Prodrug of opicapone

Abstract

The present invention relates to prodrugs of opicapone, their synthetic intermediates, and pharmaceutically acceptable salts thereof. The present invention also relates to methods for preparing the prodrugs of opicapone and their pharmaceutically acceptable salts. In particular, the present invention relates to certain phosphate prodrugs of opicapone, their pharmaceutically acceptable salts, and their synthetic intermediates, as well as methods for preparing the same. The present invention also relates to routes of administration for the prodrugs of opicapone.

Description

[Technical field]

[0001] The present invention relates to prodrugs of opicapone, their synthetic intermediates, and pharmaceutically acceptable salts thereof. The present invention also relates to methods for preparing the prodrugs of opicapone and their pharmaceutically acceptable salts. In particular, the present invention relates to certain phosphate prodrugs of opicapone, their pharmaceutically acceptable salts, and their synthetic intermediates, as well as methods for preparing the same. The present invention also relates to routes of administration for the prodrugs of opicapone. [Background technology]

[0002] Levodopa (L-dopa (L-DOPA)) has been used in clinical practice for decades in the symptomatic treatment of various conditions, including Parkinson's disease. L-dopa can cross the blood-brain barrier, where it is then converted to dopamine by the enzyme amino acid decarboxylase (AADC), thus increasing dopamine levels in the brain. However, conversion of L-dopa to dopamine can also occur in peripheral tissues, potentially causing deleterious effects. It has therefore become standard clinical practice to co-administer peripheral AADC inhibitors, such as carbidopa or benserazide, which prevent conversion to dopamine in peripheral tissues. It is also known that inhibitors of the enzyme catechol-O-methyltransferase (COMT) can provide clinical improvement in patients suffering from Parkinson's disease who are being treated with L-dopa, as COMT catalyzes the breakdown of L-dopa to the inactive metabolite 3-O-methyldopa.

[0003] Opicapone is a potent and long-acting COMT inhibitor. It is bioactive, bioavailable, and exhibits low toxicity. This is in part due to the pyridine N-oxide, which is not common as a pharmaceutical active ingredient due to its supposed high chemical and biological reactivity. Opicapone has potentially useful pharmaceutical properties in the treatment of several central and peripheral nervous system disorders in which inhibition of COMT may provide therapeutic benefit, such as mood disorders; movement disorders such as Parkinson's disease, Parkinson's disorder, and restless legs syndrome; gastrointestinal disorders; edematous conditions; and hypertension. The development of opicapone is described in LE Kiss et al, J. Med. Chem., 2010, 53, 3396-3411, and it was approved in the EU in June 2016 and in the US in April 2020 for the treatment of Parkinson's disease, in combination with L-dopa.

[0004] WO2007 / 013830 is the first disclosure of opicapone and relates to its use in the treatment of disorders of the central and peripheral nervous system. WO2008 / 094053 discloses that opicapone has good pharmacokinetic properties, allowing for administration only once a day. WO2013 / 089573 discloses that micronization can be used to provide good oral bioavailability. Given the extent of the improvement, opicapone is manufactured and sold in a micronized crystalline form. However, although opicapone can be used to treat disorders of the central and peripheral nervous system by oral administration of a daily dose of 25 mg or 50 mg, attempts continue to be made to maximize its solubility, absorption, and distribution while simultaneously minimizing its metabolism and excretion, thereby improving its pharmacokinetic profile.

[0005] It is important to prevent the reduction of opicapone to this metabolite, as WO2007 / 013830 teaches that the reduced pyridine analogue is more toxic.

[0006] Water-soluble derivatives of other COMT inhibitors containing a nitrocatechol moiety have been considered. Leppanen. J. et al., Bioorg. Med. Chem. Lett. 10 (2000), 1967-1969 described the synthesis of water-soluble derivatives of entacapone. In particular, it disclosed the synthesis of entacapone monophosphate via the reaction of entacapone with phosphorus oxychloride in dehydrated pyridine. However, the yield was low (45%), many general synthetic strategies failed, and the phosphorylation site was not identified. Furthermore, in the conversion of the prodrug, only about 60% of entacapone was recovered, with the remainder converted to the active metabolite Z-entacapone. Perhaps for these reasons, in the 20 years since this disclosure, no prodrug form of entacapone has been developed into a viable drug. WO2019 / 195761 describes various prodrugs of tolcapone. However, most are uncharged to ensure retention in the eye and permeability through the cornea. WO2019 / 195761 discloses a phosphate derivative of tolcapone when produced using phosphorus oxychloride in THF and pyridine. The compound is not characterized, and the yield and purity are not disclosed. WO2019 / 195761 is directed to the topical administration of a prodrug in the treatment of presbyopia and cataracts. Thus, this method is unrelated to the use of COMT inhibitors to treat disorders of the central and peripheral nervous system, which does not appear to be suitable for the prodrug approach. Thus, prior to the present invention, it was unclear whether the prodrug approach was applicable to COMT inhibitors used to treat disorders of the central and peripheral nervous system, or whether a specific phosphate derivative of opicapone could be reliably synthesized.

[0007] WO2021 / 182981 identified certain "shelf aggregates" that may adversely affect the bioavailability of individual preparations of micronized crystalline opicapone and disclosed methods for detecting and removing the shelf aggregates. WO2022 / 025781 disclosed kinetically soluble and bioavailable solid dispersions of opicapone.

[0008] Thus, maximizing the bioavailability of opicapone remains an active area of ​​research, and there remains a need for stable forms of opicapone that have improved bioavailability and that can be reliably synthesized in good yields. Summary of the Invention

[0009] The present inventors have identified certain derivatives of opicapone that have improved solubility compared to opicapone itself, for example, certain phosphate derivatives of opicapone and pharma- ceutically acceptable salts thereof.

[0010] The phosphoric acid derivatives of the present invention and their pharma- ceutically acceptable salts show improved solubility in water compared to opicapone itself. Preferably, the phosphoric acid derivatives of opicapone and their pharma- ceutically acceptable salts show at least 100-fold increase in solubility (mg / ml) in pure water compared to opicapone itself. Furthermore, the phosphoric acid derivatives of opicapone and their pharma- ceutically acceptable salts are preferably stable in potassium buffer at pH=7.4, rat / human plasma and rat / human liver S9 fraction (i.e., the supernatant fraction obtained from the liver by centrifugation at 9000 g, which contains both cytosol and microsomes), but are easily converted to opicapone in rat liver homogenate. Thus, the phosphoric acid derivatives of opicapone and their pharma- ceutically acceptable salts can act as prodrugs of opicapone in vivo.

[0011] The present inventors have also identified methods for synthesizing certain water-soluble prodrugs of opicapone, and pharma- ceutically acceptable salts thereof.

[0012] The present inventors have found that the methods used in the prior art to synthesize water-soluble prodrugs of COMT inhibitors are not suitable for synthesizing phosphate prodrugs of opicapone. This is due to the reaction of phosphorus oxychloride (POCl3) with the pyridine N-oxide moiety of opicapone. The literature reports that POCl3 can be used to convert 2-picoline-N-oxide to the corresponding 2-(chloromethyl)pyridine derivative (Redl, S. et al., J. Het. Chem., 43(6), 1447-1453; 2006).

[0013] The inventors have also determined that different prodrugs of opicapone have different pharmacokinetic properties depending on the route of administration.

[0014] Thus, in a first general embodiment, the present invention provides a compound of formula (I): [ka] or a pharma- ceutically acceptable salt thereof; In the formula, R is H or C1-C6 alkyl, and n is 0 or 1.

[0015] In a second general embodiment, the present invention provides a process for preparing a compound of formula (I) above, or a pharma- ceutically acceptable salt thereof, comprising deprotecting a compound of formula (II): [ka] wherein R and R are each independently a monovalent phosphate protecting group or together form a divalent phosphate protecting group; R is H or C-C alkyl, and n is 0 or 1.

[0016] In a third general embodiment, the present invention provides a method for preparing a compound of formula (II) above, which method comprises the step of obtaining opicapone, i.e. a compound of formula (III): [ka] with a compound of formula (IV): [ka] reacting with wherein R and R are each independently a monovalent phosphate protecting group or, in the presence of a base and an aprotic solvent, combine to form a divalent phosphate protecting group; R is H or C-C alkyl, and n is 0 or 1.

[0017] In a fourth general embodiment, the present invention provides a compound of formula (II) above, wherein R1 and R2 are each independently a monovalent phosphate protecting group or together form a divalent phosphate protecting group; R is H or C1-C6 alkyl, and n is 0 or 1.

[0018] In a fifth general embodiment, the present invention provides a pharmaceutical formulation for intravenous administration to a human, comprising: a. a compound of formula (I) above or a pharma- ceutically acceptable salt thereof; and b. Providing a pharmaceutical formulation comprising a pharma- ceutically acceptable vehicle.

[0019] In a sixth general embodiment, the invention provides a pharmaceutical formulation for subcutaneous administration to a human, comprising: a. a compound of formula (I) above or a pharma- ceutically acceptable salt thereof; and b. Providing a pharmaceutical formulation comprising a pharma- ceutically acceptable vehicle.

[0020] In a seventh general embodiment, the present invention provides a compound of formula (I) or a pharma- ceutically acceptable salt thereof, or a pharmaceutical formulation of a compound of formula (I) or a pharma- ceutically acceptable salt thereof, for use in the treatment of Parkinson's disease, preferably wherein the compound of formula (I) or a pharma- ceutically acceptable salt thereof is administered in a daily dose equivalent to less than 50 mg / day of opicapone, preferably less than 25 mg / day of opicapone.

[0021] The present invention will now be described in detail with reference to the accompanying drawings in which: [Brief description of the drawings]

[0022] [Figure 1] The stability of compound 1 and compound 4 in different matrices is shown. A shows the clearance of compound 1 in different matrices (buffer (closed circle); rat liver homogenate (closed square); human plasma (closed inverted triangle); rat plasma (closed diamond); human liver S9 fraction (open circle)) over 1 hour, with measurements taken at 0, 0.1, 0.25, 0.5, 0.75, and 1 hour. Compound concentration = 1 μM. B shows the clearance of compound 1 (closed circle) and compound 4 (closed square) in rat liver homogenate over 1 hour, with measurements taken at 0, 0.1, 0.25, 0.5, 0.75, and 1 hour. Compound concentration = 1 μM. [Diagram 2] The stability of compound 1 and compound 4 at different pH values ​​(2500 ng / mL at pH values ​​of 1.2 (closed circle), 4.5 (closed square), and 6.8 (closed triangle) for 4 hours at 37° C.) is shown. A shows that compound 1 was stable in buffers of pH 1.2, pH 4.5, and 6.8, but required some time to solubilize at pH 1.2. B shows that compound 4 was stable in buffers of pH 1.2 (closed circle), 4.5 (closed square), and 6.8 (closed triangle). [Diagram 3] Figure 1 shows the oral pharmacokinetic properties of Compound 1 and Compound 4 (3 mg / kg; 0.2% HPMC) in rats compared to micronized crystalline opicapone. A shows that Compound 1 (closed circle) demonstrated improved pharmacokinetic properties compared to Compound 4 (closed square). B shows that both Compound 1 (closed circle) and Compound 4 (closed square) were converted to opicapone, with Compound 1 producing a pharmacokinetic profile of opicapone comparable to opicapone itself. Compound 4 demonstrated the worst oral pharmacokinetic parameters compared to Compound 1 and opicapone. [Figure 4]Figure 1 shows the intravenous pharmacokinetic properties of Compound 1 and Compound 4 (1 mg / kg; DMSO:20% HPBCD (1:9)) in rats compared to micronized crystalline opicapone. A shows that Compound 1 (closed circles) demonstrated improved pharmacokinetic properties compared to Compound 4 (closed squares). B shows that both Compound 1 (open circles) and Compound 4 (open squares) were converted to opicapone, with Compound 1 producing a pharmacokinetic profile of opicapone comparable to opicapone itself (closed triangles). Compound 4 demonstrated the worst intravenous pharmacokinetic parameters compared to Compound 1 and opicapone. [Diagram 5] 1 shows the subcutaneous pharmacokinetic properties of Compound 1 and Compound 4 (3 mg / kg, DMSO:20% HPBCD (1:9)) in rats compared to the oral pharmacokinetic properties of micronized crystalline opicapone. A shows that Compound 1 (closed circle) was converted to opicapone (open circle), resulting in a pharmacokinetic profile of opicapone with improved exposure (approximately 3-fold increase) compared to opicapone itself (closed triangle). B shows that Compound 4 (closed square) was converted to opicapone (open square), resulting in a pharmacokinetic profile of opicapone with improved exposure (approximately 3-fold increase) compared to opicapone itself (closed triangle). [Figure 6] Pharmacodynamic properties of Compound 1 and Compound 4 for COMT inhibition are shown. The conversion of Compound 1 (closed circle) and Compound 4 (closed square) to opicapone resulted in rapid inhibition of COMT activity in erythrocytes, with maximal effect at 2 hours after administration (96% and 94% inhibition for Compound 1 and Compound 4, respectively). Inhibition of COMT was maintained at over 80% for at least 8 hours after dosing. COMT inhibition of Compound 1 and Compound 4 is higher and more sustained than orally administered opicapone (closed circle). [Figure 7]Figure 1 shows the pharmacodynamic profile of compound 4 on L-dopa bioavailability and 3-OMD production compared to vehicle. Figure 2 shows the pharmacodynamic profile of compound 4 (filled squares) on L-dopa bioavailability compared to vehicle (open squares). Figure 3 shows the pharmacodynamic profile of compound 4 (filled squares) on 3-OMD production compared to vehicle (open squares). Coadministration of compound 4 with L-dopa / benserazide in a single dose increased circulating levels of L-dopa (AUClast increased 1.7-fold) with a corresponding decrease in the levels of its metabolites. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] A.Definition The following definitions apply to terms used throughout this specification, unless limited in specific instances.

[0024] The term "prodrug" refers to a compound with no pharmacological activity that is converted in vivo by enzymatic and / or chemical reactions into a compound having the desired pharmacological activity, which compound then exerts the desired pharmacological effect.

[0025] The term "protecting group" refers to a chemical moiety introduced onto a functional group to block its reactivity under synthetic conditions required to effect modifications elsewhere in the molecule. Protecting groups are stable to certain chemical conditions, but can be easily removed under certain conditions in a process known as "deprotection."

[0026] The term "phosphate protecting group" refers to a protecting group as described above that has been introduced onto the phosphate functionality. Common examples of moieties used as phosphate protecting groups are C1-C6 alkyl and benzyl groups.

[0027] The term "C1-C6 alkyl" means a monovalent unsubstituted saturated straight or branched chain hydrocarbon radical having from 1 to 6 carbon atoms. "C1-C2 alkyl", "C1-C3 alkyl", "C1-C4 alkyl" and "C1-C5 alkyl" have similar meanings. Common examples used as phosphate protecting groups include methyl (C1) and tert-butyl (C4).

[0028] The term "pharmaceutically acceptable salts" refers to salts as described in standard texts on salt formation, see, for example, P. Stahl, et al., Handbook of Pharmaceutical Salts: Properties, Selection and Use (VCHA / Wiley-VCH, 2002), or S. M. Berge, et al., "Pharmaceutical Salts" (1977) Journal of Pharmaceutical Sciences, 66, 1-19.

[0029] The term "pharmaceutical acceptable excipient" refers to any ingredient of a pharmaceutical composition other than the compound(s) of the present invention, or other known pharmacologically active ingredients. The choice of excipient will largely depend on factors such as the particular mode of administration, the effect of the excipient on solubility and stability, and the nature of the dosage form.

[0030] The term "vehicle" refers to a carrier or inert medium used as a vehicle in which a pharma- ceutical active agent is formulated and / or administered in liquid form (Dictionary of Pharmacy, 1986). The term "pharmaceutical acceptable vehicle" refers to any vehicle that is useful in the preparation of a liquid pharmaceutical formulation, is generally compatible with other ingredients of the formulation, and produces no adverse reactions when administered to humans. A vehicle includes a solvent (e.g., water) and, optionally, one or more pharma- ceutical acceptable excipients (e.g., buffer(s), surfactant(s), preservative(s), etc.).

[0031] The terms "therapy," "treatment," and "treating" include both preventative and curative treatment of a condition, disease, or disorder. It also includes slowing, interrupting, controlling, or halting the progression of a condition, disease, or disorder. It also includes preventing, curing, slowing, interrupting, controlling, or halting the symptoms of a condition, disease, or disorder.

[0032] When one therapeutic agent must be administered "in combination with" another therapeutic agent, this means that they must be administered in such a way that both therapeutic agents are present in the patient's body at the same time. The two agents may be administered simultaneously or sequentially, via the same or different routes of administration, in a single preparation or in separate preparations.

[0033] An "effective daily dose" of a compound is the total amount of that compound that must be administered daily to produce the desired pharmacological (and therefore therapeutic) effect throughout the entire period of treatment. The effective daily dose may be administered as one or more individual doses that add up to the effective daily dose, or as a continuous infusion.

[0034] B. Water-soluble prodrugs of opicapone and their precursors The present invention relates to a compound of formula (I); [ka] or a pharma- ceutically acceptable salt thereof; wherein R is H or C1-C6 alkyl, and n is 0 or 1. The inventors have discovered that the compound of formula (I) acts as a prodrug of opicapone by converting back to opicapone in rat liver homogenates while remaining stable in buffered solutions.

[0035] In one embodiment, the present invention relates to a compound of formula (I) or a pharma- ceutically acceptable salt thereof;

[0036] In another embodiment, the present invention relates to a compound of formula (I) or a pharma- ceutically acceptable salt thereof; wherein n is 1. In a preferred embodiment where n is 1, R is H. In an alternative embodiment where n is 1, R is C1-C6 alkyl, preferably C1-C4 alkyl, more preferably C1-C2 alkyl, even more preferably methyl.

[0037] The pharma- ceutically acceptable salt of the compound of formula (I) is preferably selected from the group consisting of sodium salt, ammonium salt or potassium salt. In a more preferred embodiment, the pharma- ceutically acceptable salt is selected from the group consisting of sodium salt and ammonium salt. For example, the pharma- ceutically acceptable salt is a sodium salt. For example, the pharma- ceutically acceptable salt is an ammonium salt. In a more preferred embodiment, the sodium salt is a disodium salt and the ammonium salt is a triammonium salt. These salts of the opica- amp prodrug have been found to be stable, soluble and non-toxic.

[0038] Compounds of formula (I) may be prepared from compounds of formula (II): [ka] wherein R1 and R2 are each independently a monovalent phosphate protecting group or together form a divalent phosphate protecting group; R is H or C1-C6 alkyl, and n is 0 or 1. The present inventors have surprisingly discovered that the prior art methods for phosphorylating entacapone and tolcapone are not suitable for directly phosphorylating opicapone to obtain the compound of formula (I). However, by first forming an intermediate compound of formula (II), the compound of formula (I) could be isolated in high yield and purity without modifying the critical pyridine N-oxide moiety.

[0039] In a preferred embodiment, the phosphate protecting groups are each independently selected from the group consisting of C1-C6 alkyl and benzyl. In a more preferred embodiment, the phosphate protecting groups are the same and are selected from the group consisting of methyl, tert-butyl, and benzyl. In an alternative more preferred embodiment, the phosphate protecting groups are the same and are ethyl. In an even more preferred embodiment, the phosphate protecting groups are both benzyl or both tert-butyl.

[0040] C. Methods for synthesizing water-soluble prodrugs of opicapone and pharma- ceutically acceptable salts thereof The present invention also relates to a process for preparing a compound of formula (I) or a pharma- ceutically acceptable salt thereof, comprising: (a) deprotecting a compound of formula (II) as defined above to obtain a compound of formula (I), and (b) optionally converting the compound of formula (I) into a pharma- ceutically acceptable salt thereof.

[0041] The deprotection step may be carried out using any one of the following methods: deprotection using a boron agent such as boron tribromide; deprotection using a trimethylsilyl halide; deprotection by hydrolysis using a strong acid such as hydrogen bromide (HBr) or hydrochloric acid (HCl); deprotection by oxidation using an oxidizing agent such as cerium ammonium nitrate (CAN); or deprotection by catalytic hydrogenolysis, the catalyst being selected from the group consisting of palladium on charcoal or platinum (IV) oxide. For example, deprotection using a boron agent. For example, deprotection using a trimethylsilyl halide. For example, deprotection by hydrolysis using a strong acid such as hydrogen bromide (HBr) or hydrochloric acid (HCl). For example, deprotection by catalytic hydrogenolysis, the catalyst being selected from the group consisting of palladium on charcoal or platinum (IV) oxide. In a preferred embodiment, the deprotection step is carried out using a trimethylsilyl halide. In a more preferred embodiment, the trimethylsilyl halide is trimethylsilyl bromide.

[0042] In a preferred embodiment, the method for preparing a compound of formula (I) comprises deprotection of a compound of formula (II) using trimethylsilyl halide in an aprotic solvent, followed by aqueous work-up. In a more preferred embodiment, the trimethylsilyl halide is trimethylsilyl bromide. In a preferred embodiment, the aprotic solvent may be selected from the group consisting of dichloromethane and acetonitrile. In a more preferred embodiment, the aprotic solvent is dichloromethane. In a most preferred embodiment, the trimethylsilyl halide is trimethylsilyl bromide and the aprotic solvent is dichloromethane.

[0043] The optimum reaction temperature depends on the structure of R1, R2, R and n in the compound of formula (II). Preferably, the reaction temperature is in the range of 10° C. to 25° C. In a more preferred embodiment, the reaction temperature is a controlled temperature of 20 to 25° C., more preferably room temperature (rt) of 25° C.

[0044] Preferably, the compound of formula (I) is purified by reverse phase chromatography, for example using a C18 reserved phase column and a water / acetonitrile gradient as the mobile phase. Alternatively, the compound of formula (I) (e.g., compound 1) is converted to the equivalent amine salt (e.g., compound 3) by adding aqueous ammonia (e.g., 30% aqueous ammonia) to precipitate the product. The pure amine salt (e.g., compound 3) can be converted to the compound of formula (I) (e.g., compound 1) by adding a strong acid (e.g., HCl).

[0045] The present invention also extends to a process for preparing a pharma- ceutically acceptable salt of a compound of formula (I).

[0046] In one embodiment, the present invention relates to a process for preparing the sodium salt of a compound of formula (I), comprising reacting a compound of formula (I) with sodium hydroxide in a suitable solvent system. For example, a suitable solvent system is ethanol.

[0047] In one embodiment, the present invention relates to a method for preparing the sodium salt of a compound of formula (I), comprising reacting a compound of formula (I) with ammonium in a suitable solvent system. For example, a suitable solvent system is methanol and diethyl ether. Alternatively, a suitable solvent system is isopropanol and water, and the ammonium salt of the compound of formula (I) is recovered as a precipitate.

[0048] D. Methods for the synthesis of useful intermediates in the synthesis of water-soluble prodrugs of opicapone and pharma-ceutically acceptable salts thereof The present invention relates to a process for the preparation of a compound of formula (II), comprising the step of: [ka] with a compound of formula (IV): [ka] reacting with; wherein R and R are each independently a monovalent phosphate protecting group or taken together form a divalent phosphate protecting group, R is H or C-C alkyl, and n is 0 or 1; reacting in the presence of a base and an aprotic solvent.

[0049] In a preferred embodiment, the phosphate protecting groups are each independently selected from the group consisting of C1-C6 alkyl and benzyl. In a more preferred embodiment, the phosphate protecting groups are the same and are selected from the group consisting of methyl, tert-butyl, and benzyl. In an alternative more preferred embodiment, the phosphate protecting groups are the same and are ethyl. In an even more preferred embodiment, the phosphate protecting groups are both benzyl or both tert-butyl.

[0050] Preferably, the compound of formula (II) is purified by column chromatography, for example using a silica stationary phase and a methanol / dichloromethane mixture as the mobile phase.

[0051] In further embodiments, the base may be selected from the group consisting of trimethylamine or Hunig's base (N,N-diisopropylethylamine). In a preferred embodiment, the base is trimethylamine (TEA).

[0052] In further embodiments, the aprotic solvent may be selected from the group consisting of dichloromethane, tetrahydrofuran, acetonitrile, and ethyl acetate. In a more preferred embodiment, the aprotic solvent is dichloromethane.

[0053] Preferably, the reaction temperature is in the range of 10° C. to 25° C. In a more preferred embodiment, the reaction temperature is a controlled temperature of 20 to 25° C., more preferably room temperature (rt) of 25° C.

[0054] As will be apparent to those skilled in the art, the process for preparing a compound of formula (II), comprising reacting a compound of formula (III) with a compound of formula (IV), may be directly combined with the process for preparing a compound of formula (I), or a pharma- ceutically acceptable salt thereof, comprising deprotecting a compound of formula (II) and optionally converting the product to a pharma- ceutically acceptable salt. In the combined process, the compound of formula (II) may be purified by column chromatography prior to deprotection.

[0055] In the above method, R1 and R2 are preferably each independently selected from the group consisting of C1-C6 alkyl and benzyl. In a more preferred embodiment, the phosphate protecting groups are the same and are selected from the group consisting of methyl, tert-butyl, and benzyl. In an alternative more preferred embodiment, the phosphate protecting groups are the same and are ethyl. In an even more preferred embodiment, the phosphate protecting groups are both benzyl or both tert-butyl.

[0056] In one embodiment, the present invention relates to a process for the preparation of a compound of formula (II), comprising reacting a compound of formula (III) with a compound of formula (IV);

[0057] In another embodiment, the present invention relates to a process for the preparation of a compound of formula (II), comprising reacting a compound of formula (III) with a compound of formula (IV), wherein n is 1. In a preferred embodiment where n is 1, R is H. In an alternative embodiment where n is 1, R is C1-C6 alkyl, preferably C1-C4 alkyl, more preferably C1-C2 alkyl, even more preferably methyl.

[0058] E. Pharmaceutical Formulations of Water-Soluble Prodrugs of Opicapone and Pharmaceutically Acceptable Salts Thereof The present invention relates to a pharmaceutical formulation of a compound of formula I or a pharma- ceutically acceptable salt thereof, and one or more pharma- ceutically acceptable excipients. The pharmaceutical formulation may be in a solid form, such as a tablet or capsule, or in a liquid form, or in a semi-solid form, such as a gel.

[0059] In a preferred embodiment, the present invention relates to a pharmaceutical formulation for intravenous, subcutaneous, intraperitoneal or intraduodenal administration (preferably to humans), more preferably for intravenous or subcutaneous administration, most preferably for subcutaneous administration, which pharmaceutical formulation comprises: a. A compound of formula (I) or a pharma- ceutically acceptable salt thereof; and b. Contains a pharma- ceutically acceptable vehicle.

[0060] In a preferred embodiment, the pharma- ceutically acceptable vehicle is an aqueous solution. For example, the pharma- ceutically acceptable vehicle may include water, optionally together with one or more water-miscible solvents, such as ethanol, propylene glycol, polyethylene glycol, transcutol, glycerol, or DMSO. The aqueous solution may also include one or more additives selected from the group consisting of NaCl (saline) and a buffer (e.g., phosphate buffer or sodium bicarbonate) to form an isotonic solution at neutral pH (pH 5-7) suitable for intravenous or subcutaneous administration (e.g., to humans), preferably suitable for subcutaneous administration (e.g., to humans).

[0061] In a particular embodiment, the present invention relates to a pharmaceutical formulation for intravenous or subcutaneous (preferably subcutaneous) administration comprising a compound of formula (I), preferably comprising compound 1 or compound 4 (more preferably compound 4) and a pharma- ceutically acceptable vehicle. The formulation may further comprise L-dopa and / or carbidopa (preferably L-dopa and carbidopa). Alternatively, the formulation may further comprise foslevodopa and / or foscarbidopa (preferably foslevodopa and foscarbidopa).

[0062] F. Therapeutic Use The present invention also relates to the compounds of formula (I), pharma- ceutically acceptable salts thereof, and pharmaceutical formulations of the compounds of formula (I) and pharma- ceutically acceptable salts thereof, as described above, for use in the treatment of Parkinson's disease.

[0063] In a preferred embodiment, the compound or pharmaceutical preparation is administered in combination with L-dopa or foslevodopa, more preferably in combination with L-dopa or foslevodopa and a peripheral AADC inhibitor, such as carbidopa, foscarbidopa, or benserazide. L-dopa or foslevodopa and / or an AADC inhibitor can be administered separately or in combination with each other. When the compound of formula (I) or a pharma- ceutically acceptable salt thereof is administered in the form of a solid, such as a tablet or capsule, it may be administered together with L-dopa or foslevodopa and / or an AADC inhibitor, but is preferably administered separately from L-dopa or foslevodopa and / or an AADC inhibitor. When the compound of formula (I) is administered in the form of an intravenous, subcutaneous or intraperitoneal liquid (preferably an intravenous or subcutaneous liquid, more preferably a subcutaneous liquid), the compound of formula (I) may be administered separately or simultaneously (in a single daily dose or in multiple daily or consecutive doses) with L-dopa or foslevodopa and / or an AADC inhibitor. When the compound of formula (I) is administered in the form of an intraduodenal liquid, suspension, or semisolid (e.g., a gel, preferably an intraduodenal gel or suspension, more preferably an intraduodenal gel), the compound of formula (I) may be administered separately or simultaneously with L-dopa or foslevodopa and / or an AADC inhibitor.

[0064] In one embodiment, the compound of formula (I) or a pharma- ceutically acceptable salt thereof is administered at an effective daily dose equivalent to less than 50 mg / day of opicapone. However, the compound of formula (I) or a pharma- ceutically acceptable salt thereof may be administered at an effective daily dose equivalent to 50 mg / day of opicapone. In a preferred embodiment, the compound of formula (I) has an effective daily dose equivalent to 1-30 mg / day of opicapone, more preferably 2-25 mg / day, even more preferably 5-20 mg / day. In this context, the term "equivalent amount" means that the daily dose contains less than 50 mg of opicapone, excluding the phosphate moiety and any associated counterions of its pharma- ceutically acceptable salts, by weight.

[0065] The effective daily dose can be administered in individual doses (solid, liquid or semisolid, preferably liquid) or as a continuous liquid or semisolid infusion.

[0066] Subcutaneous injection is suitable for continuous administration, but has the advantage of being less invasive than intravenous or intraduodenal administration, which may improve patient health and / or treatment compliance. However, the bioavailability of a particular compound or prodrug via a particular route is unpredictable.

[0067] Based on the data shown in Figures 3 to 7, intravenous administration is preferred for the compound of formula (I). In particular, intravenous administration is most preferred for the compound of formula (I) where n is 0 (e.g., compound 1 or a salt thereof (e.g., compound 2 or compound 3)). When the compound of formula (I) is administered in the form of an intravenous liquid, the compound of formula (I) may be administered separately from or together with L-dopa or foslevodopa and / or an AADC inhibitor.

[0068] Based on the data shown in Figures 3 to 7, subcutaneous administration is preferred for the compound of formula (I). In particular, subcutaneous administration is most preferred for the compound of formula (I) where n is 1 (e.g., compound 4). When the compound of formula (I) is administered in the form of a subcutaneous liquid, the compound of formula (I) may be administered separately or together with L-dopa or foslevodopa and / or an AADC inhibitor. In a particularly preferred embodiment, the present invention provides compound 4 for use in the treatment of Parkinson's disease, where compound 4 is administered subcutaneously in combination with L-dopa or foslevodopa, more preferably in combination with L-dopa or foslevodopa and a peripheral AADC inhibitor, such as carbidopa, foscarbidopa, or benserazide.

[0069] L-dopa and / or AADC inhibitors are preferably administered in the form of intravenous, subcutaneous or intraperitoneal liquid (preferably subcutaneous or intravenous liquid, more preferably subcutaneous liquid). They may themselves be administered in the form of a prodrug. For example, L-dopa may be administered in the form of photorevodopa (levodopa-4'-monophosphate). For example, AADC inhibitors may be administered in the form of foscarbidopa (carbidopa-4'-monophosphate). For example, L-dopa may be administered in the form of host levodopa, and AADC inhibitors may be administered in the form of foscarbidopa. Foslevodopa and foscarbidopa may be administered in the form of a binary composition (e.g., foslevodopa / foscarbidopa; ABBV-951) with the compound of formula (I) administered separately. Foslevodopa, foscarbidopa, and the compound of formula (I) may be administered in the form of a ternary composition (eg, foslevodopa / foscarbidopa / compound of formula (I)).

[0070] G. Working Example Preparation of intermediates Compound of formula (IV) - dibenzyl phosphorochloridate [ka] To a stirred solution of dibenzyl phosphate (1 mL, 1,187 g, 4.53 mmol) in toluene (20 mL) was added N-chlorosuccinimide. The reaction was stirred at room temperature for 3 h. After that, succinimide was filtered off (through a short pad of Celite) and the filtrate was evaporated to give dibenzyl phosphorochloridate (1.6 g) as a colorless oil, which was used in the next step without further purification.

[0071] The compound of formula (III) - 2,5-dichloro-3-(5-(3,4-dihydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide The synthesis of opicapone, i.e. the compound of formula (III), is described in WO2007 / 013830 or WO2013 / 089573. The method described in WO2013 / 089573 is preferred.

[0072] The compound of formula (II) -3-(5-(3-((bis(ethoxy)phosphoryl)oxy)-4-hydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-2,5-dichloro-4,6-dimethylpyridine 1-oxide [ka]

[0073] A mixture of 2,5-dichloro-3-(5-(3,4-dihydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide (10 g, 24.2 mmol), diethyl phosphorochloridate (4.59 g, 26.6 mmol), and triethylamine (10.12 mL, 72.6 mmol) in dichloromethane (100 mL) was mixed at 0° C., warmed to room temperature, and stirred at this temperature overnight. The resulting brown solution was quenched with water (100 mL). The organic layer was washed with HCl 4 M solution (2×100 mL), brine, dried over sodium sulfate, filtered, and evaporated to give 11.6 g of the product 3-(5-(3-((bis(ethoxy)phosphoryl)oxy)-4-hydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-2,5-dichloro-4,6-dimethylpyridine 1-oxide as a yellow solid.

[0074] The compound of formula (II) -3-(5-(3-((bis(benzyloxy)phosphoryl)oxy)-4-hydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-2,5-dichloro-4,6-dimethylpyridine 1-oxide [ka] A mixture of 2,5-dichloro-3-(5-(3,4-dihydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide (1.559 g, 3.77 mmol), dibenzyl phosphorochloridate (1.343 g, 4.53 mmol), and triethylamine (1.577 mL, 11.32 mmol) in dichloromethane (25 mL) was stirred at room temperature overnight. To the resulting brown solution was added a few drops of methanol and water. The organic layer was washed with brine, dried over magnesium sulfate, filtered and then evaporated to give the crude product as an orange solid. Chromatographic purification on silica (in methanol / dichloromethane mixtures) gave 1.027 g of 3-(5-(3-((bis(benzyloxy)phosphoryl)oxy)-4-hydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-2,5-dichloro-4,6-dimethylpyridine 1-oxide as an orange solid.

[0075] The compound of formula (II) - 2,5-dichloro-3-(5-(3-(((di-tert-butoxyphosphoryl)oxy)methoxy)-4-hydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide [ka]

[0076] Sodium hydride (17.01 mg, 0.425 mmol) was added to a solution of 2,5-dichloro-3-(5-(3,4-dihydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide (160 mg, 0.387 mmol) in DMF (1 mL). After 10 min, tetrabutylammonium iodide (100 mg, 0.271 mmol) and di-tert-butyl (chloromethyl)phosphate (120 mg, 0.464 mmol) in DMF (1 mL) were added and the mixture was stirred at room temperature for 1 h and at 50° C. for 1 h. After cooling, 5% aqueous citric acid was added slowly and the solution was extracted with ethyl acetate. The combined organic layers were washed with brine, dried over MgSO4, filtered and evaporated to dryness. The resulting crude material was purified by flash column to give a fluffy yellow solid as the title compound (95mg, 27%).

[0077] Preparation of opicam prodrugs and pharma-ceutically acceptable salts thereof Compound of formula (I) - 2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-(phosphonooxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide (Compound 1) [ka]

[0078] To an ice-cold solution of 3-(5-(3-((bis(benzyloxy)phosphoryl)oxy)-4-hydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-2,5-dichloro-4,6-dimethylpyridine 1-oxide (350 mg, 0.520 mmol) was added trimethylsilyl bromide (183 mg, 0.155 mL, 1.195 mmol) under nitrogen atmosphere. After stirring for 30 min at low temperature, the reaction was quenched with a few drops of water and then evaporated. Purification by reverse phase chromatography in acetonitrile-water (gradient elution, 0-10% acetonitrile) afforded 105 mg of 2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-(phosphonooxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide as a pale yellow solid (purity 90%, yield: 37%).

[0079] 1 H NMR (DMSO d6 ):8.39(1H,d,J=2.2Hz),8.18(1H,dd,J=1.2,2.2Hz),2.66(3H,s),2.24(3H,s). 13 C NMR (DMSO d6 ):174.8,164.6,150.4,149.5(d,J=5.5Hz),143.3(d,J=5.5Hz),139.4,139.3,134.2,131.1,123.3(d,J=3Hz),122.6,120.3,112.1,17.9,16.5.

[0080] Disodium salt of the compound of formula (I)-5-(3-(2,5-dichloro-4,6-dimethyl-1-oxidepyridin-3-yl)-1,2,4-oxadiazol-5-yl)-2-hydroxy-3-nitrophenyl phosphate disodium salt (compound 2) [ka]

[0081] To a solution of 2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-(phosphonooxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide (48 mg, 0.097 mmol) in absolute ethanol (3 mL) was added diethyl ether (3 mL), followed by dropwise addition of 1 M sodium hydroxide (0.195 mL, 0.195 mmol) with stirring at 20-25 °C. After stirring for 15 min, the resulting solid was collected by filtration, washed with a mixture of ethanol-diethyl ether (1:1), and then dried in vacuum at 40 °C to give sodium 5-(3-(2,5-dichloro-4,6-dimethyl-1-oxidepyridin-3-yl)-1,2,4-oxadiazol-5-yl)-2-hydroxy-3-nitrophenyl phosphate as an orange powder (47 mg, yield: 90%). 1 H NMR(D2O):8.37(1H,d,J=2.4Hz),7.83(1H,dd,J=1.4,2.4Hz),2.60(3H,s),2.15(3H,s)

[0082] 13 C NMR(D2O):178.4,165.4,161.7(d,J=4Hz),153.7,149.0(d,J=6Hz),142. 9,142.3,139.5,134.2,124.6,124.4,123.5(d,J=3Hz),108.0,19.5,17.9

[0083] Triammonium salt of the compound of formula (I) - 2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-(phosphonooxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide, triammonium salt (compound 3) [ka]

[0084] To a stirred solution of 2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-(phosphonooxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide (20 mg, 0.041 mmol) in absolute ethanol (1 mL) was added a 2 M solution of ammonia in methanol (0.101 mL, 0.203 mmol). After stirring for 15 minutes, the resulting solid was collected by filtration, washed with ethanol, and then dried in vacuum at 40° C. to give 2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-(phosphonooxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide, triammonia salt as an orange powder (15 mg, yield: 68%).

[0085] 1 H NMR (DMSO d6 ):8.25(1H,d,J=2.4Hz),7.67(1H,dd,J=0.7,2.4Hz),6.90(12H,br),2.66(3H,s),2.23(3H,s).

[0086] 13 C NMR (DMSO d6 ):176.7,164.3(d,J=5Hz),164.2,150,149.9(d,J=7Hz),139.4,137.1,134.0,130.9,123.5,121.9,117.8(d,J=2.5Hz),100.2,17.9,16.5.

[0087] Triammonium salt of the compound of formula (I)-2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-(phosphonooxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide (compound 3) [ka]

[0088] To a solution of 3-(5-(3-((bis(ethoxy)phosphoryl)oxy)-4-hydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-2,5-dichloro-4,6-dimethylpyridine 1-oxide (5.00 g, 9.10 mmol) in DCM (100 mL) at -10°C and nitrogen atmosphere was added trimethylsilyl bromide (13.94 g, 12.01 mL, 91 mmol). The mixture was warmed to 40°C and allowed to stir at room temperature overnight. The solvent was evaporated and the solid was dissolved in a mixture of MeOH (50 mL) and water (5 mL) and evaporated again. The residue was dissolved in 100 mL IPA and water (10 mL) and ammonia solution (30% in water, 5 mL) were added to the filtered clear solution to precipitate the product. The resulting suspension was heated to 70°C, cooled to 0-5°C and allowed to warm to room temperature. The solid product was filtered, washed with IPA (2×20 mL) and dried under vacuum at 40° C. at 2 mbar to give 4.2 g of 2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-(phosphonooxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide triammonium salt as an orange solid (purity 90%, yield: 85%).

[0089] Compound of formula (I) - Compound 4: 2,5-dichloro-3-(5-(4-hydroxy-3-nitro-5-((phosphonooxy)methoxy)phenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide [ka]

[0090] Trifluoroacetic acid (0.108 ml, 1.416 mmol) was added to a solution of 2,5-dichloro-3-(5-(3-(((di-tert-butoxyphosphoryl)oxy)methoxy)-4-hydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide (90 mg, 0.142 mmol) in dichloromethane (1.5 ml) at 0° C. The reaction mixture was stirred at room temperature for 45 min. The solvent was evaporated and the residue was purified by flash chromatography using a reverse phase column to give a pale yellow solid as the desired compound (28 mg, 34%).

[0091] 1 H NMR (DMSO d6 ):8.37(1H,d,J=2.1Hz),8.15(1H,d,J=2.1Hz),5.68(2H,d,J=14.0Hz),2.66(3H,s),2.25(3H,s).

[0092] 13 C NMR (DMSO d6 ):175.0,164.6,150.4,149.3,147.8,139.4,138.7,134.1,131.1,122.7,120.2,119.9,111.9,90.2(d,J=4.5Hz),17.9,16.5.

[0093] The free form of a compound of formula (I) (eg, compound 1 or compound 4) can be readily obtained from the relevant salt by acidification of the relevant salt.

[0094] Solubility and stability studies of prodrugs of opicapone. Solubility Test

[0095] Aqueous solubility studies were completed for compounds 1, 2, and 3 as described above, as well as for opicapone itself. Solubility tests were performed at room temperature. To determine solubility, increasing amounts of distilled water were added to 5 mg of test sample until the product was completely dissolved as observed by the naked eye. A total of 0.8 mL of distilled water was sufficient to completely dissolve it, which corresponds to an approximate solubility of 6 mg / mL.

[0096] The results are shown in Table 1 below. [Table 1]

[0097] The solubility data in Table 1 confirms that compounds 1-4 have significantly increased solubility in pure water compared to opicapone by itself. Compound 1 showed a 160-fold increase in solubility in pure water compared to opicapone by itself.

[0098] In vitro stability testing The stability of 1 μM compound 1 was evaluated in the following fractions: phosphate buffer, human plasma, rat plasma, human liver S9 fraction, rat liver S9 fraction and rat liver homogenate.

[0099] Reactions were initiated by adding 1 μM of test compound to the desired matrix (plasma, liver homogenate 0.4 g / mL, or S9 fraction 1 mg / mL, respectively) in a final volume of 350 μL. At the following time points: 0, 5, 15, 30, 45, and 60 minutes, 50 μL samples were taken and the internal standard (opicapone) was added. 13 C6) at 1 μM and precipitated with 200 μL of acetonitrile 1% formic acid. Samples were centrifuged at 20,000 g for 10 min at 4 °C and then analyzed by LC-MS / MS using a bioanalytical method previously developed in-house.

[0100] Solutions of test compounds were prepared at 10 μM using 50 mM potassium phosphate buffer (KPB) pH 7.4 by adding 1 μL of a 10 mM compound stock solution to 999 μL of 50 mM KPB.

[0101] A solution of 100 mM K2HPO4 was prepared by weighing 17.42 g and adding to 1 L of MilliQ water. A solution of 100 mM KH2PO4 was prepared by weighing 13.61 g and adding to 1 L of MilliQ water. To achieve a pH of 7.4, approximately 250 ml of 100 mM KH2PO4 solution was added to the 100 mM K2HPO4 and the pH was continuously measured. To prepare a solution of 50 mM potassium phosphate buffer, 500 mL of 100 mM potassium phosphate buffer (pH 7.4) was added to 500 mL of MilliQ water.

[0102] As shown in Figure 1a, compound 1 was stable in both human and rat plasma and in both human and rat liver S9 fractions in buffer after 0.75 hours. However, compound 1 was successfully converted to opicapone in rat liver homogenate. After 0.5 hours, the remaining % of the parent compound was less than 25%.

[0103] The stability of 1 μM compound 4 was evaluated in the following fractions: phosphate buffer, human plasma, rat plasma, human liver S9 fraction, rat liver S9 fraction and rat liver homogenate.

[0104] The reaction was initiated by adding 1 μM of test compound to the desired matrix (plasma or 1 mg / mL S9 fraction) in a final volume of 250 μL. For plasma, 50 μL samples were taken at 0, 15, 30, 45, and 60 minutes of incubation and the internal standard (opicapone) was added. 13C6) at 1 μM and precipitated with 100 μL of internal standard working solution (ISWS) consisting of acetonitrile 1% formic acid. For the S9 fraction, a 50 μL sample was taken and precipitated with 100 μL of ISWS after 60 min of incubation. For rat liver homogenate (0.2 g / mL protein), the reaction was started by adding 1 μM of test compound (final volume 350 μL). At the following incubation times: 0, 5, 15, 30, 45, 60 min, a 50 μL sample was taken and precipitated with 200 μL of ISWS. Samples were centrifuged at 20,000 g for 10 min at 4 °C and then analyzed by LC-MS / MS using a bioanalytical method previously developed in-house. Compound 4 was stable in all matrices except rat liver homogenate, with approximately 31% compound remaining after 60 min of incubation. Solutions of test compounds were prepared at 10 μM using 50 mM potassium phosphate buffer (KPB) pH 7.4 by adding 1 μL of a 10 mM compound stock solution to 999 μL of 50 mM KPB.

[0105] A solution of 100 mM K2HPO4 was prepared by weighing 17.42 g and adding to 1 L of MilliQ water. A solution of 100 mM KH2PO4 was prepared by weighing 13.61 g and adding to 1 L of MilliQ water. To achieve a pH of 7.4, approximately 250 ml of 100 mM KH2PO4 solution was added to the 100 mM K2HPO4 and the pH was continuously measured. To prepare a solution of 50 mM potassium phosphate buffer, 500 mL of 100 mM potassium phosphate buffer (pH 7.4) was added to 500 mL of MilliQ water.

[0106] Compound 4 was stable in both human and rat plasma and in both human and rat liver S9 fractions in buffer after 0.75 h. As shown in Figure 1b, compound 4 was successfully converted to opicapone in rat liver homogenate (along with a repeat experiment of compound 1).

[0107] The stability of compounds 1 and 4 at 2500 ng / mL was evaluated at different pH values ​​of 1.2, 4.5 and 6.8 over a period of 4 hours at 37°C.

[0108] The buffer solutions were prepared as follows. Buffer solution pH1.2: Prepare 1L: 3.73 g potassium chloride 7mL HCl 37% Add purified water Check / adjust pH to 1.20 ± 0.05 (use the following solutions: HCl 1M and / or NaOH 1M)

[0109] Buffer solution pH4.5 Prepare 1L: 2.99 g sodium acetate trihydrate 14mL of acetic acid 2M Add purified water Check / adjust pH to 4.50 ± 0.05 (use the following solutions: Acetic Acid 2M and / or NaOH 1M)

[0110] Buffer solution pH6.8 Prepare 1L: 6.81 g of potassium dihydrogen phosphate 22mL NaOH 1M Add purified water Check / adjust pH to 6.80±0.05 (use the following solutions: HCl 1M and / or NaOH 1M)

[0111] As shown in Figure 2a, compound 1 was stable in buffers of pH 1.2, pH 4.5, and 6.8, but did not dissolve immediately in pH 1.2, and as shown in Figure 2b, compound 4 was stable in buffers of pH 1.2, 4.5, and 6.8.

[0112] Long-term stability studies in the solid state indicate that compound 4 is particularly stable.

[0113] Pharmacokinetic properties of opicapone prodrugs. Oral Pharmacokinetics The pharmacokinetic properties of compounds 1 and 4 compared to micronized crystalline opicapone were evaluated by oral administration to four male Wistar rats (3 mg / kg, 0.2% HPMC).

[0114] Blood was collected from the tail vein at different time points during the study, centrifuged at 1500×g for 15 min in a refrigerated centrifuge (4° C.), and the resulting plasma was stored at −80° C. until further analysis. Collected plasma samples were analyzed for Compound 1, Compound 4, and opicapone exposure. Biopsies were analyzed using LC-MS / MS after plasma precipitation.

[0115] As shown in FIG. 3a, compound 1 demonstrated improved pharmacokinetic properties compared to compound 4.

[0116] As shown in Figure 3b, both compound 1 and compound 4 were converted to opicapone, with compound 1 yielding a pharmacokinetic profile of opicapone comparable to opicapone itself, while compound 4 opicapone demonstrated poorer oral pharmacokinetic parameters compared to opicapone and opicapone derived from compound 1.

[0117] Intravenous Pharmacokinetics The pharmacokinetic properties of compounds 1 and 4 compared to micronized crystalline opicapone were evaluated by intravenous injection in three male Wistar rats (1 mg / kg; DMSO:20% HPBCD (1:9)).

[0118] Blood was collected from the jugular vein at different time points during the study, centrifuged at 1500×g for 15 min in a refrigerated centrifuge (4° C.), and the resulting plasma was stored at −80° C. until further analysis. Collected plasma samples were analyzed for Compound 1, Compound 4, and opicapone exposure. Biopsies were analyzed using LC-MS / MS after plasma precipitation.

[0119] As shown in FIG. 4a, compound 1 demonstrated improved pharmacokinetic properties compared to compound 4.

[0120] As shown in Figure 4b, both Compound 1 and Compound 4 were converted to opicapone, with Compound 1 yielding a pharmacokinetic profile of opicapone comparable to opicapone itself. Opicapone derived from Compound 4 demonstrated poorer intravenous pharmacokinetic parameters compared to opicapone derived from Compound 1 and opicapone.

[0121] Subcutaneous Pharmacokinetics The pharmacokinetic properties of compounds 1 and 4 were evaluated by subcutaneous injection in four male Wistar rats (3 mg / kg; DMSO:20% HPBCD (1:9)). The compounds showed low levels of irritation at the injection site.

[0122] Blood was collected from the tail vein at different time points during the study, centrifuged at 1500×g for 15 min in a refrigerated centrifuge (4° C.), and the resulting plasma was stored at −80° C. until further analysis. Collected plasma samples were analyzed for Compound 1, Compound 4, and opicapone exposure. Biopsies were analyzed using LC-MS / MS after plasma precipitation.

[0123] The pharmacokinetic parameters of Compound 1 and Compound 4 are shown in Table 2. Table 2 - Pharmacokinetic parameters of Compound 1 and Compound 4 administered orally (po), intravenously (iv) and subcutaneously (sc) [Table 2]

[0124] The pharmacokinetic parameters of opicapone converted from Compound 1 and Compound 4 are shown in Table 3 (along with those of micronized crystalline opicapone).

[0125] Table 3 - Pharmacokinetic parameters of opicapone transformed by the following compounds administered orally (po), intravenously (iv) and subcutaneously (sc) [Table 3]

[0126] As shown in Figure 5a, compound 1 was converted to opicapone, resulting in a pharmacokinetic profile of opicapone that was superior to opicapone itself after oral administration (AUC last (Increased approximately 3-fold) Surprisingly, unlike oral or intravenous administration, compound 1, opicapone, exhibited an improved pharmacokinetic profile (compared to orally administered opicapone) when administered subcutaneously.

[0127] As shown in Figure 5b, compound 4 was converted to opicapone, resulting in an excellent pharmacokinetic profile of opicapone that was comparable to opicapone itself after oral administration (AUC last (increased approximately 3-fold). Surprisingly, unlike oral or intravenous administration, opicapone from compound 4 showed an improved pharmacokinetic profile (compared to orally administered opicapone) when administered subcutaneously. This is particularly surprising since opicapone from compound 4 was significantly worse than opicapone or opicapone from compound 1 when administered intravenously or orally. Thus, opicapone from compound 4 is significantly worse than opicapone from compound 1 when administered intravenously, but has a similar pharmacokinetic profile to opicapone from compound 1 when administered subcutaneously. Such unusual pharmacodynamic behavior could not be predicted by theory. Moreover, compound 4 exhibited a significantly improved pharmacokinetic profile (compared to orally administered opicapone) when administered subcutaneously, compared to compound 1. max Despite the low C of opicapone, max was higher.

[0128] Combined, the data suggest that compound 1 is surprisingly more stable than compound 4 when administered intravenously, suggesting improved stability in the bloodstream. Similarly, compound 1 has a significantly lower C of the prodrug of compound 1 in Figure 5a (filled circles) compared to compound 4 in Figure 5b (filled squares). maxCompound 4 is more bioavailable via the subcutaneous route due to its higher . Therefore, it is particularly unexpected that more opicapone is produced by compound 4 in FIG. 5b (open squares) compared to compound 1 in FIG. 5a (open circles). Compound 4 may have a different distribution profile when administered subcutaneously and may find stable reservoirs within certain tissues or blood binding sites.

[0129] Subcutaneous Pharmacodynamics: COMT Inhibition The pharmacodynamic properties of compounds 1 and 4 compared to orally administered micronized crystalline opicapone were evaluated by subcutaneous injection in four male Wistar rats (3 mg / kg; DMSO:20% HPBCD (1:9)) followed by measurement of red blood cell S-COMT activity over time.

[0130] Blood was collected from the tail vein at different time points during the study, centrifuged at 1500×g for 15 min in a refrigerated centrifuge (4° C.), and the resulting plasma and red blood cells were stored at −80° C. until further analysis. Collected plasma samples were analyzed for Compound 1, Compound 4, and opicapone exposure as previously described.

[0131] Erythrocyte S-COMT activity was assessed by its ability to methylate adrenaline to metanephrine. Aliquots of erythrocytes were hemolyzed by adding 4 volumes of ice-cold ultrapure water and homogenized in a bead mill homogenizer with glass beads, followed by incubation on wet ice for 10 min. After centrifugation (20000×g, 20 min, 4° C.), the supernatants containing S-COMT were quantified for total protein using the Bradford assay. The supernatants were diluted with water to 4 mg total protein per ml. 100 μL of these diluted supernatants were then preincubated with 80 μL of phosphate buffer (10 mM, pH 7.8) in a 96-well plate for 20 min; the reaction mixture was then incubated with adrenaline (10 mM, 20 μL) in the presence of a saturating concentration of S-adenosyl-L-methionine, a methyl donor (500 μM), for 10 min. The incubation medium also contained pargyline (100 μM), MgCl2 (100 μM) and EGTA (1 mM). Preincubation and incubation were performed at 37°C under light protection with continuous shaking and without oxygenation. At the end of the incubation period, the plate was transferred to ice and the reaction was stopped by adding 15 μL of glacial acetic acid. Then, 60 μL of each sample was transferred to a new 96-well containing 400 μL of 0.1% formic acid, followed by plate centrifugation (2000×g, 5 min, 4°C). The supernatant was used for quantification of metanephrines by LC-MS / MS.

[0132] As shown in Figure 6, conversion of Compound 1 and Compound 4 to opicapone resulted in rapid inhibition of COMT activity in red blood cells with maximal effect at 2 hours post-dosing (96% and 94% inhibition for Compound 1 and Compound 4, respectively). Inhibition of COMT remained above 80% for at least up to 8 hours post-dosing, much longer than achieved with orally administered opicapone.

[0133] Subcutaneous pharmacodynamics: effects on L-dopa As a proof of concept, the effect of compound 4 on L-dopa metabolism was evaluated in four male Wistar rats. Animals were subcutaneously injected with a single formulation (in DMSO:PEG 400:30% SBEBCD (1:2:2)) containing 12 mg / kg L-dopa + 3 mg / kg benserazide, with or without 3 mg / kg compound 4. Plasma samples were collected as described above and analyzed for levels of L-dopa and its metabolite 3-O-methyldopa (3-OMD).

[0134] As shown in FIG. 7, coadministration of compound 4 with L-dopa / benserazide increased circulating levels of L-dopa (AUC last increased 1.7-fold), with a corresponding decrease in the levels of its metabolite 3-OMD.

[0135] summary For both Compound 1 and Compound 4, subcutaneous administration was the route of highest conversion to opicapone, with greater than 80% COMT inhibition for at least 8 hours post-dose. When co-administered with L-dopa / benserazide, Compound 4 showed increased L-dopa levels and decreased 3-OMD levels.

[0136] Other variations of the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from studying the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be interpreted as limiting the scope.

Claims

1. Compound of formula (I): 【Chemistry 1】 or a pharmaceutically acceptable salt thereof; where R is H or C １ -C ６ A pharmaceutically acceptable salt thereof of the compound or the compound, wherein it is alkyl and n is 0 or 1.

2. The compound according to claim 1, wherein the pharmaceutically acceptable salt is selected from the group consisting of sodium salts, ammonium salts, and potassium salts.

3. The compound according to claim 2, wherein the pharmaceutically acceptable salt is selected from the group consisting of sodium salts and ammonium salts.

4. The compound according to claim 3, wherein the sodium salt is a disodium salt and the ammonium salt is a triammonium salt.

5. A method for preparing a compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt thereof, (a) Deprotecting a compound of formula (II) to provide a compound of formula (I): 【Chemistry 2】 In the formula, R １ and R ２ Each of these is either independently a monovalent phosphate protecting group or together forms a divalent phosphate protecting group; R is H or C １ -C ６ The deprotection is performed on an alkyl group where n is 0 or 1; (b) The method comprising optionally converting the compound of formula (I) to a pharmaceutically acceptable salt thereof.

6. The phosphate protecting group R １ and R ２ are each independently selected from the group consisting of C １ -C ６ alkyl and benzyl, the method according to claim 5.

7. The phosphate protecting group R １ and R ２ The method according to claim 6, wherein both are benzyl, or both are tert-butyl, or both are ethyl.

8. The method according to any one of claims 5 to 7, wherein step (a) is carried out by reacting the compound of formula (II) with trimethylsilyl halogenate in an aprotic solvent such as dichloromethane or acetonitrile, followed by an aqueous work-up.

9. The method according to claim 8, wherein the halide trimethylsilyl is bromide trimethylsilyl.

10. The method according to claim 5, wherein the compound of formula (I) is converted to a pharmaceutically acceptable salt thereof.

11. The method according to claim 10, wherein the pharmaceutically acceptable salt is selected from the group consisting of sodium salts, ammonium salts, and potassium salts.

12. The method according to claim 11, wherein the pharmaceutically acceptable salt is selected from the group consisting of sodium salts and ammonium salts.

13. The method according to claim 12, wherein the sodium salt is a disodium salt and the ammonium salt is a triammonium salt.

14. A method for preparing a compound of formula (II) as defined in claim 5, Compound of formula (III): 【Transformation 3】 And the compound of formula (IV): 【Chemistry 4】 And in the formula, R １ and R ２ Each of these is either independently a monovalent phosphate protecting group or together forms a divalent phosphate protecting group; R is H or C １ -C ６ The compound is alkyl and n is 0 or 1; The method comprising carrying out the reaction in the presence of a base and an aprotic solvent.

15. The phosphate protecting group R １ and R ２ However, each is independent of C １ -C ６ The method according to claim 14, selected from the group consisting of alkyl and benzyl.

16. The phosphate protecting group R １ and R ２ The method according to claim 15, wherein both are benzyl, or both are tert-butyl, or both are ethyl.

17. The method according to claim 14, wherein the base is triethylamine.

18. Compound of formula (II): 【Transformation 5】 And in the formula, R １ and R ２ Each of these is either independently a monovalent phosphate protecting group or together forms a divalent phosphate protecting group; R is H or C １ -C ６ The compound is alkyl, and n is 0 or 1.

19. The phosphate protecting group R １ and R ２ However, each is independent of C １ -C ６ The compound according to claim 18, selected from the group consisting of alkyl and benzyl.

20. The phosphate protecting group R １ and R ２ The compound according to claim 19, wherein both are benzyl, or both are tert-butyl, or both are ethyl.

21. It is a pharmaceutical preparation, (i) a compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt thereof; (ii) One or more pharmaceutically acceptable excipients, The pharmaceutical preparation comprising the above.

22. A pharmaceutical preparation for intravenous administration to humans, (i) a compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt thereof; (ii) Pharmaceutically acceptable vehicles and The pharmaceutical preparation comprising the above.

23. A pharmaceutical formulation for subcutaneous administration to humans, (i) a compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt thereof; (ii) Pharmaceutically acceptable vehicles and The pharmaceutical preparation comprising the above.

24. The pharmaceutical preparation according to claim 21, claim 22, or claim 23, wherein the pharmaceutically acceptable salt is selected from the group consisting of sodium salts, ammonium salts, and potassium salts.

25. The pharmaceutical preparation according to claim 24, wherein the pharmaceutically acceptable salt is selected from the group consisting of sodium salts and ammonium salts.

26. The pharmaceutical preparation according to claim 25, wherein the sodium salt is a disodium salt and the ammonium salt is a triammonium salt.

27. The pharmaceutical preparation according to claim 22, wherein the pharmaceutically acceptable vehicle includes water for injection.

28. A pharmaceutical preparation according to claim 21, for use in the treatment of Parkinson's disease.

29. The pharmaceutical preparation according to claim 28, wherein the pharmaceutical preparation is administered in combination with L-dopa or foslevodopa.

30. The pharmaceutical formulation according to claim 29, wherein the pharmaceutical formulation is administered in combination with an AADC inhibitor, preferably carbidopa, benserazide, or foscarbidopa.

31. The pharmaceutical preparation according to claim 28, wherein the pharmaceutical preparation is administered in combination with L-dopa and carbidopa or benserazide.

32. The pharmaceutical preparation according to claim 28, wherein the pharmaceutical preparation is administered in combination with foslevodopa and foscarbidopa.

33. The pharmaceutical preparation according to claim 28, wherein the pharmaceutical preparation is administered intravenously or subcutaneously, preferably subcutaneously.

34. The pharmaceutical formulation according to claim 28, wherein the compound of formula (I) or a pharmaceutically acceptable salt thereof is administered in a daily dose equivalent to less than 25 mg / day of the compound of formula (III) as defined in claim 14.

35. The pharmaceutical preparation according to claim 28, wherein the compound of formula (I) is administered in a daily dose equivalent to less than 50 mg / day of the compound of formula (III) as defined in claim 14.

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