5-Fluorenyl)-(p2-OH)]2 catalyst, the method comprising: i. dissolving Fluorene in methanol; ii. preparing three equivalents of NaOH ( 0.3 mole, 12 gm) solution in 100 mL of methanol followed by adding one equivalent of fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Co(II)X.nH2O, wherein, n is selected from 0 or 6 to the Na-fluorenide solution; iv. stirring the mixture until the solution changes color from blue or pink to dark reddish- orange followed by filtering the mixture obtained from step (iv) to obtain a filtrate; v. concentrating the filtrate under inert conditions and washing the residue with hexane; and vi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol to obtain solvated catalyst complex [Co(r|1-Fluorenyl)-(p2-OH)]2.4(MeOH).

[0016] In another embodiment, A method for preparing a [Fe(r|5-Fluorenyl)-(p2-OH)]2 catalyst, the method comprising the steps of: i. dissolving fluorene in methanol ii. preparing three equivalents of NaOH (0.3 mole, 12 gm) solution in 100 mL of methanol followed by adding one equivalent of fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Fe(II)X.nH2O, wherein, n is selected from 0 or 7 to the Na-fluorenide solution; iv. stirring the mixture until the solution changes color from greenish red to reddish- orange followed by filtering the mixture obtained from step (iv) to obtain a filtrate; v. concentrating the filtrate under inert conditions and washing the residue with hexane; and vi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol to get solvated catalyst complex [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH).

[0017] In another embodiment, the present invention discloses a method for preparing a [Mn(r|5-Fluorenyl) -(p2-OH)]2catalyst, the method comprising: i. dissolving fluorene in methanolii. preparing three equivalents of NaOH (0.3 mole, 12 gm) solution in 100 mL of methanol followed by adding one equivalent of fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Mn(II)X.nH20, wherein, n is selected from 0 or 6 to the Na-fluorenide solution; iv. stirring the mixture until the solution changes color from green to dark reddish-orange followed by filtering the mixture obtained from step (iv) to obtain a filtrate; v. concentrating the filtrate under inert conditions and washing the residue with hexane; and vi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol to get solvated catalyst complex [Mn(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH).

[0018] In another embodiment, the present invention discloses method for preparing a [Co(r|5-Fluorenyl)-(p2-OH)]2catalyst, the method comprising: i. dissolving one equivalent of fluorene (0.1 mole, 16.6 gm) in 100 mL methanol; ii. adding three equivalents of sodium (0.3 mole, 7.0 gm) to form Na-fluorenide; iii. adding a ferric salt selected from FeX; iv. stirring the mixture at a temperature ranging from 10-30 °C for the time ranging from 7-10 hours until the solution changes color from brown to reddish-orange for the mixture having one equivalent of Co(III) salts (0.1 mole); v. filtering the mixture obtained from step (iv) to remove insoluble salts followed by concentrating the filtrate on rota vapour; vi. washing the residue with hexane; and vii. dissolving the purified catalyst in methanol to get solvated catalyst complex [CoCq1- Fluorenyl)-(p2-OH)]2.4(MeOH).

[0019] In another embodiment, present invention discloses a method for preparing a [Fe(r|5- Fluorenyl)-(p2-OH)]2catalyst, the method comprising: i. dissolving one equivalent of Fluorene (0.1 mole, 16.6 gm) in 100 mL methanol; ii. adding three equivalents of sodium (0.3 mole, 7.0 gm) to form Na-fluorenide; iii. adding a ferric salt selected from FeX, iv. stirring the mixture at a temperature ranging from 10-30 °C for the time ranging from 7-10 hours until the solution changes color from brown to reddish-orange for the mixture having one equivalent of Fe(III) salts (0.1 mole); v. filtering the mixture obtained from step (iv) to remove insoluble salts followed by concentrating the filtrate on rota vapour;vi. washing the residue with hexane; and viii. dissolving the purified catalyst in methanol to get solvated catalyst complex | Fc(r]' - Fluorenyl)-(p2-OH)]2.2(MeOH).

[0020] In another embodiment, present invention discloses a method for preparing a [Mn(r|5- Fluorenyl)-(p2-OH)]2.2Na catalyst, the method comprising: i. dissolving fluorene in methanol and adding sodium to form Na-fluorenide; adding a manganese salt selected from MnX, wherein X is selected from Cl2, Br2, (NO2)2, (SO4), or (acac)2and n is selected from 0 or 6) to the Na-fluorenide solution; ii. stirring the mixture at 40°C until the solution changes color from pinkish white to yellowish-orange or color from pink to dark reddish-orange; iii. filtering the formed catalyst to remove insoluble salts followed by concentrating the filtrate under inert conditions; iv. washing the residue with hexane; and vii. obtaining the catalyst by dissolving the purified residue in methanol to get solvated catalyst complex [Mn^1-Fluorenyl) -(p2-OH)]2.2(MeOH).

[0021] In another embodiment, present invention discloses a method for performing C-H alkylation of arenes, the method comprising: i. dissolving sodium acetate in methanol; ii. adding a catalyst selected from [Co(r|5-Fluorenyl)-(p2-OH)]2, [Fe(r|5-Fluorenyl)-(p2- OH)]2, or [Mn(r|5-Fluorenyl)-(p2-OH)]2 iii. adding arenes and alkyl halides to a solvent mixture of methanol and THF at a methanol-to-THF in the ratio range of 1:3; iv. stirring the mixture at 65 °C for 9-12 hours to yield mono C-H alkylated products; evaporating the solvent under vacuum; v. purifying the crude product by column chromatography if required; and vi. obtaining the catalyst from methanol for further reuse.

[0022] In another embodiment, present invention discloses a method for performing C-H alkylation of arenes under non-inert conditions, the method comprising: i. dissolving sodium acetate in methanol; ii. adding arenes, alkyl halides, and a catalyst selected from [Co(r|5-Fluorenyl)-(p2- OH)]2, [Fe(r|5-Fluorenyl)-(p2-OH)]2, or [Mn(r|5-Fluorenyl)-(p2-OH)]2 to a methanol-THF mixture; iii. stirring the reaction mixture at 65°C for 9-12 hours in the absence of inert atmosphere;iv. evaporating the solvent under vacuum; v. purifying the reaction product by column chromatography; and vi. obtaining the catalyst using methanol for further reuse.

[0023] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.BRIEF DESCRIPTION OF FIGURES

[0024] The accompanying drawings are included to provide a clear understanding of the present invention and a detailed description, and they constitute a part of this complete specification.

[0025] FIG. 1 illustrates 1H NMR spectrum of [Co(r|l -Fluorenyl) -(p2-OH)]2.4(MeOH) Catalyst.

[0026] FIG. 2 shows 13C NMR spectrum [Co(r|l-Fluorenyl)-(p2- OH)]2.4(MeOH) Catalyst

[0027] FIG. 3 shows HRMS spectrum of [Co(r|1-Fluorenyl)-(p2- OH)]2.4(MeOH) Catalyst.

[0028] FIG. 4 discloses EPR spectrm of [Co(r|l-Fluorenyl)-(p2- OH)]2.4(MeOH) Catalyst

[0029] FIG. 5 shows 'id NMR spectrum of [Fe(r|1-Fluorenyl)-(p2- OH)]2.2(MeOH) Catalysts.

[0030] FIG. 6 shows Figure 6.13C NMR spectrum of [Fe(r|1-Fluorenyl)-(p2- OH)]2.2(MeOH) Catalyst

[0031] FIG. 7 shows Figure 7. HRMS spectrum of [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) Catalyst.

[0032] FIG. 8 shows Figure 8. EPR spectrum of [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) Catalyst

[0033] FIG. 9 shows Figure 9. 'id NMR spectrum of [Mn(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) catalyst

[0034] FIG. 10 displays13C NMR spectrum of [Mn(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) Catalyst.

[0035] FIG. 11 displays HRMS spectrum of [Mn(r|1-Fluorenyl)-(p2-OH)]2,2(MeOH) Catalyst.

[0036] FIG. 12 displays EPR spectrum of [Mn(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) Catalyst

[0037] FIG. 13 displays: Figure 13 [Co(r|1-Fluorenyl)-(p2-OH)]2.4(MeOH), | Fc(ii'- Fluorenyl)-(p2-OH)]2.2(MeOH) and [Mn(r|1-Fluorenyl)-(p2-OH)]2,2(MeOH) catalysts in methanol.

[0038] FIG. 14 displays TLC of compound A-F (TLC in Hexane)

[0039] FIG. 15 displays TLC of compound G-L (TLC in Hexane)

[0040] FIG. 16 displays TLC of compound M-R (TLC in Hexane)DETAILED DESCRIPTION OF THE INVENTION

[0041] The following is a full description of the disclosure's embodiments. The embodiments are described in such a way that the disclosure is clearly communicated. The level of detail provided, on the other hand, is not meant to limit the expected variations of embodiments; rather, it is designed to include all modifications, equivalents, and alternatives that come within the spirit and scope of the current disclosure as defined by the attached claims. Unless the context indicates otherwise, the term "comprise" and variants such as "comprises" and "comprising" throughout the specification are to be read in an open, inclusive meaning, that is, as "including, but not limited to."

[0042] When "one embodiment" or "an embodiment" is used in this specification, it signifies that a particular feature, structure, or characteristic described in conjunction with the embodiment is present in at least one embodiment. As a result, the expressions "in one embodiment" and "in an embodiment" that appear throughout this specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, the specific features, structures, or qualities may be combined in any way that is appropriate.

[0043] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.

[0044] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference.

[0045] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations.

[0046] It should also be appreciated that the present invention can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to asprocesses. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.

[0047] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.Definitions:

[0048] For the purpose of the present invention, C-H Alkylation may be defined as a chemical reaction in which an alkyl group (a saturated hydrocarbon group with or without other functionalities) is introduced into an aromatic ring by breaking a carbon-hydrogen (C- H) bond and forming a new carbon-carbon bond.

[0049] For the purpose of the present invention, C-H Editing may be defined as a highly selective process for replacing multiple hydrogen atoms in an aromatic ring with different functional groups, allowing for stepwise functionalization of the molecule.

[0050] For the purpose of the present invention, Metal-Fluorenyl Catalysts may be defined as catalysts that consist of a transition metal (such as cobalt, iron, or manganese) coordinated with a fluorenyl and hydroxy ligands. These catalysts promote selective C-H alkylation and editing of arenes.

[0051] For the purpose of the present invention, Non-Directing Alkylation may be defined as a type of alkylation reaction where no additional functional groups (directing groups) are required to control the position of alkylation on the aromatic ring.

[0052] For the purpose of the present invention, green solvents may be defined as the solvents that have a lower environmental impact, such as methanol and THF, as opposed to harmful solvents like dichloromethane or chloroform.

[0053] In a general embodiment, the present invention relates to a method for preparing a [Co(r|5-Fluorenyl) -(p2-OH)]2 or [CoO^-Fluorenyl) -(p2-OH)]2.4(MeOH) catalyst, the method comprising: i. dissolving Fluorene in methanol; ii. preparing three equivalents of NaOH (0.3 mole, 12 gm) solution in 100 m of methanol followed by adding one equivalent of Fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Co(II)X.nH2O, wherein, n is selected from 0 or 6 to the Na-fluorenide solution;iv. stirring the mixture until the solution changes color from blue or pink to dark reddish- orange followed by filtering the mixture obtained from step (iv) to obtain a filtrate; v. concentrating the filtrate under inert conditions and washing the residue with hexane; and vi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol to get stable catalyst complex [Co^1-Fluorenyl) -(p2-OH)]2.4(MeOH)

[0054] In another embodiment, said cobalt salt is selected from Co(II).

[0055] In another embodiment, the amount of NaOH and methanol ranges from 12 gm and 100 mb respectively

[0056] In another embodiment, the amount of fluorene ranges from 16.6 gm to obtain Na- fluorenide.

[0057] In another embodiment, the amount of cobalt salt ranges from 0.1 mole (23.8 for C0CI2 6H2O; 25.72 for Co(acetylacetonate)2; 29.1 for Co(NC>3)2-6 H2O; 21.9 gm for CoBr2nH2O 28. 1 gm for COSO4 7H2O) to obtain a filtrate.

[0058] In another embodiment, the cobalt is selected from CoX, wherein X is selected from Cl2, Br2, (NO2)2, SO4, or (acetylacetonate)2.

[0059] In another embodiment, stirring of the mixture is performed at the temperature ranging from 40-50°C for the time ranging from 10-14 hours.

[0060] In another embodiment, the shelf life of 5%-40 % methanol solution of | Co(ii '- Fluorenyl) -(p2-OH)]2.4(MeOH) catalyst ranges from 3-4 months at room temperature.

[0061] In a general embodiment, the present invention relates to a method for preparing a [Fe(r|5-Fluorenyl) -(p2-OH)]2or [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) catalyst, the method comprising: i. dissolving fluorene in methanol ii. preparing three equivalents of NaOH (0.3 mole, 12 gm) solution in 100 mb of methanol followed by adding one equivalent of Fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Fe(II)X.nH2O, wherein, n is selected from 0 or 7 to the Na-fluorenide solution; iv. stirring the mixture until the solution changes color from pink or green to dark reddish-orange followed by fdtering the mixture obtained from step (iv) to obtain a filtrate; v. concentrating the filtrate under inert conditions and washing the residue with hexane; andvi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol to get stable catalyst complex | Fc(r|' -Flnorcny 1 ) -(p2-OH)]2.2(MeOH)

[0062] In another embodiment, the said iron salt is selected from Fe(II) or a combination thereof.

[0063] In another embodiment, the amount of NaOH and methanol ranges from 12 gm and 100 mL respectively

[0064] In another embodiment, the amount of fluorene ranges from 16.6 gm to obtain Na- fluorenide.

[0065] In another embodiment, the amount of iron salt ranges from 0.1 mole (19.9 gm for FeCl24H2O; 17.4 gm for Fe(II)acetate; 27.8 gm for FeSCL 7H2O; 21.6 gm for FeBr2) to obtain a fdtrate.

[0066] In another embodiment, the cobalt is selected from CoX, wherein X is selected from Cl2, Br2, (NO2)2, (SO4), or (acetate)2.

[0067] In another embodiment, the stirring of the mixture is performed at the temperature ranging from 40-50°C for the time ranging from 10-14 hours.

[0068] In another embodiment, the shelf life of 5%-40 % methanol solution of | Fc(i^' - Fluorenyl) -(p2-OH)]2.2(MeOH) catalyst ranges from 3-4 months at room temperature.

[0069] In a general embodiment, the present invention relates to a method for preparing a [Mn(r|5-Fluorenyl)-(p2-OH)]2or | Mn(i]' -Fluorenyl) -(p2-OH)]2.2(MeOH) catalyst, the method comprising: i. dissolving fluorene in methanol ii. preparing three equivalents of NaOH (0.3 mole, 12 gm) solution in 100 mL of methanol followed by adding one equivalent of Fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Mn(II)X.nH20, wherein, n is selected from 0 or 6 to the Na-fluorenide solution; iv. stirring the mixture until the solution changes color from green to dark reddish-orange followed by filtering the mixture obtained from step (iv) to obtain a filtrate; v. concentrating the filtrate under inert conditions and washing the residue with hexane; and vi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol to obtain stable catalyst complex [Mn(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH)

[0070] In another embodiment, said manganese salt is selected from Mn(II) or a combination thereof.

[0071] In another embodiment, the amount of NaOH and methanol ranges from 12 gm and 100 mL respectively

[0072] In another embodiment, the amount of fluorene ranges from 16.6 gm to obtain Na- fluorenide.

[0073] In another embodiment, the amount of manganese salt ranges from 0.1 mole (12.58 gm for MnCl2; 24.51 gm for Mn(II)acetate.4H2O; 16.9 gm for MnSO4 H2O; 28.7 gm for MnBr2-4H2O; 25.3 gm for Mn(II)acetylacetonate) to obtain a fdtrate.

[0074] In another embodiment, the manganese is selected from MnX, wherein X is selected from Cl2, Br2, (NO2)2, SO4, (acac)2or (acetate)2.

[0075] In another embodiment, stirring of the mixture is performed at the temperature ranging from 40-50 °C for the time ranging from 10-14 hours.

[0076] In another embodiment, the shelf life of 5%-40 % methanol solution of [Mn(r|5- Fluorenyl)-(p2-OH)]2or [Mn(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) catalyst ranges from 3-4 months at room temperature.

[0077] In a general embodiment, the present invention relates to a method for preparing a [Co(r|5-Fluorenyl)-(p2-OH)]2or | Co(r]1-Fluorenyl) -(p2-OH)]2.4(MeOH) catalyst, the method comprising: i. dissolving one equivalent of Fluorene (0.1 mole, 16.6 gm) in 100 mL methanol; ii. adding three equivalents of sodium (0.3 mole, 7.0 gm) to form Na-fluorenide; iii. adding a ferric salt selected from FeX; iv. stirring the mixture at a temperature ranging from 10-30 °C for the time ranging from 7-10 hours until the solution changes color from brown to reddish-orange for the mixture having one equivalent of Co(III) salts (0.1 mole); v. filtering the mixture obtained from step (iv) to remove insoluble salts followed by concentrating the filtrate on rota vapour; vi. washing the residue with hexane; and vii. dissolving the purified catalyst in methanol.

[0078] In a general embodiment, the present invention relates to a method for preparing a [Fe(r|5-Fluorenyl)-(p2-OH)]2or [Fe(r|1-Fluorenyl)-(p2-OH)]2.4(MeOH) catalyst, the method comprising: i. dissolving one equivalent of Fluorene (0.1 mole, 16.6 gm) in 100 mL methanol; ii. adding three equivalents of sodium (0.3 mole, 7.0 gm) to form Na-fluorenide; iii. adding a ferric salt selected from FeX,iv. stirring the mixture at a temperature ranging from 10-30 °C for the time ranging from 7-10 hours until the solution changes color from brown to reddish-orange for the mixture having one equivalent of Fe(III) salts (0.1 mole); v. filtering the mixture obtained from step (iv) to remove insoluble salts followed by concentrating the filtrate on rota vapour; vi. washing the residue with hexane; and vii. dissolving the purified catalyst in methanol.

[0079] In a general embodiment, the present invention relates to a method for preparing a [Mn(r|5-Fluorenyl)-(p2-OH)]2.2Na catalyst, the method comprising: i. dissolving fluorene in methanol and adding sodium to form Na-fluorenide; adding a manganese salt selected from MnX, wherein X is selected from Cb, Br2, (NO3)2, or (acac)2 and n is selected from 0 or 6) to the Na-fluorenide solution; ii. stirring the mixture at 40°C until the solution changes color from pinkish white to yellowish-orange or color from pink to dark reddish-orange; iii. filtering the formed catalyst to remove insoluble salts followed by concentrating the filtrate under inert conditions; iv. washing the residue with hexane; and v. obtaining the catalyst by dissolving the purified residue in methanol.

[0080] In a general embodiment, the present invention relates to a method for performing C- H alkylation of arenes, the method comprising: i. dissolving sodium acetate in methanol; ii. adding a catalyst selected from [Co(T|5-Fluorenyl)-(p2-OH)]2or [Co(r|1-Fluorenyl)-(p2- OH)h 4(MeOH), [Fe(r|5-Fluorenyl)-(p2-OH)]2 or [Fe(r|1-Fluorenyl)-(p2- OH)]2.2(MeOH), or [Mn(r|5-Fluorenyl)-(p2-OH)]2 or [Mn(r|1-Fluorenyl)-(p2- OH)]2.2(MeOH) iii. adding arenes and alkyl halides to a solvent mixture of methanol and THF at a methanol-to-THF in the ratio range of 1:3; iv. stirring the mixture at 65 °C for 9-12 hours to yield mono C-H alkylated products; evaporating the solvent under vacuum; v. purifying the crude product by column chromatography if required; and vi. obtaining the catalyst from methanol for further reuse.

[0081] In a general embodiment, the present invention relates to a method for performing C- H alkylation of arenes under non-inert conditions, the method comprising:i. dissolving sodium acetate in methanol from [Co(T|5-Fluorenyl)-(p2-OH)]2or [CoCq1- Fluorenyl)-(p2-OH)]2.4(MeOH), [Fe(r|5-Fluorenyl)-(p2-OH)]2 or | Fc(r] -Fliiorcnyl)- (p2-OH)]2.2(MeOH), or [Mn(T|5-Fluorenyl)-(p2-OH)]2or [Mn(r|1-Fluorenyl)-(|i2- OH)]2.2(MeOH) to a methanol-THF mixture; ii. stirring the reaction mixture at 65°C for 9-12 hours in the absence of inert atmosphere; iii. evaporating the solvent under vacuum; iv. purifying the reaction product by column chromatography; and v. obtaining the catalyst using methanol for further reuse.

[0082] In another embodiment, the methanol-to-THF ratio is 1:3.

[0083] In another embodiment, the reaction is carried out without dry conditions and inert atmosphere.

[0084] In a general embodiment, the present invention relates to a method for preparing and storing metal-fluorenyl catalysts, the method comprising: i. synthesizing the catalyst using Na-fluorenide and metal salts selected from cobalt, iron, and manganese salts; ii. purifying the catalyst by fdtering and washing with hexane; iii. characterizing the catalyst by NMR, HRMS, and EPR; and iv. storing the catalyst in methanol for future use.

[0085] In a general embodiment, the present invention relates to a metal-fluorenyl catalyst having the general formula [M(T|5-Fluorenyl)-(p2-OH)]2or [M(r|5-Fluorenyl)-(p2- OH)]2.X(MeOH), wherein M is selected from the group consisting of cobalt (Co), iron (Fe), and manganese (Mn) and X ranges from 2 to 4.

[0086] In another embodiment, wherein M is cobalt (Co) and the catalyst is [Co(r|5- Fluorenyl)-(p2-OH)]2 or is [Co(r|1-Fluorenyl)-(p2-OH)]2.4(MeOH).

[0087] In another embodiment, wherein M is iron (Fe) and the catalyst is [Fe(r|5-Fluorenyl)- (p2-OH)]2or [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH).

[0088] In another embodiment, wherein M is manganese (Mn) and the catalyst is [Mn(r|5- Fluorenyl)-(p2-OH)]2or | Mn(r|l-Fhiorcnyl)-(p2-OH)|2.2(McOH).

[0089] Accordingly, in an exemplary embodiment, present invention provides a metal- fluorenyl catalyst, where the metal is selected from cobalt (Co), iron (Fe), or manganese (Mn), is coordinated with fluorenyl and hydroxy ligands. These catalysts are prepared through a process that involves complexing the metal with a Na-fluorenide ligand in the presence of a suitable solvent such as THF or methanol. The resulting catalyst is air- andmoisture-stable, requiring no special handling or inert atmosphere for storage or use. The catalyst loading required for aromatic alkylation reactions is only 3-5 mol%, making it cost- effective for industrial applications. It can also be recovered and reused multiple times without a loss of activity.

[0090] In an exemplary embodiment, present invention describes the selective C-H alkylation of aromatic compounds, using the metal-fluorenyl. The process involves reacting an aromatic substrate such as benzene, toluene, or xylene and many other with an alkylating agent, such as an alkyl halide with different functionalities, in the presence of the metal-fluorenyl catalyst.

[0091] The reaction is carried out at mild temperatures between 60-65°C, avoiding the extreme conditions required by traditional methods like Friedel-Crafts alkylation.

[0092] The reaction results in the selective mono-alkylation of the aromatic ring, with yields of 93-98%. Importantly, the process avoids polysubstitution and polyalkylation, which are common issues with existing methods.

[0093] In an exemplary embodiment, present invention provides a unique feature of the invention, this embodiment allows for the stepwise replacement of multiple hydrogen atoms on an aromatic ring with different alkyl groups. This process, referred to as C-H editing, enables precise control over the introduction of alkyl substituents. The catalyst enables selective mono-alkylation in the first step and additional steps allow for the sequential replacement of remaining C-H bonds with different alkyl groups, providing flexibility in functionalizing the aromatic ring.

[0094] This stepwise process offers precise control, allowing the reaction to stop after each alkylation step, making it possible to design and synthesize highly functionalized aromatic compounds.

[0095] In an exemplary embodiment, present invention demonstrates excellent performance in green solvents, particularly methanol and THF. These solvents are used as alternatives to halogenated solvents such as dichloromethane, which are traditionally used in Friedel-Crafts reactions but pose significant environmental hazards.

[0096] The reaction operates effectively in methanol or THF at temperatures around 60- 65 °C. Both solvents are commercially available and easy to handle, contributing to the greener, more sustainable nature of the process. By-products of the reaction include only NaCl / NaBr and acetic acid, which are environmentally benign and easy to dispose of or reuse in subsequent reactions.

[0097] Further, the invention addresses the recyclability of the catalyst, an important feature for industrial scalability. After each alkylation or C-H editing cycle the catalyst can be recovered through simple filtration or extraction processes and can be reused for multiple reaction cycles without any significant loss of activity or selectivity, reducing the overall cost of production.

[0098] Nevertheless, this recyclability makes the invention highly suitable for large-scale industrial applications, particularly in industries that require the production of alkylated aromatic compounds in high volumes.

[0099] In an exemplary embodiment, the invention is not limited to benzene but can be applied to a wide range of aromatic compounds. This includes, but is not limited to substituted benzenes such as toluene, xylene, and mesitylene; more complex arenes like naphthalene and anthracene.

[0100] The catalysts show excellent tolerance for various functional groups on the aromatic ring, maintaining high selectivity for C-H alkylation even in the presence of reactive functional groups.

[0101] In an exemplary embodiment, present invention focuses on the potential industrial applications of the invention. The process is particularly suitable for the production of alkylbenzenes (e.g., ethylbenzene, cumene), which are widely used in the petrochemical industry, the synthesis of pharmaceutical intermediates, where precise functionalization of aromatic rings is crucial and the perfume and flavor industry, where the introduction of alkyl groups into aromatic molecules is often required to achieve desired olfactory or taste properties.

[0102] The catalysts' cost-effectiveness, recyclability, and use of green solvents make the process highly attractive for large-scale commercial production.

[0103] These embodiments highlight the versatility, environmental benefits, and practical advantages of this invention across various fields. The process can be tailored to meet specific industrial needs, offering a significant improvement over traditional alkylation method.

[0104] Accordingly, the present invention discloses a novel method for C-H alkylation and C-H editing of arenes, using catalysts based on metals like cobalt, iron, or manganese coordinated with fluorenyl ligands. These catalysts offer several benefits over conventional methods, including:-Inexpensive and air-stable catalysts that require only 3-5 mol% loading, making them commercially viable.-The ability to operate in green solvents such as methanol and tetrahydrofuran (THF), which are less harmful to the environment compared to traditional solvents used in Friedel-Crafts alkylation.-Selective and high-yielding C-H alkylation that generates mono-alkylated products in yields of 93-98%.-No hazardous waste generation: Only NaCl / NaBr and acetic acid are formed as by-products, which are environmentally benign.-Catalyst recyclability, allowing for multiple reaction cycles without loss of efficiency or selectivity.-C-H editing capabilities, which enable the stepwise replacement of multiple hydrogen atoms in an aromatic ring, allowing for the selective introduction of different alkyl groups in a controlled manner, something that has not been achieved by any existing catalyst system.

[0105] These features make the invention particularly suitable for large-scale industrial applications, where cost-effectiveness and sustainability are crucial.

[0106] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions, or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.EXAMPLES

[0107] The present invention is further explained in the form of the following examples. However, it is to be understood that the following examples are merely illustrative and are not to be taken as limitations upon the scope of the invention.

[0108] All the raw materials used in this invention are commercially available in the open markets and can be procured easily.Example 1: Material Synthesis: Synthesis of ZIF-8 for Synthesis of catalysts:Method I: Preparation of Co(r|5-Fluorenyl)-(p2-OH)]2or [Co(r|1-Fluorenyl)-(p2- OH)]2.4(MeOH).Catalyst from Co(III) salts

[0109] To a solution of Fluorene (1 equiv.) in methanol, sodium (3 equiv.) was added and stirred to get clear solution of Na-fluorenide. Moving further, CoX: nH20 salts (X =C13, Br3, (NO2)3J(SO4), (acac)3etc. and n = 0,6) (1 equiv.) was added to Na-fluorenide solutionand stirred until the colour of the solution changed from blue / pink to dark reddish orange at 40 °C. The progress of the reaction was monitored using TLC. Once the Co(r|5-Fluorenyl)- (p2-OH)]2or [Co(T|1-Fluorenyl)-(p2-OH)]2.4(MeOH) was formed, a sintered glass column was used to fdter the catalyst to remove insoluble salts and then concentrated on a rotary vacuum under inert conditions to avoid rapid flow of air. The dried residue was washed with hexane until traces of unreacted fluorene were removed. The purified catalyst was then weighed and dissolved in methanol. It was subsequently stored for use in further catalysis applications. The catalyst was characterized by using NMR, HRMS and EPR.Example 2: Method II:Preparation of [Co(r|3-Fluorenyl)-(p2-OH)]2catalyst from Co(II) salts

[0110] To methanol solution of NaOH (3 equiv.), fluorene ( 1 equiv.) was added and stirred until a clear solution of Na-fluorenide obtained. Then CoX: nH20 salts (X =C12, Br2, SO4, (NO2)3etc and n = 0,6) (1 equiv.) was added to solution of Na-fluorenide and stirred until the colour of the solution changed from pink to dark reddish orange. The progress of the reaction was monitored using TLC. Once the [Co(r|3-Fluorenyl)-(p2-OH)]2catalyst was formed, a sintered glass column was used to filter the catalyst to remove salts formed in the reaction and then concentrated on a rotary vacuum under inert conditions to avoid rapid flow of air. The dried residue was washed with hexane until traces of unreacted fluorene were removed. The purified catalyst was then weighed and dissolved in methanol. It was subsequently stored for use in further catalysis applications. The catalyst was characterized by using NMR (FIG. 1-2), HRMS (FIG. 3) and EPR (FIG. 4)Example 3: Method I: Preparation of [Fe(q3-Fluorenyl)-(ji2-OH)]2 Catalyst from Fe(III) salts:

[0111] To a solution of Fluorene (1 equiv.) in methanol, sodium (2.5 equiv. ) was added and stirred to get clear solution of Na-fluorenide. Then Then FeX: nH20 salts (X =C13, Br3,(NO2 (acac)s etc and n = 0,6) (1 equiv.) was added to Na-fluorenide solution and stirred until the colour of the solution changed from brownish red to yellowish orange at 40 °C. The progress of the reaction was monitored using TLC. Once the [Fe(r|3-Fluorenyl)-(p2-OH)]2catalyst was formed, a sintered glass column was used to fdter the catalyst to remove insoluble salts and then concentrated on a rotary vacuum under inert conditions to avoid rapid flow of air. The dried residue was washed with hexane until traces of unreacted fluorene were removed. The purified catalyst was then weighed and dissolved in methanol. It was subsequently stored for use in further catalysis applications. The catalyst was characterized by using NMR (FIG. 5-6), HRMS (FIG. 7) and EPR (FIG. 8)Example 4: Method II: Preparation of [Fe(q5-Fluorenyl)-(ji2-OH)]2or [Fe(q1-Fluorenyl)- (p2-OH)|2.2(MeOH) catalyst from Fe(II) sails

[0112] To methanol solution of NaOH (3 equiv.), fluorene ( 1 equiv.) was added and stirred until a clear solution of Na-fluorenide obtained. Then FeX: nH2O salts (X =C12, Br2, SO4, NO2, (acac)2, (acetate)2etc and n = O, 4) (1 equiv.) was added to solution of Na- fluorenide and stirred until the colour of the solution changed from pink to dark reddish orange. The progress of the reaction was monitored using TLC. Once the [Fe(r|5-Fluorenyl)- (p2-OH)]2or [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) catalyst was formed, a sintered glass column was used to filter the catalyst to remove salts formed in the reaction and then concentrated on a rotary vacuum under inert conditions to avoid rapid flow of air. The dried residue was washed with hexane until traces of unreacted fluorene were removed. The purified catalyst was then weighed and dissolved in methanol. It was subsequently stored for use in further catalysis applications. The catalyst was characterized by using NMR, HRMS and EPR.Example 5: Method I: Preparation of [Mn(q5-Fluorenyl)-(p2-OH)]2or [Mn(i - Fluorenyl)-(p2-OH)|2.2(MeOH) Catalyst from Mn(II)salts

[0113] To a solution of Fluorene (1 equiv.) in methanol, Na (3 equiv. ) was added and stirred to get clear solution of Na-fluorenide. Then MnX:nH20 (X = Cl2, Br2, (NO2)2JSO4,(acetate)2, (acac)2 etc and n = 0,6) (1 equiv. ) was added to Na-fluorenide solution and stirred until the colour of the solution changed from brownish red to yellowish orange at 40 °C. The progress of the reaction was monitored using TLC. Once the [Mn(r|5-Fluorenyl)-(p2- OH)]2or [Mn(T|1-Fluorenyl)-(p2-OH)]2.2(MeOH) catalyst was formed, a sintered glass column was used to filter the catalyst to remove insoluble salts and then concentrated on a rotary vacuum under inert conditions to avoid rapid flow of air. The dried residue was washed with hexane until traces of unreacted fluorene were removed. The purified catalyst was then weighed and dissolved in methanol. It was subsequently stored for use in further catalysis applications. The catalyst was characterized by using NMR, HRMS and EPR.Example 6: Method II: Preparation [Mn(q5-Fluorenyl)-(p2-OH)|2 or [Mn(q’-Fluorenyl)- (p2-OH)|2.2(MeOH) catalyst from Mn (II) Salts

[0114] To methanol solution of NaOH (3 equiv.), fluorene ( 1 equiv.) was added and stirred until a clear solution of Na-fluorenide obtained. Then MnX:nH20 salts (X =C12, Br2, SO4, (NO3)2, (acetate)2, (acac)2 etc) (1 equiv.) was added to solution of Na-fluorenide and stirred until the colour of the solution changed from pink to dark reddish orange. The progress of the reaction was monitored using TLC. Once the [Mn(r|5-Fluorenyl)-(p2-OH)]2 or [Mn(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) catalyst was formed, a sintered glass column was used to fdter the catalyst to remove salts formed in the reaction and then concentrated on a rotary vacuum under inert conditions to avoid rapid flow of air. The dried residue was washed with hexane until traces of unreacted fluorene were removed. The purified catalyst was then weighed and dissolved in methanol. It was subsequently stored for use in further catalysis applications. The catalyst was characterized by using NMR (FIG. 9-10), HRMS (FIG. 11) and EPR (FIG. 12)Example: 7 Synthesis of C-H alkylated arenes:

[0115] In a reaction tube, sodium acetate (1 equiv.) was dissolved in one-third methanol. To this solution, a catalyst [Co(r|5-Fluorenyl)-(p2-OH)]2 or [Co(r|1-Fluorenyl)-(p2- OH)]2-4(MeOH) / [Fe(r|5-Fluorenyl)-(p2-OH)]2 or [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) / [Mn(q5-Fluorenyl)-(p2-OH)]2or [Mn(q1-Fluorenyl)-(p2-OH)]2.2(MeOH) (2-5 mol%) was added, followed by addition of arenes (1 equiv.) and an alkyl halide (1 equiv.) in two-thirds of THF, maintaining a methanol-to-THF ratio of 1:3. This reaction continued under the absence of any inter atmosphere or dry conditions. The reaction mixture was stirred at 65 °C for 9-12 hours to yield the mono C-H alkylated products. The progress of the reaction was monitored by thin-layer chromatography. Upon completion, the solvent was evaporated under vacuum, and the residue was adsorbed directly onto silica or alumina for column chromatography. The crude product was then purified by column chromatography using a 2.5% hexane / ethyl acetate mixture as the eluent. The catalyst was recovered by using methanol as the eluent and concentrated and stored under methanol. The products were characterized by 'H and13C-NMR and HRMS.

[0116] Example 8: General Procedures for C-H alkylation of Naphthalene and Benzene1 equiv. 1 equiv.Co(II): [Co(r]3-Fluorenyl)-(|r2-OH)]2Scheme 1. General Scheme for non-directing group C-H alkylation of naphthalene and benzene.C-H alkylation of naphthalene:C-H alkylation of benzene:C-H alkylation of substituted benzeneExample 9: C-H editing: A stepwise alkylation of arenes to get differently substituted multi-alkylated productsSynthesis of compound A-F (see FIG. 14 )Step-I: Synthesis of AIn a round-bottom flask covered with aluminum foil (to avoid light exposure of light sensitive cyclopropane and cyclobutane derivatives), a methanolic solution of sodium acetate (1 equiv.) was placed then [Co(r|3-Fluorenyl)-(p2-OH)]2 (2 mol%), benzene (1 equiv. ) andbromocyclopropane (11 equiv.) were added followed by the addition THF (three times that of methanol). The resulting solution stirred for 10 hours at 65 °C to get the C-H alkylated product, AStep-II Synthesis of compound BA methanolic solution of sodium acetate (1 equiv.) was added to the above reaction (Step I) mixture. Subsequently, bromocyclopentane (1 equiv.) was introduced. Then tetrahydrofuran (THF) in a volume three times that of the methanol was added to the reaction mixture. The resulting solution was stirred at 65°C for 10 hours to yield the C-H alkylated product, B. Step-Ill Synthesis of compound CA methanolic solution of sodium acetate (1 equiv.) was added to the above reaction (Step II) mixture. Subsequently, bromo-2f / -pyranc (1 equiv.) was introduced. Then tetrahydrofuran (THF) in a volume three times that of the methanol was added to the reaction mixture. The resulting solution was stirred at 65°C for 10 hours to yield the C-H alkylated product, C. Step-IV Synthesis of compound DA methanolic solution of sodium acetate (1 equiv.) was added to the above reaction (Step III) mixture. Subsequently, benzyl bromide (1 equiv.) was introduced. Then THF in a volume three times that of the methanol was added to the reaction mixture. The resulting solution was stirred at 65 °C for 10 hours to yield the C-H alkylated product, D.Step-V Synthesis of compound EA methanolic solution of sodium acetate (1 equiv.) was added to the above reaction (Step IV) mixture. Subsequently, bromocyclobutane (1 equiv.) was introduced. Then THF in a volume three times that of the methanol was added to the reaction mixture. The resulting solution was stirred at 65 °C for 10 hours to yield the C-H alkylated product, E Step-VI Synthesis of compound FA methanolic solution of sodium acetate (1 equiv.) was added to the above reaction (Step V) mixture. Subsequently, (chloromethyl)cyclopropane (1 equiv.) was introduced. Then THF in a volume three times that of the methanol was added to the reaction mixture. The resulting solution was stirred at 65°C for 10 hours to yield the C-H alkylated product, F.All products from steps I to VI were isolated and purified using column chromatography and their yields were analyzed using GC-MS.Reaction 2: The same reaction protocol was used as per Reaction 1 for the conversion (see Fig. 15 and 16).Reaction 3: The same reaction protocol was used as per Reaction 1 for the following conversion (see Fig. 15 and 16).Reaction-4 The same reaction protocol was used as per Reaction 1 for the following conversion (see Fig. 15 and 16).Procedure for C-H editing of naphthalene ringStep-I Synthesis of compound 3wIn a round-bottom flask which is covered with aluminium foil to avoid light exposure, sodium acetate (10 mmol, 1 equiv., 0.820 g) was placed and dissolved in 2.5 mL of methanol followed by the addition of Co(II) catalyst (2 mol%), naphthalene (10 mmol, 1 equiv. 1.28 gm) and chlorocyclopentane (10 mmol, 1 equiv., 1.04 gm). The resulting mixture was stirred in 7.5 mL THF for 9 hours at 65 °C to get the C-H alkylated product. (3w)Step-II Synthesis of compound 10Sodium acetate (10 mmol, 0.820 g) and 2-Chloro-2-methylpropane (10 mmol, 1 equiv., 0.928 gm) were added with 1.5 mL of MeOH, 3.5 mL THF and stirred the resulting reaction mixture 10 hours at 65 °C to get the respective C-H alkylated product (10). A 2.5 mL (300mg) aliquot of the reaction mixture was removed for further analysis.Step-Ill Synthesis of compound 11Sodium acetate (9 mmol, 0.7910 g) and (chloromethyl)cyclopropane (9 mmol, 1 equiv., 0.814 gm) were added with 1.5 mL of MeOH, 3.5 mL THF and stirred the resulting reaction mixture 10 hours at 65 °C to get respective C-H alkylated product (11). A 3 mL (314 mg) aliquot of the reaction mixture was removed for further analysis.Step-IV Synthesis of compound 12Sodium acetate (8 mmol, 0.656 g) and bromocyclopropane (8 mmol, 1 equiv., 0.967 gm) were added with 1.5 mL of MeOH, 3.5 mL THF and stirred the resulting reaction mixture 11 hours at 65 °C to get respective C-H alkylated product (12). A 3 mL aliquot of the reaction mixture was removed for further analysis.Step-V Synthesis of compound 13Sodium acetate (7.03 mmol, 0.576 g) and 4-chlorotctrahydro-2f / -pyran (7.03 mmol, 1 equiv., 0.843 gm) were added with 1.5 mL of MeOH, 3.5 mL THF and stirred the resulting reaction mixture 12 hours at 65 °C to get respective C-H alkylated product (13). A 3 mL aliquot of the reaction mixture was removed for further analysis.Step-VI Synthesis of compound 14Sodium acetate (6.13 mmol, 0.502 g) and 1 -bromopentene (6.13 mmol, 1 equiv., 0.894 gm) were added with 1.5 mL of MeOH, 3.5 mL THF and stirred the resulting reaction mixture 12 hours at 65 °C to get respective C-H alkylated product (14). A 3 mL aliquot of the reaction mixture was removed for further analysis.Step-VI Synthesis of compound 15Sodium acetate (5 mmol, 0.410 g) and 1 -bromoethanol (5 mmol, 1 equiv., 0.624 gm) were added with 1.5 mL of MeOH, 3.5 mL THF and stirred the resulting reaction mixture 12 hours at 65 °C to get respective C-H alkylated product (15). A 3 mL aliquot of the reaction mixture was removed for further analysis.Step-VI Synthesis of compound 16Sodium acetate (4.5 mmol, 0.369 g) and methyl-2-bromo-propionate (4.5 mmol, 1 equiv., 0.724 gm) were added with 1.5 mL of MeOH, 3.5 mL THF and stirred the resulting reaction mixture 13 hours at 65 °C to get respective C-H alkylated product.All products from steps 3w to 16 were isolated and purified using column chromatography and their yields were analyzed using GC-MS.

[0117] Accordingly, the present invention offers a groundbreaking approach to the alkylation and C-H editing of aromatic compounds, overcoming the significant limitations of traditional methods such as Friedel-Crafts alkylation and other carbon-carbon coupling reactions like Suzuki, Heck, and Negishi. Through the development of novel, air- and moisture-stable metal-fluorenyl catalysts based on cobalt, iron, or manganese, this process enables highly selective C-H alkylation under mild reaction conditions using environmentally friendly solvents like methanol and THF.

[0118] The foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.ADVANTAGES OF THE PRESENT INVENTION

[0119] The Low Catalyst Loading: The new catalysts require only 3-5 mol% loading, making them more cost-effective than traditional catalysts like AICT used in Friedel-Crafts reactions or palladium catalysts in coupling reactions.

[0120] Air and Moisture Stability: Unlike traditional catalysts that require extremely dry conditions or inert atmospheres, the metal-fluorenyl catalysts are stable in the presence of air and moisture, simplifying reaction setup and reducing operational costs.

[0121] Green Solvents: The invention operates efficiently in solvents like methanol and THF, which are both greener alternatives to chlorinated solvents (e.g., dichloromethane) used in traditional processes. This contributes to a safer and more environmentally friendly process.

[0122] Recyclability: The catalysts can be recovered and reused for multiple reaction cycles without any loss of activity or selectivity. This not only lowers operational costs but also reduces waste and makes the process suitable for large-scale industrial applications.

[0123] High Yield and Selectivity: The new method achieves mono-alkylation with a very high yield (93-98%), and more importantly, it avoids polysubstitution or polyalkylation, which are common drawbacks of traditional alkylation processes like Friedel-Crafts alkylation.

[0124] Stepwise C-H Editing: A unique feature of this invention is its ability to replace multiple hydrogen atoms on an aromatic ring with different functional groups in a controlled, stepwise manner. This is a significant advancement, as it allows for precise functionalization of arenes, which has not been achievable with other catalyst systems.

[0125] No Hazardous Waste: Traditional alkylation reactions produce large quantities of hazardous waste, such as metal hydroxide sludge, which require careful disposal. In contrast, the present invention generates only small amounts of NaCl / NaBr and acetic acid as by- products, which are easy to dispose of or reuse.

[0126] Mild Reaction Conditions: The reactions occur at temperatures around 60-65°C, in contrast to Friedel-Crafts reactions, which often require either sub-zero temperatures or very high temperatures. This reduces energy consumption and simplifies reaction conditions.

Claims

1. We Claim:

1. A method for preparing a [Co(r|5-Fluorenyl)-(p2-OH)]2or [Co(r|1-Fluorenyl)-(p2- OH)]2.4(MeOH) catalyst, the method comprising: i. dissolving Fluorene in methanol; ii. preparing three equivalents of NaOH (0.3 mole, 12 gm) solution in 100 mL of methanol followed by adding one equivalent of Fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Co(II)X.nH2O, wherein, n is selected from 0 or 6 to the Na-fluorenide solution; iv. stirring the mixture until the solution changes color from pink or green to dark reddish-orange followed by filtering the mixture obtained from step (iv) to obtain a fdtrate; v. concentrating the fdtrate under inert conditions and washing the residue with hexane; and vi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol.

2. The method as claimed in claim 1, wherein said cobalt salt is selected from Co(II).

3. The method as claimed in claim 1, wherein the amount of NaOH and methanol ranges from 12 gm and 100 mL respectively4. The method as claimed in claim 1, wherein the amount of fluorene ranges from 16.6 gm to obtain Na-fluorenide.

5. The method as claimed in claim 1, wherein the amount of cobalt salt ranges from 0.1 mole (23.8 for CoCl26H2O; 25.72 for Co(acetylacetonate)2; 29.1 for Co(NO3)2-6 H2O; 21.9 gm for CoBr2nH2O 28.1 gm for COSO4-7H2O) to obtain a fdtrate.

6. The method as claimed in claim 1, wherein the cobalt is selected from CoX, wherein X is selected from Cl2, Br2, (NO2)2, SO4, or (acetate)2, (acetylacetonate)2.

7. The method as claimed in claim 1, wherein stirring of the mixture performed at the temperature ranging from 40-50°C for the time ranging from 10-14 hours.

8. The method as claimed in claim 1, wherein the shelf life of 5%-40 % methanol solution of [Co(r|5-Fluorenyl)-(p2-OH)]2or [Co(r|1-Fluorenyl)-(p2-OH)]2.4(MeOH) catalyst ranges from 3-4 months at room temperature.

9. A method for preparing a [Fe(r|5-Fluorenyl)-(p2-OH)]2or [Fe(r|1-Fluorenyl)-(p2- OH)]2.2(MeOH) catalyst, the method comprising:i. dissolving fluorene in methanol ii. preparing three equivalents of NaOH (0.3 mole, 12 gm) solution in 100 mL of methanol followed by adding one equivalent of Fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Fe(II)X.nH2O, wherein, n is selected from 0 or 7 to the Na-fluorenide solution; iv. stirring the mixture until the solution changes color from pink or green to dark reddish-orange followed by filtering the mixture obtained from step (iv) to obtain a filtrate; v. concentrating the filtrate under inert conditions and washing the residue with hexane; and vi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol.

10. The method as claimed in claim 9, wherein said iron salt is selected from Fe(II) or a combination thereof.

11. The method as claimed in claim 9, wherein the amount of NaOH and methanol ranges from 12 gm and 100 mL respectively12. The method as claimed in claim 9, wherein the amount of fluorene ranges from 16.6 gm to obtain Na-fluorenide.

13. The method as claimed in claim 9, wherein the amount of iron salt ranges from 0.1 mole (19.9 gm for FeCl2• 4H2O; 17.4 gm for Fe(II)acetate; 27.8 gm for FeSO4 7H2O; 21.6 gm for FeBr2) to obtain a filtrate.

14. The method as claimed in claim 9, wherein the cobalt is selected from CoX, wherein X is selected from Cl2, Br2, (NO2)2, SO4, (acetate)2or (acac)2.

15. The method as claimed in claim 9, wherein stirring of the mixture performed at the temperature ranging from 40-50°C for the time ranging from 10-14 hours.

16. The method as claimed in claim 9, wherein the shelf life of 5%-40 % methanol solution of [Fe(r|5-Fluorenyl)-(p2-OH)]2or [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) catalyst ranges from 3-4 months at room temperature.

17. A method for preparing a [Mn(r|5-Fluorenyl)-(p2-OH)]2or [Mn(r|1-Fluorenyl)-(p2- OH)]2.2(MeOH) catalyst, the method comprising:

1. dissolving fluorene in methanol;ii. preparing three equivalents of NaOH (0.3 mole, 12 gm) solution in 100 mL of methanol followed by adding one equivalent of Fluorene (0.1 mole, 16.6 gm) to the NaOH solution to obtain Na-fluorenide in-sitw, iii. mixing Na-fluorenide with a one equivalent of cobalt salt selected from Mn(II)X.nH20, wherein, n is selected from 0 or 6 to the Na-fluorenide solution; iv. stirring the mixture until the solution changes color from green to dark reddish- orange followed by fdtering the mixture obtained from step (iv) to obtain a fdtrate; v. concentrating the fdtrate under inert conditions and washing the residue with hexane; and vi. obtaining the catalyst by dissolving the residue obtained from step (iv) in methanol.

18. The method as claimed in claim 17, wherein said manganese salt is selected from Mn(II) or a combination thereof.

19. The method as claimed in claim 17, wherein the amount of NaOH and methanol ranges from 12 gm and 100 mL respectively20. The method as claimed in claim 17, wherein the amount of fluorene ranges from 16.6 gm to obtain Na-fluorenide.

21. The method as claimed in claim 17, wherein the amount of manganese salt ranges from 0.1 mole (12.58 gm for MnCl2; 24.51 gm for Mn(II)acetate.4H2O; 16.9 gm for MnSO4'H2O; 28.7 gm for MnBr2-4H2O; 25.3 gm for Mn(II)acetylacetonate) to obtain a fdtrate.

22. The method as claimed in claim 17, wherein the manganese is selected from MnX, wherein X is selected from Cl2, Br2, (NO2)2, SO4, (acac)2or (acetate)2.

23. The method as claimed in claim 17, wherein stirring of the mixture performed at the temperature ranging from 40-50 °C for the time ranging from 10-14 hours.

24. The method as claimed in claim 17, wherein the shelf life of 5%-40 % methanol solution of [Mn(r|5-Fluorenyl)-(p2-OH)]2or [Mn(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) catalyst ranges from 3-4 months at room temperature.

25. A method for preparing a [Co(r|5-Fluorenyl)-(p2-OH)]2or [Co(r|1-Fluorenyl)-(p2- OH)]2.4(MeOH) catalyst, the method comprising: i. dissolving one equivalent of Fluorene (0.1 mole, 16.6 gm) in 100 mL methanol; ii. adding two equivalents of sodium (0.3 mole, 7.0 gm) to form Na-fluorenide;iii. adding a ferric salt selected from FeX; iv. stirring the mixture at a temperature ranging from 10-30 °C for the time ranging from 7-10 hours until the solution changes color from brown to reddish-orange for the mixture having one equivalent of Co(III) salts (0.1 mole); v. The method of claim 25, wherein the manganese is selected from Fe(III)X, wherein X is selected from Ch, Br , (NCh , (804)3, (acac)3 or (acetate)?. vi. filtering the mixture obtained from step (iv) to remove insoluble salts followed by concentrating the filtrate on rota vapour; vii. washing the residue with hexane; and viii. dissolving the purified catalyst in methanol.

26. A method for preparing a [Fe(r|5-Fluorenyl)-(p2-OH)]2 or [Fe(r|1-Fluorenyl)-(p2- OH)]2.2(MeOH) catalyst, the method comprising: i. dissolving one equivalent of Fluorene (0.1 mole, 16.6 gm) in 100 mb methanol; ii. adding two equivalents of sodium (0.3 mole, 7.0 gm) to form Na-fluorenide; iii. adding a ferric salt selected from FeX, iv. stirring the mixture at a temperature ranging from 10-30 °C for the time ranging from 7-10 hours until the solution changes color from brown to reddish-orange for the mixture having one equivalent of Fe(III) salts (0.1 mole); v. filtering the mixture obtained from step (iv) to remove insoluble salts followed by concentrating the filtrate on rota vapour; vi. washing the residue with hexane; and vii. dissolving the purified catalyst in methanol.

27. A method for preparing a [Mn(r|5-Fluorenyl)-(p2-OH)]2.2Na catalyst, the method comprising: i. dissolving Fluorene in methanol and adding sodium to form Na-fluorenide; adding a manganese salt selected from MnX, wherein X is selected from Cl2, Br2, (NO3)2, SO4, (acetate)? or (acac)? and n is selected from 0 or 6) to the Na- fluorenide solution; ii. stirring the mixture at 40°C until the solution changes color from brownish-red to yellowish-orange or color from pink to dark reddish-orange;iii. filtering the formed catalyst to remove insoluble salts followed by concentrating the filtrate under inert conditions; iv. washing the residue with hexane; and v. obtaining the catalyst by dissolving the purified residue in methanol.

28. A method for performing C-H alkylation of arenes, the method comprising: i. dissolving sodium acetate in methanol; ii. adding a catalyst selected from [Co(r|5-Fluorenyl)-(p2-OH) Fluorenyl)-(p2-OH)]2-4(MeOH) / [Fe(r|5-Fluorenyl)-(p2-OH)]2 Fluorenyl)-(p2-OH)]2.2(MeOH) / [Mn(r|5-Fluorenyl)-(p2-OH)]2Fluorenyl)-(p2-OH)]2.2(MeOH) iii. adding arenes and alkyl halides to a solvent mixture of methanol and THF at a methanol-to-THF in the ratio range of 1:3; iv. stirring the mixture at 65 °C for 9-12 hours to yield mono C-H alkylated products; evaporating the solvent under vacuum; v. purifying the crude product by column chromatography if required; and vi. obtaining the catalyst from methanol for further reuse.

29. A method for performing C-H alkylation of arenes under non-inert conditions, the method comprising: i. dissolving sodium acetate in methanol; vii. adding arenes, alkyl halides, and a catalyst selected from [Co(r|5-Fluorenyl)- (p2-OH)]2or [C(T|o1-Fluorenyl)-(p2-OH)]2.4(MeOH) / [Fe(r|5-Fluorenyl)-(p2- OH)]2or [Fe(r|1-Fluorenyl)-(p2-OH)]2.2(MeOH) / [Mn(r|5-Fluorenyl)-(p2- OH)]2or [Mn(T|1-Fluorenyl)-(p2-OH)]2.2(MeOH) ii. to a methanol-THF mixture; iii. stirring the reaction mixture at 65°C for 9-12 hours in the absence of inert atmosphere; iv. evaporating the solvent under vacuum; v. purifying the reaction product by column chromatography; and vi. obtaining the catalyst using methanol for further reuse.

30. The method as claimed in claim 29, wherein the methanol-to-THF ratio is 1:3.

31. The method as claimed in claim 29, wherein the reaction is carried out without dry conditions and inert atmosphere.

32. A method for preparing and storing metal -fluorenyl catalysts, the method comprising: i. synthesizing the catalyst using Na-fluorenide and metal salts selected from cobalt, iron, and manganese salts; ii. purifying the catalyst by fdtering and washing with hexane; iii. characterizing the catalyst by NMR, HRMS, and EPR; and iv. storing the catalyst in methanol for future use.

33. A metal-fluorenyl catalyst having the general formula [M(r|5-Fluorenyl)-(p2-OH)]2 or [M(r|5-Fluorenyl)-(p2-OH)]2 X(MeOH), wherein M is selected from the group consisting of cobalt (Co), iron (Fe), and manganese (Mn) and X =2-4.

34. The metal-fluorenyl catalyst as claimed in claim 23, wherein M is cobalt (Co) and the catalyst is [Co(p5-Fhiorenyl)-(p2-OH)]2or [Co(p5-Fhiorenyl)-(p2-OH)]2.4(MeOH) .

35. The metal-fluorenyl catalyst as claimed in claim 23, wherein M is iron (Fe) and the catalyst is [Fe(p5-Fhiorenyl)-(p2-OH)]2or [Fe(p5-Fhiorenyl)-(p2-OH)]2.2(MeOH).

36. The metal-fluorenyl catalyst as claimed in claim 23, wherein M is manganese (Mn) and the catalyst is [Mn(T|5-Fluorenyl)-(p2-OH)]2or [Mn(T|5-Fluorenyl)-(p2-OH)]22(MeOH) .

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