Patent Publication Number: US-2023151029-A1

Title: Boronic acid derivatives and therapeutic uses thereof

Description:
STATEMENT REGARDING FEDERALLY SPONSORED R&amp;D 
     This invention was made with U.S. government support under the Department of Health and Human Services Contract No. HHS0100201600026C. The U.S. government has certain rights in the invention. 
    
    
     BACKGROUND 
     Field 
     The present application relates to the fields of chemistry and medicine. More particularly, the present application relates to boronic acid antimicrobial compounds, compositions, their preparation, and their use as therapeutic agents. 
     Description of the Related Art 
     Antibiotics have been effective tools in the treatment of infectious diseases during the last half-century. From the development of antibiotic therapy to the late 1980s there was almost complete control over bacterial infections in developed countries. However, in response to the pressure of antibiotic usage, multiple resistance mechanisms have become widespread and are threatening the clinical utility of anti-bacterial therapy. The increase in antibiotic resistant strains has been particularly common in major hospitals and care centers. The consequences of the increase in resistant strains include higher morbidity and mortality, longer patient hospitalization, and an increase in treatment costs. 
     Various bacteria have evolved β-lactam deactivating enzymes, namely, β-lactamases, that counter the efficacy of the various β-lactam antibiotics. β-lactamases can be grouped into 4 classes based on their amino acid sequences, namely, Ambler classes A, B, C, and D. Enzymes in classes A, C, and D include active-site serine β-lactamases, and class B enzymes, which are encountered less frequently, are Zn-dependent. These enzymes catalyze the chemical degradation of β-lactam antibiotics, rendering them inactive. Some β-lactamases can be transferred within and between various bacterial strains and species. The rapid spread of bacterial resistance and the evolution of multi-resistant strains severely limits β-lactam treatment options available. 
     The increase of class D β-lactamase-expressing bacterium strains such as  Acinetobacter baumannii  has become an emerging multidrug-resistant threat.  A. baumannii  strains express A, C, and D class β-lactamases. The class D β-lactamases such as the OXA families are particularly effective at destroying carbapenem type β-lactam antibiotics, e.g., imipenem, the active carbapenems component of Merck&#39;s Primaxin® (Montefour, K. et al., Crit. Care Nurse 2008, 28, 15; Perez, F. et al., Expert Rev. Anti Infect. Ther. 2008, 6, 269; Bou, G.; Martinez-Beltran, J., Antimicrob. Agents Chemother. 2000, 40, 428. 2006, 50, 2280; Bou, G. et al., J. Antimicrob. Agents Chemother. 2000, 44, 1556). This has imposed a pressing threat to the effective use of drugs in that category to treat and prevent bacterial infections. Indeed the number of catalogued serine-based β-lactamases has exploded from less than ten in the 1970s to over 300 variants. These issues fostered the development of five “generations” of cephalosporins. When initially released into clinical practice, extended-spectrum cephalosporins resisted hydrolysis by the prevalent class A β-lactamases, TEM-1 and SHV-1. However, the development of resistant strains by the evolution of single amino acid substitutions in TEM-1 and SHV-1 resulted in the emergence of the extended-spectrum β-lactamase (ESBL) phenotype. 
     New β-lactamases have recently evolved that hydrolyze the carbapenem class of antimicrobials, including imipenem, biapenem, doripenem, meropenem, and ertapenem, as well as other β-lactam antibiotics. These carbapenemases belong to molecular classes A, B, and D. Class A carbapenemases of the KPC-type predominantly in  Klebsiella pneumoniae  but now also reported in other Enterobacteriaceae,  Pseudomonas aeruginosa  and  Acinetobacter baumannii . The KPC carbapenemase was first described in 1996 in North Carolina, but since then has disseminated widely in the US. It has been particularly problematic in the New York City area, where several reports of spread within major hospitals and patient morbidity have been reported. These enzymes have also been recently reported in France, Greece, Sweden, United Kingdom, and an outbreak in Germany has recently been reported. Treatment of resistant strains with carbapenems can be associated with poor outcomes. 
     The zinc-dependent class B metallo-β-lactamases are represented mainly by the VIM, IMP, and NDM types. IMP and VIM-producing  K. pneumonia  were first observed in 1990s in Japan and 2001 in Southern Europe, respectively. IMP-positive strains remain frequent in Japan and have also caused hospital outbreaks in China and Australia. However, dissemination of IMP-producing Enterobacteriaceae in the rest of the word appears to be somewhat limited. VIM-producing enterobacteria can be frequently isolated in Mediterranean countries, reaching epidemic proportions in Greece. Isolation of VIM-producing strains remains low in Northern Europe and in the United States. In stark contrast, a characteristic of NDM-producing  K. pneumonia  isolates has been their rapid dissemination from their epicenter, the Indian subcontinent, to Western Europe, North America, Australia and Far East. Moreover, NDM genes have spread rapidly to various species other than  K. pneumonia.    
     The plasmid-expressed class D carbapenemases belong to OXA-48 type. OXA-48 producing  K. pneumonia  was first detected in Turkey, in 2001. The Middle East and North Africa remain the main centers of infection. However, recent isolation of OXA-48-type producing organisms in India, Senegal and Argentina suggest the possibility of a global expansion. Isolation of OXA-48 in bacteria other than  K. pneumonia  underlines the spreading potential of OXA-48. 
     Treatment of strains producing any of these carbapenemases with carbapenems can be associated with poor outcomes. 
     Another mechanism of β-lactamase mediated resistance to carbapenems involves combination of permeability or efflux mechanisms combined with hyper production of beta-lactamases. One example is the loss of a porin combined in hyperproduction of ampC beta-lactamase results in resistance to imipenem in  Pseudomonas aeruginosa . Efflux pump over expression combined with hyperproduction of the ampC β-lactamase can also result in resistance to a carbapenem such as meropenem. 
     In view of β-lactamase mediated resistance, new β-lactamase inhibitors (BLIs) are needed. 
     SUMMARY OF THE INVENTION 
     In some embodiments, provided herein is a crystalline form of Compound II′: 
     
       
         
         
             
             
         
       
     
     or a solvate thereof. In some embodiments, the crystalline form may exhibits an X-ray powder diffraction pattern comprising at least three characteristic peaks, wherein said characteristic peaks are selected from the group consisting of 4.3, 7.0, 7.2, 8.3, 11.0, 12.5, 15.0, 16.7, 17.5, 18.2, 19.1, 20.3, 22.3, 22.7, and 25.6 degrees 2θ. In some embodiments, the crystalline form of Compound II′ may exhibit an X-ray powder diffraction pattern comprising at least three characteristic peaks, wherein said characteristic peaks are selected from the group consisting of 4.3, 7.0, 7.2, 8.3, 11.0, 12.5, 15.0, 16.7, 17.5, 18.2, 19.1, 20.3, 22.3, 22.7, and 25.6 degrees 2θ. 
     In some embodiments, the crystalline form of Compound II′ may have an endotherm at about 141° C. 
     In some embodiments, the crystalline form may exhibits an X-ray powder diffraction pattern comprising at least three characteristic peaks, wherein said characteristic peaks are selected from the group consisting of 4.3, 7.0, 7.2, 8.3, 11.0, 12.5, 15.0, 16.7, 17.5, 18.2, 19.1, 20.3, 22.3, 22.7, and 25.6 degrees 2θ. In some embodiments, the crystalline form of Compound II′ may exhibit an X-ray powder diffraction pattern comprising at least three characteristic peaks, wherein said characteristic peaks are selected from the group consisting of 4.3, 7.0, 7.2, 8.3, 11.0, 12.5, 15.0, 16.7, 17.5, 18.2, 19.1, 20.3, 22.3, 22.7, and 25.6 degrees 2θ. 
     In some embodiments, the crystalline form of Compound II′ may have an endotherm at about 141° C. 
     In some embodiments, the crystalline form of Compound II′ may have an endotherm at about 152° C. 
     In some embodiments, the crystalline form of Compound II′ may be unsolvated. 
     In some embodiments, provided herein is a compound having the structure of 
     
       
         
         
             
             
         
       
     
     or a pharmaceutically acceptable salt of any of the foregoing. In some embodiments, the pharmaceutically acceptable salt is the sodium salt. 
     In some embodiments provided herein is a pharmaceutical composition comprising a therapeutically effective amount of a compound described herein and a pharmaceutically acceptable excipient. In some embodiments, the composition may further comprise an additional medicament. In some embodiments, the additional medicament may be selected from the group consisting of an antibacterial agent, an antifungal agent, an antiviral agent, an anti-inflammatory agent, and an anti-allergic agent. 
     In some embodiments, the pharmaceutical composition may comprise a β-lactam antibacterial agent. In some embodiments, the β-lactam antibacterial agent may be selected from the group consisting of Amoxicillin, Ampicillin (Pivampicillin, Hetacillin, Bacampicillin, Metampicillin, Talampicillin), Epicillin, Carbenicillin (Carindacillin), Ticarcillin, Temocillin, Azlocillin, Piperacillin, Mezlocillin, Mecillinam (Pivmecillinam), Sulbenicillin, Benzylpenicillin (G), Clometocillin, Benzathine benzylpenicillin, Procaine benzylpenicillin, Azidocillin, Penamecillin, Phenoxymethylpenicillin (V), Propicillin, Benzathine phenoxymethylpenicillin, Pheneticillin, Cloxacillin (Dicloxacillin, Flucloxacillin), Oxacillin, Meticillin, Nafcillin, Faropenem, Tomopenem, Razupenem, Cefazolin, Cefacetrile, Cefadroxil, Cefalexin, Cefaloglycin, Cefalonium, Cefaloridine, Cefalotin, Cefapirin, Cefatrizine, Cefazedone, Cefazaflur, Cefradine, Cefroxadine, Ceftezole, Cefaclor, Cefamandole, Cefminox, Cefonicid, Ceforanide, Cefotiam, Cefprozil, Cefbuperazone, Cefuroxime, Cefuzonam, Cefoxitin, Cefotetan, Cefmetazole, Loracarbef, Cefixime, Ceftriaxone, Cefcapene, Cefdaloxime, Cefdinir, Cefidericol, Cefditoren, Cefetamet, Cefmenoxime, Cefodizime, Cefoperazone, Cefotaxime, Cefpimizole, Cefpiramide, Cefpodoxime, Cefpodoxime proxetil, Cefsulodin, Cefteram, Ceftibuten, Ceftiolene, Ceftizoxime, Flomoxef, Latamoxef, Cefepime, Cefozopran, Cefpirome, Cefquinome, Ceftobiprole, Ceftaroline, Ceftolozane (CXA-101), RWJ-54428, MC-04,546, ME1036, Ceftiofur, Cefquinome, Cefovecin, RWJ-442831, RWJ-333441, and RWJ-333442. In other embodiments, the β-lactam antibacterial agent may be selected from the group consisting of Ceftazidime, Biapenem, Doripenem, Ertapenem, Imipenem, Meropenem, Tebipenem, Tebipenem pivoxil, Apapenem, and Panipenem. In yet other embodiments, the β-lactam antibacterial agent may be selected from the group consisting of Aztreonam, Tigemonam, BAL30072, SYN 2416, and Carumonam. 
     Also provided herein is method of treating a bacterial infection, comprising administering a compound described herein to a subject in need thereof. In some embodiments, the method further comprises administering to the subject an additional medicament. In some embodiments, the additional medicament may be an antibacterial agent, an antifungal agent, an antiviral agent, an anti-inflammatory agent, or an antiallergic agent. In some embodiments, the additional medicament is a β-lactam antibacterial agent. In some embodiments, the β-lactam antibacterial agent may be selected from the group consisting of Amoxicillin, Ampicillin (Pivampicillin, Hetacillin, Bacampicillin, Metampicillin, Talampicillin), Epicillin, Carbenicillin (Carindacillin), Ticarcillin, Temocillin, Azlocillin, Piperacillin, Mezlocillin, Mecillinam (Pivmecillinam), Sulbenicillin, Benzylpenicillin (G), Clometocillin, Benzathine benzylpenicillin, Procaine benzylpenicillin, Azidocillin, Penamecillin, Phenoxymethylpenicillin (V), Propicillin, Benzathine phenoxymethylpenicillin, Pheneticillin, Cloxacillin (Dicloxacillin, Flucloxacillin), Oxacillin, Meticillin, Nafcillin, Faropenem, Tomopenem, Razupenem, Cefazolin, Cefacetrile, Cefadroxil, Cefalexin, Cefaloglycin, Cefalonium, Cefaloridine, Cefalotin, Cefapirin, Cefatrizine, Cefazedone, Cefazaflur, Cefradine, Cefroxadine, Ceftezole, Cefaclor, Cefamandole, Cefminox, Cefonicid, Ceforanide, Cefotiam, Cefprozil, Cefbuperazone, Cefuroxime, Cefuzonam, Cefoxitin, Cefotetan, Cefmetazole, Loracarbef, Cefixime, Ceftriaxone, Cefcapene, Cefdaloxime, Cefdinir, Cefidericol, Cefditoren, Cefetamet, Cefmenoxime, Cefodizime, Cefoperazone, Cefotaxime, Cefpimizole, Cefpiramide, Cefpodoxime, Cefpodoxime proxetil, Cefsulodin, Cefteram, Ceftibuten, Ceftiolene, Ceftizoxime, Flomoxef, Latamoxef, Cefepime, Cefozopran, Cefpirome, Cefquinome, Ceftobiprole, Ceftaroline, Ceftolozane (CXA-101), RWJ-54428, MC-04,546, ME1036, Ceftiofur, Cefquinome, Cefovecin, RWJ-442831, RWJ-333441, and RWJ-333442. In other embodiments, the β-lactam antibacterial agent may be selected from the group consisting of Ceftazidime, Biapenem, Doripenem, Ertapenem, Imipenem, Meropenem, Tebipenem, Tebipenem pivoxil, Apapenem, and Panipenem. In yet other embodiments, the β-lactam antibacterial agent may be selected from the group consisting of Aztreonam, Tigemonam, BAL30072, SYN 2416, and Carumonam. 
     In some embodiments, subject is a mammal. In some specific embodiments, the mammal is a human. 
     In some embodiments, the infection comprises a bacteria selected from the group consisting of  Pseudomonas acidovorans, Pseudomonas alcaligenes, Pseudomonas putida, Burkholderia cepacia, Aeromonas hydrophilia, Francisella tularensis, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia alcalifaciens, Providencia rettgeri, Providencia stuartii, Acinetobacter baumannii, Bordetella pertussis, Bordetella  para pertussis,  Bordetella bronchiseptica, Haemophilus ducreyi, Pasteurella multocida, Pasteurella haemolytica, Branhamella catarrhalis, Borrelia burgdorferi, Kingella, Gardnerella vaginalis, Bacteroides distasonis, Bacteroides  3452A homology group,  Clostridium difficile, Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium leprae, Corynebacterium diphtheriae, Corynebacterium ulcerans, Streptococcus pneumoniae, Streptococcus agalactiae, Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Staphylococcus intermedius, Staphylococcus hyicus  subsp.  hyicus, Staphylococcus haemolyticus, Staphylococcus hominis , and  Staphylococcus saccharolyticus . In other embodiments, the infection comprises a bacteria selected from the group consisting of  Pseudomonas aeruginosa, Pseudomonas fluorescens, Stenotrophomonas maltophilia, Escherichia coli, Citrobacter freundii, Salmonella typhimurium, Salmonella typhi, Salmonella paratyphi, Salmonella enteritidis, Shigella dysenteriae, Shigella flexneri, Shigella sonnei, Enterobacter cloacae, Enterobacter aerogenes, Klebsiella pneumoniae, Klebsiella oxytoca, Serratia marcescens, Acinetobacter calcoaceticus, Acinetobacter haemolyticus, Yersinia enterocolitica, Yersinia pestis, Yersinia pseudotuberculosis, Yersinia intermedia, Haemophilus influenzae, Haemophilus parainfluenzae, Haemophilus haemolyticus, Haemophilus parahaemolyticus, Helicobacter pylori, Campylobacter fetus, Campylobacter jejuni, Campylobacter coli, Vibrio cholerae, Vibrio parahaemolyticus, Legionella pneumophila, Listeria monocytogenes, Neisseria gonorrhoeae, Neisseria meningitidis, Moraxella, Bacteroides fragilis, Bacteroides vulgatus, Bacteroides ovalus, Bacteroides thetaiotaomicron, Bacteroides uniformis, Bacteroides eggerthii , and  Bacteroides splanchnicus.    
     Also provided herein is a method of preparing crystalline Form A of Compound II′, the method comprising the steps of: dissolving Compound II′ in a solvent system to form a crystallization solution, wherein the solvent system consists of isopropyl acetate; heating the crystallization solution to about 50° C.; adding heptane to the crystallization solution; and adding seed crystals of crystalline Form A of Compound II′ to the crystallization solution. 
     Also provided herein is a method of preparing crystalline Form A of Compound II′, the method comprising the steps of: dissolving Compound II′ in a solvent system to form a crystallization solution, wherein the solvent system consists of isopropyl acetate and isopropanol; adding heptane to the crystallization solution; and adding seed crystals of crystalline Form B of Compound II′ to the crystallization solution. In some embodiments, the solvent system consists of isopropyl acetate and isopropanol in a 1:1 (v/v) ratio. 
     Also provided herein is a method of preparing crystalline Form A of Compound II′, the method comprising the steps of: dissolving Compound II′ in a solvent system to form a crystallization solution, wherein the solvent system consists of isopropyl acetate; heating the crystallization solution; adding heptane to the crystallization solution; and adding seed crystals of crystalline Form A of Compound II′ to the crystallization solution. 
     In some embodiments, the crystallization solution may be heated to a temperature of 30 to 80° C. In other embodiments, the crystallization solution may be heated to a temperature of 40 to 70° C. In some embodiments, the crystallization solution may be heated to a temperature of 50° C. 
     Also provided herein is a method of preparing crystalline Form B of Compound II′, the method comprising the steps of: dissolving Compound II′ in a solvent system to form a crystallization solution, wherein the solvent system consists of isopropyl acetate and isopropanol; adding heptane to the crystallization solution; and adding seed crystals of crystalline Form B of Compound II′ to the crystallization solution. In some embodiments, the solvent system may consist of isopropyl acetate and isopropanol in a 1:1 (v/v) ratio. 
     Also provided herein is a method of preparing crystalline Form A of Compound II′, the method comprising the steps of: dissolving Compound II′ in a solvent system to form a crystallization solution, wherein the solvent system consists of hexanes and ethyl acetate; heating the crystallization solution; initially cooling the crystallization solution; stirring the crystallization solution; further cooling the crystallization solution to room temperature; and allowing the crystallization mixture to stand at room temperature. 
     In some embodiments, the crystallization solution may be heated to a temperature of 30 to 80° C. In other embodiments, the crystallization solution may be heated to a temperature of 50 to 70° C. In some embodiments, the crystallization solution may heated to a temperature of 65° C. 
     In some embodiments, the crystallization solution may initially be cooled to a temperature of 30 to 50° C. In some embodiments, the crystallization solution may initially be cooled to a temperature of 50° C. 
     In some embodiments, the crystallization solution may further be stirred for 12 to 36 hours. In some specific embodiments, the crystallization solution may further be stirred for 24 hours. In some embodiments, the crystallization solution may further be allowed to stand at room temperature for 72 hours. 
     In some embodiments provided herein is a method of preparing crystalline Form A of Compound II′, the method comprising the steps of: dissolving Compound II′ in isopropanol to form a crystallization solution; heating the crystallization solution; and cooling the crystallization solution to room temperature. 
     In another embodiment, provided herein is a method of preparing Compound II′ comprising the steps of: combining Compound I, or a salt thereof, a halomethyl isobutyrate, and a base in a polar organic solvent to form a reaction mixture; and heating the reaction mixture. 
     In some embodiments, the reaction mixture may further comprise an iodide source. In some specific embodiments, the iodide source may be sodium iodide, potassium iodide, or cesium iodide. 
     In some embodiments, the base may be NaH 2 PO 4 . In other embodiments, the base may be Na 2 B 4 O 7 . 
     In some embodiments, the molar ratio of base to Compound I may be from about 0.5 to about 2.0. In some embodiments, the molar ratio of base to Compound I may be 1.0. In other embodiments, the molar ratio of base to Compound I may be 1.5. 
     In some embodiments, the solvent may be acetonitrile. In some specific embodiments, the acetonitrile may be anhydrous. 
     In some embodiments, the halomethyl isobutyrate may be chloromethyl isobutyrate. 
     In some embodiments, the reaction mixture may be heated to a temperature of from about 50° C. to about 80° C. In some embodiments, the reaction mixture may be heated to a temperature of 60° C. In other embodiments, the reaction mixture may be heated to a temperature of 70° C. In yet other embodiments, the reaction mixture may heated to a temperature of 80° C. 
     In some embodiments, the reaction mixture may be heated for a period of from about 0.5 hours to about 24 hours. In some embodiments, the reaction mixture may be heated for a period of from about 4 hours to about 18 hours. In some embodiments, the reaction mixture may be heated for 6 hours. In other embodiments, the reaction mixture may be heated for 8 hours. In some embodiments, the reaction mixture may be heated for 16 hours. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an X-ray powder diffraction pattern of crystalline Form A of Compound II′. 
         FIG.  2    shows a differential scanning calorimetry analysis for crystalline Form A of Compound II′. 
         FIG.  3    shows thermogravimetric analysis results for crystalline Form A of Compound II′. 
         FIG.  4    shows dynamic vapor sorption results for crystalline Form A of Compound II′. 
         FIG.  5    shows results obtained by FTIR spectroscopy for crystalline Form B of Compound II′. 
         FIG.  6    shows results obtained by FT Raman spectroscopy for crystalline Form B of Compound II′. 
         FIG.  7    shows an optical microscopy image of crystals of crystalline Form B of Compound II′. 
         FIG.  8    is an X-ray powder diffraction pattern of crystalline Form B of Compound II′. 
         FIG.  9    shows a differential scanning calorimetry analysis for crystalline Form B of Compound II′. 
         FIG.  10    shows thermogravimetric analysis results for crystalline Form B of Compound II′. 
         FIG.  11    shows dynamic vapor sorption results for crystalline Form B of Compound II′. 
         FIG.  12    shows results obtained by FTIR spectroscopy for crystalline Form B of Compound II′. 
         FIG.  13    shows results obtained by FT Raman spectroscopy for crystalline Form B of Compound II′. 
         FIG.  14    shows an optical microscopy image of crystals of crystalline Form B of Compound II′. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Compound I and pharmaceutically acceptable salts thereof are described in International Application PCT/US2017/039787, which is incorporated herein by reference in its entirety. Compound I is a β-lactamase inhibitor effective in treating bacterial infections when used in combination with β-lactam antibiotics. 
     
       
         
         
             
             
         
       
     
     Disclosed herein is a Compound II, a prodrug of Compound I. Compound II is a β-lactamase inhibitor effective in treating bacterial infections when used in combination with β-lactam antibiotics. 
     
       
         
         
             
             
         
       
     
     Where the compounds disclosed herein have at least one chiral center, they may exist as individual enantiomers and diastereomers or as mixtures of such isomers, including racemates. Separation of the individual isomers or selective synthesis of the individual isomers is accomplished by application of various methods which are well known to practitioners in the art. Unless otherwise indicated, all such isomers and mixtures thereof are included in the scope of the compounds disclosed herein. Furthermore, compounds disclosed herein may exist in one or more crystalline or amorphous forms. Unless otherwise indicated, all such forms are included in the scope of the compounds disclosed herein including any polymorphic forms. In addition, some of the compounds disclosed herein may form solvates with water (i.e., hydrates) or common organic solvents. Unless otherwise indicated, such solvates are included in the scope of the compounds disclosed herein. 
     The skilled artisan will recognize that some structures described herein may be resonance forms or tautomers of compounds that may be fairly represented by other chemical structures, even when kinetically; the artisan recognizes that such structures may only represent a very small portion of a sample of such compound(s). Such compounds are considered within the scope of the structures depicted, though such resonance forms or tautomers are not represented herein. 
     Synthesis of Compound II 
     Compound II and pharmaceutically acceptable salts thereof may be prepared from Compound I, or a salt thereof by treatment with chloromethyl isobutyrate under basic conditions. General methods for preparing (isobutyryloxy)methyl esters are described in International Patent Publication No. WO 2018/005662, which is incorporated herein by reference in its entirety. The synthesis of Compound II is provided in the Examples below. In some embodiments, the sodium salt of Compound II (Compound II′) may be formed. 
     
       
         
         
             
             
         
       
     
     In some embodiments, Compound II′ may be prepared from Compound I, or a salt thereof, according to the scheme below. Compound I, or a salt thereof, can be treated with a halomethyl isobutyrate in the presence of base and an optional iodidie source in order to form Compound II′ 
     
       
         
         
             
             
         
       
     
     In some embodiments, an excess of halomethyl isobutyrate is used in the reaction. For example, in some embodiments, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 or more molar equivalents of halomethyl isobutyrate relative to Compound I may be used for this reaction. In some embodiments, the halomethyl isobutyrate may be chloromethyl isobutyrate. In other embodiments, the halomethyl isobutyrate may be bromomethyl isobutyrate. 
     In some embodiments, the iodide source may be an alkali metal iodide. For example, the iodide source may be sodium iodide, potassium iodide, or cesium iodide. 
     The selection of base used in the reaction may affect the overall yield and purity of the final product. In some embodiments, the base may be sodium bicarbonate. In other embodiments, the base may be NaH 2 PO 4 . In yet other embodiments, the base may be Na 2 B 4 O 7 . In some specific embodiments, the base may be anhydrous Na 2 B 4 O 7 . In some embodiments, 0.1 to 10 molar equivalents of base relative to Compound I can be used for this reaction. For example, the number of molar equivalents of base relative to Compound I may be 0.1, 0.2, 0.3. 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0, or within a range defined by the aforementioned values. In some specific embodiments, 0.5 to 2.0 molar equivalents of base relative to Compound I may be used in the reaction. 
     The reaction for converting Compound I′ or a salt thereof to Compound II′ may be conducted in a variety of solvents. In some embodiments, the solvent may be a polar aprotic solvent. In some embodiments, the solvent may be acetonitrile, dimethylformamide, methylene chloride, chloroform, tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether, methyl tert butyl ether, N-methylpyrrolidinone, acetone, methyl ethyl ketone, or any combination of the aforementioned solvents. In some embodiments, the solvent may be anhydrous. In some embodiments, the solvent may be acetonitrile. 
     The reaction for converting Compound I′ or a salt thereof to Compound II′ may be conducted at a variety of temperatures. In some embodiments, the reaction temperature is from about 25° C. to about 100° C., from about about 30° C. to about 90° C., from about 40° C. to about 80° C., from about 50° C. to about 80° C., from about 55° C. to about 80° C., from about 60° C. to about 80° C., from about about 65° C. to about 80° C., or from about 70° C. to about 80° C. For instance, in some embodiments, the reaction for converting Compound I′ or a salt thereof to Compound II′ may be conducted at 25° C., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., or higher. In some embodiments, the reaction may be heated at any of the aforementioned temperatures for 0.5 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, or more. 
     Crystalline Forms of Compound II′ 
     Disclosed herein are crystalline forms of Compound II′. Two forms, Form A and Form B have been identified (described below). 
     Crystalline Form A of Compound II′ 
     Some embodiments include a crystalline form of Compound II′, referred to herein as crystalline Form A. The precise conditions for forming crystalline Form A of Compound II′ may be empirically determined and it is only possible to give a number of methods which have been found to be suitable in practice. 
     Crystalline Form A of Compound II′ was characterized using various techniques which are described in further detail in the experimental methods section.  FIG.  1    shows the crystalline structure of Form A of Compound II′ as determined by X-ray powder diffraction (XRPD). Crystalline Form B of Compound II′, which may be obtained by the methods disclosed herein, exhibits prominent peaks at approximately 4.3, 7.0, 7.2, 8.3, 11.0, 12.5, 15.0, 16.7, 17.5, 18.2, 19.1, 20.3, 22.3, 22.7, and 25.6 degrees 2θ. Thus, in some embodiments, a crystalline form of Compound II′ has at least one characteristic peak (e.g., one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, or fifteen characteristic peaks) selected from approximately 4.3, 7.0, 7.2, 8.3, 11.0, 12.5, 15.0, 16.7, 17.5, 18.2, 19.1, 20.3, 22.3, 22.7, and 25.6 degrees 2θ. In some embodiments, a crystalline form of Compound II′ has at least three characteristic peaks selected from approximately 4.3, 7.0, 7.2, 8.3, 11.0, 12.5, 15.0, 16.7, 17.5, 18.2, 19.1, 20.3, 22.3, 22.7, and 25.6 degrees 2θ. 
       FIG.  2    shows results obtained by differential scanning calorimetry (DSC) for crystalline Form A of Compound II′. The DSC results show a peak at temperature of about 141° C., which indicates the melting point for the crystal. Accordingly, in some embodiments, crystalline Form B of Compound II′ exhibits a melting point from about 138° C. to about 144° C., from about 139° C. to about 143° C., or at about 141° C. 
       FIG.  3    shows results obtained by thermogravimetric analysis (TGA) for crystalline Form A of Compound II′. The TGA results show that crystalline Form A of Compound II′ exhibited about a 1% weight loss when carried from 25° C. to 125° C. Meanwhile,  FIG.  4    shows dynamic vapor sorption (DVS) results for crystalline Form A of Compound II′, and shows slight water uptake and indicates that crystalline Form A of Compound II′ is slightly hygroscopic. Karl Fisher analysis indicates that crystalline Form A of Compound II′ contains, on average, 0.12% water, indicating that crystalline Form A of Compound II′ is unsolvated. Elemental analysis of crystalline Form A of Compound II′ is consistent with anhydrous material. 
       FIG.  5    shows results obtained by Fourier Transform Infrared (FTIR) spectroscopy for crystalline Form A of Compound II′. Crystalline Form A of Compound II′ exhibits prominent peaks at approximately 1758, 1706, 1600, 1584, 1469, 1426, 1389, 1366, and 1322 cm −1 . Thus, in some embodiments, a crystalline form of Compound II′ has at least one characteristic FTIR peak (e.g., one, two, three, four, five, six, seven, eight, or nine characteristic peaks) selected from approximately 1758, 1706, 1600, 1584, 1469, 1426, 1389, 1366, and 1322 cm −1 . In some embodiments, a crystalline form of Compound II′ has at least three characteristic peaks selected from 1758, 1706, 1600, 1584, 1469, 1426, 1389, 1366, and 1322 cm −1 . In some embodiments, peak positions recited herein include variability within ±1 cm −1 . 
       FIG.  6    shows results obtained by Fourier Transform Raman spectroscopy for crystalline Form B of Compound II′. Crystalline Form A of Compound II′ exhibits prominent peaks at approximately 1754, 1709, 1600, 1584, 1465, 1428, 1366, and 1340 cm −1 . Thus, in some embodiments, a crystalline form of Compound II′ has at least one characteristic FT Raman peak (e.g., one, two, three, four, five, six, seven, or eight characteristic peaks) selected from approximately 1754, 1709, 1600, 1584, 1465, 1428, 1366, and 1340 cm −1 . In some embodiments, a crystalline form of Compound II′ has at least three characteristic peaks selected from 1754, 1709, 1600, 1584, 1465, 1428, 1366, and 1340 cm −1 . In some embodiments, peak positions recited herein include variability within +2 cm −1 . 
     Crystalline Form A of Compound II′ can therefore be characterized as an unsolvated, slightly hygroscopic solid. Crystal Form A of Compound II′ also shows good crystallinity with needle shaped crystals of varying size ( FIG.  7   ) and a relatively high melting point (approximately 141° C.). 
     Crystalline Form B of Compound II′ 
     Some embodiments include a crystalline form of Compound II′, referred to herein as crystalline Form B. The precise conditions for forming crystalline Form B of Compound II′ may be empirically determined and it is only possible to give a number of methods which have been found to be suitable in practice. 
     Crystalline Form B of Compound II′ was characterized using various techniques which are described in further detail in the experimental methods section.  FIG.  8    shows the crystalline structure of Form B of Compound II′ as determined by X-ray powder diffraction (XRPD). Crystalline Form B of Compound II′, which may be obtained by the methods disclosed herein, exhibits prominent peaks at approximately 5.1, 7.0, 9.9, 11.0, 11.1, 14.1, 16.4, 17.1, 21.1, 22.3, 22.6, 26.9, and 28.3 degrees 2θ. Thus, in some embodiments, a crystalline form of Compound II′ has at least one characteristic peak (e.g., one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, or thirteen characteristic peaks) selected from approximately 5.1, 7.0, 9.9, 11.0, 11.1, 14.1, 16.4, 17.1, 21.1, 22.3, 22.6, 26.9, and 28.3 degrees 2θ. In some embodiments, a crystalline form of Compound II′ has at least three characteristic peaks selected from approximately 5.1, 7.0, 9.9, 11.0, 11.1, 14.1, 16.4, 17.1, 21.1, 22.3, 22.6, 26.9, and 28.3 degrees 2θ. 
       FIG.  9    shows results obtained by differential scanning calorimetry (DSC) for crystalline Form B of Compound II′. The DSC results show a peak at temperature of about 152° C., which indicates the melting point for the crystal. Accordingly, in some embodiments, crystalline Form B of Compound II′ exhibits a melting point from about 149° C. to about 155° C., from about 150° C. to about 154° C., or at about 152° C. 
       FIG.  10    shows results obtained by thermogravimetric analysis (TGA) for crystalline Form B of Compound II′. The TGA results show that crystalline Form B of Compound II′ exhibited a 0.18% weight loss when carried from 25° C. to 125° C. Meanwhile,  FIG.  11    shows dynamic vapor sorption (DVS) results for crystalline Form B of Compound II′, and shows moderate water uptake and indicates that crystalline Form B of Compound II′ is moderately hygroscopic. Karl Fisher analysis indicates that crystalline Form B of Compound II′ contains, on average, 7.29% water. However, the water is believed to be a decomposition product from heating the sample. Elemental analysis shows crystalline Form B of Compound II′ is an unsolvated material. 
       FIG.  12    shows results obtained by Fourier Transform Infrared (FTIR) spectroscopy for crystalline Form B of Compound II′. Crystalline Form B of Compound II′ exhibits prominent peaks at approximately 1608, 1592, 1553, 1473, 1416, 1364, 1334, and 1277 cm −1 . Thus, in some embodiments, a crystalline form of Compound II′ has at least one characteristic FTIR peak (e.g., one, two, three, four, five, six, seven, or eight characteristic peaks) selected from approximately 1608, 1592, 1553, 1473, 1416, 1364, 1334, and 1277 cm −1 . In some embodiments, a crystalline form of Compound II′ has at least three characteristic peaks selected from 1608, 1592, 1553, 1473, 1416, 1364, 1334, and 1277 cm −1 . In some embodiments, peak positions recited herein include variability within ±1 cm −1 . 
       FIG.  13    shows results obtained by Fourier Transform Raman spectroscopy for crystalline Form B of Compound II′. Crystalline Form B of Compound II′ exhibits prominent peaks at approximately 1611, 1591, 1574, 1472, 1426, and 1366 cm −1 . Thus, in some embodiments, a crystalline form of Compound II′ has at least one characteristic FT Raman peak (e.g., one, two, three, four, five, or six characteristic peaks) selected from approximately 1611, 1591, 1574, 1472, 1426, and 1366 cm 1 . In some embodiments, a crystalline form of Compound II′ has at least three characteristic peaks selected from 1611, 1591, 1574, 1472, 1426, and 1366 cm −1 . In some embodiments, peak positions recited herein include variability within ±2 cm −1 . 
     Crystalline Form B of Compound II′ can therefore be characterized as an unsolvated, moderately hygroscopic solid. Crystal Form B of Compound II′ also shows good crystallinity with blade shaped crystals of varying size ( FIG.  14   ) and a relatively high melting point (approximately 152° C.). 
     Methods of Crystalizing Compound II′ 
     Disclosed are methods of crystalizing Compound II′. Crystalline forms of Compound II′ may generally be obtained or produced by crystallizing the compound of Compound II′ under controlled conditions. In some embodiments, the method may produce an unsolvated crystalline form. In some embodiments, the method may produce the crystalline Form A of Compound II′. In some embodiments, the method may produce the crystalline Form B of Compound II′. 
     In some embodiments, crystalline forms of Compound II′ may be prepared by taking up Compound II′ in a solvent to form a crystallization solution, optionally heating the first solution, and optionally adding a second solvent to the crystallization solution. In some embodiments, the first solvent may be isopropyl acetate. In other embodiments, the first solvent may be isopropyl alcohol. In other embodiments, the first solvent may be hexanes. In yet still other embodiments, the first solvent may be heptane. In some embodiments, the first solvent may be ethyl acetate. In some embodiments, the first solvent may be a combination of any of isopropyl acetate, isopropyl alcohol, hexanes, heptane, and/or ethyl acetate. In some specific embodiments, the first solvent may be a combination of isopropyl acetate and isopropyl alcohol. In other specific embodiments, the first solvent may be a combination of hexanes and ethyl acetate. 
     In some embodiments, the crystallization solution may optionally be heated to 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90° C., or within a range defined by any of the aforementioned temperatures. 
     In some embodiments, the second solvent may be heptane. In other embodiments, the second solvent may be hexanes. 
     In some embodiments, seeds of the desired crystalline form of Compound II′ may optionally be added to the crystallization solution to facilitate crystallization. 
     In some embodiments, the crystallization solution may be cooled to 55, 50, 45, 40, 35, 30, 35, 20, 15, 10, 5, 0−5, or −10° C., or within a range defined by any of the aforementioned temperatures. The crystallization solution may be cooled for a period of 1, 2, 3, 4, 6, 8, 12, 16, 24, 36, 48, or 72 hours, or within a range defined by any of the aforementioned times. The cooling may be accomplished with or without stirring or agitation. 
     Definitions 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs. All patents, applications, published applications, and other publications are incorporated by reference in their entirety. In the event that there is a plurality of definitions for a term herein, those in this section prevail unless stated otherwise. 
     The term “pharmaceutically acceptable salt” refers to salts that retain the biological effectiveness and properties of a compound and, which are not biologically or otherwise undesirable for use in a pharmaceutical. In many cases, the compounds disclosed herein are capable of forming acid and/or base salts by virtue of the presence of amino and/or carboxyl groups or groups similar thereto. Pharmaceutically acceptable acid addition salts can be formed with inorganic acids and organic acids. Inorganic acids from which salts can be derived include, for example, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like. Organic acids from which salts can be derived include, for example, acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid, and the like. Pharmaceutically acceptable salts can also be formed using inorganic and organic bases. Inorganic bases from which salts can be derived include, for example, bases that contain sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum, and the like; particularly preferred are the ammonium, potassium, sodium, calcium and magnesium salts. In some embodiments, treatment of the compounds disclosed herein with an inorganic base results in loss of a labile hydrogen from the compound to afford the salt form including an inorganic cation such as Li + , Na + , K + , Mg 2+  and Ca 2+  and the like. Organic bases from which salts can be derived include, for example, primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines, basic ion exchange resins, and the like, specifically such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, and ethanolamine. Many such salts are known in the art, as described in WO 87/05297, Johnston et al., published Sep. 11, 1987 (incorporated by reference herein in its entirety). 
     Administration and Pharmaceutical Compositions 
     The compounds disclosed herein are administered at a therapeutically effective dosage. While human dosage levels have yet to be optimized for the compounds described herein, generally, a daily dose may be from about 0.25 mg/kg to about 120 mg/kg or more of body weight, from about 0.5 mg/kg or less to about 70 mg/kg, from about 1.0 mg/kg to about 50 mg/kg of body weight, or from about 1.5 mg/kg to about 10 mg/kg of body weight. Thus, for administration to a 70 kg person, the dosage range would be from about 17 mg per day to about 8000 mg per day, from about 35 mg per day or less to about 7000 mg per day or more, from about 70 mg per day to about 6000 mg per day, from about 100 mg per day to about 5000 mg per day, or from about 200 mg to about 3000 mg per day. The amount of active compound administered will, of course, be dependent on the subject and disease state being treated, the severity of the affliction, the manner and schedule of administration and the judgment of the prescribing physician. 
     Administration of the compounds disclosed herein or the pharmaceutically acceptable salts thereof can be via any of the accepted modes of administration for agents that serve similar utilities including, but not limited to, orally, subcutaneously, intravenously, intranasally, topically, transdermally, intraperitoneally, intramuscularly, intrapulmonarilly, vaginally, rectally, or intraocularly. Oral and parenteral administrations are customary in treating the indications that are the subject of the preferred embodiments. 
     The compounds useful as described above can be formulated into pharmaceutical compositions for use in treatment of these conditions. Standard pharmaceutical formulation techniques are used, such as those disclosed in Remington&#39;s The Science and Practice of Pharmacy, 21st Ed., Lippincott Williams &amp; Wilkins (2005), incorporated by reference in its entirety. Accordingly, some embodiments include pharmaceutical compositions comprising: (a) a safe and therapeutically effective amount of a compound described herein (including enantiomers, diastereoisomers, tautomers, polymorphs, and solvates thereof), or pharmaceutically acceptable salts thereof; and (b) a pharmaceutically acceptable carrier, diluent, excipient or combination thereof. 
     In addition to the selected compound useful as described above, come embodiments include compositions containing a pharmaceutically-acceptable carrier. The term “pharmaceutically acceptable carrier” or “pharmaceutically acceptable excipient” includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active ingredient, its use in the therapeutic compositions is contemplated. In addition, various adjuvants such as are commonly used in the art may be included. Considerations for the inclusion of various components in pharmaceutical compositions are described, e.g., in Gilman et al. (Eds.) (1990); Goodman and Gilman&#39;s: The Pharmacological Basis of Therapeutics, 8th Ed., Pergamon Press, which is incorporated herein by reference in its entirety. 
     Some examples of substances, which can serve as pharmaceutically-acceptable carriers or components thereof, are sugars, such as lactose, glucose and sucrose; starches, such as corn starch and potato starch; cellulose and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose, and methyl cellulose; powdered tragacanth; malt; gelatin; talc; solid lubricants, such as stearic acid and magnesium stearate; calcium sulfate; vegetable oils, such as peanut oil, cottonseed oil, sesame oil, olive oil, corn oil and oil of  theobroma ; polyols such as propylene glycol, glycerine, sorbitol, mannitol, and polyethylene glycol; alginic acid; emulsifiers, such as the TWEENS; wetting agents, such sodium lauryl sulfate; coloring agents; flavoring agents; tableting agents, stabilizers; antioxidants; preservatives; pyrogen-free water; isotonic saline; and phosphate buffer solutions. 
     The choice of a pharmaceutically-acceptable carrier to be used in conjunction with the subject compound is basically determined by the way the compound is to be administered. 
     The compositions described herein are preferably provided in unit dosage form. As used herein, a “unit dosage form” is a composition containing an amount of a compound that is suitable for administration to an animal, preferably mammal subject, in a single dose, according to good medical practice. The preparation of a single or unit dosage form however, does not imply that the dosage form is administered once per day or once per course of therapy. Such dosage forms are contemplated to be administered once, twice, thrice or more per day and may be administered as infusion over a period of time (e.g., from about 30 minutes to about 2-6 hours), or administered as a continuous infusion, and may be given more than once during a course of therapy, though a single administration is not specifically excluded. The skilled artisan will recognize that the formulation does not specifically contemplate the entire course of therapy and such decisions are left for those skilled in the art of treatment rather than formulation. 
     The compositions useful as described above may be in any of a variety of suitable forms for a variety of routes for administration, for example, for oral, nasal, rectal, topical (including transdermal), ocular, intracerebral, intracranial, intrathecal, intra-arterial, intravenous, intramuscular, or other parental routes of administration. The skilled artisan will appreciate that oral and nasal compositions comprise compositions that are administered by inhalation, and made using available methodologies. Depending upon the particular route of administration desired, a variety of pharmaceutically-acceptable carriers well-known in the art may be used. Pharmaceutically-acceptable carriers include, for example, solid or liquid fillers, diluents, hydrotropies, surface-active agents, and encapsulating substances. Optional pharmaceutically-active materials may be included, which do not substantially interfere with the inhibitory activity of the compound. The amount of carrier employed in conjunction with the compound is sufficient to provide a practical quantity of material for administration per unit dose of the compound. Techniques and compositions for making dosage forms useful in the methods described herein are described in the following references, all incorporated by reference herein: Modern Pharmaceutics, 4th Ed., Chapters 9 and 10 (Banker &amp; Rhodes, editors, 2002); Lieberman et al., Pharmaceutical Dosage Forms: Tablets (1989); and Ansel, Introduction to Pharmaceutical Dosage Forms 8th Edition (2004). 
     Various oral dosage forms can be used, including such solid forms as tablets, capsules, granules and bulk powders. Tablets can be compressed, tablet triturates, enteric-coated, sugar-coated, film-coated, or multiple-compressed, containing suitable binders, lubricants, diluents, disintegrating agents, coloring agents, flavoring agents, flow-inducing agents, and melting agents. Liquid oral dosage forms include aqueous solutions, emulsions, suspensions, solutions and/or suspensions reconstituted from non-effervescent granules, and effervescent preparations reconstituted from effervescent granules, containing suitable solvents, preservatives, emulsifying agents, suspending agents, diluents, sweeteners, melting agents, coloring agents and flavoring agents. 
     The pharmaceutically-acceptable carrier suitable for the preparation of unit dosage forms for peroral administration is well-known in the art. Tablets typically comprise conventional pharmaceutically-compatible adjuvants as inert diluents, such as calcium carbonate, sodium carbonate, mannitol, lactose and cellulose; binders such as starch, gelatin and sucrose; disintegrants such as starch, alginic acid and croscarmelose; lubricants such as magnesium stearate, stearic acid and talc. Glidants such as silicon dioxide can be used to improve flow characteristics of the powder mixture. Coloring agents, such as the FD&amp;C dyes, can be added for appearance. Sweeteners and flavoring agents, such as aspartame, saccharin, menthol, peppermint, and fruit flavors, are useful adjuvants for chewable tablets. Capsules typically comprise one or more solid diluents disclosed above. The selection of carrier components depends on secondary considerations like taste, cost, and shelf stability, which are not critical, and can be readily made by a person skilled in the art. 
     Peroral compositions also include liquid solutions, emulsions, suspensions, and the like. The pharmaceutically-acceptable carriers suitable for preparation of such compositions are well known in the art. Typical components of carriers for syrups, elixirs, emulsions and suspensions include ethanol, glycerol, propylene glycol, polyethylene glycol, liquid sucrose, sorbitol and water. For a suspension, typical suspending agents include methyl cellulose, sodium carboxymethyl cellulose, AVICEL RC-591, tragacanth and sodium alginate; typical wetting agents include lecithin and polysorbate 80; and typical preservatives include methyl paraben and sodium benzoate. Peroral liquid compositions may also contain one or more components such as sweeteners, flavoring agents and colorants disclosed above. 
     Such compositions may also be coated by conventional methods, typically with pH or time-dependent coatings, such that the subject compound is released in the gastrointestinal tract in the vicinity of the desired topical application, or at various times to extend the desired action. Such dosage forms typically include, but are not limited to, one or more of cellulose acetate phthalate, polyvinylacetate phthalate, hydroxypropyl methyl cellulose phthalate, ethyl cellulose, Eudragit coatings, waxes and shellac. 
     Compositions described herein may optionally include other drug actives. 
     Other compositions useful for attaining systemic delivery of the subject compounds include sublingual, buccal and nasal dosage forms. Such compositions typically comprise one or more of soluble filler substances such as sucrose, sorbitol and mannitol; and binders such as acacia, microcrystalline cellulose, carboxymethyl cellulose and hydroxypropyl methyl cellulose. Glidants, lubricants, sweeteners, colorants, antioxidants and flavoring agents disclosed above may also be included. 
     A liquid composition, which is formulated for topical ophthalmic use, is formulated such that it can be administered topically to the eye. The comfort should be maximized as much as possible, although sometimes formulation considerations (e.g. drug stability) may necessitate less than optimal comfort. In the case that comfort cannot be maximized, the liquid should be formulated such that the liquid is tolerable to the patient for topical ophthalmic use. Additionally, an ophthalmically acceptable liquid should either be packaged for single use, or contain a preservative to prevent contamination over multiple uses. 
     For ophthalmic application, solutions or medicaments are often prepared using a physiological saline solution as a major vehicle. Ophthalmic solutions should preferably be maintained at a comfortable pH with an appropriate buffer system. The formulations may also contain conventional, pharmaceutically acceptable preservatives, stabilizers and surfactants. 
     Preservatives that may be used in the pharmaceutical compositions disclosed herein include, but are not limited to, benzalkonium chloride, PHMB, chlorobutanol, thimerosal, phenylmercuric, acetate and phenylmercuric nitrate. A useful surfactant is, for example, Tween 80. Likewise, various useful vehicles may be used in the ophthalmic preparations disclosed herein. These vehicles include, but are not limited to, polyvinyl alcohol, povidone, hydroxypropyl methyl cellulose, poloxamers, carboxymethyl cellulose, hydroxyethyl cellulose and purified water. 
     Tonicity adjustors may be added as needed or convenient. They include, but are not limited to, salts, particularly sodium chloride, potassium chloride, mannitol and glycerin, or any other suitable ophthalmically acceptable tonicity adjustor. 
     Various buffers and means for adjusting pH may be used so long as the resulting preparation is ophthalmically acceptable. For many compositions, the pH will be between 4 and 9. Accordingly, buffers include acetate buffers, citrate buffers, phosphate buffers and borate buffers. Acids or bases may be used to adjust the pH of these formulations as needed. 
     In a similar vein, an ophthalmically acceptable antioxidant includes, but is not limited to, sodium metabisulfite, sodium thiosulfate, acetylcysteine, butylated hydroxyanisole and butylated hydroxytoluene. 
     Other excipient components, which may be included in the ophthalmic preparations, are chelating agents. A useful chelating agent is edetate disodium, although other chelating agents may also be used in place or in conjunction with it. 
     For topical use, creams, ointments, gels, solutions or suspensions, etc., containing the compound disclosed herein are employed. Topical formulations may generally be comprised of a pharmaceutical carrier, co-solvent, emulsifier, penetration enhancer, preservative system, and emollient. 
     For intravenous administration, the compounds and compositions described herein may be dissolved or dispersed in a pharmaceutically acceptable diluent, such as a saline or dextrose solution. Suitable excipients may be included to achieve the desired pH, including but not limited to NaOH, sodium carbonate, sodium acetate, HCl, and citric acid. In various embodiments, the pH of the final composition ranges from 2 to 8, or preferably from 4 to 7. Antioxidant excipients may include sodium bisulfite, acetone sodium bisulfite, sodium formaldehyde, sulfoxylate, thiourea, and EDTA. Other non-limiting examples of suitable excipients found in the final intravenous composition may include sodium or potassium phosphates, citric acid, tartaric acid, gelatin, and carbohydrates such as dextrose, mannitol, and dextran. Further acceptable excipients are described in Powell, et al., Compendium of Excipients for Parenteral Formulations,  PDA J Pharm Sci and Tech  1998, 52 238-311 and Nema et al., Excipients and Their Role in Approved Injectable Products: Current Usage and Future Directions,  PDA J Pharm Sci and Tech  2011, 65 287-332, both of which are incorporated herein by reference in their entirety. Antimicrobial agents may also be included to achieve a bacteriostatic or fungistatic solution, including but not limited to phenylmercuric nitrate, thimerosal, benzethonium chloride, benzalkonium chloride, phenol, cresol, and chlorobutanol. 
     The compositions for intravenous administration may be provided to caregivers in the form of one more solids that are reconstituted with a suitable diluent such as sterile water, saline or dextrose in water shortly prior to administration. In other embodiments, the compositions are provided in solution ready to administer parenterally. In still other embodiments, the compositions are provided in a solution that is further diluted prior to administration. In embodiments that include administering a combination of a compound described herein and another agent, the combination may be provided to caregivers as a mixture, or the caregivers may mix the two agents prior to administration, or the two agents may be administered separately. 
     The actual dose of the active compounds described herein depends on the specific compound, and on the condition to be treated; the selection of the appropriate dose is well within the knowledge of the skilled artisan. 
     Methods of Treatment 
     Some embodiments of the present invention include methods of treating bacterial infections with the compounds and compositions comprising the compounds described herein. Some methods include administering a compound, composition, pharmaceutical composition described herein to a subject in need thereof. In some embodiments, a subject can be an animal, e.g., a mammal (including a human). In some embodiments, the bacterial infection comprises a bacteria described herein. As will be appreciated from the foregoing, methods of treating a bacterial infection include methods for preventing bacterial infection in a subject at risk thereof. 
     In some embodiments, the subject is a human. 
     Further embodiments include administering a combination of compounds to a subject in need thereof. A combination can include a compound, composition, pharmaceutical composition described herein with an additional medicament. 
     Some embodiments include co-administering a compound, composition, and/or pharmaceutical composition described herein, with an additional medicament. By “co-administration,” it is meant that the two or more agents may be found in the patient&#39;s bloodstream at the same time, regardless of when or how they are actually administered. In one embodiment, the agents are administered simultaneously. In one such embodiment, administration in combination is accomplished by combining the agents in a single dosage form. In another embodiment, the agents are administered sequentially. In one embodiment the agents are administered through the same route, such as orally. In another embodiment, the agents are administered through different routes, such as one being administered orally and another being administered intravenous (i.v.). 
     Examples of additional medicaments include an antibacterial agent, antifungal agent, an antiviral agent, an anti-inflammatory agent and an anti-allergic agent. 
     Preferred embodiments include combinations of a compound, composition or pharmaceutical composition described herein with an antibacterial agent such as a β-lactam. Examples of such β-lactams include Amoxicillin, Ampicillin (e.g., Pivampicillin, Hetacillin, Bacampicillin, Metampicillin, Talampicillin), Epicillin, Carbenicillin (Carindacillin), Ticarcillin, Temocillin, Azlocillin, Piperacillin, Mezlocillin, Mecillinam (Pivmecillinam), Sulbenicillin, Benzylpenicillin (G), Clometocillin, Benzathine benzylpenicillin, Procaine benzylpenicillin, Azidocillin, Penamecillin, Phenoxymethylpenicillin (V), Propicillin, Benzathine phenoxymethylpenicillin, Pheneticillin, Cloxacillin (e.g., Dicloxacillin, Flucloxacillin), Oxacillin, Methicillin, Nafcillin, Faropenem, Biapenem, Doripenem, Ertapenem, Imipenem, Meropenem, Panipenem, Cefazolin, Cefacetrile, Cefadroxil, Cefalexin, Cefaloglycin, Cefalonium, Cefaloridine, Cefalotin, Cefapirin, Cefatrizine, Cefazedone, Cefazaflur, Cefradine, Cefroxadine, Ceftezole, Cefaclor, Cefamandole, Cefminox, Cefonicid, Ceforanide, Cefotiam, Cefprozil, Cefbuperazone, Cefuroxime, Cefuzonam, Cefoxitin, Cefotetan, Cefmetazole, Loracarbef, Cefixime, Ceftazidime, Ceftriaxone, Cefcapene, Cefdaloxime, Cefdinir, Cefidericol, Cefditoren, Cefetamet, Cefmenoxime, Cefodizime, Cefoperazone, Cefotaxime, Cefpimizole, Cefpiramide, Cefpodoxime, Cefpodoxime proxetil, Cefsulodin, Cefteram, Ceftibuten, Ceftiolene, Ceftizoxime, Flomoxef, Latamoxef, Cefepime, Cefozopran, Cefpirome, Cefquinome, Ceftobiprole, Ceftaroline, Ceftiofur, Cefquinome, Cefovecin, Aztreonam, Tigemonam and Carumonam. 
     Preferred embodiments include β-lactams such as Ceftazidime, Biapenem, Doripenem, Ertapenem, Imipenem, Meropenem, Tebipenem, Tebipenem pivoxil, Apapenem, and Panipenem. 
     Additional preferred embodiments include β-lactams such as Aztreonam, Tigemonam, and Carumonam. 
     Further preferred embodiments include β-lactam antibacterial agent such as tebipenem pivoxil. 
     Yet further preferred embodiments include β-lactam antibacterial agent such as ceftibuten. 
     Some embodiments include a combination of the compounds, compositions and/or pharmaceutical compositions described herein with an additional agent, wherein the additional agent comprises a monobactam. Examples of monobactams include aztreonam, tigemonam, nocardicin A, carumonam, and tabtoxin. In some such embodiments, the compound, composition and/or pharmaceutical composition comprises a class A, C, or D beta-lactamase inhibitor. Some embodiments include co-administering the compound, composition or pharmaceutical composition described herein with one or more additional agents. 
     Some embodiments include a combination of the compounds, compositions and/or pharmaceutical compositions described herein with an additional agent, wherein the additional agent comprises a class B beta lactamase inhibitor. An example of a class B beta lactamase inhibitor includes ME1071 (Yoshikazu Ishii et al, “In Vitro Potentiation of Carbapenems with ME1071, a Novel Metallo-β-Lactamase Inhibitor, against Metallo-β-lactamase Producing  Pseudomonas aeruginosa  Clinical Isolates.” Antimicrob. Agents Chemother. doi: 10.1128/AAC0.01397-09 (July 2010)). Some embodiments include co-administering the compound, composition or pharmaceutical composition described herein with one or more additional agents. 
     Some embodiments include a combination of the compounds, compositions and/or pharmaceutical compositions described herein with an additional agent, wherein the additional agent comprises one or more agents that include a class A, B, C, or D beta lactamase inhibitor. Some embodiments include co-administering the compound, composition or pharmaceutical composition described herein with the one or more additional agents. 
     Indications 
     The compounds and compositions comprising the compounds described herein can be used to treat bacterial infections. Bacterial infections that can be treated with the compounds, compositions and methods described herein can comprise a wide spectrum of bacteria. Example organisms include gram-positive bacteria, gram-negative bacteria, aerobic and anaerobic bacteria, such as  Staphylococcus, Lactobacillus, Streptococcus, Sarcina, Escherichia, Enterobacter, Klebsiella, Pseudomonas, Acinetobacter, Mycobacterium, Proteus, Campylobacter, Citrobacter, Nisseria, Baccillus, Bacteroides, Peptococcus, Clostridium, Salmonella, Shigella, Serratia, Haemophilus, Brucella  and other organisms. 
     More examples of bacterial infections include  Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas acidovorans, Pseudomonas alcaligenes, Pseudomonas putida, Stenotrophomonas maltophilia, Burkholderia cepacia, Aeromonas hydrophilia, Escherichia coli, Citrobacter freundii, Salmonella typhimurium, Salmonella typhi, Salmonella paratyphi, Salmonella enteritidis, Shigella dysenteriae, Shigella flexneri, Shigella sonnei, Enterobacter cloacae, Enterobacter aerogenes, Klebsiella pneumoniae, Klebsiella oxytoca, Serratia marcescens, Francisella tularensis, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia alcalifaciens, Providencia rettgeri, Providencia stuartii, Acinetobacter baumannii, Acinetobacter calcoaceticus, Acinetobacter haemolyticus, Yersinia enterocolitica, Yersinia pestis, Yersinia pseudotuberculosis, Yersinia intermedia, Bordetella pertussis, Bordetella parapertussis, Bordetella bronchiseptica, Haemophilus influenzae, Haemophilus parainfluenzae, Haemophilus haemolyticus, Haemophilus parahaemolyticus, Haemophilus ducreyi, Pasteurella multocida, Pasteurella haemolytica, Branhamella catarrhalis, Helicobacter pylori, Campylobacter fetus, Campylobacter jejuni, Campylobacter coli, Borrelia burgdorferi, Vibrio cholerae, Vibrio parahaemolyticus, Legionella pneumophila, Listeria monocytogenes, Neisseria gonorrhoeae, Neisseria meningitidis, Kingella, Moraxella, Gardnerella vaginalis, Bacteroides fragilis, Bacteroides distasonis, Bacteroides  3452A homology group,  Bacteroides vulgatus, Bacteroides ovalus, Bacteroides thetaiotaomicron, Bacteroides uniformis, Bacteroides eggerthii, Bacteroides splanchnicus, Clostridium difficile, Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium leprae, Corynebacterium diphtheriae, Corynebacterium ulcerans, Streptococcus pneumoniae, Streptococcus agalactiae, Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Staphylococcus intermedius, Staphylococcus hyicus  subsp.  hyicus, Staphylococcus haemolyticus, Staphylococcus hominis , or  Staphylococcus saccharolyticus.    
     To further illustrate this invention, the following examples are included. The examples should not, of course, be construed as specifically limiting the invention. Variations of these examples within the scope of the claims are within the purview of one skilled in the art and are considered to fall within the scope of the invention as described, and claimed herein. The reader will recognize that the skilled artisan, armed with the present disclosure, and skill in the art is able to prepare and use the invention without exhaustive examples. The following examples will further describe the present invention, and are used for the purposes of illustration only, and should not be considered as limiting. 
     EXAMPLES 
     X-ray Powder Diffraction (XRPD) 
     The Rigaku Smart-Lab X-ray diffraction system was configured for reflection Bragg-Brentano geometry using a line source X-ray beam. The x-ray source was a Cu Long Fine Focus tube that was operated at 40 kV and 44 ma. That source provides an incident beam profile at the sample that changes from a narrow line at high angles to a broad rectangle at low angles. Beam conditioning slits were used on the line X-ray source to ensure that the maximum beam size was less than 10 mm both along the line and normal to the line. The Bragg-Brentano geometry is a para-focusing geometry controlled by passive divergence and receiving slits with the sample itself acting as the focusing component for the optics. The inherent resolution of Bragg-Brentano geometry is governed in part by the diffractometer radius and the width of the receiving slit used. Typically, the Rigaku Smart-Lab is operated to give peak widths of 0.1° 2θ or less. The axial divergence of the X-ray beam was controlled by 5.0-degree Soller slits in both the incident and diffracted beam paths. The instrument was qualified using ASTM silicon standard on the same day of the analysis. 
     Powder samples were prepared in a low background Si holder using light manual pressure to keep the sample surfaces flat and level with the reference surface of the sample holder. Each sample was analyzed from 2 to 40° 2θ using a continuous scan of 6° 2θ per minute with an effective step size of 0.02° 2θ. 
     Differential Scanning calorimetry (DSC) 
     DSC analyses were carried out using a TA Instruments Q2500 Discovery Series instrument. The instrument temperature calibration was performed using indium. The DSC cell was kept under a nitrogen purge of ˜50 mL per minute during each analysis. The sample was placed in a standard, crimped, aluminum pan and was heated from approximately 25° C. to 350° C. at a rate of 10° C. per minute. 
     Melt Point (MP) Analysis 
     Melt point analysis was carried out using a Stuart SMP3 melt point apparatus. The sample was placed in a glass capillary and heated at 10° C. per minute. 
     Thermogravimetric (TG) Analysis 
     TG analysis was carried out using a TA Instruments Q5500 Discovery Series instrument. The instrument balance was calibrated using class M weights and the temperature calibration was performed using alumel. The nitrogen purge was −40 mL per minute at the balance and −60 mL per minute at the furnace. Each sample was placed into a pre-tared platinum pan and heated from approximately 25° C. to 350° C. at a rate of 10° C. per minute. 
     Dynamic Vapor Sorption (DVS) Analysis 
     DVS analysis was carried out using a TA Instruments Q5000 Dynamic Vapor Sorption analyzer. The instrument was calibrated with standard weights and a sodium bromide standard for humidity. Approximately 20 mg of sample was loaded into a metal-coated quartz pan for analysis. The sample was analyzed at 25° C. with a maximum equilibration time of one hour in 10% relative humidity (RH) steps from 5 to 95% RH (adsorption cycle) and from 95 to 5% RH (desorption cycle). The movement from one step to the next occurred either after satisfying the equilibrium criterion of 0.01% weight change or, if the equilibrium criterion was not met, after one hour. The percent weight change values were calculated using Microsoft Excel®. The temperature for the DVS analysis can impact the outcome of the results. 
     Karl Fischer (KF) Analyses 
     Karl Fischer analyses were carried out using a Mettler-Toledo C20 Coulometric KF titrator with oven attachment heated at 175° C. The instrument was calibrated using a Hydranal water standard containing 1% water. The titrant was a Hydranal methanol solution. The sample was analyzed in triplicate. 
     Optical Microscopy 
     Optical microscopy experiments were carried out on a Leica DM 2500 P compound microscope with a 10× magnification eye piece and a 10× magnification objective, for a total magnification of 100×. Images were captured using a QImaging MicroPublisher 3.3 RTV camera. 
     Infrared (IR) Spectroscopy 
     The IR spectra were obtained using a Thermo Nicolet model 6700 Fourier-transform (FT) IR spectrophotometer equipped with a deuterated triglycine sulfate (DTGS) detector, a potassium bromide (KBr) beamsplitter, and an electronically temperature controlled (ETC) Ever-Glo® IR source. The instrument was configured with a SMART iTR diamond attenuated total reflectance (ATR) sampling accessory. The single beam scan of the background (air) and sample were collected with 128 signal-averaged scans at a resolution of 2 cm −1  over the spectral range 4000-400 cm −1 . The final sample spectrum was automatically calculated and presented in Log 1/R units. The wavelength calibration was verified using a certified polystyrene standard. Data collection and processing was performed using Omnic 9.7.46 software. 
     Raman Spectroscopy 
     Fourier transform (FT) Raman spectra were acquired on a Nicolet model 6700 spectrometer interfaced to a Nexus Raman accessory module. This instrument is configured with a Nd:YAG laser operating at 1024 nm, a CaF 2  beamsplitter, and a indium gallium arsenide detector. OMNIC 8.1 software was used for control of data acquisition and processing of the spectra. Samples were packed into a 3-inch glass NMR tube for analysis. 
     Low-Frequency Raman Spectroscopy 
     Raman spectroscopy is a complementary technique to infrared (IR) spectroscopy and both techniques provide a full vibrational analysis of an entity being studied. Commercial Raman instruments typically utilize notch filters that block Rayleigh scattering and only allow for good quality Raman spectra to be obtained down to ˜100 cm −1 . The spectral region from approximately 500 to 50 cm −1  or lower, depending upon the type of filter, is referred to as the low frequency Raman spectral region. In this region, vibrational modes originate from the crystalline lattice of organic compounds, or from heavy atoms such as those incorporated into organometallic or inorganic molecules. The natural frequency of the crystal lattice is termed a phonon mode. Phonon modes arise from a fundamental structure, namely the specific crystal lattice for the particular compound being studied. Different crystalline forms typically display a unique crystal lattice, and therefore a unique phonon mode is displayed for each distinct crystalline form. 
     Low frequency (LF) Raman spectra became available owing to new filter designs, and it has been demonstrated that this region permits the identification/differentiation of different crystalline forms (See Roy, S., Chamberlin, B., and Matzger, A. J., “Polymorph Discrimination Using Low Wavenumber Raman Spectroscopy,” Org. Process Res. Dev. 2013, 17, 976-980) The LF Raman spectroscopy allows the spectral acquisition in the Raman spectrum region, including Stokes region from 2200 cm −1  to 0 cm −1  and Anti-Stokes region from 0 cm −1  to −900 cm −1 . The LF Raman spectroscopy allows observation of phonon modes (natural vibration frequency of the crystal lattice) which can be used to differentiate crystalline forms. The same “mirror image” signals corresponding to the phonon modes are visible in both Stokes and anti-Stokes regions, however, Stokes signals are normally used for differentiating crystalline forms owing to their stronger intensity than anti-Stokes signals. 
     LF Raman spectra were obtained using a Renishaw Raman, equipped with a ONDAX THz Raman system (excitation laser 853 nm, notch filter). The solid sample was analyzed with exposure time of 10 seconds and 32 accumulations. The solid sample was spread on a gold slide and analyzed using ONDAX TR-probe (Marqme TriX) contacting the solid sample. The LF-Raman was calibrated using sulfur reference standard prior to the sample analysis. 
       13 C Nuclear Magnetic Resonance (NMR) Spectroscopy 
     The solid-state  13 C cross polarization magic angle spinning (CPMAS) experiments were carried out on a Bruker Avance II 400 spectrometer. Each sample (approximately 200 mg) was packed into a 4-mm zirconia rotor closed with Kel-F end caps for subsequent data acquisition. Adamantane, set to 29.5 ppm, was used as an external standard. Acquisition and processing parameters used are shown in the table below. 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Nucleus 
                   13 C 
               
               
                   
                 Temperature (K) 
                 297 
               
               
                   
                 Observe Frequency (MHz) 
                 100.64 
               
               
                   
                 Sweep Width (Hz) 
                 29762 
               
               
                   
                 Dwell Time (μsec) 
                 16.8 
               
               
                   
                 Acquisition Time (msec) 
                 275 
               
               
                   
                 Recycle Delay (sec) 
                 20 
               
               
                   
                 Spin Speed (kHz) 
                 7.0 
               
               
                   
                 Number of Scans 
                 10240 
               
            
           
           
               
            
               
                 Processing Parameters 
               
            
           
           
               
               
               
            
               
                   
                 Reference 
                 external 
               
               
                   
                 Line Broadening (Hz) 
                 10 
               
               
                   
                   
               
            
           
         
       
     
     Example 1 
     Synthesis of (isobutyryloxy)methyl (1aR,7bS)-5-fluoro-2-hydroxy-1,1a,2,7b-tetrahydrobenzo[e]cyclopropa[c][1,2]oxaborinine-4-carboxylate (II′) 
     Chloromethyl isobutyrate (8.9 mL, 70.4 mmol) was added to a heterogeneous mixture of compound (I) (5.0 g, 17.6 mmol), sodium bicarbonate (5.92 g, 70.4 mmol) and sodium iodide (1.62 g, 8.8 mmol) in acetonitrile (ACN) (25 mL) at room temperature. The heterogeneous mixture was heated at 55° C. After stirring at 55° C. for 16 hours, HPLC shows 93.6% conversion. The reaction mixture was cooled to 0° C. Ice-water (50 mL) was added and after stirring at 0° C. for 1 min MTBE (50 mL) was added. The layers were separated. The organic layer was washed several times with 20 mM NaHCO 3  (3×50 mL) and filtered through a 0.7 μm GMF syringe filter. The filtrate was concentrated to a few mL. ACN (25 mL) was added and the solution was concentrated to almost dryness at 25° C. The residual oil was taken in ACN (25 mL) and cooled to −5° C. Water (25 mL) was added and the turbid solution was cooled to −6° C. 2 N NaOH (7.1 mL) was added slowly until pH 9 keeping the temperature &lt;−5° C. to obtain a biphasic mixture. The layers were separated (keep aqueous layer). The aqueous layer was extracted with heptane (25 mL, keep aqueous layer). The colorless aqueous layer was saturated with solid NaCl at room temperature to get a biphasic mixture. The layers were separated. The aqueous layer was back extracted with ACN (25 mL). The combined organic layers were concentrated to a few mL. ACN (25 mL) was added and the heterogeneous mixture was concentrated to a few mL. Isopropyl acetate (25 mL) was added and the heterogeneous solution was filtered through a 0.45 μm PTFE syringe filter to remove the residual salts. The clear filtrate was concentrated to dryness to get a colorless oily gel which was crystallized as described herein to give the sodium salt of compound (II) (i.e., compound (II′)). 
     Example 2 
     Alternative Synthesis of (isobutyryloxy)methyl (1aR,7bS)-5-fluoro-2-hydroxy-1,1a,2,7b-tetrahydrobenzo[e]cyclopropa[c][1,2]oxaborinine-4-carboxylate (II′) 
     Chloromethyl isobutyrate (5.6 mL, 44 mmol, 2.5 eq) was added to a heterogeneous mixture of compound (I) (5 g, 17.6 mmol), NaI (1.32 g, 8.8 mol, 0.5 eq) and crushed anhydrous Na 2 B 4 O 7  (5.31 g, 26.4 mmol, 1.5 eq) in anhydrous acetonitrile (25 mL) at room temperature. The reaction mixture was heated at 60° C. After stirring at 60° C. for 16 h and at room temperature for 2 days conversion was 97.5% by HPLC. The reaction mixture was cooled to room temperature, diluted with methyl tert-butyl ether (MTBE) (25 mL) and cooled to 0° C. Ice water (25 mL) was added at 0° C. After stirring 5 min at 0° C., the biphasic heterogeneous mixture was filtered over celite and the salts and pad were rinsed with MTBE. The clear biphasic filtrate was partitioned and organic layer was washed with water containing 20% brine (2×25 mL) then brine (25 mL). The organic layer was concentrated to dryness. The residual oil was taken up in ACN (25 mL) and cooled to 0° C. Cold water (15 mL) was added and the mixture was cooled to 0° C. 2 M Na 2 CO 3  was added keeping temperature &lt;5° C. (pH=7.6). 2 N NaOH then was added until pH 10.5 (7.6 mL). The slightly heterogeneous mixture was extracted with heptane (2×25 mL). The aqueous layer was saturated with solid NaCl and the layers were separated. The aqueous layer was back extracted with ACN (25 mL). The combined organic extracts were concentrated to dryness. The residual oil was taken up in ACN (25 mL) and concentrated to almost dryness. The residual oil was taken up isopropyl acetate (iPAc) (25 mL) and polish filtered through a 0.45 um syringe filter. The filtrate was concentrated to dryness. The residual oil was taken up in iPAc (3 mL), IPA (1 mL) and heptane (25 mL) to get a clear solution. Seeds were added followed by more heptane (25 mL). After stirring at room temperature for 30 minutes, a white slurry was obtained. After stirring at room temperature overnight, the solids were collected by filtration, rinsed with 17/3 heptane/IPAc (20 mL), air dried then dried under high vacuum to get compound (II′) as a white powder 4.601 g, 72.2% yield, 99.67% purity, mp=145.4° C., form B. 
     Example 3 
     Effect of Base on Formation of Compound (II′) 
     The effect of base was studied when preparing compound (II′) according to the methods of Example 1 and 2 Changing the base from NaHCO 3  to NaH 2 PO 4  resulted in an improved conversion of compound (I). Additionally, use of Na 2 B 4 O 7  resulted in a 96% conversion even with only 0.5 equivalents of base. Changing the base to either NaH 2 PO 4  or Na 2 B 4 O 7  resulted in significantly lower formation of the impurity isobutyryloxymethyl isobutyrate (IBOIB). The data is provided in the table below. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
               
               
                   
                   
                 Chlromethyl 
                   
                   
                   
               
               
                 Base 
                 Temp 
                 isobutylrate 
                 Time 
                   
                 IBOIB 
               
               
                 (molar eq.) 
                 (° C.) 
                 eq 
                 (h) 
                 Conversion 
                 mol % 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 NaHCO 3  (4) 
                 55 
                 4 
                 15 
                 90-95%       
                 80-100 
               
               
                 NaH 2 PO 4  (1.5) 
                 65 
                 3 
                 16 
                 97.3%     
                 15 
               
               
                 Na 2 B 4 O 7  (1.5) 
                 60 
                 2.5 
                 16 
                 97-98%       
                 3-6  
               
               
                 Na 2 B 4 O 7  (1) 
                 60 
                 2.5 
                 16 
                 97% 
                 10 
               
               
                 Na 2 B 4 O 7  (0.5) 
                 60 
                 2.5 
                 16 
                 96% 
                 14 
               
               
                 Na 2 B 4 O 7  (1.5) 
                 70 
                 2.5 
                 8 
                 98% 
                   4.7 
               
               
                 Na 2 B 4 O 7  (1.5) 
                 80 
                 2.5 
                 6 
                 98.5%     
                 13 
               
               
                   
               
            
           
         
       
     
     Example 4 
     Serum activation: Compounds 1, 2, or II were solubilized in water and added to rat, dog, monkey, and human serum at a concentration of 50 μg/mL. The samples were incubated at room temperature for 1 hour then assayed for “active” drug content using an LC/MS/MS assay. Microsomal activation: Compounds 1, 2, or II were solubilized in water and added to rat, dog, monkey, and human liver microsomes at a concentration of 1 μM. The samples were incubated at room temperature for 1 hour then assayed for “active” drug content using an LC/MS/MS assay. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Prodrug activation data 
               
            
           
           
               
               
               
               
            
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Half-life 
                 &gt;&gt; 1 hour 
                 &gt;&gt; 1 hour 
                 &gt;&gt; 1 hour 
               
               
                 human serum 
                   
                   
                   
               
               
                 Half-life 
                 &gt;&gt; 1 hour 
                 &gt;&gt; 1 hour 
                 &gt;&gt; 1 hour 
               
               
                 rat serum 
                   
                   
                   
               
               
                 Half-life 
                 &gt;&gt; 1 hour 
                 &gt;&gt; 1 hour 
                 &gt;&gt; 1 hour 
               
               
                 dog serum 
                   
                   
                   
               
               
                 Half-life 
                 &gt;&gt; 1 hour 
                 &gt;&gt; 1 hour 
                 &gt;&gt; 1 hour 
               
               
                 monkey serum 
                   
                   
                   
               
               
                 Half-life 
                 28 ± 2 min 
                  8 ± 1 min 
                  9 ± 5 min 
               
               
                 human microsomes 
                   
                   
                   
               
               
                 Half-life 
                  3 ± 1 min 
                  3 ± 2 min 
                  5 ± 3 min 
               
               
                 rat microsomes 
                   
                   
                   
               
               
                 Half-life 
                 11 ± 1 min 
                 15 ± 1 min 
                 23 ± 2 min 
               
               
                 dog microsomes 
                   
                   
                   
               
               
                 Half-life 
                  2 ± 1 min 
                  3 ± 2 min 
                  2 ± 1 min 
               
               
                 monkey micorsomes 
               
               
                   
               
            
           
         
       
     
     Example 5 
     Animals (rats, dogs, or monkeys) were administered compounds 1, 2, or II formulated in water by oral gavage. Blood samples were collected at various timepoints in EDTA containing tubes. After centrifugation, plasma samples were analyzed by LC/MS/MS for compounds 1, 2, or II as well as for “active” drug content. Bioavailability was determined by comparing the clearance after an intravenous dose of the “active” drug and the clearance of “active” drug after an oral dose of compounds 1, 2, or II. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Pharmacokinetic data 
               
            
           
           
               
               
               
               
            
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Oral bioavailability, 
                 100% 
                 100% 
                 100% 
               
               
                 rat (30 mg/kg) 
                   
                   
                   
               
               
                 Oral bioavailability, 
                 100% 
                  46% 
                 100% 
               
               
                 rat (100 mg/kg) 
                   
                   
                   
               
               
                 Oral bioavailability, 
                  54% 
                  49% 
                  64% 
               
               
                 dog (10 mg/kg) 
                   
                   
                   
               
               
                 Oral bioavailability, 
                 100% 
                 100% 
                 100% 
               
               
                 monkey (20 mg/kg) 
                   
                   
                   
               
               
                 Human microsome 
                 28 ± 2 min 
                 8 ± 1 min 
                 9 + 5 min 
               
               
                 activation t 1/2   
                   
                   
                   
               
               
                 Crystallinity 
                 Yes 
                 No 
                 Yes 
               
               
                 Permeability/ 
                 High 
                 High 
                 High 
               
               
                 transport 
               
               
                   
               
            
           
         
       
     
     The oral bioavailability of Compound 2 at 100 mg/kg was 46%, while that of Compound 1 and Compound II were both 100%. Moreover Compound 2 is not crystalline, which may affect its stability. Compound 1 has significantly slower human microsomal activation than either Compound 2 or Compound II. Compound II has the best overall profile of a micosomally activated prodrug. 
     Example 6 
     Preparation of Crystal Form a of Compound (II′) 
     At room temperature compound (II′) is dissolved in a mixture of isopropyl acetate and isopropanol (volume ratio 1:0.2 or 2 mL isopropyl acetate per gram compound (II′) and 0.4 mL isopropanol per g compound (II′)). After complete dissolution, n-heptane (10 mL per g compound (II′)) is rapidly added over a period of no longer than 1 hour. After addition of the n-heptane is complete the resulting slurry is stirred for a further 8 to 12 hours. The slurry is filtered and the filter cake is washed with a mixture of n-heptane and isopropyl acetate (volume ratio 9:1, 2 mL per g compound (II′)) and dried. 
     Example 7 
     Alternative Preparation of Crystal Form a of Compound (II′) 
     Compound II′ was taken up in isopropyl acetate (5 mL) and the solution was heated at 50° C. Heptane (10 mL) was added followed by seeds (about 10 mg) and the mixture was stirred at 50° C. Over 30 min the mixture went from a clear solution with seeds stirring around to turbid to slightly heterogeneous to a thick slurry. Heptane (10 mL) was added for better stirring. After stirring at 50° C. for 2 h, heptane (10 mL) was added for better stirring and the slurry was cooled to room temperature. After stirring at room temperature for 2 h, heptane (10 mL) was added for better stirring. After stirring at rt over the weekend, the solids were collected by filtration, rinsed with κ/1 heptane/isopropyl acetate (2×10 mL), air dried then dried under high vacuum to give a white powder 4.24 g, 66.6% yield. 
     Example 8 
     Alternative Preparation of Crystal Form a of Compound (II′) 
     Compound II′ was taken up in hexanes and heated to 60-65° C. Ethyl acetate was added such that the ratio of hexanes:ethyl acetate was 85/15 (v/v). The mixture was cooled to 50° C. and stirred for 1 day at 50° C. The mixture was slowly cooled to room temperature and allowed to stand for three days at room temperature to give crystalline Form A of Compound II′ 
     Example 9 
     Preparation Crystal Form B of Compound (II′) 
     At room temperature, compound (II′) is dissolved in a mixture of isopropyl acetate and isopropanol (volume ratio 1:0.2 or 2 mL isopropyl acetate per gram compound (II′) and 0.4 mL isopropanol per g compound (II′)). After complete dissolution, n-heptane (10 mL per g compound (II′)) is slowly added over a period of at least 8 hours up to 12 hours. After addition of the n-heptane is complete the resulting slurry is stirred for a further 8 to 12 hours. The slurry is filtered and the filter cake is washed with a mixture of n-heptane and isopropyl acetate (volume ratio 9:1, 2 mL per g compound (II′)) and dried. 
     Example 10 
     Alternative Preparation Crystal Form B of Compound (II′) 
     At room temperature compound (II′) is dissolved in a mixture of isopropyl acetate and isopropanol (volume ratio 1:0.2 or 2 mL isopropyl acetate per gram compound (II′) and 0.4 mL isopropanol per g compound (II′)). After complete dissolution, n-heptane (4 mL per g compound (II′)) is added. The solution remains clear. Seed crystals of compound (II′) Form B are added (10 mg per g compound (II′)). Thereafter n-heptane (5 mL per g compound (II′)) is slowly added over a period of at least 7 hours. After addition of the n-heptane is complete the resulting slurry is stirred for a further 8 to 12 hours. The slurry is filtered and the filter cake is washed with a mixture of n-heptane and isopropyl acetate (volume ratio 9:1, 2 mL per g compound (II′)) and dried. 
     Example 11 
     Alternative Preparation Crystal Form B of Compound (II′) 
     Compound II′ (5 g scale) was taken up in isopropyl acetate (2.5 mL) and isopropanol (2.5 mL). Heptane (15 mL) was added followed by seeds (about 10 mg) and the mixture was stirred at room temperature. Over 30 min the mixture went from a clear solution with seeds stirring around to turbid to slightly heterogeneous to a thick slurry. Heptane (3×5 mL) was added over 1 h for better stirring. After stirring at room temperature for 16 h, the solids were collected by filtration, rinsed with 10/1/1 heptane/isopropyl acetate/isopropanol (2×10 mL), air dried then dried under high vacuum to give a white powder 4.24 g, 56.6% yield. 
     Example 12 
     Alternative Preparation Crystal Form B of Compound (II′) 
     Compound II′ (200 mg scale) was taken up in isopropanol (0.3 mL) and heated to 50° C. to form a mostly clear solution. After 5-10 additional minutes of heating at 50° C., solids began to precipitate. The solution was slowly cooled to room temperature, and the slurry was allowed to stand at room temperature for one day. The solids were collected, suspended in hexanes and isolated via vacuum filtration to give crystalline Form B of Compound II′.