TITLE OF THE INVENTION

CRYSTALLINE SODIUM SALT OF AN HTV INTEGRASE INHIBITOR

FIELD OF THE INVENTION The present invention is directed to a pharmaceutically acceptable crystalline sodium salt of an HTV integrase inhibitor, Compound A as defined below. The present invention is also directed to pharmaceutical compositions containing the crystalline salt, and methods for using the salt.

BACKGROUND OF THE INVENTION

The HIV retrovirus is the causative agent for AIDS. The HTV-I retrovirus primarily uses the CD4 receptor (a 58 kDa transmembrane protein) to gain entry into cells, through high-affinity interactions between the viral envelope glycoprotein (gp 120) and a specific region of the CD4 molecule found in T-lymphocytes and CD4 (+) T-helper cells (Lasky L.A. et al., Cell 1987, 50: 975-985). HTV infection is characterized by an asymptomatic period immediately following infection that is devoid of clinical manifestations in the patient. Progressive HTV-induced destruction of the immune system then leads to increased susceptibility to opportunistic infections, which eventually produces a syndrome called ARC (AIDS-related complex) characterized by symptoms such as persistent generalized lymphadenopathy, fever, and weight loss, followed itself by full blown AIDS. After entry of the retrovirus into a cell, viral RNA is converted into DNA, which is then integrated into the host cell DNA. Integration of viral DNA is an essential step in the viral life cycle. Integration is believed to be mediated by integrase, a 32 kDa enzyme, in three steps: assembly of a stable nucleoprotein complex with viral DNA sequences; cleavage of two nucleotides from the 3' termini of the linear proviral DNA; and covalent joining of the recessed 3' OH termini of the proviral DNA at a staggered cut made at the host target site. The fourth step in the process, repair synthesis of the resultant gap, may be accomplished by cellular enzymes.

The compound 6-(3-chloro-4-fluorobenzyl)-4-hydroxy-2-isopropyl-N,N- dimethyl-3,5-dioxo-2,3,5,6,7,8-hexahydro-2,6-naphthyridine-l -carboxamide (designated herein as "Compound A") is a potent HTV integrase inhibitor. The structure of Compound A is as follows:

Compound A

SUMMARY OF THE INVENTION

The present invention is directed to a crystalline sodium salt of Compound A. The present invention also includes pharmaceutical compositions containing the crystalline Na salt of Compound A and methods of using the crystalline Na salt of Compound A for inhibition of HIV integrase, for prophylaxis or treatment of HIV infection, and for prophylaxis, treatment or delay in the onset of AIDS.

Embodiments, aspects and features of the present invention are either further described in or will be apparent from the ensuing description, examples, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is the X-ray powder diffraction pattern for the crystalline sodium salt of Compound A in Example 3.

Figure 2 is the DSC curve for the crystalline sodium salt of Compound A in Example 3.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a pharmaceutically acceptable crystalline sodium salt of Compound A, pharmaceutical compositions containing the salt, and methods of making and using the salt. The Compound A crystalline sodium salt and pharmaceutical compositions of the present invention are useful for inhibiting HIV integrase, prophylaxis of infection by HTV, treating infection by HIV, delaying the onset of AIDS, prophylaxis of AIDS, and treating AIDS, in adults, children or infants. Delaying the onset of AIDS, prophylaxis of AIDS, treating AIDS, prophylaxis of HTV infection, or treating HTV infection is defined as including, but not limited to, prophylaxis or treatment of a wide range of states of HIV infection: AIDS, ARC, both symptomatic and asymptomatic, and actual or potential exposure to HTV. For example,

the crystalline sodium salt and pharmaceutical compositions thereof of this invention are useful in treating infection by HIV after suspected past exposure to HIV by, e.g., blood transfusion, exchange of body fluids, bites, accidental needle stick, or exposure to patient blood during surgery. The crystalline salt of the invention can also be used in "salvage" therapy; i.e., it can be used to treat HIV infection, AIDS, or ARC in HIV-positive subjects whose viral load achieved undetectable levels via conventional therapies (e.g., therapies employing known protease inhibitors in combination with one or more known reverse transcriptase inhibitors), and then rebounded due to the emergence of HIV mutants resistant to the known inhibitors. Compound A is an inhibitor of HIV integrase. Compound A has been tested in an integrase inhibition assay in which strand transfer is catalyzed by recombinant integrase, and has been found to be a potent inhibitor. The strand transfer assay is described in Example 193 of WO 02/30930. Compound A has also been found to be active in an assay for the inhibition of acute HTV infection of T-lymphoid cells conducted in accordance with Vacca et al., Proc. Natl. Acad. ScL USA 1994, 91: 4096-4100.

A first embodiment of this invention is a crystalline sodium salt of

Compound A, which is characterized by an X-ray powder diffraction pattern obtained using copper K _α radiation (i.e., the radiation source is a combination of Cu K _α i and K _α 2 radiation) which comprises 2θ values (i.e., reflections at 2θ values) in degrees of 5.9, 10.9 and 12.5. A second embodiment of this invention is a crystalline sodium salt of

Compound A, which is characterized by an X-ray powder diffraction pattern obtained using copper K _α radiation which comprises 2θ values in degrees of 5.9, 10.9, 12.5, 13.3, 15.5 and

18.7.

A third embodiment of this invention is a crystalline sodium salt of Compound A, which is characterized by an X-ray powder diffraction pattern obtained using copper K _α radiation which comprises 2θ values in degrees of 5.9, 10.9, 12.5, 13.3, 15.5,

17.6, 18.7, 21.3 and 23.9.

A fourth embodiment of this invention is a crystalline sodium salt of Compound A as defined in any one of the first three embodiments, which is further characterized by a differential scanning calorimetry curve, obtained at a heating rate of 10 °C/min in a closed pan under nitrogen, exhibiting an endotherm with a peak temperature of about 22O ⁰ C.

The crystalline Na salt of Compound A as set forth in the foregoing embodiments can alternatively be described in terms of the crystallographic d-spacings

corresponding to the 2θ reflections. The corresponding d-spacings are listed in Example 3 below.

The present invention includes pharmaceutical compositions comprising an effective amount of a crystalline sodium salt of Compound A as set forth in any of the foregoing embodiments and a pharmaceutically acceptable carrier.

The present invention also includes pharmaceutical compositions which comprise the product made by combining an effective amount of a crystalline sodium salt of Compound A as set forth in any of the foregoing embodiments and a pharmaceutically acceptable carrier. Other embodiments of the present invention include the following:

(a) A method for the prophylaxis or treatment of HIV infection in a subject in need thereof, which comprises administering to the subject an effective amount of a crystalline sodium salt of Compound A.

(b) A method of delaying the onset of AIDS in a subject in need thereof, which comprises administering to the subject an effective amount of a crystalline sodium salt of Compound A.

(c) A method for the prophylaxis or treatment of AIDS in a subject in need thereof, which comprises administering to the subject an effective amount of a crystalline sodium salt of Compound A. (d) A method of inhibiting HTV integrase in a subject in need thereof, which comprises administering to the subject an effective amount of a crystalline sodium salt of Compound A.

(e) A method for the prophylaxis or treatment of HTV infection in a subject in need thereof, which comprises administering to the subject a pharmaceutical composition comprising an effective amount of a crystalline sodium salt of Compound A and a pharmaceutically acceptable carrier.

(f) A method of delaying the onset of AIDS in a subject in need thereof, which comprises administering to the subject a pharmaceutical composition comprising an effective amount of a crystalline sodium salt of Compound A and a pharmaceutically acceptable carrier.

(g) A method for the prophylaxis or treatment of AIDS in a subject in need thereof, which comprises administering to the subject a pharmaceutical composition comprising an effective amount of a crystalline sodium salt of Compound A and a pharmaceutically acceptable carrier.

(h) A method of inhibiting HTV integrase in a subject in need thereof, which comprises administering to the subject a pharmaceutical composition comprising an effective amount of a crystalline sodium salt of Compound A and a pharmaceutically acceptable carrier. (i) The method of (a) or (b) or (c) or (d), wherein the crystalline sodium salt of Compound A is administered in combination with at least one anti-HIV agent selected from the group consisting of AIDS antiviral agents, immunomodulators, and anti-infective agents, wherein the crystalline Compound A Na salt and the anti-HTV agent are each employed in an amount that renders the combination effective in said method. Q) The method of (a) or (b) or (c) or (d), wherein the crystalline sodium salt of Compound A is administered in combination with at least one antiviral agent selected from the group consisting of HTV protease inhibitors, non-nucleoside HTV reverse transcriptase inhibitors and nucleoside HTV reverse transcriptase inhibitors, wherein the crystalline Compound A Na salt and the antiviral agent are each employed in an amount that renders the combination effective in said method.

The present invention also includes a crystalline sodium salt of Compound A of the present invention (i) for use in, (ii) for use as a medicament for, or (iii) for use in the preparation of a medicament for: (a) the inhibition of HTV integrase, (b) treatment or prophylaxis of infection by HTV, or (c) treatment, prophylaxis of, or delay in the onset of AIDS. In these uses, the crystalline Na salt of Compound A of the present invention can optionally be employed in combination with one or more anti-HIV agents selected from HTV antiviral agents, anti-infective agents, and immunomodulators.

The term "administration" and variants thereof (e.g., "administered" or "administering") in reference to a crystalline Na salt of Compound A mean providing the salt to the individual in need of inhibition, treatment or prophylaxis. When a crystalline sodium salt of Compound A is provided in combination with one or more other active agents (e.g., anit-HTV agents such as antiviral agents useful for treating or prophylaxis of HTV infection or AIDS), "administration" and its variants are each understood to include provision of the compound or prodrug and other agents at the same time (separately or together) or at different times.

As used herein, the term "composition" is intended to encompass a product comprising the specified ingredients in the specified amounts, as well as any product which results, directly or indirectly, from combining the specified ingredients.

By "pharmaceutically acceptable" is meant that the ingredients of the pharmaceutical composition must be compatible with each other and not deleterious to the recipient thereof.

The term "subject" as used herein refers to an animal, preferably a mammal, most preferably a human, who has been the object of treatment, observation or experiment.

The term "effective amount" as used herein means that amount of active compound or pharmaceutical agent that elicits the biological or medicinal response in a tissue, system, animal or human that is being sought by a researcher, veterinarian, medical doctor or other clinician. The effective amount can be a "therapeutically effective amount" for the alleviation of the symptoms of the disease or condition being treated. The effective amount can also be a "prophylactically effective amount" for prophylaxis of the symptoms of the disease or condition being prevented. The term also includes herein the amount of active compound sufficient to inhibit HTV integrase and thereby elicit the response being sought (i.e., an "inhibition effective amount"). In the present invention, the active ingredient (i.e., Compound A) is administered as a crystalline sodium salt, and references to the amount of active ingredient are to the free form of Compound A.

The term "anti-HTV agent" means an agent which is effective in one or more of the following uses: inhibiting integrase or another enzyme required for HTV replication or infection, prophylaxis of HIV infection, treating HTV infection, delaying the onset of AIDS, prophylaxis of AIDS, or treating AIDS. Suitable anti-HIV agents include HIV/AIDS antiviral agents, anti-infective agents, and immunomodulators. Suitable anti-HIV agents include those listed in Table 1 of WO 01/38332 or in the Table in WO 02/30930. Suitable fflV/AIDS antivirals for use in combination with the compounds of the present invention include, for example, HTV protease inhibitors (e.g., indinavir, atazanavir, lopinavir optionally with ritonavir, saquinavir, or nelfinavir), nucleoside HTV reverse transcriptase inhibitors (e.g., abacavir, lamivudine (3TC), zidovudine (AZT), or tenofovir), and non-nucleoside HTV reverse transcriptase inhibitors (e.g., efavirenz or nevirapine). It will be understood that the scope of combinations of the compounds of this invention with HTV/AIDS antivirals, immunomodulators, anti-infectives or vaccines is not limited to the foreogoing substances or to the list in the above-referenced Tables in WO 01/38332 and WO 02/30930, but includes in principle any combination with any pharmaceutical composition useful for the treatment of AIDS. The HTV/AIDS antivirals and other agents will typically be employed in these combinations in their conventional dosage ranges and regimens as reported in the art, including, for example, the dosages described in the Physicians' Desk Reference, 57 ^th edition,

Thomson PDR, 2003. The dosage ranges for a compound of the invention in these combinations are the same as those set forth elsewhere herein.

For the purpose of inhibiting HTV integrase, treating or prophylaxis of HTV infection or treating, prophylaxis of or delaying the onset of AIDS, a crystalline sodium salt of Compound A of the present invention can be administered by any means that produces contact of the active agent with the agent's site of action. The crystalline sodium salt can be administered by any conventional means available for use in conjunction with pharmaceuticals, either as individual therapeutic agents or in a combination of therapeutic agents. It can be administered alone, but is typically administered with a pharmaceutical carrier selected on the basis of the chosen route of administration and standard pharmaceutical practice. A crystalline Na salt of Compound A of the invention can, for example, be administered orally, parenterally (including subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques), by inhalation spray, or rectally, in the form of a unit dosage of a pharmaceutical composition containing an effective amount of the crystalline Na salt and conventional non-toxic pharmaceutically- acceptable carriers, adjuvants and vehicles. Liquid preparations suitable for oral administration (e.g., suspensions, syrups, elixirs and the like) can be prepared according to techniques known in the art and can employ any of the usual media such as water, glycols, oils, alcohols and the like. Solid preparations suitable for oral administration (e.g., powders, pills, capsules and tablets) can be prepared according to techniques known in the art and can employ such solid excipients as starches, sugars, kaolin, lubricants, binders, disintegrating agents and the like. Parenteral compositions can be prepared according to techniques known in the art and typically employ sterile water as a carrier and optionally other ingredients, such as a solubility aid. Injectable solutions can be prepared according to methods known in the art wherein the carrier comprises a saline solution, a glucose solution or a solution containing a mixture of saline and glucose. Further description of methods suitable for use in preparing pharmaceutical compositions of the present invention and of ingredients suitable for use in said compositions is provided in Remington's Pharmaceutical Sciences, 18 ^th edition, edited by A. R. Gennaro, Mack Publishing Co., 1990. The crystalline Na salt of Compound A of this invention can be administered orally in a dosage range of about 0.001 to about 1000 mg/kg of mammal (e.g., human) body weight per day in a single dose or in divided doses. One preferred dosage range is about 0.01 to about 500 mg/kg body weight per day orally in a single dose or in divided doses. Another preferred dosage range is about 0.1 to about 100 mg/kg body weight per day orally in single or divided doses. For oral administration, the compositions can be provided in the form of

tablets or capsules containing about 1.0 to about 500 milligrams of the active ingredient, particularly 1, 5, 10, 15, 20, 25, 50, 75, 100, 150, 200, 250, 300, 400, and 500 milligrams of the active ingredient, for the symptomatic adjustment of the dosage to the patient to be treated. The specific dose level and frequency of dosage for any particular patient may be varied and will depend upon a variety of factors including the activity of the specific compound employed, the metabolic stability and length of action of that compound, the age, body weight, general health, sex, diet, mode and time of administration, rate of excretion, drug combination, the severity of the particular condition, and the host undergoing therapy. As an example, the crystalline Na salt of Compound A can be administered to adult humans in a neat drug-filled capsule in an amount of from about 5 mg to about 800 mg (e.g., 400 mg) twice/day.

In the above-described combinations, a Compound A sodium salt of the present invention and other active agents may be administered together or separately. In addition, the administration of one agent may be prior to, concurrent with, or subsequent to the administration of other agent(s). These combinations may have unexpected or synergistic effects on limiting the spread and degree of infection of HIV.

Abbreviations used herein include the following: AIDS = acquired immunodeficiency syndrome ARC = ADDS related complex DABCO = l,4-diazabicyclo[2.2.2]octene

DSC = differential scanning calorimetry ES MS = electrospray mass spectroscopy EtOAc = ethyl acetate g = gram(s) HTV = human immunodeficiency virus

IPAc = isopropyl acetate LC = liquid chromatography MeOH = methanol MTBE = methyl t-butyl ether NMR = nuclear magnetic resonance t-Bu = tertiary butyl TFA = trifluoroacetic acid TGA = thermogravimetric analysis THF = tetrahydrofuran XRPD = x-ray powder diffraction

The following examples serve only to illustrate the invention and its practice. The examples are not to be construed as limitations on the scope or spirit of the invention.

EXAMPLE 1 ό-CS-Chloro^-fluorobenzy^^-hydroxy^-isopropyl-HN-dimethyl-S .S-dioxo^^^^,?^- hexahydro-2,6-naphthyridine-l-carboxamide (Compound A)

Step 1: 6-(3-Chloro-4-fluorobenzyl)-4-hydroxy-5-oxo-5,6,7,8-tetrahyd ro-2,6- naphthyridine-1-carboxylic acid

To a solution of ethyl 6-(3-chloro-4-fluorobenzyl)-4-hydroxy-5-oxo-5,6,7,8- tetrahydro-2,6-naρhthyridine-l-carboxylate (27.0 g, 71 mmol) in THF (333mL) and MeOH (166 mL) was added LiOH (5.21g, 214 mmol) dissolved in enough water to make a IN solution (total volume 213 mL) and the reaction was heated to 60 ⁰ C overnight. HPLC showed completion. A white precipitate was observed. The reaction was neutralized with IN HCl and the more volatile solvents removed, leaving the water solution. 300 mL water was added the solution was acidified to pH 1 with 1 N HCl. A large amount of solids had precipitated. The resulting slurry was stirred vigorously with 100 mL CHCI3. Most of the solid had precipitated from the partitioning and the entire mix was filtered and dried over the weekend to give product. Additional less pure product was recovered from extraction of the filtrate. lH NMR (400 MHz, CD3OD) δ 8.25 (s, IH), 7.53(dd, J = 2.2, 6.9 Hz, IH), 7.36 (m, IH),

7.23 (t, J = 8.9 Hz, IH), 4.74 (s, 2H), 3.61(bt, J = 6.4 Hz, IH), 3.50(bt, J = 6.4 Hz, IH) ppm. (ES MS M+l = 351.0)

Step 2: 6-(3-Chloro-4-fluorobenzyl)-4-hydroxy-N,N-dimethyl-5-oxo-5,6 ,7,8- tetrahydro-2,6-naρhthyridine- 1 -carboxamide

To a suspension of 6-(3-chloro-4-fluorobenzyl)-4-hydroxy-5-oxo-5,6,7,8- tetrahydro-2,6-naphthyridine-l-carboxylic acid (25.0 g, 71.3 mmol) in methylene chloride (1000 mL) at 0 ⁰ C was added oxalyl chloride (12.4 mL, 143 mmol) and 8 drops of anhydrous DMF. The reaction was stirred at 0 ⁰ C for 15 minutes, during which time no bubbling was observed. The reaction was then allowed to warm to room temperature and stirred for 40 minutes. At this time bubbling had ceased. An aliquot of the solution was quenched with dimethylamine and checked by LCMS. The reaction was incomplete. An additional 0.5 equivalent of oxalyl chloride was added and the reaction stirred an additional 40 minutes.

The reaction never attained complete solution but was complete by LCMS. To the suspension of the acid chloride cooled to 0 ⁰ C was slowly added 2M dimethylamine in THF (140.8 mL, 281 mmol). The rate of addition was adjusted to avoid a large exotherm. The pH of the solution was found to be about 9. The yellow reaction was allowed to stir at room temperature overnight although the reaction appeared to proceed immediately by LCMS. The solvent was removed in vacuo, and the resulting residue was dissolved in chloroform. The solution was washed with water and 5% aqueous HCl solution and the aqueous layer back extracted to recover the product. The combined organic layers were washed with brine, dried over sodium sulfate, filtered and concentrated in vacuo to give a brown/yellow waxy solid. The initial NMR shows an excessive number of methyl group peaks, perhaps as a result of oxalyl chloride reacting with dimethylamine. A small sample was purified by reverse phase chromatography eluting with 95:5-5:95 water/acetonitrile 0.1% TFA to give clean material for NMR. lH NMR (400 MHz, CDCl ₃ ) δ 12.35 (bs, IH), 10.9 (bs, IH), 8.32 (s, IH), 7.38 (dd, J = 2.0, 6.7 Hz, IH), 7.22 (m, IH), 7.14 (t, J = 8.5 Hz, IH), 4.69 (s, 2H), 3.54 (t, J = 6.8 Hz, 2H), 3.14 (s, 3H), 3.05 (t, J = 6.8 Hz, 2H), 2.95 (s, 3H) ppm. (ES MS M+l = 378.1)

Step 3: 6-(3-Chloro-4-fluorobenzyl)-4-hydroxy-N,N-dimethyl-5-oxo-5,6 ,7,8- tetrahydro-2,6-naphthyridine- 1 -carboxamide 2-oxide 6-(3-Chloro-4-fluorobenzyl)-4-hydroxy-N,N-dimethyl-5-oxo-5,6 ,7,8- tetrahydro-2,6-naρhthyridine-l -carboxamide (24g, 63.5 mmol) was dissolved in 1000 mL glacial acetic acid and per-acetic acid (32% by weight in acetic acid, 151 mL, 635 mmol) and sodium acetate (2.6g, 31.7 mmol) was added. The reaction was warmed to 50 ^c and aged overnight at which time LCMS showed the reaction done. The solution reduced in volume to 1/3 on the rotoevaporator, cooled in an ice bath and quenched slowly with 10% Na ₂ SO ₃ solution until no peroxide was detected by a starch paper test. The reaction was transferred to a separatory funnel and water (50OmL) and chloroform was added. The layers were separated and the water extracted with CHCl ₃ several times. The combined organic layers were washed with slightly acidic water, brine and dried over Na ₂ SO ₄ , filtered and evaporated to give the product as an oil. The initial NMR shows an excessive number of methyl group peaks, perhaps as a result of oxalyl chloride reacting with dimethylamine in the second step and this impurity being carried through. A small sample was purified by reverse phase chromatography eluting with 95:5-5:95 water/acetonitrile 0.1% TFA to give clean material for NMR.

lH NMR (400 MHz, CDCl ₃ ) δ 12.75 (bs, IH), 8.4 (bs, 2H), 8.1 (s, 1 H), 7.37 (dd, J = 1.9, 6.9 Hz, IH), 7.20 (m, IH), 7.15 (t, J = 8.5 Hz, IH), 4.84 (d, J = 14.7 Hz, IH), 4.51 (d, J = 14.7 Hz, IH), 3.61 (m, IH), 3.59 (m, IH), 3.15 (s, 3H), 3.05 (in, IH)), 2.93 (s, 3H), 2.74 (m, IH) ppm. (ES MS M+l = 394.1)

Step 4: 6-(3-Chloro-4-fluorobenzyl)-l-[(dimethylamino)carbonyl]-5-ox o-5,6,7,8- tetrahydro-2,6-naphthyridine-3,4-diyl diacetate 6-(3-Chloro-4-fluorobenzyl)-4-hydroxy-N,N-dimethyl-5-oxo-5,6 ,7,8- tetrahydro-2,6-naphthyridine-l-carboxamide 2-oxide (25g, 63.5 mmol) was dissolved in 24 mL acetic anhydride and heated with stirring under nitrogen to 100 ⁰ C for 16 hours. By

LCMS, the starting material and product are close in retention time and appear as the same molecular weight. To check that the reaction was done, an aliquot was treated with NaOMe in water and CH ₃ CN. The resulting hydrolyzed product elutes at an earlier retention time and allows distinguishing between remaining N-oxide and rearranged product. The reaction was evaporated and the residue was partitioned between chloroform and water and the water layer was back-extracted with more chloroform. The aqueous layer was checked by LCMS for product and no longer contained any. The organic layers were combined, dried over Na ₂ SO ₄ , filtered and evaporated to give an oil. (ES MS M+l of NaOMe treated aliquot= 394.0)

Step 5: 6-(3-Chloro-4-fluorobenzyl)-3,4-dihydroxy-N,N-dimethyl-5-oxo -5 ,6,7,8- tetrahydro-2,6-naphthyridine-l-carboxarnide

6-(3-Chloro-4-fluorobenzyl)-l-[(dimethylamino)carbonyl]-5-ox o-5,6,7,8- tetrahydro-2,6-naphthyridine-3,4-diyl diacetate (3Og, 62.7 mmol) was dissolved in 500 mL MeOH and treated with a 30% by weight solution of NaOMe in MeOH (45.2 mL, 251 mmol 4 equivalents was sufficient to get the pH of the reaction to 9) for 1 hour at 40 ⁰ C. LCMS showed the cleavage of the acetate groups was complete. The reaction was neutralized with IN HCl and the volume reduced to remove the MeOH and the residue was diluted with water and acidified to pH 3. The cloudy aqueous layer was diluted with an equal volume (800 mL) of chloroform. After shaking, the product began to crystallize out of the solutions and gathered at the miniscus. The total contents of the funnel were filtered and the collected solids were washed with water until no more salts appeared to remain. The solid was dried in vacuo for 16 hours to give a cinnamon colored solid. The organic layer from the filtered extraction was collected, washed with water and dried over Na ₂ SO^ filtered and evaporated. The residue was crystallized from methanol to give product. The crude material was quite

insoluble but was crystallized from DMF, then boiled in MeOH, filtered and dried under vacuum to give product. lH NMR (400 MHz, DMSO) δ 13.0 (s, IH), 11.9 (s, IH), 7.58 (d, J = 6.9 Hz, IH), 7.38 (m, 2H), 4.69 (bs, 2H), 3.49 (m, 2H), 2.91 (s, 3H), 2.84 (s, 3H), 2.56 (bs, 2H), ppm. (ES MS M+l = 394.0)

Step 6: 6-(3-Chloro-4-fluorobenzyl)-4-hydroxy-2-isopropyl-N,N-dimeth yl-3,5-dioxo-

2,3,5,6,7,8-hexahydro-2,6-naphthyridine-l-carboxamide To a solution of 6~(3-chloro-4-fluorobenzyl)-3,4-dihydroxy-N,N-dimethyl-5- oxo-5,6,7,8-tetrahydro-2,6-naphthyridine-l-carboxamide (3.00 g, 7.62 mmol) in DMSO (86 mL) was added magnesium methylate (42.75 mL of a 6-10% methanol solution, 24.4 mmol), and the reaction was heated to 60 ⁰ C for 0.75 hour. The reaction mixture was reduced on a rotoevaporator to remove all of the MeOH over 45 minutes. The heat gun was used to drive all MeOH from the bump bulb. The reaction was treated with 2-iodopropane (2.84 mL, 38.1 mmol) and allowed to stir at 60 ⁰ C for 3 hours. LCMS showed 11% starting material remaining and over 70% conversion to N- and O-alkylated products (typically 2: 1). The reaction was diluted with 35OmL EtOAc to which 125 mL IN HCl was added, and the phases were separated. The aqueous layer was washed once with methylene chloride (100 mL). The combined organic layers were washed with IN HCl twice more and the organic layer was isolated. The organic layer was washed with 10% aqueous solution of NaHSO ₃ (3x 100 mL) followed by brine. The organic layer was dried over sodium sulfate and concentrated in vacuo to afford a yellow-orange foam residue. The solid combined with additional crude material from other reactions, dissolved in DMSO and Methanol and purified via reverse phase chromatography using a Biotage 75L canister and a Varian Metaflash 75L C-18 column, eluting with a gradient of 70:30 to 35:65 A:B where A= 0.05% TFA in water and B = 0.05% TFA in acetonitrile (flow rate = 300 mL/minute, detection at 214 and 254 nM). Evaporation of the fractions afforded pure oil by HPLC/LCMS and NMR. Crystallization from EtOAc-.hexane afforded white, analytically pure product. lH NMR (400 MHz, CD3OD) δ 7.50 (dd, J = 1.9, 7.2 Hz, IH), 7.32 (m, IH), 7.22 (t, J = 8.8 Hz, IH), 4.78 (d, / = 14.9 Hz, IH), 4.63 (d, J = 14.9 Hz, IH), 4.02 (m, IH), 3.50 (t, J = 6.4 Hz, 2H), 3.09 (s, 3H), 3.00 (s, 3H), 2.59 (t, J = 6.4 Hz, 2H), 1.64 (d, J = 6.8 Hz, 3H), 1.57 (d, J = 6.7 Hz, 3H) ppm. (ES MS exact mass M+l = 436.144)

EXAMPLE 2 ό-CS-Chloro^-fluorobenzy^^-hydroxy^-isopropyl-N.N-dimethyl- S^-dioxo^^^^,?^- hexahydro-2,6ταaphthyridine-l-carboxarnide (Compound A)

Step 1: l-(3-Chloro-4-fluorobenzyl)piperidm-2-one

Valerolactam (60 g) was dissolved in MTBE (1.5L) at room temperature. To this solution was added BU4NSO4 (4.9 g) as a phase transfer catalyst. The cloudy solution was stirred at room temperature for 5 minutes. Then, NaOH (50 wt%;300 mL) was slowly added as to keep the internal temperature below 3O ⁰ C. 3-Chloro-4-fluorobenzyl bromide (108.3 g) was then added slowly to this biphasic mixture, again as to keep the internal temperature under control. The reaction was then aged for 4 hours at room temperature. At this time LC showed the reaction to be complete. Water (500 mL) was then added. After phase cut, the organic layer was washed with brine (300 mL), dried under MgSO4 followed by solvent switch to heptane (400 mL). The slurry obtained was stirred at room temperature. for 1 hour and then filtered to afford the title product.

Preparation of an unsaturated sulfide of formula 1:

l-(3-Chloro-4-fluorobenzyl)piperidin~2-one (25 g) was dissolved in THP (250 mL) and cooled to -20 degrees C under nitrogen atmosphere. LHMDS (204 mL, IM in THF) was added over 40 minutes at -20 to -30 ⁰ C and aged for 1 hour at -20 ⁰ C. Methyl benzene sulfinate (17.78 g) was added over 30 minutes, again keeping the internal temperature at - 2O ⁰ C. The reaction was aged for 30 minutes at -2O ⁰ C at which time LC showed the reaction to be complete. The reaction mixture was then quenched with water (100 mL) and diluted with EtOAc (300 mL). After phase cut, the organic layer was washed with HCl 2N (2 x 100 mL). The organic layer was then washed with brine (2 x 100 mL), dried under MgSθ4 followed by solvent switch to DCM (600 mL; final volume 400 mL). To this solution was added acetic anhydride (11.6 mL) and MeSOβH (3.07 mL). The solution was then aged at room temperature overnight. The reaction was quenched with water (300 mL) and cooled to O ⁰ C. The slurry obtained was then carefully basified to pH=8 with solid Na2CO3. The organic layer obtained after phase cut was then washed with brine and dried under MgSθ4. After evaporation of solvents, the title unsaturated sulfide 1 was obtained as an oil which solidified on standing. The title sulfide 1 can be crystallized from MeOH.

Step 3: Preparation of a vinyl sulfoxide of formula 2:

Unsaturated sulfide 1 (35.47 g) was dissolved in MeOH (200 rriL) and water was added (50 mL) followed by the addition of solid Nalθ4 (39.82 g). The slurry obtained was stirred at room temperature for 3 days. The slurry was then filtered and the solid obtained was washed with EtOAc (200 mL). The filtrate was then evaporated until almost dryness and diluted with EtOAc (350 mL) and washed with KføO (200 mL). The organic layer was then washed with brine (200 mL) and dried under MgSOφ The organic solvents were then removed to completion. The oil obtained was crystallized with a JPAc:Hexane (1: 1.2) mixture and seeding to afford the title sulfoxide 2.

Preparation of a Michael adduct of formula 5:

To a solution of vinyl sulfoxide 2 (5g, 13.74 mmoles) in TBDF (70 mL) at 0 ⁰ C was added diphenylketimine glycine dimethyl amide (4g, 15.mmoles) followed by t-BuOLi (0.2g, 2.5 mmoles). The mixture was stirred for 20 minutes at 0 ⁰ C, and then HCl 2N (80 mL) was added. The resulting mixture was stirred at 2O ⁰ C for 20 minutes and MTBE (160 mL) was added. After phase separation, the aqueous layer was basified to pH=8-9 by addition of solid Na2CO3. The resulting aqueous layer was extracted twice with EtOAc (2x100 mL) and the solvent evaporated under reduced pressure to give the title adduct as an oil.

Step 5: Preparation of an isopropyl amine of formula 6:

To a solution of adduct 5 (2.5g, 5.35 mmoles) in MeOH (30 mL) was added acetone (0.8 mL, 10.7 mmoles) followed sodium triacetoxyborohydride (1.2g, 5.9mmoles). The mixture was stirred for 20 minutes, and then water (10 mL) and NaHCO3 saturated

(3OmL) were added. The resulting mixture was extracted twice with EtOAc (2x30 mL) and the solvent evaporated under reduced pressure to provide the crude title product.

Preparation of an oxamate of formula 7:

Crude amine 6 (5 mmol) is dissolved in THF (40 mL) at 0 ⁰ C and triethylamine (1.4 mL, 2.2 eq.) was added followed by dropwise addition of ethyloxalyl chloride (1 mL, 2.1 eq.). The resulting slurry was stirred for 20 minutes at 0 ⁰ C, then water (30 mL) was added. The mixture was extracted with EtOAc (2x40 mL), then solvent switched to toluene (final volume: 20 mL). The toluene solution was heated at 90 ⁰ C for 30- 45 minutes then passed through a plug of silica gel (2Og) using EtOAc/hexanes 1:1 (200 mL), then EtOAc as eluant. The title oxamate 7 was obtained after evaporation of the solvents.

Step 7: 6-(3-Chloro-4-fluorobenzyl)-4-hydroxy-2-isopropyl-N,N-dimeth yl-3,5-dioxo- 2,3,5,6,7,8-hexahydro-2,6-naphthyridine-l-carboxamide

To a solution of oxamate 7 (160mg) in THF (3 mL) was added LiBr (1 lOmg, 4eq.) followed by DABCO (56mg, 1.5 eq.). The mixture was stirred for 10 minutes at room temperature, then HCl 2N (5 mL) was added and the mixture was extracted with EtOAc (5 mL). The solvents were evaporated under reduced pressure to give the title compound.

EXAMPLE 3 Crystalline sodium salt of Compound A

Part A: Preparation MeOH (10 mL) and MTBE (50 mL) were added to 6-(3-chloro-4- fluorobenzyl)-4-hydroxy-2-isopropyl-N,N-dimethyl-3,5-dioxo-2 ,3,5,6,7,8-hexahydro-2,6- naphthyridine-1-carboxamide (6.94 g). NaOH/MeOH (1 N; 15.95 mL) was then charged thereto, and the admixture stirred until the carboxamide dissolved. The solution was filtered and additional MTBE (65 mL) was added to the filtrate. The filtrate was concentrated by removal of MeOH under vacuum (190 mm Hg at 4O ⁰ C). The resulting concentrate (140 mL) was seeded, heated to 4O ⁰ C, and aged overnight. The aged concentrate was then cooled to

room temperature, and the resulting solids were separated by filtration, washed with 10% MeOH/MTBE, and vacuum dried at room temperature to afford a crystalline sodium salt.

Part B: Characterization

An XRPD pattern of a Na salt prepared in the manner described in Part A was generated on a Philips Analytical X'Pert Pro X-ray powder diffractometer using a continuous scan from 2.5 to 40 degrees 2 θ. Copper K-Alpha 1 (K _α χ) and K-Alpha 2 (K _α 2) radiation was used as the source. The experiment was run under ambient conditions. The XRPD pattern is shown in Figure 1. 2θ values and the corresponding d-spacings in the XRPD pattern include the following:

A Na salt prepared in the manner described in Part A was also analyzed by a TA Instruments DSC 2910 differential scanning calorimeter at a heating rate of 10°C/min from room temperature to 25O ⁰ C in a closed pan in a nitrogen atmosphere. The DSC curve (see Figure 2) exhibited an endotherm with a peak temperature of 220 ⁰ C and an associated heat of fusion of 27 J/gm. The endotherm is believed to be due to melting.

A thermogravimetric analysis was performed with a Perkin-Elmer Model TGA 7 under nitrogen at a heating rate of 10°C/min from room temperature to 250 ⁰ C. The TG curve showed a 1.1 % weight loss from 20 to 220 ⁰ C.

While the foregoing specification teaches the principles of the present invention, with examples provided for the purpose of illustration, the practice of the invention encompasses all of the usual variations, adaptations and/or modifications that come within the scope of the following claims.