TITLE OF THE INVENTION

Synthesis of Substituted Tetracyclic Carboxylic Acids and Analogues Thereof

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63,398,458, fded August 16, 2022, which is incorporated herein by reference in its entirety.

BACKGROUND

Hepatitis B is one of the world's most prevalent diseases. Although most individuals resolve the infection following acute symptoms, approximately 30% of cases become chronic. 350-400 million people worldwide are estimated to have chronic hepatitis B, leading to 0.5-1 million deaths per year, due largely to the development of hepatocellular carcinoma, cirrhosis, and/or other complications. Hepatitis B is caused by hepatitis B virus (HBV), a noncytopathic, liver tropic DNA virus belonging to Hepcidnaviridcie family.

A limited number of drugs are currently approved for the management of chronic hepatitis B, including two formulations of alpha-interferon (standard and pegylated) and five nucleoside/nucleotide analogues (lamivudine, adefovir, entecavir, telbivudine, and tenofovir) that inhibit HBV DNA polymerase. At present, the first-line treatment choices are entecavir, tenofovir, or peg-interferon alfa-2a. However, peg-interferon alfa-2a achieves desirable serological milestones in only one third of treated patients and is frequently associated with severe side effects. Entecavir and tenofovir require long-term or possibly lifetime administration to continuously suppress HBV replication, and may eventually fail due to emergence of drug-resistant viruses.

HBV is an enveloped virus with an unusual mode of replication, centering on the establishment of a covalently closed circular DNA (cccDNA) copy of its genome in the host cell nucleus. Pregenomic (pg) RNA is the template for reverse transcriptional replication of HBV DNA. The encapsidation of pg RNA, together with viral DNA polymerase, into a nucleocapsid is essential for the subsequent viral DNA synthesis.

Aside from being a critical structural component of the virion, the HBV envelope is a major factor in the disease process. In chronically infected individuals, serum levels of HBV surface antigen (HBsAg) can be as high as 400 pg/ml, driven by the propensity for infected cells to secrete non-infectious subviral particles at levels far in excess of infectious (Dane) particles. HBsAg comprises the principal antigenic determinant in HBV infection and is composed of the small, middle and large surface antigens (S, M and L, respectively). These proteins are produced from a single open reading frame as three separate N-glycosylated polypeptides through utilization of alternative transcriptional start sites (for L and M/S mRNAs) and initiation codons (for L, M and S).

Although the viral polymerase and HBsAg perform distinct functions, both are essential proteins for the virus to complete its life cycle and be infectious. HBV lacking HBsAg is completely defective and cannot infect or cause infection. HBsAg protects the virus nucleocapsid, begins the infectious cycle, and mediates morphogenesis and secretion of newly forming virus from the infected cell.

People chronically infected with HBV are usually characterized by readily detectable levels of circulating antibody specific to the viral capsid (HBc), with little, if any detectable levels of antibody to HBsAg. There is evidence that chronic carriers produce antibodies to HBsAg, but these antibodies are complexed with the circulating HBsAg, which can be present in mg/mL amounts in a chronic carrier's circulation. Reducing the amount of circulating levels of HBsAg might allow any present anti-HBsA to manage the infection. Further, even if nucleocapsids free of HBsAg were to be expressed or secreted into circulation (perhaps as a result of cell death), the high levels of anti-HBc would quickly complex with them and result in their clearance.

Studies have shown that the presence of subviral particles in a culture of infected hepatocytes may have a transactivating function on viral genomic replication, and the circulating surface antigen suppresses virus-specific immune response. Furthermore, the scarcity of virus-specific cytotoxic T lymphocytes (CTLs), that is a hallmark of chronic HBV infection, may be due to repression of MHC I presentation by intracellular expression of L and M in infected hepatocytes. Existing FDA-approved therapies do not significantly affect HBsAg serum levels.

Hepatitis D virus (HDV) is a small circular enveloped RNA virus that can propagate only in the presence of the hepatitis B virus (HBV). In particular, HDV requires the HBV surface antigen protein to propagate itself. Infection with both HBV and HDV results in more severe complications compared to infection with HBV alone. These complications include a greater likelihood of experiencing liver failure in acute infections and a rapid progression to liver cirrhosis, with an increased chance of developing liver cancer in chronic infections. In combination with hepatitis B virus, hepatitis D has the highest mortality rate of all the hepatitis infections. The routes of transmission of HDV are similar to those for HBV. Infection is largely restricted to persons at high risk of HBV infection, particularly injecting drug users and persons receiving cloting factor concentrates.

Currently, there is no effective antiviral therapy available for the treatment of acute or chronic type D hepatitis. Interferon-alfa, given weekly for 12 to 18 months, is the only licensed treatment for hepatitis D. Response to this therapy is limited-in only about one- quarter of patients is serum HDV RNA undetectable 6 months post therapy.

There is thus a need in the art for novel compounds and/or compositions that can be used to treat, ameliorate, and/or prevent HBV infection in a subject. In certain embodiments, the compounds can be used in patients that are HBV infected, patients who are at risk of becoming HBV infected, and/or patients that are infected with drug-resistant HBV. In other embodiments, the HBV-infected subject is further HDV-infected. There is further a need in the art to identify scalable synthetic schemes that allow for the preparation of large scale batches of such compounds. The present disclosure addresses this need.

BRIEF SUMMARY

The present disclosure provides methods of preparing (.S)-5-(tcrt-butyl)- 1 1- (difIuoromethoxy)-9-methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2 ',T:2,3]imidazo[4,5- h] quinoline -3 -carboxylic acid, also known as compound ((A)-L), or a salt, solvate, prodrug, isotopically labeled derivative, stereoisomer (such as, in non-limiting embodiments, an enantiomer or any mixtures thereof, such as, in a non-limiting example, mixtures in any proportions of enantiomers thereof), and/or tautomer thereof, and any mixtures thereof:

DETAILED DESCRIPTION OF THE DISCLOSURE

This disclosure relates, in certain aspects, to the discovery of scalable synthetic routes that allow for reproducible multi-gram synthesis of certain substituted tetracyclic carboxylic acids containing compounds that are useful to treat, ameliorate, and/or prevent hepatitis B virus (HBV) and/or hepatitis D virus (HDV) infection and related conditions in a subject.

The disclosure of PCT International Patent Application No. PCT/IB2022/053112, fded April 4, 2022 and U.S. Provisional Patent Application No. 63/170,920, fded April 5, 2021, are incorporated herein by reference in their entireties.

Definitions

As used herein, each of the following terms has the meaning associated with it in this section. Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Generally, the nomenclature used herein and the laboratory procedures in animal pharmacology, pharmaceutical science, separation science, and organic chemistry are those well-known and commonly employed in the art. It should be understood that the order of steps or order for performing certain actions is immaterial, so long as the present teachings remain operable. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section. All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference.

In the application, where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that the element or component can be any one of the recited elements or components and can be selected from a group consisting of two or more of the recited elements or components.

In the methods described herein, the acts can be carried out in any order, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” or “at least one of A or B” has the same meaning as “A, B, or A and B.”

As used herein, the term “about” will be understood by persons of ordinary skill in the art and will vary to some extent on the context in which it is used. As used herein, “about” when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20%, ±10%, ±5%, ±1%, or ±0.1% from the specified value, as such variations are appropriate to perform the disclosed methods. As used herein, the term “alkenyl,” employed alone or in combination with other terms, means, unless otherwise stated, a stable monounsaturated or diunsaturated straight chain or branched chain hydrocarbon group having the stated number of carbon atoms. Examples include vinyl, propenyl (or allyl), crotyl, isopentenyl, butadienyl, 1,3 -pentadienyl, 1,4-pentadienyl, and the higher homologs and isomers. A functional group representing an alkene is exemplified by -CH2-CH=CH2.

As used herein, the term “alkoxy” employed alone or in combination with other terms means, unless otherwise stated, an alkyl group having the designated number of carbon atoms, as defined elsewhere herein, connected to the rest of the molecule via an oxygen atom, such as, for example, methoxy, ethoxy, 1 -propoxy, 2-propoxy (or isopropoxy) and the higher homologs and isomers. A specific example is (Ci-C3)alkoxy, such as, but not limited to, ethoxy and methoxy.

As used herein, the term “alkyl” by itself or as part of another substituent means, unless otherwise stated, a straight or branched chain hydrocarbon having the number of carbon atoms designated (i.e., C1-C10 means one to ten carbon atoms) and includes straight, branched chain, or cyclic substituent groups. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, and cyclopropylmethyl. A specific embodiment is (Ci-Ce)alkyl, such as, but not limited to, ethyl, methyl, isopropyl, isobutyl, M-pentyl, w-hcxyl. and cyclopropylmethyl.

As used herein, the term “alkynyl” employed alone or in combination with other terms means, unless otherwise stated, a stable straight chain or branched chain hydrocarbon group with a triple carbon-carbon bond, having the stated number of carbon atoms. Nonlimiting examples include ethynyl and propynyl, and the higher homologs and isomers. The term “propargylic” refers to a group exemplified by -CH2-C=CH. The term “homopropargylic” refers to a group exemplified by -CEECEE-C^CEI.

As used herein, the term “aromatic” refers to a carbocycle or heterocycle with one or more polyunsaturated rings and having aromatic character, i. e. , having (4n+2) delocalized n (pi) electrons, where ‘n’ is an integer.

As used herein, the term “aryl” employed alone or in combination with other terms means, unless otherwise stated, a carbocyclic aromatic system containing one or more rings (typically one, two or three rings) wherein such rings may be attached together in a pendent manner, such as a biphenyl, or may be fused, such as naphthalene. Examples include phenyl, anthracyl and naphthyl. Aryl groups also include, for example, phenyl or naphthyl rings fused with one or more saturated or partially saturated carbon rings (e.g., bicyclo [4.2.0] octa- 1,3, 5 -trienyl, or indanyl), which can be substituted at one or more carbon atoms of the aromatic and/or saturated or partially saturated rings.

As used herein, the term “aryl-(Ci-C6)alkyl” refers to a functional group wherein a one-to-six carbon alkylene chain is attached to an aryl group, e.g., -CH2CH2-phenyl or -CH2- phenyl (or benzyl). Specific examples are aryl-CH2- and aryl-CH(CH3)-. The term “substituted aryl-(Ci-C6)alkyl” refers to an aryl-(Ci-Ce)alkyl functional group in which the aryl group is substituted. A specific example is substituted aryl(CH2)-. Similarly, the term “heteroaryl-(Ci-C6)alkyl” refers to a functional group wherein a one-to-three carbon alkylene chain is attached to a heteroaryl group, e.g., -CH2CH2 -pyridyl. A specific example is heteroaryl-(CH2)-. The term “substituted heteroaryl-(Ci-C6)alkyl” refers to a heteroaryl-(Ci- Cejalkyl functional group in which the heteroaryl group is substituted. A specific example is substituted heteroaryl-(CH2)-.

As used herein, the term “cycloalkyl” by itself or as part of another substituent refers to, unless otherwise stated, a cyclic chain hydrocarbon having the number of carbon atoms designated (i.e., Ci-Ce refers to a cyclic group comprising a ring group consisting of three to six carbon atoms) and includes straight, branched chain or cyclic substituent groups. Examples of (C3-Ce)cycloalkyl groups are cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl. Cycloalkyl rings can be optionally substituted. Non-limiting examples of cycloalkyl groups include: cyclopropyl, 2 -methyl -cyclopropyl, cyclopropenyl, cyclobutyl, 2,3 -dihydroxy cyclobutyl, cyclobutenyl, cyclopentyl, cyclopentenyl, cyclopentadienyl, cyclohexyl, cyclohexenyl, cycloheptyl, cyclooctanyl, decalinyl, 2,5 -dimethylcyclopentyl, 3,5- dichlorocyclohexyl, 4-hydroxy cyclohexyl, 3 ,3 ,5 -trimethylcyclohex- 1 -yl, octahydropentalenyl, octahydro- IH-indenyl, 3a,4,5,6,7,7a-hexahydro-3H-inden-4-yl, decahydroazulenyl; bicyclo[6.2.0]decanyl, decahydronaphthalenyl, and dodecahydro- 1H- fluorenyl. The term “cycloalkyl” also includes bicyclic hydrocarbon rings, non-limiting examples of which include, bicyclo [2. l.l]hexanyl, bicyclo[2.2.1]heptanyl, bicyclo [3. l.l]heptanyl, l,3-dimethyl[2.2.1]heptan-2-yl, bicyclo[2.2.2]octanyl, and bicyclo [3.3.3 ]undecanyl .

The term “Dean-Stark apparatus” as used herein refers to a distilling trap, which is a piece of laboratory glassware used in synthetic chemistry to collect water (and/or other liquid distillate) from a reactor. In certain embodiments, it is used in combination with a reflux condenser and a batch reactor for continuous removal of water and/or another liquid distillate that is produced during a chemical reaction performed under reflux conditions.

As used herein, a “disease” is a state of health of a subject wherein the subject cannot maintain homeostasis, and wherein if the disease is not ameliorated then the subject’s health continues to deteriorate.

As used herein, a “disorder” in a subject is a state of health in which the subject is able to maintain homeostasis, but in which the subject’s state of health is less favorable than it would be in the absence of the disorder. Left untreated, a disorder does not necessarily cause a further decrease in the subject’s state of health.

As used herein, the term “halide” refers to a halogen atom bearing a negative charge. The halide anions are fluoride (F“), chloride (Cl-), bromide (Br-), and iodide (I-).

As used herein, the term “halo” or “halogen” alone or as part of another substituent refers to, unless otherwise stated, a fluorine, chlorine, bromine, or iodine atom.

As used herein, the term “heteroalkenyl” by itself or in combination with another term refers to, unless otherwise stated, a stable straight or branched chain monounsaturated or diunsaturated hydrocarbon group consisting of the stated number of carbon atoms and one or two heteroatoms selected from the group consisting of O, N, and S, and wherein the nitrogen and sulfur atoms may optionally be oxidized and the nitrogen heteroatom may optionally be quatemized. Up to two heteroatoms may be placed consecutively. Examples include - CH=CH-O-CH ₃ , -CH=CH-CH ₂ -OH, -CH ₂ -CH=N-OCH3, -CH=CH-N(CH ₃ )-CH ₃ , and -CH ₂ - CH=CH-CH ₂ -SH.

As used herein, the term “heteroalkyl” by itself or in combination with another term refers to, unless otherwise stated, a stable straight or branched chain alkyl group consisting of the stated number of carbon atoms and one or two heteroatoms selected from the group consisting of O, N, and S, and wherein the nitrogen and sulfur atoms may be optionally oxidized and the nitrogen heteroatom may be optionally quatemized. The heteroatom(s) may be placed at any position of the heteroalkyl group, including between the rest of the heteroalkyl group and the fragment to which it is attached, as well as attached to the most distal carbon atom in the heteroalkyl group. Examples include: -OCH ₂ CH ₂ CH ₃ , - CH ₂ CH ₂ CH ₂ OH, -CH ₂ CH ₂ NHCH ₃ , -CH ₂ SCH ₂ CH ₃ , and -CH ₂ CH ₂ S(=O)CH ₃ . Up to two heteroatoms may be consecutive, such as, for example, -CH ₂ NH-OCH ₃ , or -CH ₂ CH ₂ SSCH ₃ .

As used herein, the term “heteroaryl” or “heteroaromatic” refers to a heterocycle having aromatic character. A polycyclic heteroaryl may include one or more rings that are partially saturated. Examples include tetrahydroquinoline and 2,3 -dihydrobenzofuryl.

As used herein, the term “heterocycle” or “heterocyclyl” or “heterocyclic” by itself or as part of another substituent refers to, unless otherwise stated, an unsubstituted or substituted, stable, mono- or multi-cyclic heterocyclic ring system that comprises carbon atoms and at least one heteroatom selected from the group consisting of N, O, and S, and wherein the nitrogen and sulfur heteroatoms may be optionally oxidized, and the nitrogen atom may be optionally quatemized. The heterocyclic system may be attached, unless otherwise stated, at any heteroatom or carbon atom that affords a stable structure. A heterocycle may be aromatic or non-aromatic in nature. In certain embodiments, the heterocycle is a heteroaryl.

Examples of non-aromatic heterocycles include monocyclic groups such as aziridine, oxirane, thiirane, azetidine, oxetane, thietane, pyrrolidine, pyrroline, imidazoline, pyrazolidine, dioxolane, sulfolane, 2,3 -dihydrofuran, 2,5-dihydrofuran, tetrahydrofuran, thiophane, piperidine, 1,2,3,6-tetrahydropyridine, 1,4-dihydropyridine, piperazine, morpholine, thiomorpholine, pyran, 2, 3 -dihydropyran, tetrahydropyran, 1,4-dioxane, 1,3- dioxane, homopiperazine, homopiperidine, 1,3-dioxepane, 4,7-dihydro-l,3-dioxepin, and hexamethyleneoxide .

Examples of heteroaryl groups include pyridyl, pyrazinyl, pyrimidinyl (such as, but not limited to, 2- and 4-pyrimidinyl), pyridazinyl, thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,3,4-triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl, 1,3,4-thiadiazolyl, and 1,3,4-oxadiazolyl.

Examples of polycyclic heterocycles include indolyl (such as, but not limited to, 2-, 3- , 4-, 5-, 6- and 7-indolyl), indolinyl, quinolyl, tetrahydroquinolyl, isoquinolyl (such as, but not limited to, 1- and 5 -isoquinolyl), 1,2,3,4-tetrahydroisoquinolyl, cinnolinyl, quinoxalinyl (such as, but not limited to, 2- and 5 -quinoxalinyl), quinazolinyl, phthalazinyl, 1,8- naphthyridinyl, 1,4-benzodioxanyl, coumarin, dihydrocoumarin, 1,5-naphthyridinyl, benzofuryl (such as, but not limited to, 3-, 4-, 5-, 6- and 7 -benzofuryl), 2,3- dihydrobenzofuryl, 1,2-benzisoxazolyl, benzothienyl (such as, but not limited to, 3-, 4-, 5-, 6- , and 7-benzothienyl), benzoxazolyl, benzothiazolyl (such as, but not limited to, 2- benzothiazolyl and 5 -benzothiazolyl), purinyl, benzimidazolyl, benztriazolyl, thioxanthinyl, carbazolyl, carbolinyl, acridinyl, pyrrolizidinyl, and quinolizidinyl.

The aforementioned listing of heterocyclyl and heteroaryl moieties is intended to be representative and not limiting.

As used herein, the term “pharmaceutical composition” or “composition” refers to a mixture of at least one compound useful within the disclosure with a pharmaceutically acceptable carrier. The pharmaceutical composition facilitates administration of the compound to a subject.

As used herein, the term “pharmaceutically acceptable” refers to a material, such as a carrier or diluent, which does not abrogate the biological activity or properties of the compound useful within the disclosure, and is relatively non-toxic, i.e., the material can be administered to a subject without causing undesirable biological effects or interacting in a deleterious manner with any of the components of the composition in which it is contained.

As used herein, the term “pharmaceutically acceptable carrier” means a pharmaceutically acceptable material, composition or carrier, such as a liquid or solid fdler, stabilizer, dispersing agent, suspending agent, diluent, excipient, thickening agent, solvent or encapsulating material, involved in carrying or transporting a compound useful within the disclosure within or to the subject such that it can perform its intended function. Typically, such constructs are carried or transported from one organ, or portion of the body, to another organ, or portion of the body. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation, including the compound useful within the disclosure, and not injurious to the subject. Some examples of materials that can serve as pharmaceutically acceptable carriers include: sugars, such as lactose, glucose and sucrose; starches, such as com starch and potato starch; cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; powdered tragacanth; malt; gelatin; talc; excipients, such as cocoa butter and suppository waxes; oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, com oil and soybean oil; glycols, such as propylene glycol; polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol; esters, such as ethyl oleate and ethyl laurate; agar; buffering agents, such as magnesium hydroxide and aluminum hydroxide; surface active agents; alginic acid; pyrogen-free water; isotonic saline; Ringer’s solution; ethyl alcohol; phosphate buffer solutions; and other non-toxic compatible substances employed in pharmaceutical formulations. As used herein, “pharmaceutically acceptable carrier” also includes any and all coatings, antibacterial and antifungal agents, and absorption delaying agents, and the like that are compatible with the activity of the compound useful within the disclosure, and are physiologically acceptable to the subject. Supplementary active compounds can also be incorporated into the compositions. The “pharmaceutically acceptable carrier” can further include a pharmaceutically acceptable salt of the compound useful within the disclosure. Other additional ingredients that can be included in the pharmaceutical compositions used in the practice of the disclosure are known in the art and described, for example in Remington’s Pharmaceutical Sciences (Genaro, Ed., Mack Publishing Co., 1985, Easton, PA), which is incorporated herein by reference.

As used herein, the language “pharmaceutically acceptable salt” refers to a salt of the administered compound prepared from pharmaceutically acceptable non-toxic acids and/or bases, including inorganic acids, inorganic bases, organic acids, inorganic bases, solvates (including hydrates) and clathrates thereof.

As used herein, a “pharmaceutically effective amount,” “therapeutically effective amount,” or “effective amount” of a compound is that amount of compound that is sufficient to provide a beneficial effect to the subject to which the compound is administered.

The term “prevent,” “preventing,” or “prevention” as used herein means avoiding or delaying the onset of symptoms associated with a disease or condition in a subject that has not developed such symptoms at the time the administering of an agent or compound commences. Disease, condition and disorder are used interchangeably herein.

By the term “specifically bind” or “specifically binds” as used herein is meant that a first molecule preferentially binds to a second molecule (e.g. , a particular receptor or enzyme), but does not necessarily bind only to that second molecule.

As used herein, the terms “subject” and “individual” and “patient” can be used interchangeably and can refer to a human or non-human mammal or a bird. Non-human mammals include, for example, livestock and pets, such as ovine, bovine, porcine, canine, feline and murine mammals. In certain embodiments, the subject is human.

As used herein, the term “substituted” refers to that an atom or group of atoms has replaced hydrogen as the substituent attached to another group.

As used herein, the term “substituted alkyl,” “substituted cycloalkyl,” “substituted alkenyl,” or “substituted alkynyl” refers to alkyl, cycloalkyl, alkenyl, or alkynyl, as defined elsewhere herein, substituted by one, two or three substituents independently selected from the group consisting of halogen, -OH, alkoxy, tetrahydro-2-H-pyranyl, -NH2, -NH(Ci-Ce alkyl), -N(Ci-Ce alkyl)2, 1 -methyl -imidazol-2-yl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, - C(=O)OH, -C(=O)O(Ci-C ₆ )alkyl, trifluoromethyl, -C=N, -C(=O)NH ₂ , -C(=O)NH(Ci- C ₆ )alkyl, -C(=O)N((Ci-C ₆ )alkyl)2, -SO2NH2, -SO ₂ NH(CI-C6 alkyl), -SO ₂ N(CI-C6 alkyl) ₂ , - C(=NH)NH2, and -NO2, in certain embodiments containing one or two substituents independently selected from halogen, -OH, alkoxy, -NH2, trifluoromethyl, -N(CH3)2, and - C(=O)OH, in certain embodiments independently selected from halogen, alkoxy and -OH. Examples of substituted alkyls include, but are not limited to, 2,2-difluoropropyl, 2- carboxy cyclopentyl and 3 -chloropropyl.

For aryl, aryl-(Ci-C3)alkyl and heterocyclyl groups, the term “substituted” as applied to the rings of these groups refers to any level of substitution, namely mono-, di-, tri-, tetra-, or penta-substitution, where such substitution is permitted. The substituents are independently selected, and substitution can be at any chemically accessible position. In certain embodiments, the substituents vary in number between one and four. In other embodiments, the substituents vary in number between one and three. In yet another embodiments, the substituents vary in number between one and two. In yet other embodiments, the substituents are independently selected from the group consisting of Ci-Ce alkyl, -OH, Ci-Ce alkoxy, halogen, amino, acetamido and nitro. As used herein, where a substituent is an alkyl or alkoxy group, the carbon chain can be branched, straight or cyclic.

Unless otherwise noted, when two substituents are taken together to form a ring having a specified number of ring atoms (e.g. , R ² and R ³ taken together with the nitrogen to which they are attached to form a ring having from 3 to 7 ring members), the ring can have carbon atoms and optionally one or more (e.g., 1 to 3) additional heteroatoms independently selected from nitrogen, oxygen, or sulfur. The ring can be saturated or partially saturated, and can be optionally substituted.

Whenever a term or either of their prefix roots appear in a name of a substituent the name is to be interpreted as including those limitations provided herein. For example, whenever the term “alkyl” or “aryl” or either of their prefix roots appear in a name of a substituent (e.g., arylalkyl, alkylamino) the name is to be interpreted as including those limitations given elsewhere herein for “alkyl” and “aryl” respectively.

In certain embodiments, substituents of compounds are disclosed in groups or in ranges. It is specifically intended that the description include each and every individual subcombination of the members of such groups and ranges. For example, the term “Ci-6 alkyl” is specifically intended to individually disclose Ci, C2, C3, C4, C5, Ce, Ci-Ce, C1-C5, C1-C4, C1-C3, C1-C2, C2-C6, C2-C5, C2-C4, C2-C3, C3-C6, C3-C5, C3-C4, C4-C6, C4-C5, and C5-C6 alkyl.

The terms “treat,” “treating” and “treatment,” as used herein, means reducing the frequency or severity with which symptoms of a disease or condition are experienced by a subject by virtue of administering an agent or compound to the subject.

Certain abbreviations used herein follow: cccDNA, covalently closed circular DNA; DMSO, dimethylsulfoxide; HBsAg, HBV surface antigen; HBV, hepatitis B virus; HDV, hepatitis D virus; HPLC, high pressure liquid chromatography; LCMS, liquid chromatography mass spectrometry; NMR, Nuclear Magnetic Resonance; pg RNA, pregenomic RNA; RT, retention time; sAg, surface antigen; TLC, thin layer chromatography.

Ranges: throughout this disclosure, various aspects of the present disclosure can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the present disclosure. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. For example, a range of “about 0. 1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, l. l% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise. This applies regardless of the breadth of the range.

Synthesis

The present disclosure further provides methods of preparing certain compounds of the present disclosure. Compounds of the present teachings can be prepared in accordance with the procedures outlined herein, from commercially available starting materials, compounds known in the literature, or readily prepared intermediates, by employing standard synthetic methods and procedures known to those skilled in the art. Standard synthetic methods and procedures for the preparation of organic molecules and functional group transformations and manipulations can be readily obtained from the relevant scientific literature or from standard textbooks in the field.

It is appreciated that where typical or preferred process conditions (i.e., reaction temperatures, times, mole ratios of reactants, solvents, pressures, and so forth) are given, other process conditions can also be used unless otherwise stated. Optimum reaction conditions can vary with the particular reactants or solvent used, but such conditions can be determined by one skilled in the art by routine optimization procedures. Those skilled in the art of organic synthesis will recognize that the nature and order of the synthetic steps presented can be varied for the purpose of optimizing the formation of the compounds described herein.

The processes described herein can be monitored according to any suitable method known in the art. For example, product formation can be monitored by spectroscopic means, such as nuclear magnetic resonance spectroscopy (e.g., 'H or ¹³ C), infrared spectroscopy, spectrophotometry (e.g., UV-visible), mass spectrometry, or by chromatography such as high-performance liquid chromatograpy (HPLC), gas chromatography (GC), gel-permeation chromatography (GPC), or thin layer chromatography (TLC).

Preparation of the compounds can involve protection and deprotection of various chemical groups. The need for protection and deprotection and the selection of appropriate protecting groups can be readily determined by one skilled in the art. The chemistry of protecting groups can be found, for example, in Greene, et al. , Protective Groups in Organic Synthesis, 2d. Ed. (Wiley & Sons, 1991), the entire disclosure of which is incorporated by reference herein for all purposes.

The reactions or the processes described herein can be carried out in suitable solvents that can be readily selected by one skilled in the art of organic synthesis. Suitable solvents typically are substantially nonreactive with the reactants, intermediates, and/or products at the temperatures at which the reactions are carried out, i. e. , temperatures that can range from the solvent’s freezing temperature to the solvent’s boiling temperature. A given reaction can be carried out in one solvent or a mixture of more than one solvent. Depending on the particular reaction step, suitable solvents for a particular reaction step can be selected.

The disclosure includes methods of preparing (.S)-5 -(tert-butyl)- 1 l-(difluoromethoxy)- 9-methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2',T:2,3]imidazo[4, 5-h]quinoline-3-carboxylic acid, also known as compound (CS’)-L). or a salt, solvate, prodrug, isotopically labeled derivative, stereoisomer (such as, in non-limiting embodiments, an enantiomer or any mixtures thereof, such as, in a non-limiting example, mixtures in any proportions of enantiomers thereof), and/or tautomer, and any mixtures thereof:

In certain embodiments, the compound of formula ((A)-L). or a salt, solvate, prodrug, isotopically labelled derivative, and/or tautomer thereof, can be prepared according to the non-limiting synthetic scheme outlined in Schemes 1-2, wherein R ¹ and R ² are selected from the group consisting of H, optionally substituted Ci-Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl, R ³ is selected from the group consisting of Ci- Ce alkoxy, N(Ci-Ce alkyl)(Ci-Ce alkyl), CN, halogen, triflate, mesylate, and tosylate, and R ^4a and R ^4b are each independently selected from the group consisting of Ci-Ce alkyl and Ci-Ce cycloalkyl, or R ^4a and R ^4b combine with the atoms to which they are bound to form a Ce-Cx heterocyclyl.

Commercially available 5-bromopyridin-3-ol (A) can be converted to the corresponding nitroheteroarene (B) by nitration, for example, by reaction of (A) with a suitable nitrating agent, such as but not limited to nitric acid, in the presence of an acid, such as but not limited to sulfuric acid, under suitable reaction conditions, such as but not limited to having a temperature of about 0 °C to about 25 °C.

Compound (B) can be converted to the corresponding methoxy-substituted heteroarene (C) by nucleophilic aromatic substitution using a methoxide nucleophile, for example sodium methoxide, in the presence of a suitable solvent, such as but not limited to dimethylacetamide (DMAC), under suitable reaction conditions, such as but not limited to having a temperature of about 60 °C.

The hydroxyl group of compound (C) can be difluoromethylated to provide difluoromethoxyheteroarene (D) by a suitable difluoromethylating reagent, for example, sodium 2-chloro-2,2-difluoroacetate, in the presence of a suitable base, such as but not limited to K2CO3, in the presence of a suitable solvent, such as but not limited to dimethylformamide (DMF), under suitable reaction conditions, such as but not limited to having a temperature of about 90 °C.

The nitro group of compound (D) can be reduced to provide pyridinamine (E), for example, by reaction of (D) with a suitable reducing agent, such as but not limited to iron powder, in the presence of a suitable acid, such as but not limited to HC1, in the presence of a suitable solvent, such as but not limited to ethanol (EtOH), under suitable reaction conditions, such as but not limited to having a temperature of about 80 °C.

Commercially available 4-(tert-butyl)cyclohexan-l-one (F) can be converted to bis-a- bromoketone (G) by treatment of (F) with a suitable brominating reagent, such as but not limited to pyridinium tribromide (PyH-Brs), in the presence of a suitable solvent, such as but not limited to acetonitrile (ACN), under suitable reaction conditions, such as but not limited to having a temperature of 25 °C.

Bis-a-bromoketone (G) can be converted to dione (H) by treatment of (G) with a suitable carboxylate salt, including but not limited to potassium formate, and a suitable acid, including but not limited to formic acid, in the presence of a suitable solvent, such as but not limited to water, under suitable reaction conditions, such including but not limited to having a temperature of about 85 °C.

Imidazopyridine (I) can be prepared from dione (H) and pyridinamine (E), for example, by an oxidative cyclization reaction, by contacting (H) and (E) in the presence of a suitable acid, including but not limited to acetic acid (AcOH), under suitable reaction conditions, in the presence of a suitable oxidant, including but not limited to O2, under suitable reaction conditions, including but not limited to conditions wherein O2 has a pressure of 50 psi and/or wherein the reaction occurs at a temperature of about 90 °C to about 95 °C. Further, imidazopyridine ((/?)-!) can be obtained from (I) by chiral separation, optionally comprising chiral column chromatography.

Imidazopyridine ((7?)-I) can be converted to pyridinone ((A)-K) in a two-step process comprising: (a) an initial condensation of ((/?)-!) with a suitable primary amine (i.e., R ¹ R ² CH-NH2), including but not limited to diphenyhnethanamine, in the presence of a suitable solvent, including but not limited to toluene (PhMe), under suitable reaction conditions, including but not limited to being heated at reflux in a vessel equipped with a Dean-Stark apparatus to provide an imine intermediate; and (b) an annulation wherein the imine intermediate is reacted with a suitable a,P-unsaturated diester (J), including but not limited to 5-(methoxymethylene)-2,2-dimethyl-l,3-dioxane-4, 6-dione, in the presence of a suitable solvent, including but not limited to toluene, under suitable reaction conditions including but not limited to having a temperature of about 70 °C, with subsequent addition of a suitable base, including but not limited to tetramethylguanidine (TMG).

Compound ((A’)-K) can be converted to compound ((A)- L) by deprotection with a suitable deprotecting agent, for example, an acid, including but not limited to trifluoroacetic acid (TFA), in the presence of a suitable solvent, including but not limited to methyl isobutyl ketone (MIBK), under suitable reaction conditions, including but not limited to having a temperature of about 25 °C. In certain embodiments, an excess of acid is used to achieve deprotection.

Scheme 1.

Scheme 2.

It is understood that the reactions or processes described herein for preparing (.S')-5- (tert-butyl)- 11 -(difluoromethoxy)-9-methoxy-2-oxo- 1 ,2,5,6- tetrahydropyrido[2',r:2,3]imidazo[4,5-h]quinoline-3-carboxyl ic acid ((A)-L) are not limited to the embodiments described in Schemes 1-2.

In view of the present disclosure, one skilled in the art would appreciate that ((A) -L) can be prepared by incorporating chiral separation at different points in the synthetic sequence (e.g., isolation of compound (fS’)-K) by chiral separation of compound (K) prepared from (I) without chiral separation, inter alia). Additional embodiments encompassed within the present disclosure are provided in Schemes 3-4, wherein R ¹ , R ² , R ³ , R ^4a , and R ^4b are defined elsewhere herein.

Scheme 3.

Scheme 4.

In one aspect, the present disclosure provides a method of preparing (.S)-5-(tcrt-butyl)- l l-(difluoromethoxy)-9-methoxy-2-oxo-l,2,5,6-tetrahydropyrido [2',r:2,3]imidazo[4,5- h] quinoline -3 -carboxylic acid ((A)-L). or a salt or solvate thereof: the method comprising reacting an acid and (5)- l-(CHR ¹ R ² )-5 -(tert-butyl)- 11- (difluoromethoxy)-9-methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2 ',r:2,3]imidazo[4,5- h] quinoline -3 -carboxylic acid ((A)-K): wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci-Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl.

In certain embodiments, R ¹ is phenyl. In certain embodiments, R ² is phenyl. In certain embodiments, R ¹ and R ² are phenyl. In certain embodiments, compound (K) is (S)- l - benzhydryl-5 -(tert-butyl)- 11 -(difluoromethoxy)-9-methoxy-2-oxo- 1 ,2,5,6- tetrahydropyrido[2',r:2,3]imidazo[4,5-h]quinoline-3-carboxyl ic acid.

In certain embodiments, the acid is trifluoroacetic acid (TFA).

In certain embodiments, the reaction of ((A)-K) occurs in the presence of a superstoichiometric amount (i.e., excess) of TFA. In certain embodiments, the use of superstoichiometric TFA abrogates the need for cation scavengers, including but not limited to EtsSiH.

In certain embodiments, the reaction occurs in a solvent comprising methyl isobutyl ketone (MIBK).

In certain embodiments, ((5)-K) is prepared by:

(a) reacting (R)-8-(tert-butyl)-4-(difluoromethoxy)-2-methoxy-8,9- dihydrobenzo [4,5] imidazo [ 1 ,2-a] pyridin-6(7H)-one ((/?)-!) :

(W-I), with a primary amine to form an imine intermediate; and

(b) reacting the imine intermediate with (J): wherein:

R ³ is selected from the group consisting of Ci-Ce alkoxy, N(Ci-Ce alkyl)(Ci-

Ce alkyl), CN, halogen, triflate, mesylate, and tosylate;

R ^4a and R ^4b are each independently selected from the group consisting of Ci-

Ce alkyl and Cs-Cs cycloalkyl, wherein R ^4a and R ^4b can combine with the atoms to which they are bound to form a Ce-Cx heterocyclyl; in the presence of a base.

In certain embodiments, the primary amine comprises R ¹ R ² CH-NH2, wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci- Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl.

In certain embodiments, R ¹ is phenyl. In certain embodiments, R ² is phenyl. In certain embodiments, the primary amine is diphenylmethanamine.

In certain embodiments, the reaction of ((/?)-!) and the primary amine occurs in a solvent comprising toluene. In certain embodiments, the reaction of ((/?)-!) and the primary amine occurs under reflux conditions. In certain embodiments, the primary amine occurs in a vessel equipped with a Dean-Stark apparatus. In certain embodiments, the reaction of ((/?)-!) and the primary amine occurs in the absence of an acid. In certain embodiments, the absence of an acid in the reaction of ((/?)-!) and the primary amine permits use of the imine intermediate without isolation and/or purification.

In certain embodiments, R ³ is OMe. In certain embodiments, (J) is 5- (methoxymethylene)-2,2-dimethyl-l,3-dioxane-4, 6-dione. In certain embodiments, the reaction of (J) and the imine intermediate occurs in a solvent comprising toluene. In certain embodiments, the reaction of (J) and the imine intermediate occurs at a temperature of about 70 °C. Without wishing to be bound by theory, use of a cyclic malonate derivative (e.g., a compound of formula (J)) permits the reaction to proceed at a relatively low temperature (e.g., about 70 °C).

In certain embodiments, the base is 1,1,3,3-tetramethylguanidine (TMG). Without wishing to be bound by theory, use of a base (e.g. , TMG) permits the reaction to proceed at a relatively low temperature (e.g., about 70 °C).

In certain embodiments, ((/?)-!) is prepared by chiral resolution of 8-(tert-butyl)-4- (difhioromethoxy)-2-methoxy-8,9-dihydrobenzo[4,5]imidazo[l,2 -a]pyridin-6(7H)-one (I):

In certain embodiments, the chiral resolution comprises chiral column chromatography .

In certain embodiments, (I) is prepared by reacting 3-(difluoromethoxy)-5- methoxypyridin-2 -amine (E): and 4-(tert-butyl)cyclohexane- 1,2-dione (H), in the presence of an oxidant and an acid.

In certain embodiments, the oxidant is O2. In certain embodiments, the reaction of (E) and (H) occurs at an O2 pressure of 50 psi.

In certain embodiments, the acid is acetic acid.

In certain embodiments, the reaction of (E) and (H) occurs at a temperature of about 90 °C to about 95 °C.

In certain embodiments, (E) is prepared by reacting 3-(difluoromethoxy)-5-methoxy- 2 -nitropyridine (D): with a reducing agent.

In certain embodiments, the reducing agent is iron powder.

In certain embodiments, the reaction of (D) and the reducing agent occurs in the presence of an acid. In certain embodiments, the acid is hydrochloric acid (HC1).

In certain embodiments, (D) is prepared by reacting 5-methoxy-2-nitropyridin-3-ol (C): with a difluoromethylating reagent.

In certain embodiments, the difluoromethylating reagent is sodium 2-chloro-2,2- difluoroacetate.

In certain embodiments, the reaction of (D) and the difluoromethylating reagent occurs in the presence of a base. In certain embodiments, the base is K2CO3.

In certain embodiments, the reaction of (D) and the difluoromethylating reagent occurs in a solvent comprising dimethylformamide (DMF).

In certain embodiments, the reaction of (D) and the difluoromethylating reagent occurs at a temperature of about 90 °C.

In certain embodiments, (C) is prepared by reacting 5-bromo-2-nitropyridin-3-ol (B) with a methoxide salt:

OH X

(B).

In certain embodiments, the methoxide is sodium methoxide. In certain embodiments, the sodium methoxide comprises a 30% w/w solution of sodium methoxide in methanol.

In certain embodiments, the reaction of (B) and a methoxide occurs in a solvent comprising dimethylacetamide (DMAC).

In certain embodiments, the reaction of (B) and a methoxide occurs at a temperature of about 60 °C.

In certain embodiments, (B) is prepared by reacting 5-bromopyridin-3-ol (A): with a nitrating agent.

In certain embodiments, the nitrating agent is a nitronium ion (O=N ⁺ =O). In certain embodiments, the nitronium ion is generated by reacting nitric acid and a second acid. In certain embodiments, the second acid is sulfuric acid.

In certain embodiments, (H) is prepared by reacting 2,6-dibromo-4-(tert- butyl)cyclohexan-l-one (G): with water in the presence of an acid and a carboxylate salt.

In certain embodiments, the acid is formic acid.

In certain embodiments, the carboxylate salt is potassium formate.

In certain embodiments, the reaction of (E) and water occurs at a temperature of about 80 °C.

In certain embodiments, (G) is prepared by reacting 4-(/ -butyl)cyclohcxan- l -one (F):

O < (F), with a brominating reagent.

In certain embodiments, the brominating agent is pyridinium tribromide. In certain embodiments, the brominating agent is pyridinium tribromide and the reaction occurs in a solvent comprising acetonitrile.

In certain embodiments, the brominating agent is Bn. In certain embodiments, the brominating agent is Bn and the reaction occurs in a solvent comprising AcOH. In certain embodiments, the brominating reagent is Bn and the reaction occurs in a solvent comprising acetonitrile.

In certain embodiments, ((A)-K) is prepared by chiral resolution of l-(CHR ¹ R ² )-5- (tert-butyl)- 11 -(difluoromethoxy)-9-methoxy-2-oxo- 1 ,2,5,6- tetrahydropyrido[2',r:2,3]imidazo[4,5-h]quinoline-3-carboxyl ic acid (K): wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci-Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl.

In certain embodiments, R ¹ is phenyl. In certain embodiments, R ² is phenyl. In certain embodiments, compound (K) is 1 -benzhydryl-5 -(tert-butyl)- 1 l-(difhroromethoxy)-9- methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2',r:2,3]imidazo[4,5- h]quinoline-3-carboxylic acid.

In certain embodiments, (K) is prepared by:

(a) reacting 8-(tert-butyl)-4-(difluoromethoxy)-2-methoxy-8,9- dihydrobenzo[4,5]imidazo[l,2-a]pyridin-6(7H)-one (I):

O

F ₂ HCO qAy.

MeO (I), with a primary amine to form an imine intermediate; and

(b) reacting the imine intermediate with (J) in the presence of a base: wherein: R ³ is selected from the group consisting of Ci-Ce alkoxy, N(Ci-Ce alkyl)(Ci- Ce alkyl), CN, halogen, triflate, mesylate, and tosylate;

R ^4a and R ^4b are each independently selected from the group consisting of Ci- Ce alkyl and Cs-Cs cycloalkyl, or R ^4a and R ^4b combine with the atoms to which they are bound to form a Ce-Cx heterocyclyl.

In certain embodiments, the primary amine comprises R ¹ R ² CH-NH2, wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci- Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl.

In certain embodiments, the primary amine is diphenyhnethanamine.

In certain embodiments, the reaction of (I) and the primary amine occurs in a solvent comprising toluene.

In certain embodiments, the reaction of (I) and the primary amine occurs under reflux conditions. In certain embodiments, the reaction of (I) and the primary amine occurs in a vessel equipped with a Dean-Stark apparatus. In certain embodiments, the reaction of (I) and the primary amine occurs in the absence of an acid. In certain embodiments, the absence of an acid in the reaction of (I) and the primary amine permits use of the imine intermediate without isolation and/or purification.

In certain embodiments, R ³ is OMe. In certain embodiments, (J) is 5- (methoxymethylene)-2,2-dimethyl-l,3-dioxane-4, 6-dione. In certain embodiments, the reaction of (J) and the imine intermediate occurs in a solvent comprising toluene. In certain embodiments, the reaction of (J) and the imine intermediate occurs at a temperature of about 70 °C. Without wishing to be bound by theory, use of a cyclic malonate derivative (e.g., a compound of formula (J)) permits the reaction to proceed at a relatively low temperature (e.g., about 70 °C).

In certain embodiments, the base is 1,1,3,3-tetramethylguanidine (TMG). Without wishing to be bound by theory, use of a base (e.g. , TMG) permits the reaction to proceed at a relatively low temperature (e.g., about 70 °C). Compound (I) can be prepared as described elsewhere herein.

In another aspect, the present disclosure provides a method of preparing (.S)-5 -(tert- butyl)- 11 -(difhroromethoxy)-9-methoxy-2-oxo- 1,2, 5,6- tetrahydropyrido[2',T:2,3]imidazo[4,5-h]quinoline-3-carboxyl ic acid (GS’)-L). or a salt or solvate thereof: the method comprising chiral resolution of 5 -(tert-butyl)- 1 l-(difluoromethoxy)-9-methoxy-2- oxo-l,2,5,6-tetrahydropyrido[2',r:2,3]imidazo[4,5-h]quinolin e-3-carboxylic acid (L):

In certain embodiments, the chiral resolution comprises chiral column chromatography .

In certain embodiments, (L) is prepared by reacting an acid with 1 -(CHR ¹ R ² ) -5 -(tert- butyl)- 1 l-(difluoromethoxy)-9-methoxy-2-oxo- 1,2, 5,6- tetrahydropyrido[2',r:2,3]imidazo[4,5-h]quinoline-3-carboxyl ic acid (K): wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci-Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl.

In certain embodiments, the acid is trifluoroacetic acid (TFA). In certain embodiments, a the reaction of (K) occurs in the presence of a superstoichiometric amount (i.e., excess) of TFA. In certain embodiments, (K) is reacted with about 1 to about 50 molar equivalents of TFA. In certain embodiments, (K) is reacted with about 24 molar equivalents of TFA. In certain embodiments, the use of superstoichiometric TFA abrogates the need for cation scavengers, including but not limited to EtsSiH. In certain embodiments, the reaction occurs in a solvent comprising methyl isobutyl ketone (MIBK). The compounds of the disclosure can possess one or more stereocenters, and each stereocenter can exist independently in either the (R)- or (^-configuration. In certain embodiments, compounds described herein are present in optically active or racemic forms. The compounds described herein encompass racemic, optically active, regioisomeric and stereoisomeric forms, or combinations thereof that possess the therapeutically useful properties described herein. Preparation of optically active forms is achieved in any suitable manner, including, by way of non-limiting example, by resolution of the racemic form with recrystallization techniques, synthesis from optically active starting materials, chiral synthesis, or chromatographic separation using a chiral stationary phase. A compound illustrated herein by the racemic formula further represents either of the two enantiomers or any mixtures thereof, or in the case where two or more chiral centers are present, all diastereomers or any mixtures thereof.

In certain embodiments, the compounds of the disclosure exist as tautomers. All tautomers are included within the scope of the compounds recited herein.

Compounds described herein also include isotopically labeled compounds wherein one or more atoms is replaced by an atom having the same atomic number, but an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes suitable for inclusion in the compounds described herein include and are not limited to ² H, ³ H, ⁿ C, ¹³ C, ¹⁴ C, ³⁶ C1, ¹⁸ F, ¹²³ I, ¹²⁵ I, ¹³ N, ¹⁵ N, ¹⁵ O, ¹⁷ O, ¹⁸ 0, ³² P, and ³⁵ S. In certain embodiments, substitution with heavier isotopes such as deuterium affords greater chemical stability. Isotopically labeled compounds are prepared by any suitable method or by processes using an appropriate isotopically labeled reagent in place of the non-labeled reagent otherwise employed.

In certain embodiments, the compounds described herein are labeled by other means, including, but not limited to, the use of chromophores or fluorescent moieties, bioluminescent labels, or chemiluminescent labels.

In all of the embodiments provided herein, examples of suitable optional substituents are not intended to limit the scope of the claimed disclosure. The compounds of the disclosure can contain any of the substituents, or combinations of substituents, provided herein.

Salts

The compounds described herein can form salts with acids or bases, and such salts are included in the present disclosure. The term “salts” embraces addition salts of free acids or bases that are useful within the methods of the disclosure. The term “pharmaceutically acceptable salt” refers to salts that possess toxicity profiles within a range that affords utility in pharmaceutical applications. In certain embodiments, the salts are pharmaceutically acceptable salts. Pharmaceutically unacceptable salts can nonetheless possess properties such as high crystallinity, which have utility in the practice of the present disclosure, such as for example utility in process of synthesis, purification or formulation of compounds useful within the methods of the disclosure.

Suitable pharmaceutically acceptable acid addition salts can be prepared from an inorganic acid or from an organic acid. Examples of inorganic acids include sulfate, hydrogen sulfate, hydrochloric, hydrobromic, hydriodic, nitric, carbonic, sulfuric, and phosphoric acids (including hydrogen phosphate and dihydrogen phosphate). Appropriate organic acids can be selected from aliphatic, cycloaliphatic, aromatic, araliphatic, heterocyclic, carboxylic and sulfonic classes of organic acids, examples of which include formic, acetic, propionic, succinic, glycolic, gluconic, lactic, malic, tartaric, citric, ascorbic, glucuronic, maleic, fumaric, pyruvic, aspartic, glutamic, benzoic, anthranilic, 4- hydroxybenzoic, phenylacetic, mandelic, embonic (or pamoic), methanesulfonic, ethanesulfonic, benzenesulfonic, pantothenic, sulfanilic, 2-hydroxyethanesulfonic, trifluoromethanesulfonic, p-toluenesulfonic, cyclohexylaminosulfonic, stearic, alginic, P- hydroxybutyric, salicylic, galactaric, galacturonic acid, glycerophosphonic acids and saccharin (e.g., saccharinate, saccharate). Salts can be comprised of a fraction of one, one or more than one molar equivalent of acid or base with respect to any compound of the disclosure.

Suitable pharmaceutically acceptable base addition salts of compounds of the disclosure include, for example, ammonium salts and metallic salts including alkali metal, alkaline earth metal and transition metal salts such as, for example, calcium, magnesium, potassium, sodium and zinc salts. Pharmaceutically acceptable base addition salts also include organic salts made from basic amines such as, for example, NJ -dibenzylethylene - diamine, chloroprocaine, choline, diethanolamine, ethylenediamine, meglumine (or N- methylglucamine) and procaine. All of these salts can be prepared from the corresponding compound by reacting, for example, the appropriate acid or base with the compound.

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures, embodiments, claims, and examples described herein. Such equivalents were considered to be within the scope of this disclosure and covered by the claims appended hereto. For example, it should be understood, that modifications in reaction conditions, including but not limited to reaction times, reaction size/volume, and experimental reagents, such as solvents, catalysts, pressures, atmospheric conditions, e.g., nitrogen atmosphere, and reducing/oxidizing agents, with art- recognized alternatives and using no more than routine experimentation, are within the scope of the present application.

It is to be understood that, wherever values and ranges are provided herein, the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosure. Accordingly, all values and ranges encompassed by these values and ranges are meant to be encompassed within the scope of the present disclosure. Moreover, all values that fall within these ranges, as well as the upper or lower limits of a range of values, are also contemplated by the present application. The description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range and, when appropriate, partial integers of the numerical values within ranges. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range.

The examples provided herein illustrate aspects of the present disclosure. However, they are in no way a limitation of the teachings or disclosure of the present disclosure as set forth herein. The examples herein are provided for the purpose of illustration only, and the disclosure is not limited to these examples, but rather encompasses all variations that are evident as a result of the teachings provided herein.

EXAMPLES

The disclosure is now described with reference to the following Examples. These Examples are provided for the purpose of illustration only, and the disclosure is not limited to these Examples, but rather encompasses all variations that are evident as a result of the teachings provided herein.

Step 1 - Synthesis of 5-bromo-2-nitropyridin-3-ol (B) To a 1 L reactor, was added sulfuric acid (500 mL) followed by 5-bromopyridin-3-ol

(A) (100 g, 0.57 mol) portion-wise, with agitation, while maintaining an internal temperature of about 25 °C to 30 °C. The resulting clear brown colored solution was cooled to a temperature of about 0 °C to 5 °C. Nitric acid (100 mL) was added slowly over a period of about 2 h, and the reaction was maintained at a temperature below 10 °C. T reaction mixture was allowed to warm to about 20 °C to 25 °C, and agitated for no less than 20 h until no more than 1.0% of compound A remained, as confirmed by HPLC. A second reactor, having a volume of 5 L, was charged with water (1.5 L) and cooled to about 0 °C to 5 °C. The reaction mixture from the 1 L reactor was slowly transferred to the second reactor comprising cooled water, and the resultant mixture was agitated at a temperature of about 20 °C to 25 °C for 3 h. Resultant solids were filtered and washed with water (300 mL) until the filtrate was observed to have a pH of about 6 to 7, and the solids were deliquored. Solids were subsequently dried in vacuo at no more than 50 °C for 12 h to provide the title compound as an off-white solid (90 g, 72% yield). *H NMR (400 MHz, CDCh) 5: 10.30 - 10.24 (s, 1H), 8.23 (d, J= 1.8 Hz, 1H), 7.84 (d, J= 1.7 Hz, 1H). MS (ESI+, m/z): Calc’d for [CsHsBr^Os + H] ⁺ : 220.0; Found: 220.8.

Step 2 - Synthesis of 5-methoxy-2-nitropyridin-3-ol (C)

To a 5 L reactor was added DMAC (1.2 L) and 5-bromo-2-nitropyridin-3-ol 2 (B) (100 g, 0.45 mol), and the mixture was agitated to give a clear solution. The mixture was cooled to a temperature of about 10 °C to 20 °C and 30% NaOMe (329 g, 1.8 mol) was added slowly over a period of 4 h, while maintaining the temperature below 20 °C. The reaction mixture was warmed to 30 °C and agitated for 2 h. Next, the reaction mixture was gradually heated to 60 °C over a period of 5 h and maintained at about 55 °C to 60 °C for no less than 36 h, until no more than 3.0% of compound B remained, as confirmed by HPLC. The reaction mixture was cooled to about 15 °C to 20 °C and quenched by slow addition of cold water (about 10 °C to 15 °C), wherein the mixture was maintained at a temperature below 20 °C. The reaction mixture was agitated at a temperature of about 15 °C to 20 °C for 15 min, then cooled to a temperature of about 5 °C to about 10 °C. Next, cone. HC1 (0.3 L, 12 M) was slowly added to the reaction mixture so as to adjust to the pH to a pH of about 1-2, while maintaining internal temperature of about 5 °C to 10 °C. The resulting mixture was agitated at about 5 °C to 10 °C for 2 h. Next, the resultant solids were fdtered, washed with water (1 L), and deliquored. Wet solids were dried in vacuo at no more than 55 °C for 12 h to provide the title compound as a yellow solid (65 g, 84% yield). ^J H NMR (400 MHz, DMSO-tfc) 5: 6.89 (d, J= 1.3 Hz, 1H), 6.23 (d, J= 1.2 Hz, 1H), 3.65 (s, 3H), 1.60 (s, 1H). MS (ESI+, m/z): Calc’d for [C6H6N2O4 + H] ⁺ : 171.04; Found 171.0.

Step 3 - Synthesis of 3-(difluoromethoxy)-5-methoxy-2-nitropyridine (D)

To a 20 L reactor was added DMF (2.3 L) and 5-methoxy-2-nitropyridin-3-ol (C) (230 g, 1.3 mol), and the mixture was agitated to obtain a clear solution. K2CO3 (224.2 g, 1.6 mol) was added, the mixture was degassed, then back fdled with N2, and sparged with N2 for a period of 15 min. The reaction mixture was heated to a temperature of about 90 °C to 95 °C. A 2 L reactor was charged with DMF (920 mL) and sodium chlorodifluoroactate (515 g, 3.3 mol), the mixture was agitated, degassed, and back fdled with N2. Next, sodium chlorodifluoroactate solution was added slowly to the reaction mixture at a temperature of about 90 °C to 95 °C over a period of 3 h. The reaction mixture was agitated at a temperature of about 90 °C to 95 °C for no less than 1 h, until no more than 1.0% of compound C remained, as confirmed by HPLC. The reaction mixture was cooled to a temperature of about 25 °C to 30 °C, then ethyl acetate (3.4 L) and water (3.4 L) were added. The mixture was subsequently agitated for a period of 30 mins. The resulting slurry was filtered through a bed of celite and washed with ethyl acetate ( 1.1 L). The filtrate was transferred to 20 L reactor, agitated for 20 min, and the layers were subsequently allowed to settle. The phases were separated, and the aqueous layer was transferred to a 5 L reactor, extracted twice with ethyl acetate (2.3 L, then 1.6 L), then the organic phases were pooled in a 20 L reactor. The pooled organic layer was washed with water four times [(2 x 3.4 L) + (2 x 2.3 L)], then washed with brine (2.3 L, 33 wt%). The organic phase was evaporated in vacuo to 300 mL and solvent swapped with hexanes (3 x 460 mL) (i.e., iterative addition of hexanes with partial removal of solvent in vacuo), and the final volume of hexanes was adjusted to 690 mL. The resulting slurry was agitated at a temperature of about 25 °C to 30 °C for 2 h, filtered, washed with hexanes, and deliquored. Wet solids were dried in vacuo at a temperature of no more than 30 °C for 12 h to provide the title compound as a yellow to brown solid (250 g, 84% yield). 'H NMR (400 MHz, CDCk) 5: 7.95 (d, J= 2.0 Hz, 4H), 7.19 (d, J= 2.6, 1.3 Hz, 3H), 6.66 (t, ./ = 72 Hz. 3H), 3.92 (s, 3H).

Step 4 - Synthesis of 3-(difluoromethoxy)-5-methoxypyridin-2-amine (E)

To a 15 L reactor was added ethanol (2.5 L) and 3-(difluoromethoxy)-5-methoxy-2- nitropyridine (D) (250 g, 1.1 mol), and the mixture was agitated at a temperature of about 25 °C to 30 °C to obtain a clear solution. Iron powder (269 g, 4.8 mol) and cone. HC1 (175 m , 12 M) were added, and the mixture was agitated at a temperature of about 25 °C to 45 °C for 15 min. The reaction mixture was allowed to heat to a temperature of about 75 °C to 80 °C and agitated for no less than 12 h, until no more than 1.0% of compound D remained, as confirmed by HPLC. In certain embodiments, additional iron and cone. HC1 can be added to promote the reaction. The reaction mixture was cooled to a temperature of about 25 °C to 30 °C, then water (1.25 L) and aq. NaHCOs (1.75 L, 8 wt%) were slowly added to the reaction mixture, and the mixture was agitated for 15 min. The reaction mixture was filtered through celite, and the celite was washed with ethyl acetate (2.5 L). An aqueous solution of NaHCOs solution (1.25L, 8 wt%) and ethyl acetate (1.25 L) were added to the filtrate, and the mixture was transferred to a 15 L reactor, and the biphasic mixture was agitated for 15 min, and layers were allowed to settle. The phases were separated, and the aqueous phase was transferred to a 10 L reactor, extracted twice with ethyl acetate (2.5 + 1.25 L), and all organic phases were pooled in a 15 L reactor. The pooled organic phase was washed with aq. NaHCOs (1.25 L, 4 wt%), water (1.25 L), and brine (2.3 L, 33 wt%). Next, activated carbon (25 g) was added, and the mixture was agitated at a temperature of about 25 °C to 30 °C for 30 min. The mixture was filtered through celite and washed with ethyl acetate (1 L). The filtrate was transferred back into cleaned 5 L reactor, evaporated under vacuum, solvent swapped with hexanes (3 x 500 L), and the final volume was adjusted to 500 m with hexanes. The resulting suspension was agitated at a temperature of about 25 °C to 30 °C for 2 h, filtered, washed with hexanes (500 mb) and deliquored. Wet solids were dried in vacuo at a temperature of no more than 35 °C for 12 h to provide the title compound as a brown solid (179 g, 83% yield). ¹ H NMR (400 MHz, CDCk) 5: 7.67 (d, J= 2.5 Hz, 1H), 6.99 (d, J = 2.5 Hz, 1H), 6.48 (t, J= 132 Hz, 1H), 4.42 (br s, 2H), 3.79 (s, 3H); MS (ESI+, m/z): Calc’d for [C7H8F2N2O2 + H] ⁺ : 191.06; Found 191.0.

Step 1’ - Synthesis of 2,6-dibromo-4-(tert-butyl)cyclohexan-l-one (G)

To a 10 L reactor was added acetonitrile (5 L) and 4-(tert-butyl)cyclohexan-l-one (F) (0.5 kg, 3.24 mol) at a temperature of about 25 °C to 30 °C. The mixture was cooled to 5 °C and pyridinium tribromide (2.07 kg, 6.48 mol) was added portion-wise over 2 h while maintaining an internal temperature of no more than 15 °C. Next, the reaction mixture was warmed to a temperature of about 25 °C to 30 °C and stirred for 3 to 4 h until the reaction is complete. In certain embodiments, reaction progress can be assessed by TLC (10% EtOAc in hexanes with TLC stain 2,4-DNPH). The reaction mixture was cooled to a temperature of about 5 °C to 10 °C, then purified water (5L) was added, and the mixture was stirred for about 10 min to 20 min. Ethyl acetate (5 L) was added and the mixture was stirred for 30 min. The agitation was stopped and the phases were allowed to settle for 30 min. The phases were separated and the aqueous phase was extracted with Ethyl acetate (2.5 L) at a temperature of about 25 °C to 30 °C. The organic phases were pooled, and aq. NaHCOs (5 L, 8 wt%) was slowly added. The reaction mixture was stirred for 30 min and allowed to settle for 30 min. The aqueous phase was discarded, and the organic was washed with aq. NaCl (5 L, 10 wt%). The organic was concentrated to dryness in vacuo at a temperature of no more than 50 °C to provide the title compound (830 g, 82% yield). 'H NMR (1.7: 1 ratio of trans:cis isomers, 400 MHz, CDCh) 5: 5.44 (dd, J = 6.0, 13.5 Hz, 1H, trans isomer), 4.77 (dd, J = 5.8, 13.3 Hz, 2H, cis isomer), 4.59 (s, 1H, trans isomer), 2.70-2.57 (m, 1.4H), 2.39-2.28 (m, 0.6H), 2.21-1.72 (m, 3H), 0.92 (s, 9H). Alternatively, compound (G) can be prepared using Bn in acetic acid or acetonitrile.

Step 2’ - Synthesis of 4-(tert-butyl)cyclohexane-l, 2-dione (H) To a 3 L reactor, was added HCO2H (1 L), 2,6-dibromo-4-(tert-butyl)cyclohexan-l- one (G) (200 g, 0.64 mol) and potassium formate (162 g, 1.92 mol) at a temperature of about 25 °C to 30 °C, and the mixture was stirred. Purified water (0.20 L) was added and the reaction mixture was heated to a temperature of about 80 °C to 85 °C for 3 to 4 h until the reaction was complete. In certain embodiments, reaction progressed can be assessed by TLC (10% EtOAc in hexanes with TLC stain 2,4-DNPH). The reaction mixture was cooled to a temperature of about 20 °C to 25 °C and slowly added to another reactor containing aq. NaHCOs (2 L, 8 wt%) solution at a temperature of about 25 °C to 30 °C. Dichloromethane (2 L) was added and the mixture was stirred for 20 min. The mixture was allowed to settle for 30 min and the phases were separated. The aqueous phase was back extracted with DCM (2 L), with stirring, and the phases were again separated. The organic phases were pooled, and the combined organic phases were concentrated to 2 to 3 volumes under vacuum at a temperature of no more than 50 °C to provide the title compound as a red-brown viscous residue, which was used without further purification (100 g, 89% yield).

Step 5 - Synthesis of 8-(tert-butyl)-4-(difluoromethoxy)-2-methoxy-8,9- dihydrobenzo[4,5]imidazo[l,2-a]pyridin-6(7H)-one (I)

To a 10 L pressure reactor/autoclave was added acetic acid (3.5 L) and 3- (difluoromethoxy)-5-methoxypyridin-2 -amine (E) (0.35 kg, 1.84 mol) at a temperature of about 25 °C to 30 °C. Next, 4-(tert-butyl)cyclohexane- 1,2-dione (H) (0.77 kg, 4.61 mol) was added at a temperature of about 25 °C to 30 °C. The pressure reactor/autoclave was degassed (i.e., air atmosphere replaced with N2) by application of N2 (g) (10 to 20 psi) to the pressure reactor/autoclave with slow release of air, and this degassing process was repeated twice. Next, O2 (g) (10 to 20 psi) was applied to the pressure reactor/autoclave and released safely to replace the N2 (g), and this was repeated two more times. Finally, O2 (g) (45 to 50 psi) was applied to the pressure reactor/autoclave and the reaction mixture was heated to a temperature of about 90 °C to 95 °C for a period of about 16 h to 24 h until no more than 5.0% of compound (E) remained, as determined by HPLC. The reaction mixture was cooled to a temperature of about 25 °C to 30 °C and concentrated in vacuo at a temperature of no more than 50 °C to remove acetic acid. Dichloromethane (5.25 L) was added, followed by purified water (3.5 L) at a temperature of about 25 °C to 30 °C. The solution was stirred for 30 min, allowed to settle for 30 min, and the phases were separated. The aqueous phase was back extracted with DCM (1.75 L), stirred for 30 min, settled for 30 min, and separated. The organic phases were pooled, and the combined organic phases were washed with aq. NaHCOs (3.5 L, 8 wt%). The organic phase was collected and washed with aq. NaCl (3.5 L, 10 wt%). The organic layer was concentrated to dryness in vacuo at a temperature of no more than 50 °C. Next, 2-propanol (1.05 L) and ethyl acetate (0.35 L) were added to the residue and heated to 50 °C. Heptane (2.45 L) was slowly added over 30 min at 50 °C. The mixture was slowly cooled to a temperature of about 25 °C to 30 °C over a period of 2 h to 3 h. The mixture was stirred at a temperature of about 25 °C to 30 °C for a period of 1 h to 2 h and then cooled to a temperature of about 5 °C to 10 °C and held at 5 °C to 10 °C for a period of 12 h to 14 h. The slurry was filtered, and the wet cake was washed with cold mixture of heptane and 2-propanol (0.35 L). The solid was dried in vacuo at a temperature of no more than 50 °C for a period of 12 h to 14 h to afford the title compound as a light brown solid (193 g, 31% yield). 'H NMR (1: 1 tautomer ratio, 400 MHz, CDCh) 5: 6.23 (t, J = 2. 1 Hz, 0.5H), 6.15 (dd, J = 2.7, 6.8 Hz, 0.5H), 5.93 (s, 0.5H), 5.89 (s, 0.5H), 2.69-2.61 (m, 1H), 2.45-2.02 (m, 3H), 1.87 (ddt, J = 4.0, 11.3, 14.8 Hz, 0.5H), 1.74-1.63 (m, 0.5H), 0.96 (s, 4.5H), 0.91 (s, 4.5H).

Chiral Chromatography

Compound I was subjected to chiral preparative HPLC to provide (/?)-8-(tcrt-butyl)-4- (difhioromethoxy)-2-methoxy-8,9-dihydrobenzo[4,5]imidazo[l,2 -a]pyridin-6(7H)-one (( ?)- I) (>99% ee). 'H NMR (400 MHz, CDCh) 5: 7.57 (t, J = 74.7 Hz, 1H), 7.23 (d, J = 2.0 Hz, 1H), 6.85 (d, J = 2.0 Hz, 1H), 3.88 (s, 3H), 3.04 (dd, J = 4.9, 16.0 Hz, 1H), 2.85-2.72 (m, 2H), 2.47 (dd, J = 13.6, 16.1 Hz, 1H), 2.23 (dddd, J = 3.2, 4.8, 11.6, 13.5 Hz, 1H), 1.05 (s, 9H); MS (ESI+, m/z): Calc’d for [Ci7H2oF2N ₂ 03+H]+: 339.15; Found 339.1.

Chiral Preparative Separation Method 1

Column: CHIRALPAK IH® (250 x 80 mm), 10 pm particle size, DAC column; mobile phase: hexanes/dichloromethane/Ao-propyl alcohol (40:30:30); flow rate: 220 mL/min; detection: UV 340 nm; temperature: 25 °C; loading: 1.8 g/injection (60 mb total volume), 30 mg/mL in hexanes/dichloromethane/Ao-propyl alcohol (40:30:30); runtime: 15 min.

Chiral Preparative Separation Method 2

Column: Chiral Art Cellulose-SC (250 x 100 mm), 10 pm particle size; mobile phase: MeOH; flow rate: 100 mL/min; detection: UV 210 nm; temperature: 25 °C; loading: 500 mg/injection (20 mL total volume), 25 mg/mL in MeOH; runtime: 60 min.

Step 6 - Synthesis of (5)-l-benzhydryl-5-(tert-butyl)-ll-(difluoromethoxy)-9-metho xy- 2-oxo-l,2,5,6-tetrahydropyrido[2',l':2,3]imidazo[4,5-h]quino line-3-carboxylic acid ((A)- K)

8-(tert-butyl)-4-(difluoromethoxy)-2-methoxy-8,9-dihydrob enzo[4,5]imidazo[l,2- a]pyridin-6(7H)-one ((/?)-!) (25 g, 73.9 mmol) was suspended in toluene (250 mL) and benzhydrylamine (14.0 mL, 14.9 g, 81.3 mmol) was added. The mixture was heated to reflux in a vessel equipped with a Dean- Stark trap for 12 h. The resulting solution was cooled to 70 °C and 5-(methoxymethylene)-2,2-dimethyl-l,3-dioxane-4, 6-dione (20.63 g, 110.8 mmol) was added. The solution was heated at 70 °C for 1 h, then cooled to 40 °C. Next, 1, 1,3,3- tetramethylguanidine (23.2 mL, 21.3 g, 184.7 mmol) was added and the resulting solution was heated at 70 °C for 8 h. The reaction mixture was cooled to 50 °C and a 10% aqueous solution of citric acid (250 mL) was added while maintaining the temperature above 45 °C. The mixture was stirred at 50 °C for 2 h, then cooled to room temperature. The mixture was filtered, and the cake was washed sequentially with water (125 mL) and toluene (25 mL), then the cake was deliquored. The wet solid was dried in vacuo to provide the title compound as a brown to yellow solid (30.55 g, 69%). ¹ H NMR (400 MHz, CDCh) 5: 14.25 (s, 1H), 9.46 (br s, 1H), 8.40 (s, 1H), 7.49-7.20 (m, 11H), 7.11 (t, J = 74.4 Hz, 1H), 6.81 (d, J = 1.9 Hz, 1H), 3.89 (s, 3H), 3.32-3.25 (m, 2H), 2.93 (dd, J = 2.5, 6.7 Hz, 1H), 0.77 (s, 9H); MS (ESI+, m/z): Calc’d for [C34H31F2N3O5 + H]+: 600.2; Found 600.2.

Step 7 - Synthesis of (5)-5-(tert-butyl)-ll-(difluoromethoxy)-9-methoxy-2-oxo-l, 2,5,6- tetrahydropyrido [2 ’ ,1 ' :2,3]imidazo [4,5-h] quinoline-3-carboxylic acid ((*S)-L)

(.S')- l-benzhydryl-5 -(tert-butyl)- 1 l-(difhroromethoxy)-9-methoxy-2-oxo- 1,2, 5, 6- tetrahydropyrido[2',r:2,3]imidazo[4,5-h]quinoline-3-carboxyl ic acid ((5 ^T )-K) (7.19 g, 12.0 mmol) was added to a mixture of trifluoroacetic acid (21.5 mL) and methyl isobutyl ketone (21.5 mL) at 0 °C. The resulting solution was warmed to room temperature and stirred for 1 h. Water (29 mL) was added, and the mixture was stirred at room temperature for 2.5 h, after which it was diluted with methyl isobutyl ketone (86 mL, 12 V). The layers were separated, and the organic layer was cooled to a temperature of about 0 °C to 10 °C. The pH was adjusted to 7 using a 20% aqueous solution of NarCO? (72 mL) and mixed. The layers were separated, and the organic layer was washed with a 5% aqueous solution of NaCl (72 mL, 10 V), and the layers were again separated. The organic layer was dried over MgSOr and filtered. The filtered solution was concentrated to a total volume of 15 mL at 50 °C. Methanol (57 mL) and water (3.6 mL) were added, and the resulting slurry was cooled to 0 °C. The slurry was filtered, and the wet cake was washed with ice-cold methanol (15 mL) and fully deliquored. The wet cake was dried in vacuo to provide the title compound as a bright yellow solid (4.13 g, 79%). 'H NMR (400 MHz, DMSO-tfc) 5: 14.94 (s, 1H), 13.58 (br s, 1H), 8.27 (s, 1H), 8.13 (s, 1H), 8.01 (t, J= 74.2 Hz, 1H), 6.98 (s, 1H), 3.88 (s, 3H), 3.67 (d, J= 17.7 Hz, 1H), 3.18 (dd, J= 8.4, 17.7 Hz, 1H), 3.07 (d, J= 8.4 Hz, 1H), 0.74 (s, 9H); MS (ESI+, m/z): Calc’d for [C2iH ₂ iE2N3O ₅ +H] ⁺ : 434.15; Eound 434.2.

Enumerated Embodiments

The following exemplary embodiments are provided, the numbering of which is not to be construed as designating levels of importance:

Embodiment 1 provides a method of preparing (.S)-5-(tcrt-butyl)- 1 1- (difhioromethoxy)-9-methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2 ',r:2,3]imidazo[4,5- h] quinoline -3 -carboxylic acid (GS’)-L). or a salt or solvate thereof: the method comprising reacting an acid and (S')- 1 -(CHR ¹ R ² )-5-(tc rt-bntyl )- 1 1- (difluoromethoxy)-9-methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2 ',r:2,3]imidazo[4,5- h] quinoline -3 -carboxylic acid ((A)-K): wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci-Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl.

Embodiment 2 provides the method of Embodiment 1, wherein R ¹ and R ² are each independently phenyl.

Embodiment 3 provides the method of Embodiment 1 or 2, wherein the acid is trifluoroacetic acid (TFA).

Embodiment 4 provides the method of Embodiment 3, wherein ((5)-K) is contacted with a superstoichiometric amount of TFA.

Embodiment 5 provides the method of any one of Embodiments 1-4, wherein the acid and (A)-K are contacted in a solvent comprising methyl isobutyl ketone (MIBK).

Embodiment 6 provides the method of any one of Embodiments 1-5, wherein ((A)-K) is prepared by:

(a) reacting (R)-8-(tert-butyl)-4-(difluoromethoxy)-2-methoxy-8,9- dihydrobenzo [4,5] imidazo [ 1 ,2-a] pyridin-6(7H)-one ((/?)-!) : ((/?)-!), with a primary amine to form an imine intermediate; and

(b) reacting the imine intermediate with (J) in the presence of a base: wherein:

R ³ is selected from the group consisting of Ci-Ce alkoxy, N(Ci-Ce alkyl)(Ci- Ce alkyl), CN, halogen, triflate, mesylate, and tosylate;

R ^4a and R ^4b are each independently selected from the group consisting of Ci- Ce alkyl and Cs-Cs cycloalkyl, or R ^4a and R ^4b combine with the atoms to which they are bound to form a Ce- heterocyclyl.

Embodiment 7 provides the method of Embodiment 6, wherein the primary amine comprises R ¹ R ² CH-NH2, wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci-Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl.

Embodiment 8 provides the method of Embodiment 6 or 7, wherein the primary amine is diphenylmethanamine.

Embodiment 9 provides the method of any one of Embodiments 6-8, wherein the reaction of ((/?)-!) and the primary amine occurs in a solvent comprising toluene.

Embodiment 10 provides the method of any one of Embodiments 6-9, wherein the reaction of ((/?)-!) and the primary amine occurs under reflux conditions.

Embodiment 11 provides the method of Embodiment 10, wherein the reaction of ((/?)- I) and the primary amine occurs in a vessel equipped with a Dean-Stark apparatus.

Embodiment 12 provides the method of any one of Embodiments 6-11, wherein the reaction of ((/?)-!) and the primary amine occurs in the absence of an acid.

Embodiment 13 provides the method of any one of Embodiments 6-12, wherein R ³ is OMe.

Embodiment 14 provides the method of any one of Embodiments 6-13, wherein (J) is 5 -(methoxymethylene)-2,2-dimethyl-l,3-dioxane-4, 6-dione.

Embodiment 15 provides the method of any one of Embodiments 6-14, wherein the reaction of (J) and the imine intermediate occurs in a solvent comprising toluene. Embodiment 16 provides the method of any one of Embodiments 6-15, wherein the reaction of (J) and the imine intermediate occurs at a temperature of about 70 °C.

Embodiment 17 provides the method of any one of Embodiments 6-16, wherein the base is 1,1, 3, 3 -tetramethylguanidine (TMG).

Embodiment 18 provides the method of any one of Embodiments 6-17, wherein ((/?)- I) is prepared by chiral resolution of 8-(tert-butyl)-4-(difluoromethoxy)-2-methoxy-8,9- dihydrobenzo [4,5] imidazo [ 1 ,2-a] pyridin-6(7H)-one (I) :

Embodiment 19 provides the method of Embodiment 18, wherein the chiral resolution comprises chiral column chromatography.

Embodiment 20 provides the method of Embodiment 18 or 19, wherein (I) is prepared by reacting 3-(difluoromethoxy)-5-methoxypyridin-2-amine and 4-(tert-butyl)cyclohexane- 1,2-dione ( the presence of an oxidant and an acid.

Embodiment 21 provides the method of Embodiment 20, wherein the oxidant is O2.

Embodiment 22 provides the method of Embodiment 21, wherein the reaction of (E) and (H) occurs at an O2 pressure of 50 psi.

Embodiment 23 provides the method of any one of Embodiments 20-22, wherein the acid is acetic acid.

Embodiment 24 provides the method of any one of Embodiments 20-23, wherein the reaction of (E) and (H) occurs at a temperature of about 90 °C to about 95 °C.

Embodiment 25 provides the method of any one of Embodiments 20-24, wherein (E) is prepared by reacting 3-(difluoromethoxy)-5-methoxy-2-nitropyridine (D): reducing agent.

Embodiment 26 provides the method of Embodiment 25, wherein the reducing agent is iron powder.

Embodiment 27 provides the method of Embodiment 25 or 26, wherein the reaction of (D) and the reducing agent occurs in the presence of an acid.

Embodiment 28 provides the method of Embodiment 27, wherein the acid is hydrochloric acid (HC1).

Embodiment 29 provides the method of any one of Embodiments 25-28, wherein (D) is prepared by reacting 5-methoxy-2-nitropyridin-3 difluoromethylating reagent.

Embodiment 30 provides the method of Embodiment 29, wherein the difluoromethylating reagent is sodium 2-chloro-2,2-difluoroacetate.

Embodiment 31 provides the method of Embodiment 29 or 30, wherein the reaction of (D) and the difluoromethylating reagent occurs in the presence of a base.

Embodiment 32 provides the method of Embodiment 31, wherein the base is K2CO3.

Embodiment 33 provides the method of any one of Embodiments 29-32, wherein the reaction of (D) and the difluoromethylating reagent occurs in a solvent comprising dimethylformamide (DMF).

Embodiment 34 provides the method of any one of Embodiments 29-33, wherein the reaction of (D) and the difluoromethylating reagent occurs at a temperature of about 90 °C.

Embodiment 35 provides the method of any one of Embodiments 29-34, wherein (C) is prepared by reacting 5-bromo-2-nitropyridin-3-ol (B) with a methoxide salt:

Embodiment 36 provides the method of Embodiment 35, wherein the methoxide is sodium methoxide.

Embodiment 37 provides the method of Embodiment 36, wherein the sodium methoxide comprises a 30% w/w solution of sodium methoxide in methanol. Embodiment 38 provides the method of any one of Embodiments 35-37, wherein the reaction of (B) and the methoxide salt occurs in a solvent comprising dimethylacetamide (DMAC).

Embodiment 39 provides the method of any one of Embodiments 35-38, wherein the reaction of (B) and the methoxide salt occurs at a temperature of about 60 °C.

Embodiment 40 provides the method of any one of Embodiments 35-39, wherein (B) is prepared by reacting 5-bromopyridin-3 nitrating agent.

Embodiment 41 provides the method of Embodiment 40, wherein the nitrating agent is nitronium ion (O=N ⁺ =O).

Embodiment 42 provides the method of Embodiment 41, wherein nitronium ion is generated by reacting nitric acid and a second acid.

Embodiment 43 provides the method of Embodiment 42, wherein the second acid is sulfuric acid.

Embodiment 44 provides the method of any one of Embodiments 20-24, wherein (H) is prepared by reacting 2,6-dibromo-4-(tert-butyl)cyclohexan-l-one ( with water in the presence of an acid and a carboxylate salt.

Embodiment 45 provides the method of Embodiment 44, wherein at least one of the following applies: (a) the acid is formic acid; and (b) the carboxylate salt is potassium formate.

Embodiment 46 provides the method of Embodiment 44 or 45, wherein the reaction of (E) and water occurs at a temperature of about 80 °C.

Embodiment 47 provides the method of any one of Embodiments 44-46, wherein (G) is prepared by reacting 4-(tert-butyl)cyclohexan- 1 -one ( brominating reagent.

Embodiment 48 provides the method of Embodiment 47, wherein the brominating agent comprises pyridinium tribromide or Bn.

Embodiment 49 provides the method of Embodiment 47 or 48, wherein the reaction of (F) and the brominating agent occurs in a solvent comprising acetonitrile (ACN) or acetic acid.

Embodiment 50 provides the method of any one of Embodiments 1-5, wherein ((A)- K) is prepared by chiral resolution of l-(CHR ¹ R ² )-5 -(tert-butyl)- 1 l-(difluoromethoxy)-9- methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2',r:2,3]imidazo[4,5- h]quinoline-3-carboxylic acid (K): wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci-Ce alkyl, and optionally substituted phenyl.

Embodiment 51 provides the method of Embodiment 50, wherein R ¹ and R ² are each independently phenyl.

Embodiment 52 provides the method of Embodiment 50 or 51, wherein (K) is prepared by:

(a) reacting 8-(tert-butyl)-4-(difhioromethoxy)-2-methoxy-8,9- dihydrobenzo [4,5] imidazo [ 1 ,2-a] pyridin-6(7H)-one : with a primary amine to form an imine intermediate; and

(b) reacting the imine intermediate with (J) in the presence of a base: wherein:

R ³ is selected from the group consisting of Ci-Ce alkoxy, N(Ci-Ce alkyl)(Ci-Ce alkyl), CN, halogen, triflate, mesylate, and tosylate; R ^4a and R ^4b are each independently selected from the group consisting of Ci-Ce alkyl and Cs-Cs cycloalkyl, or R ^4a and R ^4b combine with the atoms to which they are bound to form a Ce-Cx heterocyclyl.

Embodiment 53 provides the method of Embodiment 52, wherein the primary amine comprises R ¹ R ² CH-NH2, wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci-Ce alkyl, and optionally substituted phenyl.

Embodiment 54 provides the method of Embodiment 52 or 53, wherein the primary amine is diphenylmethanamine.

Embodiment 55 provides the method of any one of Embodiments 52-54, wherein the reaction of (I) and the primary amine occurs in a solvent comprising toluene.

Embodiment 56 provides the method of any one of Embodiments 52-55, wherein the reaction of (I) and the primary amine occurs under reflux conditions.

Embodiment 57 provides the method of any one of Embodiments 56, wherein the reaction of (I) and the primary amine occurs in a vessel equipped with a Dean-Stark apparatus.

Embodiment 58 provides the method of any one of Embodiments 52-57, wherein the reaction of (I) and the primary amine occurs in the absence of an acid.

Embodiment 59 provides the method of any one of Embodiments 52-58, wherein R ³ is OMe.

Embodiment 60 provides the method of any one of Embodiments 52-59, wherein (J) is 5-(methoxymethylene)-2,2-dimethyl- 1 ,3-dioxane-4, 6-dione .

Embodiment 61 provides the method of any one of Embodiments 52-60, wherein the reaction of (J) and the imine intermediate occurs in a solvent comprising toluene.

Embodiment 62 provides the method of any one of Embodiments 52-61, wherein the reaction of (J) and the imine intermediate occurs at a temperature of about 70 °C.

Embodiment 63 provides the method of any one of Embodiments 52-62, wherein the base is 1,1, 3, 3 -tetramethylguanidine (TMG).

Embodiment 64 provides a method of preparing (.S')-5 -(tert-butyl)- 11- (difhioromethoxy)-9-methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2 ',r:2,3]imidazo[4,5- h] quinoline -3 -carboxylic acid (GS’)-L). or a salt or solvate thereof: the method comprising chiral resolution of 5 -(tert-butyl)- 1 l-(difluoromethoxy)-9-methoxy-2- oxo-l,2,5,6-tetrahydropyrido[2',r:2,3]imidazo[4,5-h]quinolin e-3-carboxylic acid (L):

Embodiment 65 provides the method of Embodiment 64, wherein the chiral resolution comprises chiral column chromatography.

Embodiment 66 provides the method of Embodiment 64 or 65, wherein (L) is prepared by reacting an acid and l-(CHR ¹ R ² )-5 -(tert-butyl)- 1 l-(difluoromethoxy)-9- methoxy-2-oxo-l,2,5,6-tetrahydropyrido[2',r:2,3]imidazo[4,5- h]quinoline-3-carboxylic acid (K): wherein R ¹ and R ² are each independently selected from the group consisting of H, optionally substituted Ci-Ce alkyl, optionally substituted Cs-Cs cycloalkyl, and optionally substituted phenyl.

Embodiment 67 provides the method of Embodiment 66, wherein R ¹ and R ² are each independently phenyl.

Embodiment 68 provides the method of Embodiment 66 or 67, wherein the acid is trifluoroacetic acid (TFA).

Embodiment 69 provides the method of any one of Embodiments 66-68, wherein the reaction of (K) and the acid is performed in a solvent comprising methyl isobutyl ketone (MIBK).

The terms and expressions employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the embodiments of the present application. Thus, it should be understood that although the present application describes specific embodiments and optional features, modification and variation of the compositions, methods, and concepts herein disclosed can be resorted to by those of ordinary skill in the art, and that such modifications and variations are considered to be within the scope of embodiments of the present application.