Synthesis of prostate-specific membrane antigen (PSMA) ligands

Abstract

The present disclosure relates to the synthesis of prostate-specific membrane antigen (PSMA) ligands useful in the treatment of diseases such as cancer. In particular, the present disclosure relates to methods for synthesizing PSMA ligands having a glutamic acid-urea-lysine (GUL) moiety and a chelator that may include a radiometal.

Description

Technical Field

[0001] The present disclosure relates to the synthesis of prostate-specific membrane antigen (PSMA) ligands useful in the treatment of diseases such as cancer. In particular, the present disclosure relates to a method for synthesizing a PSMA ligand having a glutamate-urea-lysine (GUL) moiety and a chelating agent that may contain a radioactive metal.

Background Art

[0002] Prostate cancer is one of the most prevalent cancers in the United States and Europe. In particular, metastatic castration-resistant prostate cancer (mCRPC) is associated with poor prognosis and a decline in quality of life.

[0003] Recently, PSMA has been regarded as a suitable target for imaging and treatment due to its overexpression in primary cancer lesions and soft tissue / bone metastatic diseases. Therefore, PSMA ligand-based radioligand therapy (RLT) has become a new development trend for treating prostate cancer. Also, PSMA expression appears to be even higher in the most aggressive castration-resistant variants of this disease, which constitute a patient population with a large unmet medical need (Marchal et al., Histol Histopathol, 2004, Jul; 19(3):715-8; Mease et al., Curr Top Med Chem, 2013, 13(8):951-62).

[0004] Among the many small molecule ligands that target PSMA, the most extensively studied are urea-based low molecular weight drugs. These drugs have been shown to be suitable for clinical evaluation of prostate cancer and for PRRT therapy (Kiess et al., QJ Nucl Med Mol Imaging, 2015;59:241-68). Some of these drugs have glutamate-urea-lysine (GUL) as a targeting scaffold. A class of molecules was created according to a strategy for linking a linker between the chelating agent and the GUL moiety. This approach allows urea to reach the binding site while keeping the metal chelating portion outside the binding site. This strategy has been successful in xenograft PSMA-positive tumors due to its demonstrated high uptake and retention rates, as well as rapid renal clearance (Banerjee et al., J Med Chem, 2013; 56:6108-21).

[0005] moreover, 177 Specific compounds like Lu-PSMA-617 are being widely studied. Various studies have been conducted. 177 Lu-PSMA-617 has been shown to be a promising radiopharmaceutical for the treatment of prostate cancer (Delker et al., European Journal of Nuclear Medicine and Molecular Imaging (2016), 43(1), 42-51; Yadav et al., European Journal of Nuclear Medicine and Molecular Imaging (2017), 44(1), 81-91).

[0006] Due to interest in urea-based PSMA ligands, particularly PSMA-617, there is a need for a cost-effective synthesis method that can deliver essential amounts of high-purity products. [Overview of the Initiative]

[0007] This disclosure relates to a method for synthesizing PSMA ligands useful in the treatment of cancer, particularly prostate cancer.

[0008] This disclosure also relates to a method for synthesizing a compound of formula (I) or a pharmaceutically acceptable salt thereof using solid-phase synthesis.

[0009] [ka]

[0010] The compound of formula (I) is PSMA-617.

[0011] According to the first embodiment, the method includes at least one of the following steps: a) A supported compound of formula (II), preferably a resin-supported compound and

[0012] [ka] By contacting the compound of formula (III)

[0013] [ka] A step to obtain a supported compound of formula (IV), preferably a resin-supported compound;

[0014] [ka] b) A step of contacting a supported compound of formula (IV), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (V), preferably a resin-supported compound;

[0015] [ka] c) Contacting a supported compound of formula (V), preferably a resin-supported compound, with a compound of formula (VI)

[0016] [Chemical formula] Step of obtaining the supported compound of formula (VII), preferably a resin-supported compound;

[0017] [Chemical formula] d) Step of contacting the supported compound of formula (VII), preferably a resin-supported compound, with a deprotecting agent to obtain the supported compound of formula (VIII), preferably a resin-supported compound;

[0018] [Chemical formula] e) Step of contacting the supported compound of formula (VIII), preferably a resin-supported compound, with the compound of formula (IX) to

[0019] [Chemical formula] obtain the supported compound of formula (X), preferably a resin-supported compound;

[0020] [Chemical formula] f) Step of contacting the supported compound of formula (X), preferably a resin-supported compound, with a deprotecting agent to obtain the supported compound of formula (XI), preferably a resin-supported compound;

[0021] [Chemical formula] g) Step of contacting the supported compound of formula (XI), preferably a resin-supported compound, with compound (XII) to

[0022] [Chemical formula] obtain the supported compound of formula (XIII), preferably a resin-supported compound;

[0023] [Chemical formula] h) A step of contacting a supported compound of formula (XIII), preferably a resin-supported compound, with a cleavage reagent and optionally a deprotecting agent to obtain a compound of formula (I) or a pharmaceutically acceptable salt thereof; During the ceremony, -PG, PG1, PG5, PG6, and PG7 are each independently carboxyl protecting groups; -L is a linker; -PG2, PG3, and PG4 are each independently amino protecting groups; -R1, R2, and R3 are each independently H or an activated ester group; -LG is a leaving group selected from the group consisting of imidazole, halogen, and activated ester groups.

[0024] According to the second embodiment, the method includes at least one of the following steps: a') A supported compound of formula (II'), preferably a resin-supported compound

[0025] [ka] By contacting the compound of formula (III')

[0026] [ka] A step to obtain a supported compound of formula (IV'), preferably a resin-supported compound;

[0027] [ka] b') A step of contacting a supported compound of formula (IV'), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (V'), preferably a resin-supported compound;

[0028] [ka] c') A supported compound of formula (V'), preferably a resin-supported compound, is brought into contact with a compound of formula (VI').

[0029] [ka] A step to obtain a supported compound of formula (VII'), preferably a resin-supported compound;

[0030] [ka] d') A step of contacting a supported compound of formula (VII'), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (VIII'), preferably a resin-supported compound;

[0031] [ka] e') Contacting a supported compound of formula (VIII'), preferably a resin-supported compound, with a compound of formula (IX')

[0032] [ka] A step to obtain a supported compound of formula (X'), preferably a resin-supported compound;

[0033] [ka] f') A step of contacting a supported compound of formula (X'), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (XI'), preferably a resin-supported compound;

[0034] [ka] g') The supported compound of formula (XI'), preferably a resin-supported compound, is brought into contact with compound (XII')

[0035] [ka] A step to obtain a supported compound of formula (XIII'), preferably a resin-supported compound;

[0036] [ka] h') A step of contacting a supported compound of formula (XIII'), preferably a resin-supported compound, with a cleavage reagent and optionally a deprotective agent to obtain a compound of formula (I) or a pharmaceutically acceptable salt thereof; During the ceremony, -PG', PG1', PG5', PG6', and PG7' are each independently carboxyl protecting groups; -L' is a linker; -PG2', PG3', and PG4' are each independently amino protecting groups; -R1', R2', and R3' are each independently either H or an activated ester group; -LG' is a leaving group selected from the group consisting of imidazole, halogen, and activated ester groups.

[0037] The fact that this synthesis is carried out using solid-phase synthesis enables a cost-effective and efficient synthesis. In particular, the total yield of this synthesis can be 20% or more relative to the supported starting compound (II) or (II'). [Brief explanation of the drawing]

[0038] [Figure 1] This figure shows a 1D 1H spectrum with Watergate H2 signal suppression applied, used for reference and as a fingerprint. [Modes for carrying out the invention]

[0039] definition As used herein, the term “solid-phase synthesis” refers to the synthesis of compounds by chemically bonding reactive molecules to an insoluble material (a solid support, usually a resin) and adding reagents in a solution phase. The reactive molecules are typically chemically bonded to the solid support via a linker. Solid-phase synthesis is commonly used for peptide synthesis, and therefore, those skilled in the art are familiar with the techniques and apparatus used to perform solid-phase synthesis. In solid-phase peptide synthesis, amino acids or peptides are bonded to a solid support, usually via the C-terminus. New amino acids are added to the bonded amino acids or peptides through coupling reactions. Protecting groups are typically used due to the possibility of unintended reactions. The use of solid-phase synthesis allows for the isolation and purification of intermediates by simple filtration and rinsing, avoiding the time-consuming and costly isolation and purification of intermediates.

[0040] As used herein, the term "supported compound" refers to a compound chemically bonded to an insoluble material, usually a resin.

[0041] As used herein, the term "resin-based compound" refers to a compound chemically bonded to a resin, which is a solid support. Resin-based compounds are used in solid-phase synthesis.

[0042] As used herein, the term "linker" refers to the divalent portion that connects a reactive molecule to an insoluble material.

[0043] As used herein, the term “protecting group” means a chemical substituent that can be selectively removed by readily available reagents that do not attack the regenerated functional group or other functional groups within the molecule. Suitable protecting groups are known in the art and are under ongoing development. Suitable protecting groups can be found, for example, in Wutz et al. ("Greene's Protective Groups in Organic Synthesis, Fourth Edition," Wiley-Interscience, 2007).

[0044] In certain embodiments, protecting groups for carboxyl groups described by Wutz et al. (pages 533-643) are used. In some embodiments, the protecting groups can be removed by treatment with acid. Representative examples of carboxyl protecting groups include, but are not limited to, benzyl, p-methoxybenzyl (PMB), tert-butyl (t-Bu), methoxymethyl (MOM), methoxyethoxymethyl (MEM), methylthiomethyl (MTM), tetrahydropyranyl (THP), tetrahydrofuranyl (THF), benzyloxymethyl (BOM), trimethylsilyl (TMS), triethylsilyl (TES), t-butyldimethylsilyl (TBDMS), and triphenylmethyl (Trityl, Tr). Those skilled in the art will recognize appropriate situations in which protecting groups are needed.

[0045] In certain embodiments, protecting groups for protecting amino groups described by Wutz et al. (pages 696-927) are used. Representative examples of amino protecting groups include, but are not limited to, t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), allyloxycarbonyl (alloc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl)(Dde), 1-(1-adamantyl)-1-methylethoxycarbonyl (Adpoc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexa-1-ylidene)-3-methylbutyl)(ivDde), monomethoxytrityl (MMt), and 4-methyltrityl (Mtt). Those skilled in the art will recognize appropriate situations in which protecting groups are needed.

[0046] As used herein, the term “activated ester group” refers to an electron-withdrawing group used to activate an ester functional group and increase its susceptibility to nucleophilic attack. Activated esters are commonly used in organic chemistry. Examples of activated ester groups include succinimidyl, p-nitrophenyl, tetrafluorophenyl, 3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl, pentafluorophenyl, and 2,4,5-trichlorophenyl.

[0047] Various embodiments of this disclosure are described herein. It will be recognized that further embodiments can be realized by combining the features defined in each embodiment with other defined features.

[0048] This disclosure includes compounds of formulas (I) to (XIII) and (II') to (XIII'), their stereoisomers, tautomers, enantiomers, diastereomers, racemates, or mixtures thereof, as well as their hydrates, solvates, or pharmaceutically acceptable salts.

[0049] The term "pharmaceutically acceptable salt" means a salt that retains the biological efficacy and properties of the compound of this disclosure and is not typically biologically or otherwise undesirable. Examples of pharmaceutically acceptable salts include trifluoroacetate (TFA) salts, acetates, or hydrochlorides.

[0050] Synthesis of the compound of formula (I) This disclosure also relates to a method for synthesizing a compound of formula (I), preferably using solid-phase synthesis.

[0051] According to one embodiment, the compound of formula (I) is a trifluoroacetic acid (TFA) salt or an acetate salt.

[0052] The resin used in this method may be any type of resin conventionally used in solid-phase synthesis. These resins are well known to those skilled in the art. Examples of resins include polystyrene resins such as microporous polystyrene resins or macroporous polystyrene resins, polyacrylamide resins, and copolymer resins. Linker L or L' is preferably an acid-unstable linker. An acid-unstable linker can be cleaved during step h) or h') when acidic conditions are used. Linker L or L' varies depending on the resin used, and these are well known to those skilled in the art. Examples of resins containing linker group L or L' include p-alkoxybenzyl alcohol resin (Wang resin), 4-(1',1'-dimethyl-1'-hydroxypropyl)phenoxyacetyl-alanyl-aminomethyl resin (DHPP resin), diphenyldiazomethane resin (PDDM resin), trityl chloride resin, and 2-chlorotrityl chloride resin.

[0053] The protecting groups PG, PG1, PG5, PG6, PG7, PG', PG1', PG5', PG6', and PG7' can each be independently selected from the group consisting of benzyl, p-methoxybenzyl (PMB), tert-butyl (t-Bu), methoxymethyl (MOM), methoxyethoxymethyl (MEM), methylthiomethyl (MTM), tetrahydropyranyl (THP), tetrahydrofuranyl (THF), benzyloxymethyl (BOM), trimethylsilyl (TMS), triethylsilyl (TES), t-butyldimethylsilyl (TBDMS), and triphenylmethyl (Trityl, Tr).

[0054] According to one embodiment, PG, PG1, PG5, PG6, and PG7 are tertiary butyl (t-Bu). According to one embodiment, PG', PG1', PG5', PG6', and PG7' are tertiary butyl (t-Bu).

[0055] The protecting groups PG2, PG3, PG4, PG2', PG3', and PG4' can each be independently selected from the group consisting of t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), allyloxycarbonyl (alloc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl) (Dde), monomethoxytrityl (MMt), 1-(1-adamantyl)-1-methylethoxycarbonyl (Adpoc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexa-1-ylidene)-3-methylbutyl) (ivDde), and 4-methyltrityl (Mtt), preferably from the group consisting of Dde, ivDde, and Fmoc.

[0056] According to one embodiment, PG2, PG3, and PG4 are 9-fluorenyl methoxycarbonyl (Fmoc). According to one embodiment, PG2' is N-(1-(4,4-dimethyl-2,6-dioxocyclohexa-1-ylidene)-3-methylbutyl)(ivDde) ​​or Dde, and PG3' and PG4' are 9-fluorenyl methoxycarbonyl (Fmoc). Dde and ivDde are preferred protecting groups as PG2'. In particular, deprotection of these groups does not require the use of a metal catalyst, which is in contrast to the Alloc protecting group, which is removed using Pd(PPh3)4. Furthermore, these groups are not as bulky as MMt and Mtt, and therefore can be added in larger amounts to the resin, and they are also less sensitive to acidic conditions than Mtt.

[0057] The R1, R2, R3, R1', R2', and R3' groups can each be independently selected from the group consisting of H, succinimidyl, p-nitrophenyl, tetrafluorophenyl, 3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl, pentafluorophenyl, and 2,4,5-trichlorophenyl, preferably from the group consisting of H and succinimidyl. According to one embodiment, R1, R2, and R3 are H. According to one embodiment, R1', R2', and R3' are H.

[0058] LG and LG' are leaving groups independently selected from imidazole, halogen, and activated ester group. Chlorine can be an example of a halogen. The fact that compounds (III) and (III') have a -NH-(CO)-LG or LG' moiety and no -N=C=O reactive moiety makes it possible to synthesize compounds of formula (I) without using toxic compounds such as phosgene or triphosgene, which are highly toxic products. LG or LG' is preferably imidazole because it allows synthesis without the use of phosgene or triphosgene, which are highly toxic products. Furthermore, when imidazole is used as the leaving group, the product is a stable solid that can be easily handled.

[0059] According to a preferred embodiment, a method for synthesizing the compound of formula (I) comprises all steps a) to h), or all steps a') to h').

[0060] Each step a) to h) or a') to h') can be carried out at room temperature or under heating, for example, at a temperature of 25°C to 70°C. Each step a) to h) or a') to h') can be carried out over a period of 5 minutes to 3 hours. Each step a) to h) or a') to h') can be carried out in an inert atmosphere, for example, under argon.

[0061] Between each step, the resulting supported compound can be washed with a solvent such as dimethylformamide (DMF), dichloromethane (DCM), or isopropanol (IPA). Washing may be done using different solvents alternately, for example, by alternating between DMF and IPA.

[0062] Each step a) to h) or a') to h') can be carried out using a polar aprotic solvent. According to one embodiment, the polar aprotic solvent usable in each step a) to h) or a') to h') is selected from the group consisting of dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dichloromethane (DCM), dichloromethane / dimethylformamide mixture, acetonitrile (ACN), acetonitrile / dimethylformamide mixture, and dimethyl sulfoxide (DMSO). Advantageously, the polar aprotic solvent usable in either step a) to h) or a') to h') is dimethylformamide (DMF).

[0063] Each step a), c), e), g), a'), c'), e'), or g') can be carried out using a coupling agent and / or a base. The bases that can be used in each step a), c), e), g), a'), c'), e'), or g') are independently N,N-diisopropylethylamine (DIPEA), N,N-diisopropylethylamine ( iThe coupling agent can be selected from the group consisting of Pr2NEt), triethylamine (TEA), 4-methylmorpholine (NMM), imidazole, pyridine, and colidine. Preferably, the base is DIPEA. The coupling agents usable in any of steps a), c), e), a'), c'), or e') are independently benzotriazole-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (PyBOP), 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate (HATU), 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU), and 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium Hexafluorophosphate (HBTU), 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT), N-[(5-chloro-3-oxide-1H-benzotriazol-1-yl)-4-morpholinylmethylene]-N-methylmethaneaminium; Hexafluorophosphate (HDMC), 1-cyano-2-ethoxy-2-oxoethylideneaminooxy)dimethylamino-morpholino-carbenium; Hexafluorophosphate (COMU), dimethylamino(triazolo[4,5-b]pyridine-3-yloxy)methylidene]-dimethylazanium; Tetrafluoroborate (TATU), N,N,N',N'-tetramethyl-S-(1-oxide-2-pyridyl)thiouronium The following can be selected from the group consisting of tetrafluoroborate (TOTT), N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), 1-propanephosphonic anhydride (T3P), and 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMTMM), preferably from the group consisting of PyBOP and TBTU.

[0064] According to one embodiment, step a) is performed using a base, usually DIPEA. According to one embodiment, step a') is performed using a base, usually DIPEA. According to one embodiment, step c) is performed using a coupling agent and a base, usually TBTU and DIPEA. According to one embodiment, step c') is performed using a coupling agent and a base, usually TBTU and DIPEA. According to one embodiment, step e) is performed using a coupling agent and a base, usually TBTU and DIPEA. According to one embodiment, step e') is performed using a coupling agent and a base, usually TBTU and DIPEA. According to one embodiment, step g) is performed using a coupling agent and a base, usually PyBOP and DIPEA. According to one embodiment, step g') is performed using a coupling agent and a base, usually PyBOP and DIPEA.

[0065] The deprotective agent used in any of steps b), d), f), b'), d'), or f') can be independently selected from the group consisting of hydrazine, piperidine, morpholine, 1,8-diazabicyclo[5.4.0]undeca-7-ene (DBU), diethylamine (DEA), dicyclohexamine, 4-methylpiperidine (4MP), tris(2-aminoethyl)amine, pyridine, and collidine, preferably from the group consisting of hydrazine and piperidine. According to one embodiment, the deprotective agent used in step b) is piperidine. According to one embodiment, the deprotective agent used in step b') is hydrazine. According to one embodiment, the deprotective agent used in step d) is piperidine. According to one embodiment, the deprotective agent used in step d') is piperidine. According to one embodiment, the deprotective agent used in step f) is piperidine. According to one embodiment, the deprotective agent used in step f') is piperidine.

[0066] The cleavage reagent in step h) or h') may be an acid, preferably trifluoroacetic acid (TFA) or a trifluoroacetic acid (TFA) / water / triisopropylsilane mixture.

[0067] According to one embodiment, the total yield of this synthesis may be 10% or more, preferably 15% or more, and more preferably 20% or more, relative to the supported starting compound (II) or (II'). The total yield may range from 15% to 100%.

[0068] In some cases, the method may include a deprotection step to obtain compound (II) prior to step a).

[0069] In some cases, the method may include a deprotection step to obtain compound (II') prior to step a').

[0070] Embodiment The following specific embodiments are disclosed.

[0071] 1. A method for synthesizing a compound of formula (I) or a pharmaceutically acceptable salt thereof using solid-phase synthesis.

[0072] [ka]

[0073] 2. The method according to Embodiment 1, comprising at least one of the following steps: a) A supported compound of formula (II), preferably a resin-supported compound and

[0074] [ka] By contacting the compound of formula (III)

[0075] [ka] A step to obtain a supported compound of formula (IV), preferably a resin-supported compound;

[0076] [ka] b) A step of contacting a supported compound of formula (IV), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (V), preferably a resin-supported compound;

[0077] [ka] c) Contacting a supported compound of formula (V), preferably a resin-supported compound, with a compound of formula (VI)

[0078] [ka] A step to obtain a supported compound of formula (VII), preferably a resin-supported compound;

[0079] [ka] d) A step of contacting a supported compound of formula (VII), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (VIII), preferably a resin-supported compound;

[0080] [ka] e) Contacting a supported compound of formula (VIII), preferably a resin-supported compound, with a compound of formula (IX)

[0081] [ka] A step to obtain a supported compound of formula (X), preferably a resin-supported compound;

[0082] [ka] f) A step of contacting a supported compound of formula (X), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (XI), preferably a resin-supported compound;

[0083] [ka] g) A supported compound of formula (XI), preferably a resin-supported compound, is brought into contact with compound (XII).

[0084] [ka] A step to obtain a supported compound of formula (XIII), preferably a resin-supported compound;

[0085] [ka] h) A step of contacting a supported compound of formula (XIII), preferably a resin-supported compound, with a cleavage reagent and optionally a deprotecting agent to obtain a compound of formula (I) or a pharmaceutically acceptable salt thereof; During the ceremony, -PG, PG1, PG5, PG6, and PG7 are each independently carboxyl protecting groups; -L is a linker; -PG2, PG3, and PG4 are each independently amino protecting groups; -R1, R2, and R3 are each independently H or an activated ester group; -LG is a leaving group selected from the group consisting of imidazole, halogen, and activated ester groups.

[0086] 3. The method according to Embodiment 2, comprising all steps a) to h).

[0087] 4. The method according to any one of Embodiments 2 to 3, wherein PG, PG1, PG5, PG6, and PG7 are independently selected from the group consisting of benzyl, p-methoxybenzyl (PMB), tert-butyl (t-Bu), methoxymethyl (MOM), methoxyethoxymethyl (MEM), methylthiomethyl (MTM), tetrahydropyranyl (THP), tetrahydrofuranyl (THF), benzyloxymethyl (BOM), trimethylsilyl (TMS), triethylsilyl (TES), t-butyldimethylsilyl (TBDMS), and triphenylmethyl (Trityl, Tr), preferably PG, PG1, PG5, PG6, and PG7 are tert-butyl (t-Bu).

[0088] 5. The method according to any one of Embodiments 2 to 4, wherein PG2, PG3, and PG4 are independently selected from the group consisting of t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), allyloxycarbonyl (alloc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl) (Dde), monomethoxytrityl (MMt), 1-(1-adamantyl)-1-methylethoxycarbonyl (Adpoc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexa-1-ylidene)-3-methylbutyl) (ivDde), and 4-methyltrityl (Mtt), preferably PG2, PG3, and PG4 are 9-fluorenylmethoxycarbonyl (Fmoc).

[0089] 6. The method according to any one of Embodiments 2 to 5, wherein R1, R2, and R3 are independently selected from the group consisting of H, succinimidyl, p-nitrophenyl, tetrafluorophenyl, 3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl, pentafluorophenyl, and 2,4,5-trichlorophenyl, preferably R1, R2, and R3 are selected from the group consisting of H or succinimidyl.

[0090] 7. The method according to any one of Embodiments 2 to 6, wherein at least one of steps a) to h) is performed using a polar aprotic solvent.

[0091] 8. The method according to Embodiment 7, wherein the polar aprotic solvent is selected from the group consisting of dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dichloromethane (DCM), dichloromethane / dimethylformamide mixture, acetonitrile (ACN), acetonitrile / dimethylformamide mixture, and dimethyl sulfoxide (DMSO), and preferably the solvent is dimethylformamide (DMF).

[0092] 9. The method according to any one of Embodiments 2 to 8, wherein at least one of steps a), c), e), or g) is performed using a coupling agent and / or a base.

[0093] 10. The base is N,N-diisopropylethylamine (DIPEA), N,N-diisopropylethylamine ( i The method according to Embodiment 9, selected from the group consisting of Pr2NEt), triethylamine (TEA), 4-methylmorpholine (NMM), imidazole, pyridine, and colidine.

[0094] 11. The coupling agents are benzotriazole-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (PyBOP), 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate (HATU), 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU), 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU), 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT), and N-[(5-chloro-3-oxide-1H-benzotriazole-1-yl)-4-morpholinylmethylene]-N-methylmethaneaminium The method according to Embodiment 9 or 10, selected from the group consisting of hexafluorophosphate (HDMC), 1-cyano-2-ethoxy-2-oxoethylideneaminooxy)dimethylamino-morpholino-carbenium hexafluorophosphate (COMU), dimethylamino(triazolo[4,5-b]pyridine-3-yloxy)methylidene]-dimethylazanium; tetrafluoroborate (TATU), N,N,N',N'-tetramethyl-S-(1-oxide-2-pyridyl)thiouronium tetrafluoroborate (TOTT), N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), 1-propanephosphonic anhydride (T3P), and 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMTMM).

[0095] 12. The method according to any one of Embodiments 9 to 11, wherein step a) is performed using a base, usually DIPEA; step c) is performed using a coupling agent and a base, usually TBTU and DIPEA; step e) is performed using a coupling agent and a base, usually TBTU and DIPEA; and step g) is performed using a coupling agent and a base, usually PyBOP and DIPEA.

[0096] 13. The method according to any one of Embodiments 2 to 12, wherein the deprotective agent used in step b), d), or f) is selected from the group consisting of hydrazine, piperidine, morpholine, 1,8-diazabicyclo[5.4.0]undeca-7-ene (DBU), diethylamine (DEA), dicyclohexamine, 4-methylpiperidine (4MP), tris(2-aminoethyl)amine, pyridine, and colidine, preferably from the group consisting of hydrazine and piperidine.

[0097] 14. The method according to any one of Embodiments 2 to 13, wherein step h) is performed using an acid, preferably trifluoroacetic acid (TFA) or a trifluoroacetic acid (TFA) / water / triisopropylsilane mixture.

[0098] 15. The method according to Embodiment 1, comprising at least one of the following steps: a') A supported compound of formula (II'), preferably a resin-supported compound

[0099] [ka] By contacting the compound of formula (III')

[0100] [ka] A step to obtain a supported compound of formula (IV'), preferably a resin-supported compound;

[0101] [ka] b') A step of contacting a supported compound of formula (IV'), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (V'), preferably a resin-supported compound;

[0102] [ka] c') A supported compound of formula (V'), preferably a resin-supported compound, is brought into contact with a compound of formula (VI').

[0103] [ka] A step to obtain a supported compound of formula (VII'), preferably a resin-supported compound;

[0104] [ka] d') A step of contacting a supported compound of formula (VII'), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (VIII'), preferably a resin-supported compound;

[0105] [ka] e') Contacting a supported compound of formula (VIII'), preferably a resin-supported compound, with a compound of formula (IX')

[0106] [ka] A step to obtain a supported compound of formula (X'), preferably a resin-supported compound;

[0107] [ka] f') A step of contacting a supported compound of formula (X'), preferably a resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (XI'), preferably a resin-supported compound;

[0108] [ka] g') The supported compound of formula (XI'), preferably a resin-supported compound, is brought into contact with compound (XII')

[0109] [ka] A step to obtain a supported compound of formula (XIII'), preferably a resin-supported compound;

[0110] [ka] h') A step of contacting a supported compound of formula (XIII'), preferably a resin-supported compound, with a cleavage reagent and optionally a deprotective agent to obtain a compound of formula (I) or a pharmaceutically acceptable salt thereof; During the ceremony, -PG', PG1', PG5', PG6', and PG7' are each independently carboxyl protecting groups; -L' is a linker; -PG2', PG3', and PG4' are each independently amino protecting groups; -R1', R2', and R3' are each independently either H or an activated ester group; -LG' is a leaving group selected from the group consisting of imidazole, halogen, and activated ester groups.

[0111] 16. The method according to Embodiment 15, comprising all steps a') to h').

[0112] 17. The method according to any one of Embodiments 15 to 16, wherein PG', PG1', PG5', PG6', and PG7' are independently selected from the group consisting of benzyl, p-methoxybenzyl (PMB), tert-butyl (t-Bu), methoxymethyl (MOM), methoxyethoxymethyl (MEM), methylthiomethyl (MTM), tetrahydropyranyl (THP), tetrahydrofuranyl (THF), benzyloxymethyl (BOM), trimethylsilyl (TMS), triethylsilyl (TES), t-butyldimethylsilyl (TBDMS), and triphenylmethyl (Trityl, Tr), preferably PG', PG1', PG5', PG6', and PG7' are tert-butyl (t-Bu).

[0113] 18. PG2', PG3', and PG4' are independently t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), allyloxycarbonyl (alloc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl) (Dde), monomethoxytrityl (MMt), 1-(1-adamantyl)-1-methylethoxycarbonyl (Adpoc), N-(1-(4,4-dimethyl-2,6-di) The method according to any one of Embodiments 15 to 17, wherein PG2' is selected from the group consisting of oxocyclohexa-1-ylidene)-3-methylbutyl)(ivDde) ​​and 4-methyltrityl (Mtt), preferably, PG2' is N-(1-(4,4-dimethyl-2,6-dioxocyclohexa-1-ylidene)-3-methylbutyl)(ivDde) ​​or Dde, and PG3' and PG4' are 9-fluorenylmethoxycarbonyl (Fmoc).

[0114] 19. The method according to any one of Embodiments 15 to 18, wherein R1', R2', and R3' are independently selected from the group consisting of H, succinimidyl, p-nitrophenyl, tetrafluorophenyl, 3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl, pentafluorophenyl, and 2,4,5-trichlorophenyl, preferably R1', R2', and R3' are selected from the group consisting of H or succinimidyl.

[0115] 20. The method according to any one of Embodiments 15 to 19, wherein at least one of steps a') to h') is performed using a polar aprotic solvent.

[0116] 21. The method according to Embodiment 20, wherein the polar aprotic solvent is selected from the group consisting of dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dichloromethane (DCM), dichloromethane / dimethylformamide mixture, acetonitrile (ACN), acetonitrile / dimethylformamide mixture, and dimethyl sulfoxide (DMSO), and preferably the solvent is dimethylformamide (DMF).

[0117] 22. The method according to any one of Embodiments 15 to 21, wherein at least one of steps a'), c'), e'), or g') is performed using a coupling agent and / or a base.

[0118] 23. The base is N,N-diisopropylethylamine (DIPEA), N,N-diisopropylethylamine ( i The method according to Embodiment 22, selected from the group consisting of Pr2NEt), triethylamine (TEA), 4-methylmorpholine (NMM), imidazole, pyridine, and colidine.

[0119] 24. The coupling agents are benzotriazole-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (PyBOP), 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate (HATU), 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU), 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU), 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT), and N-[(5-chloro-3-oxide-1H-benzotriazole-1-yl)-4-morpholinylmethylene]-N-methylmethaneaminium The method according to Embodiment 22 or 23, selected from the group consisting of hexafluorophosphate (HDMC), 1-cyano-2-ethoxy-2-oxoethylideneaminooxy)dimethylamino-morpholino-carbenium hexafluorophosphate (COMU), dimethylamino(triazolo[4,5-b]pyridine-3-yloxy)methylidene]-dimethylazanium; tetrafluoroborate (TATU), N,N,N',N'-tetramethyl-S-(1-oxide-2-pyridyl)thiouronium tetrafluoroborate (TOTT), N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), 1-propanephosphonic anhydride (T3P), and 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMTMM).

[0120] 25. The method according to any one of Embodiments 22 to 24, wherein step a') is performed using a base, usually DIPEA; step c') is performed using a coupling agent and a base, usually TBTU and DIPEA; step e') is performed using a coupling agent and a base, usually TBTU and DIPEA; and step g') is performed using a coupling agent and a base, usually PyBOP and DIPEA.

[0121] 26. The method according to any one of Embodiments 15 to 25, wherein the deprotective agent used in step b'), d'), or f') is selected from the group consisting of hydrazine, piperidine, morpholine, 1,8-diazabicyclo[5.4.0]undeca-7-ene (DBU), diethylamine (DEA), dicyclohexamine, 4-methylpiperidine (4MP), tris(2-aminoethyl)amine, pyridine, and colidine, preferably from the group consisting of hydrazine and piperidine.

[0122] 27. The method according to any one of Embodiments 15 to 26, wherein step h') is carried out using an acid, preferably trifluoroacetic acid (TFA) or a trifluoroacetic acid (TFA) / water / triisopropylsilane mixture.

[0123] This disclosure further relates to the use of any one of the compounds defined herein by formulas (II) to (XIII) or (II') to (XIII'), or the compound of formula (I), or a pharmaceutically acceptable salt thereof, as intermediates in a method for synthesizing such compounds. For example, in one embodiment, this disclosure relates to the compound defined herein by formula (II), or a pharmaceutically acceptable salt thereof. In another embodiment, this disclosure relates to the use of the compound defined herein by formula (II), or a pharmaceutically acceptable salt thereof, as an intermediate in a method for synthesizing the compound of formula (I), or a pharmaceutically acceptable salt thereof.

[0124] Similarly, further embodiments of the present disclosure relate to compounds defined by formulas (III), (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII), (XIII), (II'), (III'), (IV'), (V'), (VI'), (VII'), (VIII'), (IX'), (X'), (XI'), (XII'), or (XIII'). In another embodiment, the present disclosure relates to the use of two or more compounds defined herein by any one of formulas (II)-(XIII) or (II')-(XIII'), or pharmaceutically acceptable salts thereof, as intermediates in a method for synthesizing a compound of formula (I) or a pharmaceutically acceptable salt thereof. [Examples]

[0125] All chemicals and solvents were obtained from commercial suppliers and used without purification. Fmoc-L-Lys(ivDde)-Wang PS resin was purchased from Rapp Polymere in Germany. 1,1'-Carbonyldiimidazole was purchased from SAF in Germany. Fmoc-3-(2-naphthyl)-L-alanine (Fmoc-Nal-OH) was purchased from Iris Biotech in Germany. Fmoc-trans-4-aminomethyl)cyclohexanecarboxylic acid (FMOC-AMCHC) was purchased from Iris Biotech in Germany. H-Glu(OtBu)-OtBu×HCl was purchased from Bachem in Switzerland. 3-(3-(((2-(tert-butoxy)-2-oxoethyl)(2-((2-(tert-butoxy)-2-oxoethyl)(5-(3-(tert-butoxy)-3-oxopropyl)-2-hydroxybenzyl)amino)ethyl)amino)methyl)-4-hydroxyphenyl)propanoic acid (DOTA(tBu)3) was purchased from Macrocyclics in the United States or Chematec in France. Fmoc-L-Glu(otbu)-Wang PS resin was purchased from Rapp Polymere in Germany. H-Lys(Fmoc)-OtBu·HCl was purchased from CHI Scientific, Inc. in the United States.

[0126] NMR experiments were performed on a Bruker Avance Neo 500 MHz system.

[0127] PSMA-617 (TFA salt) was synthesized using solid-phase peptide synthesis technology (SPPS) with a semi-automated batch synthesizer via two different synthetic routes.

[0128] [Example 1] PSMA-617 (TFA salt); (((S)-1-carboxy-5-((S)-3-(naphthalene-2-yl)-2-((1r,4S)-4-((2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane-1-yl)acetamide)methyl)cyclohexane-1-carboxamide)propanamide)pentyl)carbamoyl)-L-glutamic acid trifluoroacetate, synthesis of compound [7]

[0129] [ka]

[0130] Synthesis of di-tert-butyl N-(1H-imidazole-1-carbonyl)glutamate building block [3]: Transfer 1,1'-carbonyldiimidazole (CDI) (430 mg; 1.1 equivalents) to a 250 ml round-bottom flask and dissolve in dichloromethane (50 ml). Cool the solution to 0°C and add DIPEA (3.26 ml; 5 equivalents) with stirring. Dissolve H-Glu(OtBu)-OtBu×HCl (714 mg; 1 equivalent) in DCM (20 ml), cool to 0°C, and slowly add to the stirred imidazole solution. Remove the ice bath and stir the reaction mixture at room temperature for 2-3 hours. Monitor the progress of the reaction using in-process control (RP-HPLC; Nucleosil-100 RP-C18, 150 × 4 mm, 5 μm, gradient 15 min for 10-90 min, eluent H2O / ACN 0.1% TFA).

[0131] After confirmation that the conversion was complete, the solution was reduced on a rotary evaporator. The residue was redissolved in DCM and washed with 1M NaHCO3 and water. The organic layer was first concentrated under reduced pressure on a rotary evaporator and then dried on a freeze-dryer. The purity and identity of the building block were confirmed by RP-HPLC Nucleosil-100 RP-C18, 150×4mm, 5μm, gradient 30 min for 10 min to 90 min, eluent H2O / ACN 0.1% TFA (14.4 min, purity 97% @ 215 nm) and Maldi TOF-MS ([M+H]+354.2±1.0) Matrix DHB. This obtained solid was used directly in the next step.

[0132] Construction of PSMA-617 using the SPPS approach: Synthesis of compound [2] 1 g of Fmoc-L-Lys(ivDde)-Wang PS resin ([1], 0.69 mmol / g; 0.69 mmol) was placed in a reaction vessel, and the resin was swollen with 10 ml of DMF. Then, FMOC groups were cleaved from the resin using 3 × 10 ml of 30% piperidine in DMF. After filtering off the cleaved mixture, the resin was washed three times alternately with DMF and i-propanol to remove the piperidine solution. FMOC removal was confirmed by a ninhydrin assay as an in-process control (Lit. Weng C. Chan, Peter D. White; Fmoc Solid Phase Peptide Synthesis. A Practical Approach. Oxford University Press, Oxford / New York 2000).

[0133] Note: Unless otherwise stated, all extension and FMOC deprotection steps are checked by ninhydrin assay as an in-process control.

[0134] Synthesis of compound [4]Glu(otbu)-otBu-ureido-Lys(ivDde)-PS resin A newly prepared building block, di-tert-butyl N-(1H-imidazole-1-carbonyl)-glutamate (855 mg, 3.5 equivalents)[3], is dissolved in 5 ml of DMF, mixed with DIPEA (3.5 equivalents), and added to the resin. The slurry is stirred at room temperature for 1 hour. After filtering off excess di-tert-butyl N-(1H-imidazole-1-carbonyl)-glutamate and reagents, multiple washing steps are performed with DMF and isopropanol (10 ml each, 3 times). Completion of ureid formation is confirmed again by ninhydrin assay.

[0135] Synthesis of compound [5] The resin is treated with 2% hydrazine monohydrate in DMF (3 x 8 ml) to remove iv-Dde from the L-lysine side chain, followed by multiple washing steps with DMF and isopropanol (10 ml each).

[0136] Fmoc-3-(2-naphthyl)-L-alanine (Fmoc-Nal-OH) (905 mg, 3 equivalents) was activated by in-situ active ester formation using a mixture of 3 equivalents of O-benzotriazol-1-yl-N,N,N',N'-tetramethyluronium tetrafluoroborate (TBTU) and 3 equivalents of DIPEA in 5 ml of DMF, and this was added to the resin at room temperature over 1 hour to perform the extension step at the ε-amino group of lysine. As the conversion was incomplete, as shown by the in-process control, double coupling was performed, followed by FMOC cleavage.

[0137] Synthesis of compound [6] Fmoc-4-AMCHC-OH (785 mg, 3 equivalents) was activated by in-situ ester formation using a mixture of 3 equivalents of (TBTU) and 3 equivalents of DIPEA in 5 ml of DMF. This was then added to the resin at room temperature for 1 hour, followed by FMOC cleavage to obtain resin-bound Glu(otbu)-otBu-ureido-Lys(NH2-AMCHC-2-Nal-)-PS resin.

[0138] Synthesis of compound [7] The coupling of 2-(4,7,10-tris(2-(tert-butoxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1-yl)acetic acid (DOTA(tBu)3) (987 mg, 2.5 equivalents) to a resin-bound peptide was performed using a 5 ml solution of (1H-benzotriazole-1-yloxy)tripyrrolidino-phosphonium hexafluorophosphate (PyBOP) (2.5 equivalents) and DIPEA (5 equivalents) in DMF. DOTA binding was confirmed by test cleavage of a small amount of resin-bound peptide, and the cleaved peptide sample was analyzed by HPLC and Maldi-TOF MS.

[0139] Finally, the resin is transferred to a sintered glass funnel, and the resin-bound peptides are thoroughly washed with DMF, ethanol, and diethyl ether, and then dried.

[0140] The peptide was cleaved from the solid support by incubation with 10 ml of the cleavage cocktail TFA:H2O:TIS(94:3:3) at room temperature for 4 hours. After filtering off the resin, the cleavage solution containing the product was cooled, and the peptide solution was added to ice-cold diethyl ether to precipitate the product. The product was isolated by centrifugation, the precipitate was washed with diethyl ether and dried, and finally dissolved in a mixture of 10% acetonitrile in water, and freeze-dried to obtain 670 mg of the crude product as a lyophilized product. The purity of the crude product (42%) was determined by HPLC and Maldi-TOF.

[0141] The product was purified using a preparative RP-HPLC method (RP-18, 10 μm) with water / acetonitrile (0.1% TFA) as the eluent. The product was initially pre-purified using an isocratic gradient of 25% acetonitrile, followed by final purification using a gradient system (20% acetonitrile to 70% acetonitrile @ 225 nm). All fractions meeting the RP-HPLC purity standard (98.0% or higher) were pooled and lyophilized. The total yield was 176 mg of lyophilized material, which was 25% of the theoretical value relative to the resin added.

[0142] The synthetic molecules were analyzed using Nucleosil-100 RP-18, 150×4mm, 5μm; 1mL / min @ UV215nm; solvents A:H2O (0.1% TFA) B:CH3CN (0.1% TFA) with a linear gradient (10%B to 90%B in 30 minutes).

[0143] Calculated value from mass spectrometry (MALDI-MS) (Kratos Axima) for C49H71N9O16: 1041.5 amu. Measured value [M+H+]: 1042.7 m / z.

[0144] The peptide content of the freeze-dried material was determined by elemental analysis using only the N value (theoretical value: C, 56.47; H, 6.87; N, 12.10; O, 24.56) (measured value: 11.6%), and the net content of 96% (w / w) was calculated.

[0145] Furthermore, the presented structure was confirmed by 2D-DQ-COSY, 2D-TOCSY, 2D-ROESY, and 13C-HSQC NMR experiments on a Bruker Avance Neo 500 MHz.

[0146] [Example 2]

[0147] [ka]

[0148] Synthesis of PSMA-617 (TFA salt); (((S)-1-carboxy-5-((S)-3-(naphthalene-2-yl)-2-((1r,4S)-4-((2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane-1-yl)acetamide)methyl)cyclohexane-1-carboxamide)propanamide)pentyl)carbamoyl)-L-glutamic acid trifluoroacetate[7]

[0149] tert-butyl N6-(((9H-fluoren-9-yl)methoxy)carbonyl)-N2-(1H-imidazole-1-carbonyl)lignate (synthesis of building block

[10] : Transfer 1,1'-carbonyldiimidazole (CDI) (481 mg; 4.29 mmol; 1.1 equivalents) to a 250 ml round-bottom flask and dissolve in dichloromethane (50 ml). Cool the solution to 0°C and add DIPEA (5 equivalents) with stirring.

[0150] Dissolve H-Lys(FMOC)-OtBu×HCl (1.24 g; 1 equivalent) in DCM (40 ml), cool to 0°C, and slowly add to the stirred imidazole solution. Remove the ice bath and stir the reaction mixture at room temperature for 3 hours. Monitor the progress of the reaction using in-process control (RP-HPLC; Nucleosil-100 RP-C18, 150 × 4 mm, 5 μm, gradient 15 min for 10 to 90 mins, eluent H2O / ACN 0.1% TFA). After the conversion is complete, reduce the solution on a rotary evaporator. Dissolve the residue in DCM and wash with 1 M NaHCO3 and water. Concentrate the organic layer under reduced pressure on a rotary evaporator, then dry it on a freeze-dryer. The white solid is then used directly for the construction of the ureid compound. Confirm the purity and identity of the building blocks by RP-HPLC and MS. Nucleosil-100 RP-C18, 150×4mm, 5μm, gradient 30 minutes, 10-90 minutes, eluent: H2O / ACN 0.1%TFA; Maldi TOF-MS ([M+H]+354.3±1.0) Matrix DHB.

[0151] Construction of PSMA-617 using the FMOC-SPPS strategy: Synthesis of compound [9]: 1.5 g of Fmoc Glu(t-Bu)Wang resin (0.60 mmol / g)[8] is transferred to a reaction vessel and swollen with 15 ml of DMF. The FMOC group is then cleaved using 30% piperidine in DMF (3 × 15 ml). After removing the piperidine solution by alternating DMF / i-propanol washing steps, the removal of the FMOC group is confirmed by a ninhydrin assay used as an in-process control (Lit. Weng C. Chan, Peter D. White; Fmoc Solid Phase Peptide Synthesis. A Practical Approach. Oxford University Press, Oxford / New York 2000).

[0152] Synthesis of compound

[11] : Freshly prepared N6-(((9H-fluoren-9-yl)methoxy)carbonyl)-N2-(1H-imidazole-1-carbonyl)lignate (1.4 g, 3 equivalents)

[10] is dissolved in 10 ml of DMF, mixed with DIPEA (3.5 equivalents), and added to the resin. The slurry is stirred at room temperature for 1 hour. After filtering off excess reagent, several washing steps are performed with DMF and isopropanol (15 ml each). Completion of the reaction is confirmed by ninhydrin assay.

[0153] Synthesis of compound

[12] : Lys-otbu-ureido-Glu(otbu)-PS resin

[11] ; The FMOC group of the L-Lys side chain is cleaved using 30% piperidine in DMF and after a series of washing steps with DMF / i-propanol / DMF (3 × 10 ml each).

[0154] Fmoc-2-Nal-OH (1.60g, 4 equivalents) is used with O-benzotriazol-1-yl-N,N,N',N'-tetramethyluronium tetrafluoroborate (TBTU×BF4 -A 10 ml solution of DMF containing a mixture of 3 equivalents of ) and 3 equivalents of DIPEA is used to activate in situ active ester formation, which is then added to the resin at room temperature over 1.5 hours to perform the lysine elongation step, followed by the FMOC cleavage step and the continuous washing step.

[0155] Synthesis of compound

[13] : Fmoc-4-trans-AMCHC-OH (1.025 mg, 3 equivalents) is activated by in-situ active ester formation using a mixture of 3 equivalents of TBTU and 3 equivalents of DIPEA in 10 ml of DMF, and added to the resin at room temperature over 1 hour. This is followed by an extension step at the ε-amino group of lysine, and then FMOC cleavage to obtain resin-bound Lys(NH2-trans-4-AMCHC-2-Nal-)ureido-Glu(otbu)PS resin

[13] .

[0156] Synthesis of compound [7]: (DOTA(tBu)3) (1.3g, 2.5 equivalents) is coupled to the resin-bound peptide using a 10ml solution of PyBOP (2.5 equivalents) and DIPEA (5 equivalents) in DMF. Finally, the resin is transferred to a sintered glass funnel, and the resin-bound peptide is thoroughly washed with DMF, ethanol, and diethyl ether, and then dried.

[0157] The peptide is cleaved from the solid support by incubation with 20 ml of the cleavage cocktail TFA:H2O:TIS(94:3:3) at room temperature for 3 hours. The resin is filtered off through a sintered glass funnel and thoroughly washed with small amounts of TFA. The pooled cleavage solution is cooled, and the product is precipitated by slowly adding the peptide solution dropwise into ice-cold diethyl ether. The product is isolated by centrifugation, the precipitate is washed with diethyl ether and dried, dissolved in a mixture of water and acetonitrile, and freeze-dried.

[0158] The product is purified and isolated according to Example 1.

[0159] The total yield, including SPPS and purification, was 22% of the resin added.

[0160] Purity was confirmed by HPLC and Maldi-TOF MS. Identification with the product derived from Example 1 was confirmed by HPLC spike experiment. Furthermore, the present invention includes the following embodiments. [1] A method for synthesizing the compound of formula (I) or a pharmaceutically acceptable salt thereof, using solid-phase synthesis. [ka] [2] The method according to [1], comprising at least one of the following steps: a) A supported compound of formula (II), preferably a resin-supported compound and [ka] By contacting the compound of formula (III) [ka] A step to obtain a supported compound of formula (IV), preferably a resin-supported compound; [ka] b) A step of contacting the supported compound of formula (IV), preferably the resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (V), preferably the resin-supported compound; [ka] c) The supported compound of formula (V), preferably the resin-supported compound, is brought into contact with the compound of formula (VI). [ka] A step to obtain a supported compound of formula (VII), preferably a resin-supported compound; [ka] d) A step of contacting the supported compound of formula (VII), preferably the resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (VIII), preferably the resin-supported compound; [ka] e) The supported compound of formula (VIII), preferably the resin-supported compound, is brought into contact with the compound of formula (IX). [ka] A step to obtain a supported compound of formula (X), preferably a resin-supported compound; [ka] f) A step of contacting the supported compound of formula (X), preferably the resin-supported compound, with a deprotecting agent to obtain a supported compound of formula (XI), preferably the resin-supported compound;

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[10] The method according to any one of the above [8] to [9], wherein PG', PG1', PG5', PG6', and PG7' are independently selected from the group consisting of benzyl, p-methoxybenzyl (PMB), tert-butyl (t-Bu), methoxymethyl (MOM), methoxyethoxymethyl (MEM), methylthiomethyl (MTM), tetrahydropyranyl (THP), tetrahydrofuranyl (THF), benzyloxymethyl (BOM), trimethylsilyl (TMS), triethylsilyl (TES), t-butyldimethylsilyl (TBDMS), and triphenylmethyl (Trityl, Tr), preferably PG', PG1', PG5', PG6', and PG7' are tert-butyl (t-Bu).

[11] PG2', PG3', and PG4' are independently t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), allyloxycarbonyl (alloc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl) (Dde), monomethoxytrityl (MMt), 1-(1-adamantyl)-1-methylethoxycarbonyl (Adpoc), N-(1-(4,4-dimethyl-2,6-di) The method according to any one of the above [8] to

[10] , wherein PG2' is selected from the group consisting of oxocyclohexa-1-ylidene)-3-methylbutyl)(ivDde) ​​and 4-methyltrityl (Mtt), preferably wherein PG2' is N-(1-(4,4-dimethyl-2,6-dioxocyclohexa-1-ylidene)-3-methylbutyl)(ivDde) ​​or Dde, and PG3' and PG4' are 9-fluorenylmethoxycarbonyl (Fmoc).

[12] The method according to any one of the above [8] to

[11] , wherein at least one of the steps a') to h') is carried out using a polar aprotic solvent.

[13] The method according to any one of the above [8] to

[12] , wherein at least one of the steps a'), c'), e'), and g') is performed using a coupling agent and / or a base.

Claims

1. A method for synthesizing a compound of formula (I) or a pharmaceutically acceptable salt thereof using solid-phase synthesis, 【Chemistry 1】 The method includes all of the following steps: a) Supported compound of formula (II) and 【Chemistry 2】 By contacting the compound of formula (III) 【Transformation 3】 Steps to obtain a supported compound of formula (IV); 【Chemistry 4】 b) A step of contacting the supported compound of formula (IV) with a deprotecting agent to obtain the supported compound of formula (V); 【Transformation 5】 c) The supported compound of formula (V) and the compound of formula (VI) are brought into contact. 【Transformation 6】 Steps to obtain a supported compound of formula (VII); 【Transformation 7】 d) A step of contacting the supported compound of formula (VII) with a deprotecting agent to obtain the supported compound of formula (VIII); 【Transformation 8】 e) Contacting the supported compound of formula (VIII) with the compound of formula (IX) 【Chemistry 9】 Steps to obtain a supported compound of formula (X); 【Chemistry 10】 f) A step of contacting the supported compound of formula (X) with a deprotecting agent to obtain the supported compound of formula (XI); 【Chemistry 11】 g) The supported compound of formula (XI) and compound (XII) are brought into contact. 【Chemistry 12】 Steps to obtain a supported compound of formula (XIII); 【Chemistry 13】 h) A step of contacting the supported compound of formula (XIII) with a cleavage reagent and optionally a deprotecting agent to obtain the compound of formula (I) or a pharmaceutically acceptable salt thereof; During the ceremony, -PG, PG1, PG5, PG6, and PG7 are each independently carboxyl protecting groups; -L is the linker; -PG2, PG3, and PG4 are each independently amino protecting groups; -R1, R2, and R3 are each independently H or an activated ester group; -LG is a leaving group selected from the group consisting of imidazole, halogen, and activated ester groups. Each of the activated ester groups is selected from the group consisting of succinimidyl, p-nitrophenyl, tetrafluorophenyl, 3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl, pentafluorophenyl, and 2,4,5-trichlorophenyl. 【Chemistry 14】 It is a solid support.

2. The method according to claim 1, wherein PG, PG1, PG5, PG6, and PG7 are independently selected from the group consisting of benzyl, p-methoxybenzyl (PMB), tert-butyl (t-Bu), methoxymethyl (MOM), methoxyethoxymethyl (MEM), methylthiomethyl (MTM), tetrahydropyranyl (THP), tetrahydrofuranyl (THF), benzyloxymethyl (BOM), trimethylsilyl (TMS), triethylsilyl (TES), t-butyldimethylsilyl (TBDMS), and triphenylmethyl (Trityl, Tr), or PG, PG1, PG5, PG6, and PG7 are tert-butyl (t-Bu).

3. The method according to claim 1 or 2, wherein PG2, PG3, and PG4 are independently selected from the group consisting of t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), allyloxycarbonyl (alloc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl) (Dde), monomethoxytrityl (MMt), 1-(1-adamantyl)-1-methylethoxycarbonyl (Adpoc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexa-1-ylidene)-3-methylbutyl) (ivDde), and 4-methyltrityl (Mtt), or PG2, PG3, and PG4 are 9-fluorenylmethoxycarbonyl (Fmoc).

4. The method according to any one of claims 1 to 3, wherein at least one of the steps a) to h) is carried out using a polar aprotic solvent.

5. The method according to any one of claims 1 to 4, wherein at least one of the steps a), c), e), or g) is performed using a coupling agent and / or a base.

6. A method for synthesizing a compound of formula (I) or a pharmaceutically acceptable salt thereof using solid-phase synthesis, 【Chemistry 15】 The method includes all of the following steps: a') Supported compound of formula (II') and 【Chemistry 16】 By contacting the compound of formula (III') 【Chemistry 17】 Steps to obtain a supported compound of formula (IV'); [Chemistry 18] b') A step of contacting the supported compound of formula (IV') with a deprotecting agent to obtain the supported compound of formula (V'); 【Chemistry 19】 c') The supported compound of formula (V') is brought into contact with the compound of formula (VI') 【Chemistry 20】 Steps to obtain a supported compound of formula (VII'); 【Chemistry 21】 d') A step of obtaining a supported compound of formula (VIII') by contacting the supported compound of formula (VII') with a deprotecting agent; 【Chemistry 22】 e') The supported compound of formula (VIII') is brought into contact with the compound of formula (IX') 【Chemistry 23】 Steps to obtain a supported compound of formula (X'); 【Chemistry 24】 f') A step of obtaining a supported compound of formula (XI') by contacting the supported compound of formula (X') with a deprotecting agent; 【Chemistry 25】 g') The supported compound of formula (XI') and compound (XII') are brought into contact. 【Chemistry 26】 Steps to obtain a supported compound of formula (XIII'); 【Chemistry 27】 h') A step of contacting the supported compound of formula (XIII') with a cleavage reagent and optionally a deprotecting agent to obtain the compound of formula (I) or a pharmaceutically acceptable salt thereof; During the ceremony, -PG', PG1', PG5', PG6', and PG7' are each independently carboxyl protecting groups; -L' is a linker; -PG2', PG3', and PG4' are each independently amino protecting groups; -R1', R2', and R3' are each independently H or an activated ester group; -LG' is a leaving group selected from the group consisting of imidazole, halogen, and activated ester groups. Each of the activated ester groups is selected from the group consisting of succinimidyl, p-nitrophenyl, tetrafluorophenyl, 3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl, pentafluorophenyl, and 2,4,5-trichlorophenyl. 【Chemistry 28】 It is a solid support.

7. The method according to claim 6, wherein PG', PG1', PG5', PG6', and PG7' are independently selected from the group consisting of benzyl, p-methoxybenzyl (PMB), tert-butyl (t-Bu), methoxymethyl (MOM), methoxyethoxymethyl (MEM), methylthiomethyl (MTM), tetrahydropyranyl (THP), tetrahydrofuranyl (THF), benzyloxymethyl (BOM), trimethylsilyl (TMS), triethylsilyl (TES), t-butyldimethylsilyl (TBDMS), and triphenylmethyl (Trityl, Tr), or PG', PG1', PG5', PG6', and PG7' are tert-butyl (t-Bu).

8. PG2', PG3', and PG4' are independently t-butyloxycarbonyl (Boc), 9-fluorenylmethoxycarbonyl (Fmoc), allyloxycarbonyl (alloc), N-(1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl) (Dde), monomethoxytrityl (MMt), 1-(1-adamantyl)-1-methylethoxycarbonyl (Adpoc), N-(1-(4,4-dimethyl-2, The method according to claim 6 or 7, wherein PG2' is selected from the group consisting of 6-dioxocyclohexa-1-ylidene)-3-methylbutyl)(ivDde) ​​and 4-methyltrityl (Mtt), or PG2' is N-(1-(4,4-dimethyl-2,6-dioxocyclohexa-1-ylidene)-3-methylbutyl)(ivDde) ​​or Dde, and PG3' and PG4' are 9-fluorenylmethoxycarbonyl (Fmoc).

9. The method according to any one of claims 6 to 8, wherein at least one of the steps a') to h') is performed using a polar aprotic solvent.

10. The method according to any one of claims 6 to 9, wherein at least one of the steps a'), c'), e'), and g') is performed using a coupling agent and / or a base.

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