WO2020035011A1 - 一种制备 18f-bpa的方法及中间体 - Google Patents

一种制备 18f-bpa的方法及中间体 Download PDF

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WO2020035011A1
WO2020035011A1 PCT/CN2019/100678 CN2019100678W WO2020035011A1 WO 2020035011 A1 WO2020035011 A1 WO 2020035011A1 CN 2019100678 W CN2019100678 W CN 2019100678W WO 2020035011 A1 WO2020035011 A1 WO 2020035011A1
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group
protecting
hydrogen
amino group
boric acid
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PCT/CN2019/100678
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French (fr)
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李世红
何静
蔡飞
闫恒
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南京中硼联康医疗科技有限公司
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Priority to JP2021507794A priority Critical patent/JP7292375B2/ja
Priority to EP19850683.4A priority patent/EP3838890B1/en
Publication of WO2020035011A1 publication Critical patent/WO2020035011A1/zh
Priority to US17/171,224 priority patent/US11655261B2/en
Priority to US18/132,479 priority patent/US20230242555A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F5/00—Compounds containing elements of Groups 3 or 13 of the Periodic Table
    • C07F5/02—Boron compounds
    • C07F5/027—Organoboranes and organoborohydrides
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F5/00—Compounds containing elements of Groups 3 or 13 of the Periodic Table
    • C07F5/02—Boron compounds
    • C07F5/025—Boronic and borinic acid compounds
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B59/00—Introduction of isotopes of elements into organic compounds ; Labelled organic compounds per se
    • C07B59/004—Acyclic, carbocyclic or heterocyclic compounds containing elements other than carbon, hydrogen, halogen, oxygen, nitrogen, sulfur, selenium or tellurium
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C229/00—Compounds containing amino and carboxyl groups bound to the same carbon skeleton
    • C07C229/02—Compounds containing amino and carboxyl groups bound to the same carbon skeleton having amino and carboxyl groups bound to acyclic carbon atoms of the same carbon skeleton
    • C07C229/34—Compounds containing amino and carboxyl groups bound to the same carbon skeleton having amino and carboxyl groups bound to acyclic carbon atoms of the same carbon skeleton the carbon skeleton containing six-membered aromatic rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C249/00—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton
    • C07C249/02—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton of compounds containing imino groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C251/00—Compounds containing nitrogen atoms doubly-bound to a carbon skeleton
    • C07C251/02—Compounds containing nitrogen atoms doubly-bound to a carbon skeleton containing imino groups
    • C07C251/24—Compounds containing nitrogen atoms doubly-bound to a carbon skeleton containing imino groups having carbon atoms of imino groups bound to carbon atoms of six-membered aromatic rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C269/00—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C271/00—Derivatives of carbamic acids, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
    • C07C271/06—Esters of carbamic acids
    • C07C271/08—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms
    • C07C271/10—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms with the nitrogen atoms of the carbamate groups bound to hydrogen atoms or to acyclic carbon atoms
    • C07C271/22—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms with the nitrogen atoms of the carbamate groups bound to hydrogen atoms or to acyclic carbon atoms to carbon atoms of hydrocarbon radicals substituted by carboxyl groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B2200/00—Indexing scheme relating to specific properties of organic compounds
    • C07B2200/05—Isotopically modified compounds, e.g. labelled
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/55—Design of synthesis routes, e.g. reducing the use of auxiliary or protecting groups

Definitions

  • the invention relates to the fields of medicine and chemical synthesis, and in particular, the invention relates to a method for preparing 18 F-BPA and an intermediate thereof.
  • BNCT Boron Neutron Capture Therapy
  • the boron-containing ( 10 B) drug has the characteristics of high capture cross-section for thermal neutrons, and 4 He and 7 Li two heavy-charged particles are generated by the 10 B (n, ⁇ ) 7 Li neutron capture and nuclear fission reaction.
  • the average energy of charged particles is about two 2.33MeV, having a high linear transfer (Linear Energy Transfer, LET), wherein short range, linear energy transfer and range of ⁇ particles were 150keV / ⁇ m, 8 ⁇ m, and heavy charged particles is 7 Li It is 175keV / ⁇ m and 5 ⁇ m.
  • the total range of the two particles is about the size of a cell. Therefore, the radiation damage to the organism can be limited to the cell level.
  • the sub-radiation source can achieve the purpose of locally killing tumor cells without causing much damage to normal tissues.
  • boron neutron capture therapy depends on the concentration of boron-containing drugs and the number of thermal neutrons at the location of tumor cells, it is also known as binary cancer therapy; it can be seen that in addition to the development of neutron sources, The development of boron-containing drugs plays an important role in the research of boron neutron capture therapy.
  • ( 10 B) borono-L-phenylalanine, L- 10 BPA) is a boron-containing drug used in BNCT to treat cancer.
  • Malignant tumors, such as glioblastoma multiforme, melanoma, and other diseases have very good curative effects.
  • BNCT treatment plan needs to be guided by the tumor targeting results of 18 F-BPA (2-fluoro-4-dihydroxyboryl-L-phenylalanine).
  • positron radionuclide 18 F labeled BPA combined with positive Electronic tomography (PET) is used to diagnose brain tumors and other types of solid tumors.
  • CN105916836A discloses a method for producing 2-fluoro-4-dihydroxyboryl-L-phenylalanine and a precursor of 2-fluoro-4-dihydroxyboryl-L-phenylalanine.
  • 18 F ions are used to replace the leaving group on the benzene ring to obtain an 18 F-labeled halogen-substituted phenylalanine compound, and then 18 F-BPA is obtained through a coupling reaction.
  • CN105348309B After 18 F is labeled on the benzene ring, 18 F-BPA is obtained by reacting the aldehyde group on the benzene ring with phenylazolinone.
  • CN102887913B replaces a nitro group on a phenyl ring with an 18 F ion to obtain an 18 F-labeled iodine-substituted phenylalanine compound, and then obtains 18 F-BPA through a coupling reaction.
  • the substitution reaction of borate is performed after 18 F labeling. The reaction steps are many and the preparation time is long.
  • the object of the present invention is to provide a method and an intermediate for preparing 2-fluoro-4-dihydroxyboryl-phenylalanine ( 18 F-BPA, F-BPA).
  • the method for synthesizing 18 F-BPA simplifies the synthetic steps after the 18 F labeling.
  • the method is simple, efficient, high in yield, high in product purity, and improves the radiochemical yield of the synthesis.
  • the 18 F-BPA has a structure:
  • the method includes using Intermediate I, which has a structure
  • R 1 and R 2 are halogens or R 1 and R 2 are boric acid groups or substituents that can be hydrolyzed to boric acid groups; R 3 and R 4 are respectively protecting groups of hydrogen and amino groups or together with amino groups for protecting amino groups R 5 is a protecting group for hydrogen or a carboxyl group.
  • the intermediate I includes intermediates I-1 and I-2,
  • the intermediate I-1 has a structure:
  • the intermediate I-2 has a structure:
  • X 1 and X 2 are halogens, preferably, X 1 and X 2 are chlorine, bromine or iodine; R 10 and R 20 are OH or a boron atom connected to them represents a substitution that can be hydrolyzed to a boric acid group R 3 and R 4 are respectively a protecting group for hydrogen, an amino group, or an imino group for protecting an amino group together with an amino group; R 5 is a protecting group for hydrogen or a carboxyl group.
  • the protective groups for R 3 and R 4 as amino groups include alkoxycarbonyl-based protective groups, acyl-based protective groups, and alkyl-based protective groups.
  • R 3 and R 4 as the protecting group for the amino group further include a substituent selected from the group consisting of benzyloxycarbonyl, tert-butoxycarbonyl, methoxymethoxycarbonyl, allyloxycarbonyl, trimethylsilylethoxycarbonyl, Methyl (or ethyl) oxycarbonyl, phthaloyl, p-toluenesulfonyl, trifluoroacetyl, o- (p-nitro) benzenesulfonyl, pivaloyl, benzoyl, trityl, 2,4 -Dimethoxybenzyl, p-methoxybenzyl, benzyl.
  • the substituent that can be hydrolyzed to a boric acid group is a boric acid ester group. More preferably, the -BR 10 R 20 is a boric acid pinacol ester group. In this application, boron is preferably 10 boron.
  • the protecting group of the carboxyl group includes a substituted or unsubstituted C1-20 alkyl group.
  • the substituent includes phenyl, halogen, nitro, hydroxyl, and methoxy.
  • the protecting group of the carboxyl group is a C1-10 alkyl group, a phenyl group, or a benzyl group.
  • the protecting group of the carboxyl group includes: a substituted or unsubstituted C1-C20 alkyl group; the substituent includes a phenyl group, a halogen group, a nitro group, a hydroxyl group, and a methoxy group; preferably, a C1-C10 alkyl group and a benzene group And benzyl.
  • the protecting group of the carboxyl group further includes: methyl, ethyl, isopropyl, tert-butyl, benzyl, benzyl, p-nitrobenzyl, p-methoxybenzyl, 4-pyridine Benzyl, trichloroethyl, methylthioethyl, p-toluenesulfonylethyl, p-nitrophenylthioethyl, phenyl, benzyl.
  • the intermediate I is selected from the following compounds:
  • the method includes: reacting intermediate I-2 with an 18 F ion to obtain an 18 F substituted compound
  • R 10 and R 20 are OH or the boron atom connected to them represent a substituent that can be hydrolyzed to a boronic acid group;
  • R 3 and R 4 are a protecting group for hydrogen, an amino group, or together with an amino group to protect an amino group. Imino;
  • R 5 is a protecting group for hydrogen or carboxyl.
  • the method further comprises: deprotecting a protecting group in the 18 F substituted compound to obtain the 18 F-BPA
  • the reaction of the intermediate I-2 with the 18 F ion further includes the use of a copper catalyst.
  • the preferred copper catalyst includes Cu (OTf) 2 Py 4 or Cu (OTf) 2 .
  • reaction temperature of the intermediate I-2 and the 18 F ion is 20-150 ° C, preferably 100-130 ° C.
  • the solvent used for the reaction between the intermediate I-2 and the 18 F ion includes water, methanol, DMF, DMA, DMSO, acetonitrile, n-butanol, ethanol, dichloromethane, etc., or any of them. Mixed solvents.
  • intermediate I-1 is reacted with boric acid or a boronic acid ester to obtain intermediate I-2
  • X 1 and X 2 are halogens, preferably, X 1 and X 2 are chlorine, bromine or iodine; R 10 and R 20 are OH or a boron atom connected to them represents a substitution that can be hydrolyzed to a boric acid group R 3 and R 4 are respectively a protecting group for hydrogen, an amino group, or an imino group for protecting an amino group together with an amino group; R 5 is a protecting group for hydrogen or a carboxyl group.
  • the intermediate I-1 is reacted with boric acid or a boric acid ester under the protection of nitrogen.
  • the intermediate I-1 is reacted with boric acid or boric acid ester at 20-100 ° C, preferably 50-100 ° C.
  • the palladium catalyst is not particularly limited.
  • the palladium catalyst is selected from the group consisting of tris (dibenzylideneacetone) dipalladium (Pd 2 (dba) 3 ), tetrakis (triphenylphosphine) palladium (Pd (PPh 3 ) 4 ), palladium acetate , Palladium chloride, bis (triphenylphosphine) palladium, palladium trifluoroacetate, palladium triphenylphosphine acetate, [1,1 ⁇ -bis (diphenylphosphino) ferrocene] palladium dichloride , Bis (tri-o-phenylmethylphosphine) palladium dichloride, 1,2-bis (diphenylphosphino) ethane palladium dichloride, or a combination thereof.
  • the borate is not particularly limited.
  • the borate is selected from the group consisting of pinacol diborate, bicatechol borate, bi (3,3-dimethyl-2,4-pentanediol) borate , Triethanolamine borate, trimethyl borate, triisopropyl borate, triethyl borate, tributyl borate, neopentyl glycol diborate, or a combination thereof.
  • the method further includes: chiral resolving the intermediate I-1 to obtain the compound I-1a in the L configuration and the compound I-1b in the D configuration, and then reacting with the boric acid or the borate, respectively.
  • the method further includes: i) reacting intermediate II with intermediate III to obtain intermediate I-1
  • X 1 , X 2 , and X 3 are each a halogen; preferably, X 1 , X 2 , and X 3 are chlorine, bromine, or iodine; R 3 and R 4 are each independently a hydrogen or amino protecting group or Together with the amino group, it forms an imino group for protecting the amino group; R 5 is a protecting group for hydrogen or a carboxyl group.
  • the intermediate III is The intermediate I-1 is wherein, X 1 and X 2 are halogens, preferably, X 1 and X 2 are chlorine, bromine or iodine; and R 5 is a protecting group of hydrogen or carboxyl.
  • the method further includes: hydrolyzing under acidic conditions to deprotect the amino group in the intermediate I-1, reacting with Boc 2 O under basic conditions, and protecting the intermediate I- with Boc Amino group in 1 gives compound Then, it is reacted with boric acid or boric acid ester.
  • the reaction is preferably performed at room temperature, and R 5 is preferably a C1-10 alkyl group.
  • an intermediate I is provided.
  • the intermediate I has a structure.
  • R 1 and R 2 are halogen or R 1 and R 2 are boric acid groups or substituents that can be hydrolyzed to boric acid groups;
  • R 3 and R 4 are respectively a protecting group for hydrogen and an amino group or an imino group for protecting an amino group together with the amino group;
  • R 5 is a protecting group for hydrogen or a carboxyl group.
  • the intermediate I includes intermediates I-1 and I-2, and the intermediate I-1 has a structure:
  • the intermediate I-2 has a structure:
  • X 1 and X 2 are halogens;
  • B represents boron, preferably 10 boron;
  • R 10 and R 20 are OH or the boron atom connected to them represent substituents that can be hydrolyzed to boric acid groups;
  • R 3 and R 4 are respectively Is a protecting group for hydrogen, an amino group, or an imino group for protecting an amino group together with an amino group;
  • R 5 is a protecting group for hydrogen or a carboxyl group.
  • the hydrolyzable substituent to a boric acid group is a boric acid ester group, preferably a boric acid pinacol ester group;
  • R 3 and R 4 include an alkoxycarbonyl type protecting group, an acyl type protecting group, Alkyl protecting groups;
  • R 5 includes substituted or unsubstituted C1-20 alkyl, preferably t-butyl.
  • the intermediate I is selected from the following compounds:
  • the intermediate I is used for preparing 18 F-BPA, and the 18 F-BPA has a structure:
  • Figure 1 shows N, N-bis (tert-butoxycarbonyl) -2,4-bis (4,4,5,5-tetramethyl-1,3,2-dioxaborane) prepared in Example 6.
  • FIG. 2 is an 18 F-BPA radioactive HPLC spectrum of the present invention
  • FIG. 3 is a radioactive HPLC spectrum of the 18 F-BPA and the standard 19 F-BPA according to the present invention after mixing.
  • the present inventors After extensive and intensive research, the present inventors have prepared an intermediate which can be used for the preparation of 18 F-BPA. boronic acid group ortho to the pinacol ester group is substituted with 18 F, can be obtained 18 F-BPA.
  • the method shortens the steps for preparing 18 F-BPA after 18 F labeling, is simple and efficient, has high yield, high product purity, and improves the radiochemical yield of the synthesis. Based on this, the present invention has been completed.
  • substituent When a substituent is described by a general chemical formula written from left to right, the substituent also includes a chemically equivalent substituent obtained when the structural formula is written from right to left. For example, -CH 2 O- is equivalent to -OCH 2- .
  • halogen refers to fluorine, chlorine, bromine, and iodine.
  • F means fluorine, including both radioactive and non-radioactive fluorine, such as 18 F, 19 F, and preferably 18 F.
  • B refers to boron, boron including radioactive and non-radioactive, preferably 10 B.
  • N means nitrogen.
  • Niro refers to -NO 2 group.
  • Amino refers to the -NH 2 group.
  • Borate refers to the -B (OH) 2 group.
  • alkyl means only composed of carbon atoms and hydrogen atoms, and does not contain unsaturated A straight or branched hydrocarbon chain group having a bond, having, for example, 1 to 10 carbon atoms, and connected to the rest of the molecule through a single bond.
  • alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, and the like.
  • C1-10 alkyl refers to an alkyl group having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, pentyl, and the like.
  • the inert solvent is selected from the group consisting of toluene, benzene, water, methanol, ethanol, isopropanol, ethylene glycol, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran dichloromethane, and chloroform. , 1,2-dichloroethane, acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide, dioxane, or a combination thereof; more preferably, the inert solvent It is a mixed solvent of benzene and water.
  • hydrolyzable to a boronic acid-based substituent means that the substituent can generate a boronic acid group (-B (OH) 2 ) after hydrolysis, such as a boronic acid ester group.
  • the substituent includes, but is not limited to, the following substituents: Preferably it is a boric acid pinacol ester group.
  • the alkoxycarbonyl-based protecting group includes, but is not limited to: benzyloxycarbonyl (Cbz), tert-butoxycarbonyl (Boc), watmethoxycarbonyl (Fmoc), allyloxycarbonyl (Alloc), trimethylsilyl Ethoxycarbonyl (Teoc), methyl (or ethoxy) carbonyl.
  • the acyl protecting group includes, but is not limited to, phthaloyl (Pht), p-toluenesulfonyl (Tos), trifluoroacetyl (Tfa), o- (p-) nitrobenzenesulfonyl (Ns), special Valeryl, benzoyl.
  • the alkyl-based protecting group includes, but is not limited to, trityl (Trt), 2,4-dimethoxybenzyl (Dmb), p-methoxybenzyl (PMB), and benzyl (B
  • protecting group for a carboxyl group refers to a protecting group that forms an ester group, an amide, or a hydrazide with a carboxyl group, and includes, but is not limited to, an alkyl group, a phenyl group, and an alkyl-substituted amino group.
  • alkyl is preferably a linear or branched alkyl group substituted or unsubstituted with a substituent having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, tert-butyl, and diphenyl.
  • optionally or “optionally” means that the event or condition described later may or may not occur, and the description includes both the occurrence or non-occurrence of the event or condition.
  • optionally substituted aryl means that the aryl group is substituted or unsubstituted, and the description includes both a substituted aryl group and an unsubstituted aryl group.
  • Stereoisomers refer to compounds that are composed of the same atom and are bonded by the same bond, but have different three-dimensional structures. All tautomeric forms of the compounds of the invention will also be included within the scope of the invention. “Tautomers” refer to isomers formed by the transfer of a proton from one atom of a molecule to another atom of the same molecule. .
  • the intermediate compounds described in the present invention contain chiral carbon atoms, and thus can produce enantiomers, diastereomers, and other stereoisomeric forms.
  • Each chiral carbon atom can be defined as (R)-or (S)-based on stereochemistry.
  • the invention is intended to include all possible isomers, as well as their racemates and optically pure forms.
  • the compounds of the present invention can be prepared as racemates, diastereomers or enantiomers as raw materials or intermediates.
  • Optically active isomers can be prepared using chiral synthons or chiral reagents, or resolved using conventional techniques, such as crystallization and chiral chromatography.
  • the "intermediate" according to the present invention has two configurations of an L-type phenylalanine structure and a D-type phenylalanine structure, both of which are within the scope of the present invention.
  • a novel method for preparing 18 F-BPA according to the present invention can be obtained through, for example, the following examples, but is not limited to the exemplary methods.
  • the amino group, the carboxyl group protecting group, and the borate group used in the following reaction formula can be appropriately changed, and are not limited to the exemplary methods.
  • the method includes: reacting intermediate I-2 with an 18 F ion to obtain an 18 F substituted compound
  • the reaction temperature may be appropriately selected due to the solvent, starting materials, reagents, and the like, and the reaction time may also be appropriately selected due to the reaction temperature, solvent, starting materials, reagents, and the like.
  • the target compound can be separated and purified from the reaction system according to common methods, such as filtration, extraction, recrystallization, washing, and silica gel column chromatography. Without affecting the next reaction, the target compound can be directly used in the next reaction without isolation and purification.
  • 18 F ion [18 F] F -) can be used for proton beam bombardment H 2 18 O, by the reaction 18 O (p, n), or with Obtained by methods known in the art.
  • 18 F ions were captured on an ion exchange column, eluted with a mixed solution of K2.2.2 / K 2 CO 3 , and used for labeling reaction after being dehydrated and dried.
  • the intermediate I-2 is reacted with 18 F ions, and the mixed solution is purified by a cation column, and then dried and hydrolyzed to remove the amino and carboxyl protecting groups to obtain the 18 F-BPA.
  • the reagents used include hydrogen fluoride and potassium fluoride.
  • the solvent used includes water, methanol, DMF, DMA, DMSO, acetonitrile, n-butanol, ethanol, dichloromethane, etc., or any mixed solvent thereof.
  • the reaction temperature is preferably 20-150 ° C, and more preferably 100-130 ° C.
  • the reaction time is preferably 5 minutes to 1 hour, and more preferably 10 to 30 minutes.
  • water can be azeotropically removed by adding a dry organic solvent.
  • Organic solvents that can be used include, but are not limited to, acetonitrile, dimethylsulfoxide (DMSO), dimethylformamide (DMF), and dimethylethyl Amide (DMA), or any combination thereof.
  • a copper catalyst may be added to the reaction between the intermediate I and the 18 F ion.
  • the copper catalyst that may be used includes, but is not limited to: Cu (OTf) 2 Py 4 , Cu (OTf) 2 , or a combination thereof.
  • the intermediates I and 18 F-BPA according to the present invention include all optical isomers thereof, including isomers having an L configuration phenylalanine structure and phenylalanine having a D configuration. Isomers of acid structure.
  • 18 F-BPA includes 18 FL-BPA having the L configuration phenylalanine structure or 18 FD-BPA having the D configuration phenylalanine structure.
  • the intermediate I can be obtained by chiral resolution to obtain a single configuration compound to participate in the reaction, or it can directly participate in the reaction without resolution to obtain 18 F-BPA.
  • N-diphenylmethylene-glycine tert-butyl ester 40 g, 135.42 mmol, 1 eq
  • 1,4-dibromobenzyl bromide 44.53 g, 135.42 mmol, 1 eq
  • tetrabutylammonium bromide TBAB, 436.55 mg, 1.35 mmol, 0.01 eq
  • TBAB tetrabutylammonium bromide
  • the reaction mixture was diluted with 100 mL of ethyl acetate, and then extracted with 400 mL (200 mL ⁇ 2) of ethyl acetate.
  • the organic phases were mixed, washed with 600 mL (300 mL ⁇ 2) of saturated brine, dried over Na 2 SO 4 , and filtered to obtain a solid.
  • N-Diphenylmethylene-2,4-dibromophenylalanine tert-butyl ester (30g, 55.22mmol, 1eq) was dissolved in THF (70mL), and citric acid (31.83g, 165.66mmol, 31.86mL, 3eq) was added. 20 mL of aqueous solution), and stirred at 25 ° C. for 12 h. Add 50 mL of an aqueous solution of Na 2 CO 3 (29.26 g, 276.10 mmol, 5 eq) and Boc 2 O (13.26 g, 60.74 mmol, 13.95 mL, 1.1 eq), and continue stirring for 4 h.
  • reaction mixture was extracted with 400 mL (200 mL ⁇ 2) of ethyl acetate, and the organic phases were mixed, washed with 400 mL (200 mL ⁇ 2) of saturated brine, dried over Na 2 SO 4 , and filtered to obtain a solid.
  • N-tert-Butoxycarbonyl-2,4-dibromo-phenylalanine tert-butyl ester (7.50 g, 15.6 mmol, 1.00 eq), pinacol diborate (19.8 g, 78.2 mmol, 5.00 eq), KOAc (6.14 g, 62.6 mmol, 4.00 eq), Pd (dppf) Cl 2 (1.15 g, 1.57 mmol, 0.10 eq) and dioxane (75.0 mL) were stirred under nitrogen at 90 ° C. for 1 h.
  • O-tert-butoxycarbonyl-2,4-dibromo-phenylalanine tert-butyl ester (7.00g, 14.6mmol, 1.00eq), pinacol diborate (18.5g, 73.0mmol, 5.00eq), KOAc (5.73 g, 58.4 mmol, 4.00 eq), Pd (dppf) Cl 2 (5.73 g, 58.4 mmol, 4.00 eq) and dioxane (70.0 mL) were stirred under nitrogen at 90 ° C. for 3 h.
  • N-tert-butoxycarbonyl-2,4-dibromo-phenylalanine tert-butyl ester (7.00g, 14.6mmol, 1.00eq), pinacol diborate (18.5g, 73.0mmol, 5.00eq), KOAc (5.73 g, 58.4 mmol, 4.00 eq), Pd (dppf) Cl 2 (5.73 g, 58.4 mmol, 4.00 eq) and dioxane (70.0 mL) were stirred under nitrogen at 90 ° C. for 3 h.
  • H 2 18 O is irradiated with accelerated protons, and 18 F ions are obtained by 18 O (p, n) reaction, which are captured to an ion exchange column, eluted with a K2.2.2 / K 2 CO 3 mixed solution, and dried by dehydration. After the labeling reaction.
  • the compound obtained in Example 5 was reacted with 18 F ions in the presence of Cu (OTf) 2 Py 4 for 15 min in a DMA solution. After the reaction was completed, the mixed solution was purified by a cation column and dried. The reaction was carried out in an HCl solution at 110 ° C. for 10 minutes, and the solution was neutralized by adding NaOH solution, and the amino and carboxyl protecting groups were hydrolyzed and removed to obtain a crude product. Purification of the crude product by HPLC gave 18 F-BPA with a purity higher than 99%.

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  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

提供了一种制备 18F-BPA的方法及中间体，通过所述方法可以得到高纯度的 18F-BPA，简化了在 18F标记之后的合成步骤，操作简单、效率高。

Description

一种制备 18F-BPA的方法及中间体 技术领域
本发明属涉及医药、化学合成领域，具体地，本发明涉及到一种制备 18F-BPA的方法及中间体。
背景技术
恶性肿瘤是严重危害人类健康和生命的重大疾病，目前对恶性肿瘤的治疗主要是通过放射治疗或者化学治疗。硼中子捕获治疗(Boron Neutron Capture Therapy,BNCT)是利用发生在肿瘤细胞内的核反应摧毁癌细胞。利用含硼( 10B)药物对热中子具有高捕获截面的特性，借由 10B(n,α) 7Li中子捕获及核分裂反应产生 4He和 7Li两个重荷电粒子。两荷电粒子的平均能量约为2.33MeV，具有高线性转移(Linear Energy Transfer,LET)、短射程特征，α粒子的线性能量转移与射程分别为150keV/μm、8μm，而 7Li重荷粒子则为175keV/μm、5μm，两粒子的总射程约相当于一个细胞大小，因此对于生物体造成的辐射伤害能局限在细胞层级，当含硼药物选择性地聚集在肿瘤细胞中，搭配适当的中子射源，便能在不对正常组织造成太大伤害的前提下，达到局部杀死肿瘤细胞的目的。因硼中子捕获治疗的成效取决于肿瘤细胞位置含硼药物浓度和热中子数量，故又被称为二元放射线癌症治疗(binary cancer therapy)；由此可知，除了中子源的开发，含硼药物的开发在硼中子捕获治疗的研究中占有重要角色。( 10B)二羟硼基-L-苯丙氨酸(4-( 10B)borono-L-phenylalanine，L- 10BPA)是一种用于BNCT治疗癌症的含硼药物，其对于多种恶性肿瘤，如多行性胶质母细胞瘤(glioblastoma multiforme)、黑色素细胞瘤(melanoma)等疾病具有很好的疗效。BNCT治疗方案的制定需要根据 18F-BPA(2-氟-4-二羟硼基-L-苯丙氨酸)的肿瘤靶向结果指导，使用正电子放射性核素 18F标记的BPA结合正电子断层造影法(PET)来对脑瘤以及其它类型的实体瘤进行诊断。
CN105916836A公开了一种2-氟-4-二羟硼基-L-苯丙氨酸的制造方法和2-氟-4-二羟硼基-L-苯丙氨酸的前体。该专利通过 18F离子取代苯环上的离去基团，得到 18F标记的卤素取代的苯丙氨酸化合物后，再通过偶联反应得到 18F-BPA。CN105348309B在苯环上标记 18F后，通过苯环上的醛基与苯基唑啉酮反应，得到 18F-BPA。CN102887913B通过 18F离子取代苯环上的硝基，得到 18F标记的碘取代的苯丙氨酸化合物后，再通过偶联反应得到 18F-BPA。上述方法均是在 18F标记之后再进行硼酸酯的取代反应，反应步骤多，制备时间长。
由于 18F的半衰期大约为110min，标记 18F之后，如何简化制备步骤、缩短制备时间是一项极具意义和挑战的研究，关系到其合成的放化产率和应用限制。因此开发一种满足临床 需要的简单高效、反应条件温和、产率高的制备方法对于 18F-BPA的应用极为重要。
发明内容
本发明的目的是提供一种制备2-氟-4-二羟基硼基-苯丙氨酸( 18F-BPA，F-BPA)的方法及中间体。所述的合成 18F-BPA的方法，简化了在 18F标记之后的合成步骤，所述方法简单高效，收率高，产物纯度高，提高了其合成的放化产率。
本发明第一方面，提供了一种制备 18F-BPA的方法，所述 18F-BPA具有结构：
Figure PCTCN2019100678-appb-000001
所述方法包括使用中间体I，所述中间体I具有结构
Figure PCTCN2019100678-appb-000002
其中，R 1、R 2为卤素或R 1、R 2为硼酸基或可水解为硼酸基的取代基；R 3、R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；R 5为氢或羧基的保护基。
在另一优选例中，所述中间体I包括中间体I-1和I-2，
所述中间体I-1具有结构：
Figure PCTCN2019100678-appb-000003
所述中间体I-2具有结构：
Figure PCTCN2019100678-appb-000004
其中，X 1、X 2为卤素，优选地，所述X 1、X 2为氯、溴或碘；R 10和R 20为OH或与它们连接的硼原子一起代表可水解为硼酸基的取代基；R 3和R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；R 5为氢或羧基的保护基。
在另一优选例中，所述R 3、R 4作为氨基的保护基包括烷氧羰基类保护基、酰基类保护基、烷基类保护基。优选地，R 3、R 4作为氨基的保护基还包括选自下组的取代基：苄氧羰基、叔丁氧羰基、笏甲氧羰基、烯丙氧羰基、三甲基硅乙氧羰基、甲(或乙)氧羰基、邻苯二甲酰 基、对甲苯磺酰基、三氟乙酰基、邻(对)硝基苯磺酰基、特戊酰基、苯甲酰基、三苯甲基、2,4-二甲氧基苄基、对甲氧基苄基、苄基。
在另一优选例中，R 3和R 4作为氨基的保护基一起与N形成C＝N键；优选地，-NR 3R 4为
Figure PCTCN2019100678-appb-000005
在另一优选例中，所述可水解为硼酸基的取代基为硼酸酯基。更优选地，所述-BR 10R 20为硼酸频哪醇酯基。本申请中硼优选为 10硼。
在另一优选例中，所述羧基的保护基包括：取代或未取代的C1-20烷基。所述取代基包括苯基、卤素、硝基、羟基、甲氧基。优选地，所述羧基的保护基为C1-10烷基、苯基、苄基。优选地，所述羧基的保护基包括：取代或未取代的C1-C20烷基；所述取代基包括苯基、卤素、硝基、羟基、甲氧基；优选为C1-C10烷基、苯基、苄基。优选地，所述羧基的保护基还包括：甲基、乙基、异丙基、叔丁基、二苯甲基、苄基、对硝基苄基、对甲氧基苄基、4-吡啶苄基、三氯乙基、甲基硫代乙基、对甲苯磺酰乙基、对硝基苯基硫代乙基、苯基、苄基。
在另一优选例中，所述中间体I选自下列化合物：
Figure PCTCN2019100678-appb-000006
在另一优选例中，所述方法包括：将中间体I-2与 18F离子反应得到 18F取代的化合物
Figure PCTCN2019100678-appb-000007
其中，R 10和R 20为OH或与它们连接的硼原子一起代表可水解为硼酸基的取代基；R 3和R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；R 5为氢或羧基的保护基。
在另一优选例中，所述方法还包括：脱保护所述 18F取代的化合物中的保护基，得到所述 18F-BPA
Figure PCTCN2019100678-appb-000008
在另一优选例中，所述中间体I-2与 18F离子反应还包括使用铜催化剂，优选的铜催化剂包括Cu(OTf) 2Py 4或Cu(OTf) 2。
在另一优选例中，所述中间体I-2与 18F离子反应温度为20-150℃，优选为100-130℃。
在另一优选例中，所述中间体I-2与 18F离子反应所使用的溶剂包括水、甲醇、DMF、DMA、DMSO、乙腈、正丁醇、乙醇、二氯甲烷等，或其任意的混合溶剂。
在另一优选例中，中间体I-1与硼酸或硼酸酯反应得到中间体I-2
Figure PCTCN2019100678-appb-000009
其中，X 1、X 2为卤素，优选地，所述X 1、X 2为氯、溴或碘；R 10和R 20为OH或与它们连接的硼原子一起代表可水解为硼酸基的取代基；R 3和R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；R 5为氢或羧基的保护基。
在另一优选例中，所述中间体I-1与硼酸或硼酸酯在氮气保护下反应。
在另一优选例中，所述中间体I-1与硼酸或硼酸酯在20-100℃条件下反应，优选地为50-100℃。
所述钯催化剂没有特别的限制。优选地，所述钯催化剂选自下组：三(二亚苄基丙酮)二 钯(Pd 2(dba) 3)、四(三苯基膦)钯(Pd(PPh 3) 4)、醋酸钯、氯化钯、二氯二(三苯基膦)钯、三氟醋酸钯、三苯基膦醋酸钯、[1,1`-双(二苯基膦基)二茂铁]二氯化钯、双(三邻苯甲基膦)二氯化钯、1,2-二(二苯基膦基)乙烷二氯化钯，或其组合物。
所述的硼酸酯没有特别的限制。优选地，所述硼酸酯选自下组：联硼酸频哪醇酯、联邻苯二酚硼酸酯、联(3,3-二甲基-2,4-戊二醇)硼酸酯、三乙醇胺硼酸酯、硼酸三甲酯、硼酸三异丙酯、硼酸三乙酯、硼酸三丁酯、联硼酸新戊二醇酯，或其组合。
在另一优选例中，所述方法还包括：将中间体I-1经手性拆分得到L构型的化合物I-1a和D构型的化合物I-1b，再分别与硼酸或硼酸酯反应
Figure PCTCN2019100678-appb-000010
在另一优选例中，所述方法还包括：i)中间体II与中间体III反应得到中间体I-1
Figure PCTCN2019100678-appb-000011
其中，X 1、X 2、X 3分别为卤素；优选地，所述X 1、X 2、X 3为氯、溴或碘；R 3和R 4各自独立地为氢或氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；R 5为氢或羧基的保护基。
在另一优选例中，所述中间体III为
Figure PCTCN2019100678-appb-000012
所述中间体I-1为
Figure PCTCN2019100678-appb-000013
其中，X 1、X 2为卤素，优选地，所述X 1、X 2为氯、溴或碘；R 5为氢或羧基的保护基。
在另一优选例中，所述方法还包括：在酸性条件下水解从而脱保护所述中间体I-1中的氨基，与Boc 2O在碱性条件下反应，用Boc保护中间体I-1中的氨基得到化合物
Figure PCTCN2019100678-appb-000014
后，再与硼酸或硼酸酯反应，所述反应优选在室温下反应，优选的R 5为C1-10的烷基。
本发明第二方面，提供了一种中间体I，所述中间体I具有结构
Figure PCTCN2019100678-appb-000015
其中
R 1、R 2为卤素或R 1、R 2为硼酸基或可水解为硼酸基的取代基；
R 3、R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；
R 5为氢或羧基的保护基。
在另一优选例中，所述中间体I包括中间体I-1和I-2，所述中间体I-1具有结构：
Figure PCTCN2019100678-appb-000016
所述中间体I-2具有结构：
Figure PCTCN2019100678-appb-000017
其中，X 1、X 2为卤素；B表示硼，优选为 10硼；R 10和R 20为OH或与它们连接的硼原子一起代表可水解为硼酸基的取代基；R 3和R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；R 5为氢或羧基的保护基。
在另一优选例中，所述可水解为硼酸基的取代基为硼酸酯基，优选为硼酸频哪醇酯基；R 3和R 4包括烷氧羰基类保护基、酰基类保护基、烷基类保护基；R 5包括取代或未取代的C1-20烷基，优选为叔丁基。
在另一优选例中，所述中间体I选自下列化合物：
Figure PCTCN2019100678-appb-000018
本发明第三方面，提供了一种如第二方面所述中间体I的用途，所述中间体I用于制备 18F-BPA，所述 18F-BPA具有结构：
Figure PCTCN2019100678-appb-000019
应理解，在本发明范围内，本发明的上述各技术特征和在下文(如实施例)中具体描述的各技术特征之间都可以互相组合，从而构成新的或优选的技术方案。限于篇幅，在此不再一一累述。
附图说明
图1为实施例6制备的N,N-二(叔丁氧羰基)-2,4-二(4,4,5,5-四甲基-1,3,2-二氧杂硼烷-2-基)-苯丙氨酸叔丁酯的氢谱；
图2为本发明所述 18F-BPA放射性HPLC图谱；
图3为本发明所述 18F-BPA与标准品 19F-BPA混合后放射性HPLC图谱。
具体实施方式
本发明人经过广泛而深入地研究，制备了一种可用于制备 18F-BPA的中间体，所述中间体包括了双硼酸频哪醇酯基取代的苯丙氨酸中间体，通过将丙氨酸基团邻位的硼酸频哪醇酯基取代为 18F，可以得到 18F-BPA。所述方法缩短了在 18F标记后的制备 18F-BPA的步骤，简单高效，收率高，产物纯度高，提高了其合成的放化产率。在此基础上，完成了本发明。
术语
除非另有定义，否则本文所有科技术语具有的涵义与权利要求主题所属领域技术人员通常理解的涵义相同。除非另有说明，本文全文引用的所有专利、专利申请、公开材料通过引用方式整体并入本文。
应理解，上述简述和下文的详述为示例性且仅用于解释，而不对本发明主题作任何限制。在本申请中，除非另有具体说明，否则使用单数时也包括复数。必须注意，除非文中另有清楚的说明，否则在本说明书和权利要求书中所用的单数形式包括所指事物的复数形式。还应注意，除非另有说明，否则所用“或”、“或者”表示“和/或”。此外，所用术语“包括”以及其它形式，例如“包含”、“含”和“含有”并非限制性。
当通过从左向右书写的常规化学式描述取代基时，该取代基也同样包括从右向左书写结构式时所得到的在化学上等同的取代基。举例而言，-CH 2O-等同于-OCH 2-。
本文所用的章节标题仅用于组织文章的目的，而不应被解释为对所述主题的限制。本申请中引用的所有文献或文献部分包括但不限于专利、专利申请、文章、书籍、操作手册和论文，均通过引用方式整体并入本文。
除前述以外，当用于本申请的说明书及权利要求书中时，除非另外特别指明，否则以下术语具有如下所示的含义。
在本申请中，术语“卤素”是指氟、氯、溴、碘。“F”指氟，包括具有放射性和非放射性的氟，如 18F、 19F，优选为 18F。“B”指硼，包括具有放射性和非放射性的硼，优选为 10B。“N”指氮。“硝基”指-NO 2基团。“氨基”指-NH 2基团。“硼酸基”指-B(OH) 2基团。
在本申请中，作为基团或是其它基团的一部分(例如用在卤素取代的烷基等基团中)，术语“烷基”意指仅由碳原子和氢原子组成、不含不饱和键、具有例如1至10个碳原子且通过单键与分子的其余部分连接的直链或支链的烃链基团。烷基的实例包括但不限于甲基、乙基、正丙基、异丙基、正丁基等。术语“C1-10烷基”是指具有1-10个碳原子的烷基，例如甲基、乙基、丙基、异丙基、戊基等。
优选地，所述惰性溶剂选自下组：甲苯、苯、水、甲醇、乙醇、异丙醇、乙二醇、N-甲基吡咯烷酮、二甲基亚砜、四氢呋喃二氯甲烷、三氯甲烷、1,2-二氯乙烷、乙腈、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺、二氧六环，或其组合物；更优选地，所述惰性溶剂为苯和水的混合溶剂。
术语“可水解为硼酸基的取代基”表示该取代基在水解后可以生成硼酸基(-B(OH) 2)，例如硼酸酯基，该取代基包括但不限于下列取代基：
Figure PCTCN2019100678-appb-000020
Figure PCTCN2019100678-appb-000021
优选地为硼酸频哪醇酯基。
在本发明中，R 3和R 4作为氨基的保护基可以分别为保护基，包括但不限于烷氧羰基类保护基、酰基类保护基、烷基类保护基；R 3和R 4也可以与N形成亚胺(C＝N)来保护氨基，例如
Figure PCTCN2019100678-appb-000022
以上两种保护基形式都应当在本发明所述的“氨基的保护基”的理解范围内。其中，所述烷氧羰基类保护基包括但不限于：苄氧羰基(Cbz)、叔丁氧羰基(Boc)、笏甲氧羰基(Fmoc)、烯丙氧羰基(Alloc)、三甲基硅乙氧羰基(Teoc)、甲(或乙)氧羰基。所述酰基类保护基包括但不限于：邻苯二甲酰基(Pht)、对甲苯磺酰基(Tos)、三氟乙酰基(Tfa)、邻(对)硝基苯磺酰基(Ns)、特戊酰基、苯甲酰基。所述烷基类保护基包括但不限于：三苯甲基(Trt)、2,4-二甲氧基苄基(Dmb)、对甲氧基苄基(PMB)、苄基(Bn)。
术语“羧基的保护基”是指与羧基形成酯基、酰胺或酰肼的保护基团，包括但不限于烷基、苯基、烷基取代的氨基。其中，“烷基”优选为具有1-20个碳原子的取代基取代或未取代的直链或含支链的烷基，例如甲基、乙基、异丙基、叔丁基、二苯甲基、苄基、对硝基苄基、对甲氧基苄基、4-吡啶苄基、三氯乙基、甲基硫代乙基、对甲苯磺酰乙基、对硝基苯基硫代乙基等。
在本申请中，“任选的”或“任选地”表示随后描述的事件或状况可能发生也可能不发生，且该描述同时包括该事件或状况发生和不发生的情况。例如，“任选地被取代的芳基”表示芳基被取代或未被取代，且该描述同时包括被取代的芳基与未被取代的芳基。
本发明将涵盖各种立体异构体及其混合物，“立体异构体”是指由相同原子组成，通过相同的键键合，但具有不同三维结构的化合物。本发明的化合物的所有互变异构形式也将包含在本发明的范围内，“互变异构体”是指质子从分子的一个原子转移至相同分子的另一个原子而形成的异构体。
本发明所述的中间体化合物含有手性碳原子，且因此可产生对映异构体、非对映异构体及其它立体异构形式。每个手性碳原子可以基于立体化学而被定义为(R)-或(S)-。本发明旨在包括所有可能的异构体，以及其外消旋体和光学纯形式。本发明的化合物的制备可以选择外消旋体、非对映异构体或对映异构体作为原料或中间体。光学活性的异构体可以使用手性合成子或手性试剂来制备，或者使用常规技术进行拆分，例如采用结晶以及手性色谱等方法。本发明所述的“中间体”具有L型苯丙氨酸结构和D型苯丙氨酸结构两种构型，均在本发明所要保护的范围内。
18F-BPA的制备方法
本发明所述的一种新的 18F-BPA的制备方法，例如可通过如下示例得到，但并不限于示例方法。在下述反应式中使用的氨基、羧基的保护基团以及硼酸酯基团可以适当变更，并不限于示例方法。
所述方法包括：将中间体I-2与 18F离子反应得到 18F取代的化合物
Figure PCTCN2019100678-appb-000023
脱保护所述 18F取代的化合物中的保护基，如将氨基、羧基的保护基和硼酸酯基水解，得到所述 18F-BPA
Figure PCTCN2019100678-appb-000024
各步骤的反应，反应温度可因溶剂、起始原料、试剂等适宜选择，反应时间也可因反应温度、溶剂、起始原料、试剂等适宜选择。各步骤反应结束后，目标化合物可按常用方法自反应体系中进行分离、提纯等步骤，如过滤、萃取、重结晶、洗涤、硅胶柱层析等方法。在不影响下一步反应的情况下，目标化合物也可不经过分离、纯化直接进入下一步反应。
在中间体I合成 18F-BPA的步骤中，所使用的 18F离子([ 18F]F -)可以用质子束轰击H 2 18O，通过 18O(p,n)反应得到，或者利用本领域已知的方法获得。使 18F离子俘获到离子交换柱上，用K2.2.2/K 2CO 3混合溶液洗脱，经过除水干燥后用于标记反应。将中间体I-2与 18F离子反应，将混合溶液经阳离子柱纯化后，干燥，水解脱去氨基和羧基的保护基团得到所述 18F-BPA。所使用的试剂包括氟化氢、氟化钾。所使用的溶剂包括水、甲醇、DMF、DMA、DMSO、乙腈、正丁醇、乙醇、二氯甲烷等，或其任意的混合溶剂。反应温度优选地为20-150℃，更优选为100-130℃。反应时间优选为5分钟-1小时，更优选为10-30分钟。所述除水干燥可以通过加入干燥的有机溶剂共沸去除水，可以使用的有机溶剂包括但不限于：乙腈、二甲亚砜(DMSO)、二甲基甲酰胺(DMF)、二甲基乙酰胺(DMA)，或其任意的组合溶剂。在优选的实施方案中，中间体I与 18F离子反应可以加入铜催化剂，可以使用的铜催化剂包括但不限于：Cu(OTf) 2Py 4、Cu(OTf) 2，或其组合。
需要注意的是，本发明所述的中间体I以及 18F-BPA均包括其全部的光学异构体，包括具有L构型苯丙氨酸结构的异构体和具有D构型苯丙氨酸结构的异构体。比如， 18F-BPA包括了具有L构型苯丙氨酸结构的 18F-L-BPA或D构型苯丙氨酸结构 18F-D-BPA。在本发明所述的制备方法中，中间体I可以经过手性拆分得到单一构型的化合物参与反应，也可以未经拆分直接参与反应，得到 18F-BPA。
以下结合具体实施例，进一步说明本发明。需理解，以下的描述仅为本发明的最优选实施方式，而不应当被认为是对于本发明保护范围的限制。在充分理解本发明的基础上，下列实施例中未注明具体条件的实验方法，通常按照常规条件，或按照制造厂商所建议的条件，本领域技术人员可以对本发明的技术方案作出非本质的改动，这样的改动应当被视为包括于本发明的保护范围之中的。除非另外说明，否则百分比和份数是重量百分比和重量份数。
实施例1 制备N-二苯亚甲基-2,4-二溴苯丙氨酸叔丁酯
将N-二苯亚甲基-甘氨酸叔丁酯(40g,135.42mmol,1eq)、1,4-二溴苄基溴(44.53g,135.42mmol,1eq)、四丁基溴化铵(TBAB,436.55mg,1.35mmol,0.01eq)溶于300mL甲苯，加入80mL氢氧化钾(100.00g,1.78mol,13.16eq)水溶液。在25℃下搅拌12小时至反应完全。反应混合物用100mL乙酸乙酯稀释，然后用400mL(200mL×2)乙酸乙酯萃取，混合有机相，并用600mL(300mL×2)饱和食盐水洗涤，Na 2SO 4干燥，过滤得到固体物。将粗产物通过柱层析(石油醚/乙酸乙酯＝100:1-20:1)分离，得到15g的产物。
LCMS:MS(M+H +)＝544.0
1H NMR:400MHz,CDCl 3
δ7.56-7.46(m,3H),7.35-7.16(m,7H),7.01(d,J＝8.2Hz,1H),6.59(br d,J＝6.8Hz,2H),4.23(dd,J＝4.2,9.5Hz,1H),3.31(dd,J＝4.0,13.4Hz,1H),3.11(dd,J＝9.6,13.5Hz,1H),1.41-1.28(m,9H)。
Figure PCTCN2019100678-appb-000025
实施例2 制备N-叔丁氧羰基-2,4-二溴苯丙氨酸叔丁酯
N-二苯亚甲基-2,4-二溴苯丙氨酸叔丁酯(30g,55.22mmol,1eq)溶于THF(70mL)，加入柠檬酸(31.83g,165.66mmol,31.86mL,3eq)的水溶液20mL，25℃下搅拌12h。加入Na 2CO 3(29.26g,276.10mmol,5eq)的水溶液50mL和Boc 2O(13.26g,60.74mmol,13.95mL,1.1eq)，继续搅拌4h。待反应完成后，反应混合物用400mL(200mL×2)乙酸乙酯萃取，混合有机相，并用400mL(200mL×2)饱和食盐水洗涤，Na 2SO 4干燥，过滤得到固体物。将粗产物通过柱层析(石油醚/乙酸乙酯＝100:1-10:1)分离，得到19.6g的产物，收率73.48％，纯度99.2％。
LCMS:MS(M-155 +)＝323.9
1H NMR:400MHz,CDCl 3
δ7.72(d,J＝1.5Hz,1H,7.37(dd,J＝1.8,8.1Hz,1H),7.13(br d,J＝8.1Hz,1H),5.06(br d,J＝8.3Hz,1H),4.59-4.38(m,1H),3.23(dd,J＝5.9,13.9Hz,1H),3.00(br dd,J＝8.6,13.8Hz,1H),1.40(br d,J＝16.6Hz,17H)。
Figure PCTCN2019100678-appb-000026
实施例3 手性拆分N-叔丁氧羰基-2,4-二溴苯丙氨酸叔丁酯
19.6g的N-叔丁氧羰基-2,4-二溴苯丙氨酸叔丁酯通过SFC分离(色谱柱：DAICEL CHIRALPAK AY(250mm*50mm,10um)；流动相:[0.1％NH 3H 2O MEOH])，得到9.1g产物，收率46.84％,纯度97.8％；和9.2g产物，收率48.18％,纯度99.5％。
Figure PCTCN2019100678-appb-000027
实施例4
制备N-叔丁氧羰基-2,4-二(4,4,5,5-四甲基-1,3,2-二氧杂硼烷-2-基)-苯丙氨酸叔丁酯
N-叔丁氧羰基-2,4-二溴-苯丙氨酸叔丁酯(7.50g,15.6mmol,1.00eq),联硼酸频那醇酯(19.8g,78.2mmol,5.00eq),KOAc(6.14g,62.6mmol,4.00eq),Pd(dppf)Cl 2(1.15g,1.57mmol,0.10eq)和二氧六环(75.0mL)在90℃氮气保护下搅拌1h。待反应完成后，过滤，加入200mL的水，用反应混合物用300mL(100mL×3)乙酸乙酯萃取，混合有机相，并用200mL(100mL×2)饱和食盐水洗涤，Na 2SO 4干燥，过滤得到固体物。将粗产物通过HPLC纯化，得到6.5g的产物，纯度96.3％。
LCMS:MS(M+H +-156)＝418.0
1H NMR:400MHz,CDCl 3
8.24(s,1H),7.84(d,J＝7.6,1H),7.30(d,J＝7.6,1H),5.90(d,J＝8.4,1H),4.24-4.19(m,1H),3.24-3.19(m,2H),1.47(s,9H),1.39(s,12H),1.34(s,12H),1.32(s,9H).
Figure PCTCN2019100678-appb-000028
实施例5
制备N-叔丁氧羰基-2,4-二(4,4,5,5-四甲基-1,3,2-二氧杂硼烷-2-基)-苯丙氨酸叔丁酯
O-叔丁氧羰基-2,4-二溴-苯丙氨酸叔丁酯(7.00g,14.6mmol,1.00eq),联硼酸频那醇酯(18.5g,73.0mmol,5.00eq),KOAc(5.73g,58.4mmol,4.00eq),Pd(dppf)Cl 2(5.73g,58.4mmol,4.00eq)和二氧六环(70.0mL)在90℃氮气保护下搅拌3h。待反应完成后，过滤，加入200mL的水，用反应混合物用300mL(100mL×3)乙酸乙酯萃取，混合有机相，并用200mL(100mL×2)饱和食盐水洗涤，Na 2SO 4干燥，过滤得到固体物。将粗产物通过HPLC纯化，得到5.37g的产物，纯度97.35％。
LCMS:MS(M-100-55+H +):418.3
1HNMR:400MHz,CDCl 3
δ1.31-1.35(m,21H),1.39(s,12H),1.47(s,9H),3.16-3.29(m,2H),4.19-4.26(m,1H),5.89(br d,J＝8.40Hz,1H),7.30(d,J＝8.00Hz,1H),7.84(dd,J＝7.60,1.47Hz,1H),8.24(s,1H)
Figure PCTCN2019100678-appb-000029
实施例6
制备N,N-二(叔丁氧羰基)-2,4-二(4,4,5,5-四甲基-1,3,2-二氧杂硼烷-2-基)-苯丙氨酸叔丁酯
N-叔丁氧羰基-2,4-二溴-苯丙氨酸叔丁酯(7.00g,14.6mmol,1.00eq),联硼酸频那醇酯(18.5g,73.0mmol,5.00eq),KOAc(5.73g,58.4mmol,4.00eq),Pd(dppf)Cl 2(5.73g,58.4mmol,4.00eq)和二氧六环(70.0mL)在90℃氮气保护下搅拌3h。待反应完成后，过滤，加入200mL的水，用反应混合物用300mL(100mL×3)乙酸乙酯萃取，混合有机相，并用200mL(100mL×2)饱和食盐水洗涤，Na 2SO 4干燥，过滤得到固体物。将粗产物通过HPLC纯化，得到5.37g的产物，纯度97.35％。氢谱参见图1。
Figure PCTCN2019100678-appb-000030
实施例7
制备 18F-BPA
对H 2 18O照射加速的质子，通过 18O(p,n)反应得到 18F离子，使其俘获到离子交换柱，用K2.2.2/K 2CO 3混合溶液洗脱，经过除水干燥后用于标记反应。将实施例5中得到化合物在DMA溶液中与 18F离子在Cu(OTf) 2Py 4存在下反应15min，待反应完成后，将混合溶液经阳离子柱纯化，干燥。在HCl溶液中110℃下反应10min，加入NaOH溶液中和，水解脱去氨基和羧基的保护基团得到粗产品。将粗产品通过HPLC纯化可以得到纯度高于99％的 18F-BPA。
放射性HPLC谱图参见图2。将产物与少量标准品 19F-BPA混合，共同注射入HPLC中，相同条件下在保留时间(保留时间11min±1min)位置出峰，证明标记产物是 18F-BPA，参见图3。
Figure PCTCN2019100678-appb-000031
采用上述相同的制备方法，通过实施例6中得到的化合物制备 18F-BPA，同样可以得到纯度高于99％的 18F-BPA。
Figure PCTCN2019100678-appb-000032
在本发明提及的所有文献都在本申请中引用作为参考，就如同每一篇文献被单独引用作 为参考那样。此外应理解，在阅读了本发明的上述讲授内容之后，本领域技术人员可以对本发明作各种改动或修改，这些等价形式同样落于本申请所附权利要求书所限定的范围。

Claims (15)

  1. 一种制备 18F-BPA的方法，所述 18F-BPA具有结构：
    Figure PCTCN2019100678-appb-100001
    其特征在于，所述方法包括使用中间体I，所述中间体I具有结构
    Figure PCTCN2019100678-appb-100002
    其中，R 1、R 2为卤素或R 1、R 2为硼酸基或可水解为硼酸基的取代基；
    R 3、R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；
    R 5为氢或羧基的保护基。
  2. 如权利要求1所述的方法，其特征在于，所述中间体I包括中间体I-1和I-2，
    所述中间体I-1具有结构：
    Figure PCTCN2019100678-appb-100003
    所述中间体I-2具有结构：
    Figure PCTCN2019100678-appb-100004
    其中，X 1、X 2为卤素，优选地，所述X 1、X 2为氯、溴或碘；
    R 10和R 20为OH或与它们连接的硼原子一起代表可水解为硼酸基的取代基；
    R 3和R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；
    R 5为氢或羧基的保护基。
  3. 其如权利要求1或2所述的方法，特征在于，所述中间体I选自下列化合物：
    Figure PCTCN2019100678-appb-100005
    Figure PCTCN2019100678-appb-100006
  4. 如权利要求2所述的方法，其特征在于，所述方法包括：
    将中间体I-2与 18F离子反应得到 18F取代的化合物
    Figure PCTCN2019100678-appb-100007
    其中，R 10和R 20为OH或与它们连接的硼原子一起代表可水解为硼酸基的取代基；
    R 3和R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；
    R 5为氢或羧基的保护基。
  5. 如权利要求3所述的方法，其特征在于，所述方法还包括：脱保护所述 18F取代的化合物中的保护基，得到所述 18F-BPA
    Figure PCTCN2019100678-appb-100008
  6. 如权利要求3所述的方法，其特征在于，所述中间体I-2与 18F离子反应还包括使用铜催化剂，优选的铜催化剂包括Cu(OTf) 2Py 4或Cu(OTf) 2。
  7. 如权利要求3所述的方法，其特征在于，所述中间体I-2与 18F离子反应温度为20-150℃，优选为100-130℃。
  8. 如权利要求3所述的方法，其特征在于，所述中间体I-2与 18F离子反应所使用的溶剂包括水、甲醇、DMF、DMA、DMSO、乙腈、正丁醇、乙醇、二氯甲烷等，或其任意的混合溶剂。
  9. 如权利要求2所述的方法，其特征在于，中间体I-1与硼酸或硼酸酯反应得到中间体I-2
    Figure PCTCN2019100678-appb-100009
    其中，X 1、X 2为卤素，优选地，所述X 1、X 2为氯、溴或碘；
    R 10和R 20为OH或与它们连接的硼原子一起代表可水解为硼酸基的取代基；
    R 3和R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；
    R 5为氢或羧基的保护基。
  10. 如权利要求9所述的方法，其特征在于，所述方法还包括：将中间体I-1经手性拆分后，再分别与硼酸或硼酸酯反应。
  11. 一种中间体I，其特征在于，所述中间体I具有结构
    Figure PCTCN2019100678-appb-100010
    其中
    R 1、R 2为卤素或R 1、R 2为硼酸基或可水解为硼酸基的取代基；
    R 3、R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；
    R 5为氢或羧基的保护基。
  12. 如权利要求11所述的中间体I，其特征在于，所述中间体I包括中间体I-1和I-2，
    所述中间体I-1具有结构：
    Figure PCTCN2019100678-appb-100011
    所述中间体I-2具有结构：
    Figure PCTCN2019100678-appb-100012
    其中，
    X 1、X 2为卤素；
    B表示硼，优选为 10硼；
    R 10和R 20为OH或与它们连接的硼原子一起代表可水解为硼酸基的取代基；
    R 3和R 4分别为氢、氨基的保护基或与氨基共同形成用于保护氨基的亚氨基；
    R 5为氢或羧基的保护基。
  13. 如权利要求11或12所述的中间体I，其特征在于，所述可水解为硼酸基的取代基为硼酸酯基，优选为硼酸频哪醇酯基；R 3和R 4包括烷氧羰基类保护基、酰基类保护基、烷基类保护基；R 5包括取代或未取代的C1-20烷基，优选为叔丁基。
  14. 如权利要求11所述的中间体I，其特征在于，所述中间体I选自下列化合物：
    Figure PCTCN2019100678-appb-100013
  15. 如权利要求11或12所述的中间体I的用途，其特征在于，所述中间体I用于制备 18F-BPA，所述 18F-BPA具有结构：
    Figure PCTCN2019100678-appb-100014
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