Synthesis of 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy) benzo [c] [1, 2] oxaborine-1 (3H)-alcohol

Abstract

The invention provides a method for preparing 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy) benzo [c] [1, 2] oxa-boron heterocyclic pent-1 (3H)-alcohol and a preparation method of the 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy) benzo [c] [1, 2] The method comprises the following steps: preparing ((3-chloro-7, 8-dihydro-2H-1, 6, 9-trioxa-9a-borabenzo [cd] azulen-2-yl) methyl) tert-butyl carbamate, and preparing ((3-chloro-7, 8-dihydro-2H-1, 6, 9-trioxa-9a-borabenzo [cd] azulen-2-yl) methyl And converting the compound into 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy) benzo [c] [1, 2] oxaborine-1 (3H)-alcohol or a salt thereof.

Description

TECHNICAL FIELD

[0001] The present invention relates to an improved synthesis of 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol, which is a compound useful as an anti-mycobacterial compound, for example for the treatment of tuberculosis. BACKGROUND

[0002] Mycobacteria are an genus of bacteria in the class called Actinobacteria, which itself is a unique family called Mycobacteriaceae. Mycobacteria comprise a variety of animal-specific and opportunistic pathogens that can also be transmitted to humans and cause human disease, thus exhibiting considerable zoonotic potential. In the past few decades, members of the Mycobacterium avium-intracellulare complex (MAIC) have become pathogenic for human disease, including lymphadenitis in children, tuberculosis-like disease and disseminated infection (mainly in immunocompromised people, especially AIDS patients). Likewise, important animal diseases are also caused by infection with members of this group in animals, such as avian tuberculosis and paratuberculosis in ruminants. MAIC includes M. intracellulars and 4 subspecies of M. avium, namely M. avium subsp. avium, M. avium subsp. hominissuis, M. avium subsp. silvaticum and M. avium subsp. paratuberculosis. While members of the Mycobacterium tuberculosis complex are transmitted to hosts by direct contact, MAIC species are mainly acquired from environmental sources, including soil, water, dust and feed.

[0003] Mycobacterium tuberculosis (MTB) is a small, aerobic, non-motile, high-GC gram-positive bacillus with an "outer membrane" that is unusually thick, "waxy", hydrophobic, rich in mycolic acids and extremely impermeable, which makes mycobacterial infections difficult to treat. One-third of the world's population is thought to be infected with M. tuberculosis (including latent M. tuberculosis), but this figure rises to over 80% of the population in many Asian and African countries. If left untreated, the mortality rate for active MTB infection is over 50%. Furthermore, the combination of HIV and MTB is deadly, an increasing number of strains of M. tuberculosis are developing resistance to standard treatment drugs; approximately 300,000 new cases of multi-drug resistant (MDR) M. tuberculosis are reported each year. Multi-drug resistant (MDR) M. tuberculosis is resistant to isoniazid and rifampicin, while extensively drug-resistant (XDR) M. tuberculosis is also resistant to at least one quinolone and one aminoglycoside.

[0004] Synthetic drugs for the treatment of tuberculosis (TB) have been available for over half a century, yet the incidence of the disease continues to rise worldwide. More than 2 billion people are infected with Mycobacterium tuberculosis, the majority of which are in latent cases, and an estimated 9 million new cases are produced globally each year, resulting in 1.7 to nearly 2 million deaths each year. In 2004 alone, approximately 24,500 new infections and nearly 5,500 deaths were recorded each day. See Zignol, M. et al. Surveillance of anti-tuberculosis drug resistance in the world: an updated analysis, 2007-2010. Bull. World Health Organ 2012, 90 (2), 111-119D) Co-infection with HIV is driving the rise in incidence (Williams, B. G.; Dye, C. Science, 2003, 301, 1535), with 31% of AIDS deaths in Africa attributable to tuberculosis. See Corbett, E. L. et al. Arch. Intl. Med., 2003, 163, 1009, Septkowitz, A. et al. Clin. Microbiol. Rev. 1995, 8, 180).

[0005] The limitations of tuberculosis treatment and prevention are well known. The currently available vaccine, BCG, was introduced in 1921 but does not protect most people after childhood. According to the 2006 report - "International Standards for Tuberculosis Care" - a document prepared by the Tuberculosis Technical Assistance Coalition (TBCTA) (whose partners include the Centers for Disease Control, the American Thoracic Society, the Tuberculosis Foundation, KNCV, the World Health Organization and the International Union Against Tuberculosis and Lung Disease) - patients infected with active disease currently need to receive a two-month combination therapy with drugs introduced 50 to 60 years ago - isoniazid (1952), rifampin (1963), pyrazinamide (1954) and ethambutol (1961) - followed by a 4-month isoniazid and rifampin (also known as rifampicin) regimen. Alternatively, when adherence cannot be assessed, the continuation phase can include the use of isoniazid and ethambutol for six months, but according to the report, longer continuation phases are associated with higher failure and relapse rates, especially for HIV-infected patients. In addition, as detailed in the report, the doses of anti-tuberculosis drugs used should comply with international recommendations and the use of fixed-dose combinations of two (isoniazid and rifampin), three (isoniazid, rifampin and pyrazinamide) and four (isoniazid, rifampin, pyrazinamide and ethambutol) drugs is strongly recommended, especially when patients cannot be monitored to ensure treatment.

[0006] During these treatment phases, daily dosing is required and poor adherence drives the emergence and spread of multi-drug resistant strains, which presents a challenge to treatment. There is an urgent need for more potent agents with shorter treatment courses, which can be taken less frequently and present a high barrier to the emergence of resistance, i.e. agents effective against multi-drug resistant strains of TB (MDR-TB). A report in March 2013 (http: / / www.aidsmap.com / Once-weekly-continuation-phase -TB-treatment-equals-standard-of-care / page / 2589498 / ) showed that a two-drug combination of rifapentine (a long-acting derivative of rifampicin) with moxifloxacin (a fluoroquinolone antibiotic not previously used in the treatment of tuberculosis) can enable tuberculosis (TB) treatment to be given once a week during a four-month continuation phase, and to achieve the same standard of care as conventional continuation therapy with daily isoniazid and rifampicin. Such a treatment phase would allow treatment supervision to be extended throughout the continuation phase, improving adherence. However, moxifloxacin has not been approved for the treatment of tuberculosis, and a once-weekly treatment regimen has not been endorsed or approved as an alternative to standard of care treatment - international and national guideline panels need to review the published evidence to determine whether this alternative continuation treatment regimen should be recommended and adopted. Furthermore, rifapentine is expensive, and interactions between rifapentine and anti-retroviral drugs can preclude its use in TB patients who are also HIV positive and taking anti-retroviral drugs, in the non-nucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitor classes. Therefore, currently, the cost / benefit analysis of once-weekly rifapentine versus daily rifampicin continuation therapy has not been fully evaluated.

[0007] WO2015021396A2 discloses benzoxaborole compounds that exhibit unexpected selectivity (relative to inhibition of human cells (toxicity)) for inhibiting M. tuberculosis replication, and that exhibit sub-micromolar MIC values against mycobacterial species, in particular M. tuberculosis and the M. tuberculosis complex (MTC), M. avium and the M. avium complex (MAC), and M. intracellulare complex (MAIC).

[0008] In particular, WO2015021396A2 discloses (S)-3-(aminomethyl)-4-chloro-7-(2- hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol (closed tri-cyclic form):

[0009] WO2015021396A2 discloses benzoxaborole compounds that exhibit unexpected selectivity (relative to inhibition of human cells (toxicity)) for inhibiting M. tuberculosis replication, and that exhibit sub-micromolar MIC values against mycobacterial species, in particular M. tuberculosis and the M. tuberculosis complex (MTC), M. avium and the M. avium complex (MAC), and M. intracellulare complex (MAIC).

[0010] The synthesis route describes the synthesis of the sulfate salt as described in Example 4-II. SUMMARY

[0011] Disclosed is a method of making 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol or a salt thereof:

[0012] ;

[0013] The method comprises making tert-butyl ((3-chloro-7,8-dihydro-2H-l,6,9-trioxa-9a- borabenzo[cd]azulen-2-yl)methyl)carbamate:

[0014] ;

[0015] ((3-chloro-7,8-dihydro-2H-l,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl)carbamate is then converted to 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol or a salt thereof.

[0016] Also disclosed herein are the following compounds:

[0017] tert-butyl ((3-chloro-7,8-dihydro-2H-l,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl)carbamate;

[0018] 2-amino-l-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-l-ol or a salt thereof;

[0019] 2-amino-l-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-l-ol or a salt thereof;

[0020] l-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-l-ol; and

[0021] 2-bromo-3-(2-hydroxyethoxy)benzaldehyde.

[0022] Also disclosed herein is a method of making 3-(aminomethyl)-4-chloro-7-(2- hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol or a salt thereof, comprising:

[0023] a) converting 2-bromo-3-(2-hydroxyethoxy)benzaldehyde to l-(2-bromo-3-(2- hydroxyethoxy)phenyl)-2-nitroethan-l-ol;

[0024] b) converting 1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-1-ol or a salt thereof to 2-amino-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof;

[0025] c) converting 2-amino-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof to 2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof;

[0026] d) converting 2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof to ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borphenalene-2-yl)methyl)carbamate; and

[0027] e) converting ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borphenalene-2-yl)methyl)carbamate to 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][1,2]oxaborol-1(3H)-ol or a salt thereof. DETAILED DESCRIPTION

[0028] Compared to the synthetic route disclosed in WO'396, the synthetic route described herein can have any of the following advantages:

[0029] • Improved overall yield.

[0030] • Reduced cost; cheaper reagents can be used.

[0031] • Improved reliability - no use of low temperature lithiation chemistry (as opposed to the WO'396 route);

[0032] • The present route has a greater number of isolatable intermediates (for control of purity) - the WO'396 route has several oils which need to be telescoped throughout the synthesis.

[0033] In some examples, there is provided a method of preparing 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][1,2]oxaborol-1(3H)-ol or a salt thereof:

[0034] ;

[0035] The method comprises preparing a compound selected from:

[0036] ; or a salt thereof; or a salt thereof; ; or 2-bromo-3-(2-hydroxyethoxy)benzaldehyde;

[0037] The selected compound is then converted to 3-(aminomethyl)-4-chloro-7-(2- hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol or a salt thereof.

[0038] In some examples, the method comprises:

[0039] (i) preparing from or a salt thereof; and / or

[0040] (ii) preparing from or a salt thereof; and / or

[0041] (iii) preparing from or a salt thereof; and / or

[0042] (iv) preparing from or a salt thereof; and / or

[0043] (v) preparing from 2-bromo-3-(2-hydroxyethoxy)benzaldehyde.

[0044] In some examples, 2-bromo-3-(2-hydroxyethoxy)benzaldehyde can be synthesised from 2-bromo-3-hydroxybenzaldehyde, which in some examples can be synthesised from 3-hydroxybenzaldehyde.

[0045] Preparation of 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol or a salt thereof from ((3-chloro-7,8-dihydro-2H-l,6,9-trioxa-9a-borabenzo[cd]azulen-2- yl)methyl)carbamate can comprise Boc-deprotection with sulfuric acid, and the reaction product is the sulfate salt of 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol.

[0046] In some such examples, the method can include mixing a solution of ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl)carbamate in a solvent (e.g., isopropanol) with sulfuric acid at a temperature less than 25 °C. It can also include heating (e.g., to 45-55 °C). It can also include subsequently cooling (e.g., to 20-30 °C), filtering, and mixing the filter cake with a solvent (e.g., isopropanol). In some cases, it can include one or more further cycles of heating, cooling, filtering, and washing. In some cases, the wet filter cake can be dried under vacuum. In some cases, the solid can be dissolved in a solvent (e.g., methanol) and recrystallized to improve purity.

[0047] In some cases, the preparation of ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a- borabenzo[cd]azulen-2-yl)methyl)carbamate from 2-amino-1-(2-bromo-6-chloro-3-(2- hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof can involve a Pd-catalyzed borylation reaction. In some cases, the reaction can comprise a Miyaura borylation reaction. In some cases, the borylation reaction can precede the Boc protection reaction.

[0048] In some such examples, the method includes:

[0049] (i) mixing 2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol with Boc2O, a base (e.g., KHCO3), and a solvent (e.g., MTBE (aqueous));

[0050] (ii) adding a base (e.g., potassium pivalate), a Pd catalyst (e.g., palladium(II) acetate), and a phosphine ligand (e.g., tri-tert-butylphosphonium tetrafluoroborate);

[0051] (iii) adding a borylating agent (e.g., B2pin2, HBpin, and B2(OH)4);

[0052] (iv) washing; and

[0053] (v) crystallizing ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borabenzo[cd]azulen-2- yl)methyl)carbamate.

[0054] In some cases, the preparation of 2-amino-1-(2-bromo-6-chloro-3-(2- hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof from 2-amino-1-(2-bromo-3-(2- hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof can involve chlorination by aromatic electrophilic substitution. In some cases, the chlorinating agent can include N- chlorosuccinimide. In some cases, a crystalline salt of the chlorinated product, such as a methanesulfonic acid salt, can be formed to enable isolation of the reaction product.

[0055] The preparation of 2-amino-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof from 1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-1-ol can include a nitro reduction reaction. In some cases, this can be metal catalyzed, such as a Ranev Nickel catalyzed hydrogenation to reduce the nitro group. (In other such examples, the reduction can be catalyzed by a Pt, Pd, Rh, Ru, or Ir based catalyst.) In some cases, a crystalline salt of the reaction product, such as a tartrate salt, can be formed to enable isolation of the reaction product.

[0056] In some cases, the preparation of 1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2- nitroethan-1-ol from 2-bromo-3-(2-hydroxyethoxy)benzaldehyde can involve an asymmetric nitroaldol reaction (e.g., an asymmetric Henry reaction). This can include the use of a copper catalyst, such as a copper (II) catalyst like Cu(OAc)2, Cu(OTf)2, CuCl2, and the like. In some examples, the ligand used in the reaction can be a diamine ligand (e.g., diaminocyclohexane), a chiral oxazoline, a Schiff base ligand, or a chiral salen-based ligand. In some examples, the ligand includes (1R,2R,4R)-1,7,7-trimethyl-N-(pyridin-2- ylmethyl)bicyclo[2.2.1]heptan-2-amine dihydrochloride.

[0057] In some examples, the asymmetric nitroaldol reaction includes:

[0058] (i) mixing a ligand and 2-bromo-3-(2-hydroxyethoxy)benzaldehyde in the presence of a copper catalyst, optionally in the presence of a solvent (e.g., ethanol and MeTHF co-solvent) and a base (e.g., DIPEA);

[0059] (ii) adding nitromethane, optionally in the presence of a solvent;

[0060] (iii) quenching with an acid;

[0061] (iv) washing (e.g. with Na2S04(aq), EDTA.2Na.2H20(aq)) to isolate 1-(2-bromo-3-(2- hydroxyethoxy)phenyl)-2-nitroethan-1-ol; and

[0062] (v) crystallizing 1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-1-ol.

[0063] Throughout this specification, in certain instances, the method can involve one stereoisomer of the listed compound. Thus, in certain cases, the method can involve the synthesis of (S)-3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][1,2]oxaborol-1 (3H)-ol or a salt thereof:

[0064] .

[0065] In some instances, ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl) carbamic acid tert-butyl ester can be (S)-((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borabenzo[cd]azulen-2- yl)methyl)carbamic acid tert-butyl ester:

[0066] .

[0067] In some instances, 2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof can be (S)-2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof:

[0068] .

[0069] In some instances, 2-amino-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof can be (S)-2-amino-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof:

[0070] .

[0071] In some instances, (S)-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-1-ol can be (S)-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-1-ol:

[0072] .

[0073] Abbreviations

[0074] In describing the application, chemical elements are identified in accordance with the Periodic Table of the Elements. The abbreviations and symbols used in this text are in accordance with the common usage of such abbreviations and symbols by chemists of ordinary skill in the chemical arts. The following abbreviations are used in this text:

[0075] AcOH acetic acid

[0076] AIBN 2-2'-azobisisobutyronitrile

[0077] BOCN -t-butyloxycarbonyl

[0078] B2pin2 bis(pinacolato)diboron, also known as 4,4,4',4',5,5,5',5'-octamethyl-2,2'-bi-1,3,2-dioxaborolane

[0079] DCM dichloromethane

[0080] DIPEA N,N-diisopropylethylamine

[0081] DMSO-d6 deuterated dimethyl sulfoxide

[0082] DMSO dimethyl sulfoxide

[0083] EtOH ethanol

[0084] EtOAc ethyl acetate

[0085] h hour(s)

[0086] HPLC high performance liquid chromatography

[0087] IPA isopropyl alcohol

[0088] MCH methylcyclohexane

[0089] MeOH methanol

[0090] MeCN acetonitrile

[0091] MsOH methanesulfonic acid

[0092] MTBE methyl tert-butyl ether

[0093] N-Ac-Cys N-acetylcysteine

[0094] NBS N-bromosuccinimide

[0095] NCS N-chlorosuccinimide

[0096] NMR nuclear magnetic resonance spectroscopy

[0097] THF tetrahydrofuran

[0098] 2-MeTHF 2-methyltetrahydrofuran Example

[0099] The following examples illustrate the present invention. These examples are not intended to limit the scope of the present invention, but rather to provide guidance for those skilled in the art on implementing the inventive method. Although embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes and modifications may be made.

[0100] Recording proton nuclear magnetic resonance ( 1 H NMR spectra are reported in parts per million (δ) downfield from the internal standard tetramethylsilane (TMS). NMR data abbreviations are as follows: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, dd = doublet of doublets, dt = doublet of triplets, app = apparent, br = broad. All temperatures are in degrees Celsius.

[0101] An example of the synthetic route is shown in Scheme 1 below.

[0102] Solution 1

[0103]

[0104]

[0105] Phase A-synthesis of GW415775X

[0106] At 20-30 ℃, to DCM (1160L) solution of GR44399X (116kg), MsOH (9.3kg, 0.1 equivalent) was added, followed by NBS (185kg, 1.1 equivalent). The reaction was stirred at 20-30 ℃, then quenched with Na2S2O3 / KHCO3 aqueous solution (25%w / w, 70kg) to quench the reaction mixture. The mixture was concentrated and replaced with EtOAc (348L, 3 volumes). After diluting with EtOAc (580L, 5 volumes), the mixture was washed with Na2SO4 aqueous solution (15%w / w, 3x812kg) at 30-40 ℃. The organic layer was filtered through diatomaceous earth and rinsed with more EtOAc (77L). The filtrate merged was washed with NaSO aqueous solution (15% w / w, 812 kg) at 30-40 ° C, and the organic layer was then concentrated in vacuo to approximately 6 volumes and cooled to -5 ° C. Methylcyclohexane (MCH) (460 L, 4 volumes) was then added, the mixture was filtered after stirring, and the filter cake was washed with MCH (120 L, 1 volume). The wet filter cake was dried in vacuo at 50 ° C to give GW415775X (99 kg, 52%) as a solid.

[0107] 1H NMR (400 MHz; DMSO-d6): 10.8 (1H, s), 10.3 (1H, s), 7.28 (3H, m).

[0108] Stage B - Synthesis of GSK4026152A

[0109] To a solution of GW415775X (68 kg) in 1,4-dioxane (476 L) at 20 °C was added a solution of LiOH.H2O (20 kg) in water (408 L) followed by GI148705X (52.7 kg). The reaction mixture was pumped into an HC tube reactor and heated to 130 °C for 30 minutes. The effluent from the flow reactor was cooled and collected. The mixture was concentrated in vacuo and the solution was warmed and GSK4026152A seed crystals (0.01 wt.) were added. Water (680 L) was added slowly and the resulting slurry was cooled, aged and then filtered. The filter cake was washed with water (68 L) and then dried in vacuo at 50 °C to give GSK4026152A as a white solid (72.6 kg, 86%). ° C, for 30 minutes. The effluent from the flow reactor was cooled and collected. The mixture was concentrated in vacuo and the solution was warmed and GSK4026152A seed crystals (0.01 wt.) were added. Water (680 L) was added slowly and the resulting slurry was cooled, aged and then filtered. The filter cake was washed with water (68 L) and then dried in vacuo at 50 °C to give GSK4026152A as a white solid (72.6 kg, 86%).

[0110] 1 H NMR (400 MHz; DMSO-d6): 10.8 (1H, s), 10.3 (1H, s), 7.28 (3H, m).

[0111] Stage 1 - Synthesis of GSK4364445A

[0112] To a solution of (1R,2R,4R)-1,7,7-trimethyl-N-(pyridin-2-ylmethyl)bicyclo[2.2.1]heptan-2- amine dihydrochloride (GSK2412905A) (3.65 kg) in ethanol (286 L) was added DIPEA (3.75 kg) followed by 2-MeTHF (83 L). The mixture was stirred and Cu(OAc)2.H2O (2.90 kg) was added. After stirring, 2-bromo-3-(2-hydroxyethoxy)benzaldehyde (GSK4026152A, 72.3 kg) was added followed by DIPEA (3.75 kg) and rinsed in with 2-MeTHF (1 1 L). The reaction mixture was cooled to -18 °C and a solution of nitromethane (175 kg) in 2-MeTHF (351 L) was added slowly. The reaction mixture was stirred until HPLC showed the reaction was complete. The reaction was quenched by the addition of aqueous HCI (1 M, 142 kg) and warmed to 25 °C. Aqueous Na2S04(15% w / w, 213 kg) was added followed by water (444 L) and the layers were separated. To the organic phase was added aqueous HCI (1 M, 142 kg) and aqueous EDTA.2Na.2H20 (5% w / w, 214 kg). After stirring, the layers were separated and to the organic layer was added further aqueous HCI (1 M, 142 kg) and aqueous EDTA.2Na.2H20 (5% w / w, 213 kg). The layers were separated and the organic phase was filtered. To the organic phase was added further aqueous HCI (1 M, 141 kg) and aqueous EDTA.2Na.2H20 (5% w / w, 207 kg). The mixture was filtered, washed with 2-MeTHF (29 kg) and then the layers were separated. The organic phase was concentrated in vacuo to a volume of 220 L and the solvent was converted to IPA (3 x 124 L of IPA) by addition and removal distillation at below 40 °C. The solution was concentrated in vacuo to a final volume of 150 L, cooled to 25 °C and then water (721 L) was added slowly. The resulting slurry was cooled to 0 °C, aged and then the product was collected by filtration, washing the filter cake with water (34 L). The wet filter cake was dried in vacuo at 50 °C to give GSK4364445A as a white solid (71.7 kg, 76%).

[0113] 1 H NMR (400 MHz; DMSO-d6): 7.40 (1 H, t), 7.22 (1 H, d), 7.09 (1 H, d), 6.31 (1 H, d), 5.60 (1 H, m), 4.88 (1 H, t), 4.78 (1 H, dd), 4.40 (1 H, dd), 4.07 (2 H, m), 3.75 (2 H, m).

[0114] Stage 2 - Synthesis of GSK4023557B

[0115] To the reactor was added Raney nickel (15.0 kg) followed by ethanol (598 L), GSK4364445A (71.7 kg) and acetic acid (67.6 kg) which was washed in with ethanol (13 L). The reaction mixture was then stirred under an atmosphere of hydrogen at 25 °C until HPLC showed the reaction was complete. The mixture was then filtered through a pad of celite and the filter cake washed in with ethanol (248 L). The filtrate was warmed to 50 °C and L-tartaric acid (34.0 kg) was added. The resulting slurry was stirred and then cooled to 20 °C and aged. The product was collected by filtration and the filter cake washed in with ethanol (87 L). The wet filter cake was dried under vacuum at 50 °C to give GSK4023557B as a white solid (88.1 kg, 90%).

[0116] 1 H NMR (400 MHz; D20): 7.46 (1H, t), 7.26 (1H, d), 7.12 (1H, d), 5.42 (1H, dd), 4.50 (2H, s), 4.22 (2H, m), 3.97 (2H, m), 3.30 (1H, dd), 3.16 (1H, dd).

[0117] Stage 3 - Synthesis of GSK4023558B

[0118] To a suspension of GSK4023557B (63.8 kg) in MeCN (325 L) and MeOH (93 L) was added MsOH (43.8 kg). A solution of NCS (22.0 kg) in MeCN (249 L) was then added, washing in with additional MeCN (17 L). The mixture was stirred at 20 °C until HPLC showed the reaction was complete. GSK4023557B seed crystals (0.40 kg) were added, the mixture was stirred and then MeCN (762 L) was added slowly. The mixture was cooled to -18 °C, the slurry was stirred and filtered. The filter cake was washed in with MeCN (48 L) and then dried under vacuum at 40 °C to give GSK4023558B as a white solid (50.9 kg, 82%).

[0119] 1 H NMR (400 MHz; MeOD): 7.40 (1H, d), 7.06 (1H, d), 5.79 (1H, dd), 4.14 (2H, m), 3.92 (2H, m), 3.69 (1H, t), 3.08 (1H, dd), 2.70 (3H, s).

[0120] Stage 4 - Preparation of GSK3177484A

[0121] To a solution of GSK4023558B (50.9 kg) in MTBE (147 L) and water (153 L) was added KHCO3(14.0 kg) followed by Boc2O (28.9 kg) and washed with MTBE (7 L). The mixture was stirred at 20 °C until HPLC showed the reaction was complete. The reaction mixture was allowed to settle and the organic phase was separated and then washed with H2O (2 x 100 L). The organic layer was concentrated and transferred into MeCN to give a solution of C14111825-GA in MeCN (about 290 L).

[0122] To the solution of C14111825-GA in MeCN was further added MeCN (319 L) and potassium pivalate (25.9 kg), palladium (II) acetate (1.93 kg) and tri-tert-butylphosphine tetrafluoroborate (5.0 kg) in a solution of water (50 L) and MeCN, followed by a solution of B2pin2(63.0 kg) in MeCN (99 L) and the reactor was purged with N2. The reaction mixture was warmed to 40 °C and stirred until HPLC showed the reaction was complete. The reaction mixture was filtered and the filter cake was washed with MeCN (94 L). The filtrate was concentrated to about 100 L, then diluted with EtOAc (445 L) and the layers were separated. The organic phase was washed with a mixture of a mixture of aqueous N-Ac-Cys (5% w / w, 231 kg) and aqueous KHCO3(5% w / w, 226 kg) (three times). The organic phase was then stirred with silane thiol (15 kg), filtered and the filter cake was washed with EtOAc (32 L). The filtrate was concentrated and replaced with IPA to a solution volume of about 110 L. The residue was diluted with IPA (160 L), cooled to 0 °C and stirred for 1 h. The solid was collected by filtration and the filter cake was washed with IPA (33 L) and then dried under vacuum at 40 °C to give GSK3177484A as a white solid (36.5 kg, 66% yield over two steps). o C, followed by GSK3177484A seed crystals (0.25 kg) and the mixture was stirred and then filtered. The wet filter cake was washed with isopropanol (33 L) and then dried under vacuum at 40 °C to give GSK3177484A as a white solid (36.5 kg, 66% yield over two steps).

[0123] 1 H NMR (400 MHz; DMSO-d6): 7.42 (1H, d), 6.96 (0.8H, s), 6.89 (1H, d), 6.62 (0.2H, s), 5.32 (1H, m), 4.34-4.19 (4H, m), 3.74 (1H, m), 3.21 (1H, m), 1.33 (9H, s).

[0124] Stage 5 - Preparation of GSK3036656E

[0125] To a solution of GSK3177484A (36.5 kg, 75.5%wt.) in isopropanol (196 L, 7.3 vol.) was added aqueous sulphuric acid (50% w / w, 25.1 kg, 0.91 wt.) maintaining the internal temperature below 25 °C. The reaction mixture was heated to 45-55 °C and stirred for 33 hours, after which time HPLC showed the reaction to be complete. The mixture was cooled to 20-30 °C and then filtered, washing the filter cake with isopropanol (8 L, 0.3 vol.). The wet filter cake was transferred back to the reactor and isopropanol (245 L, 8.9 vol.) was added. The mixture was heated to 45-55 °C and stirred at this temperature for 3 hours before cooling to 20-30 °C. The product was collected by filtration, washing the filter cake with isopropanol (8 L, 0.3 vol.). The wet filter cake was dried under vacuum at 40-50 °C for 24 hours to give intermediate grade GSK3036656E as a white solid (27.5 kg, 93%).

[0126] Stage 6 - Purification of GSK3036656E

[0127] GSK3036656E (27.4 kg, 1.0 wt.), purified water (19 L, 0.7 vol.) and methanol (372 L, 13.6 vol.) were charged to a reactor (R1). The mixture was heated to 64 °C and stirred at 60-68 °C for 0.2 hours to give a clear solution. The solution in R1 was transferred through a 0.22 pm in-line filter to another reactor (R2) preheated to 62-68 °C. Purified water (22 L, 0.8 vol.) was charged to R1 and the water wash was transferred through the in-line filter to R2.

[0128] The mixture in R2 was adjusted to 50-60 o C and stirred for 0.5 hours to give a clear solution. GSK3036656E seed crystals (71 g, 0.26% wt.) were then added to R2, washed with methanol / purified water (9:1 v / v). The mixture was stirred at 50-60 °C for 3 hours before cooling to 5 o C over 5 hours and stirred at this temperature for 5 hours. The slurry was wet milled for a total of 3.5 hours. The mixture was aged at 0-10 o C for 15 hours before warming to 50-60 o C over 3 hours and stirred at this temperature for 1 hour. The mixture was cooled to 0-10 o C over 5 hours and stirred at this temperature for 2 hours before warming to 50-60 o C over 5 hours and stirred at this temperature for 1 hour. The mixture was cooled to 0-10 o C over 5 hours and stirred at this temperature for 2 hours before warming to 50-60 oC and stirred at this temperature for 8 hours, and then warmed to 50-60 o C and held at this temperature range for 1.5 hours. The mixture was cooled to 0-10 o C and aged at this temperature for 19 hours. The mixture was filtered and the filter cake was washed with MeOH / purified water (9:1 v / v, 44 kg, 1.6 wt.). The wet filter cake was dried under vacuum at 35-45 o C for 5 hours, and then at 45-55 o C for an additional 26 hours to give GSK3036656E as a white solid (20.3 kg, 76%).

[0129] 1 H NMR (400 MHz; D20): 7.40 (1H, d), 6.88 (1H, d), 5.39 (1H, dd), 4.16 (2H, m), 4.03 (2H, m), 3.82 (1H, dd), 3.19 (1H, dd).

[0130] It is to be understood that the present application encompasses all combinations of the aspects described herein with all other suitable aspects and / or exemplary embodiments. It is to be understood that the present application also encompasses all combinations of the exemplary embodiments with all other suitable aspects and / or exemplary embodiments described herein.

[0131] It is to be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and that those modifications or changes are to be included within the spirit and scope of this application and scope of the appended claims. All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety for all purposes.

Claims

1. A method of preparing 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol or a salt thereof: ； the method comprising preparing tert-butyl ((3-chloro-7,8-dihydro-2H-l,6,9-trioxa-9a- borabenzo[cd]azulen-2-yl)methyl)carbamate: ； tert-butyl ((3-chloro-7,8-dihydro-2H-l,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl) carbamate to 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][l,2]oxaborol-l(3H)-ol or a salt thereof.

2. The method according to claim 1, wherein tert-butyl ((3-chloro-7,8-dihydro-2H-l,6,9- trioxa-9a-borabenzo[cd]azulen-2-yl)methyl)carbamate is prepared from 2-amino-l-(2- bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-l-ol or a salt thereof: 。 3. The method according to claim 2, further comprising preparing 2-amino-l-(2-bromo-3- (2-hydroxyethoxy)phenyl)ethan-l-ol or a salt thereof from 2-amino-l-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-l-ol or a salt thereof.

4. The method according to claim 3, further comprising preparing 2-amino-l-(2-bromo-3- (2-hydroxyethoxy)phenyl)ethan-l-ol or a salt thereof from 1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-l-ol; and 2-bromo-3-(2-hydroxyethoxy)benzaldehyde.

8. A method of preparing 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][l,2]oxaborol- l(3H)-ol or a salt thereof, comprising: ​ ​ ​ ​ ​ ​ ​ a) converting 2-bromo-3-(2-hydroxyethoxy)benzaldehyde to 1-(2-bromo-3-(2- hydroxyethoxy)phenyl)-2-nitroethan-1-ol; b) converting 1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-1-ol to 2-amino-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof; c) converting 2-amino-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof to 2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof; d) converting 2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof to ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl)carbamate; and e) converting ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl)carbamate to 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][1,2]oxaborol-1(3H)-ol or a salt thereof.

9. The method according to claim 8, wherein the method produces (S)-3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][1,2]oxaborol-1(3H)-ol and the method comprises: a) converting 2-bromo-3-(2-hydroxyethoxy)benzaldehyde to (S)-1-(2-bromo-3-(2- hydroxyethoxy)phenyl)-2-nitroethan-1-ol: ； b) converting (S)-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-1-ol to (S)-2-amino-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)ethan-1-ol: or a salt thereof; c) converting (S)-1-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2-nitroethan-1-ol or a salt thereof to (S)-2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol: or salts thereof; d) converting (S)-2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof to (S)-((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl)carbamate: ; and e) converting (S)-((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borabenzo[cd]azulen-2-yl)methyl)carbamate to (S)-3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][1,2]oxaborol-1(3H)-ol: or salts thereof.

10. The method according to claim 5, 8 or 9, wherein converting 2-bromo-3-(2- hydroxyethoxy)benzaldehyde to l-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2- nitroethan-l-ol comprises an asymmetric nitroaldol reaction.

11. The method according to claim 10, wherein the reaction is accomplished using a diamine ligand and / or a copper catalyst.

12. The method according to claim 11, wherein the diamine ligand is (1R,2R,4R)-1,7,7- trimethyl-N-(pyridin-2-ylmethyl)bicyclo[2.2.1]heptan-2-amine dihydrochloride and / or the copper catalyst comprises Cu(OAc)2-H2O.

13. The method according to any one of claims 10-12, wherein the asymmetric nitroaldol reaction comprises: (i) mixing a ligand and 2-bromo-3-(2-hydroxyethoxy)benzaldehyde in the presence of a copper catalyst, optionally in the presence of a solvent; (ii) adding nitromethane, optionally in the presence of a solvent; (iii) quenching with an acid; (iv) washing to isolate l-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2- nitroethan-l-ol; and (v) crystallizing l-(2-bromo-3-(2-hydroxyethoxy)phenyl)-2- nitroethan-l-ol.

14. The method according to claim 4, 5, 8 or 9, wherein converting l-(2-bromo-3-(2- hydroxyethoxy)phenyl)-2-nitroethan-l-ol to 2-amino-l-(2-bromo-3-(2- hydroxyethoxy)phenyl)ethan-l-ol or a salt thereof comprises a nitro reduction reaction.

15. The method according to claim 14, wherein the nitro reduction reaction is catalyzed by a metal catalyst selected from nickel, platinum, palladium, rhodium, ruthenium or iridium.

16. The method according to claim 15, wherein the nitro reduction reaction comprises hydrogenation catalyzed by Raney nickel.

17. The method according to any one of claims 14-16, wherein L-tartaric acid is added to the reaction and the reaction product is a tartrate salt of 2-amino-l-(2-bromo-3-(2- hydroxyethoxy)phenyl)ethan-l-ol.

18. The method according to claim 3, 4, 5, 8 or 9, wherein converting l-(2-bromo-3-(2- hydroxyethoxy)phenyl)-2-nitroethan-l-ol or a salt thereof to 2-amino-l-(2-bromo- 6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-l-ol or a salt thereof comprises chlorination by aromatic electrophilic substitution.

19. The method according to claim 18, wherein the chlorinating agent comprises N- chlorosuccinimide.

20. The method according to claim 18 or 19, wherein methanesulfonic acid is added to the reaction and the reaction product is a methanesulfonate salt of 2-amino-l-(2-bromo- 6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-l-ol.

21. The process according to any one of claims 2-5, 8 or 9, wherein converting 2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol or a salt thereof into ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borphenalene-2-yl)methyl)carbamate comprises a Boc-protection reaction followed by a Pd-catalysed borylation reaction.

22. The process according to claim 21, wherein the Pd-catalysed borylation reaction is a Miyarua borylation reaction.

23. The process according to claim 21 or 22, comprising: (i) mixing 2-amino-1-(2-bromo-6-chloro-3-(2-hydroxyethoxy)phenyl)ethan-1-ol with Boc20, a base and a solvent; (ii) adding a base, a Pd catalyst and a phosphine ligand; (iii) adding a borylating agent; (iv) washing; and (v) crystallising ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borphenalene-2-yl)methyl)carbamate.

24. The process according to claim 23, wherein the catalyst comprises palladium(II) acetate and / or the borylating agent is selected from B2pin2, HBpin and B2(OH)4 and / or the phosphine ligand comprises tri-tert-butylphosphonium tetrafluoroborate.

25. The process according to any one of claims 1 to 6, 8 or 9, wherein converting ((3-chloro-7,8-dihydro-2H-1,6,9-trioxa-9a-borphenalene-2-yl)methyl)carbamate into 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][1,2]oxaborol-1(3H)-ol or a salt thereof comprises a Boc-deprotection with sulfuric acid and the reaction product is the sulfate salt of 3-(aminomethyl)-4-chloro-7-(2-hydroxyethoxy)benzo[c][1,2]oxaborol-1(3H)-ol.

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