Plasmin inhibitors, their preparation method and applications

Abstract

The present invention relates to compounds of formula (I) capable of inhibiting plasmin activity and having blood coagulation and hemostatic activity, as well as pharma- ceutically acceptable salts, hydrates, isomers, prodrugs and mixtures thereof, wherein R1-R3 are as defined herein. JPEG2024508390000145.jpg46170.

Description

[Technical Field]

[0001] The present invention relates to the field of medicinal chemistry, in particular to plasmin inhibitors, their preparation and their use in medicine. [Background technology]

[0002] Plasmin is a proteolytic enzyme that breaks down fibrin. When tissue injury causes vascular rupture, hemostatic mechanisms are triggered, including vasoconstriction, platelet plug formation, initiation of the coagulation process, and eventual formation of stable fibrin. Concurrently, fibrin deposition activates the fibrinolytic system, maintaining the balance between fibrin formation and dissolution, which plays a role in maintaining vascular patency and remodeling damaged tissue during repair of the damaged vessel wall (Tengborn L, Blomback M, Berntorp E. Thromb Res. 2015 Feb; 135(2):231-42).

[0003] The fibrinolytic system includes plasminogen, tissue plasminogen activator (tPA), and urokinase plasminogen activator (uPA). Plasminogen binds to lysine residues on the surface of fibrin and is converted to plasmin by activators (i.e., tPA) released from endothelial cells. Inhibition of fibrinolysis can be used to treat bleeding. Antifibrinolytic agents can reduce blood loss in cardiac surgery, trauma, orthopedic surgery, solid organ transplantation, obstetrics and gynecology, neurosurgery, and non-surgical conditions (Ng W, Jerath A, Wasowicz M. Anaesthesiol Intensive Ther. 2015; 47(4):339-50). In the early 1950s, the amino acid lysine was discovered to inhibit plasminogen activation, but its effect was too weak to be useful in treating fibrinolytic bleeding disorders. In 1953, Akisuke Okamoto et al. demonstrated that several sulfhydryl carboxylic acids and aminocarboxylic acids have anti-plasma protein activity, and found that ε-aminocaproic acid (EACA), a synthetic derivative of lysine, had a potent inhibitory effect on plasminogen. EACA is widely used clinically, but requires large doses and is associated with mild gastrointestinal side effects such as nausea. In 1962, 4-aminomethyl-cyclohexane-carboxylic acid (AMCHA) was discovered. This compound contains two stereoisomers, and further studies showed that its trans form (trans-4-aminomethyl-cyclohexane-carboxylic acid, or tranexamic acid, TXA) has approximately 10 times the antifibrinolytic activity of EACA and is better tolerated (Tengborn L, Blomback M, Berntorp E. Thromb Res. 2015 Feb;135(2):231-42).

[0004] Tranexamic acid is a synthetic lysine derivative and an antifibrinolytic agent that forms a reversible complex with plasminogen. By binding to plasminogen, it blocks the interaction of plasminogen and plasmin heavy chains with the lysine residues of fibrin, thereby preventing plasminogen from binding to the fibrin surface and delaying fibrinolysis. Tranexamic acid has been approved for the treatment of heavy menstrual bleeding and various surgical bleeding disorders and is currently the most commonly used hemostatic agent in clinical practice. However, numerous literature reports have shown that tranexamic acid is prone to gastrointestinal side effects, such as nausea, vomiting, diarrhea, and dyspepsia, after oral administration, and its relatively high dosage may cause complications, such as epilepsy, in patients.

[0005] Other similar hemostatic agents, such as aminocaproic acid, have problems such as rapid excretion from the human body, weak hemostatic efficacy, short duration of action, and frequent toxic reactions. High doses can lead to thrombus formation, limiting their use in patients with thrombosis-prone or thrombotic vascular disease and renal failure. The mechanism of action of aminomethylbenzoic acid is similar to that of aminocaproic acid, but its effectiveness is four to five times stronger. While it is highly effective in treating general chronic bleeding, it does not have a hemostatic effect in traumatic or cancer-related bleeding. Furthermore, excessive doses may promote thrombosis. Aprotinin, a hemostatic agent commonly used in bypass surgery, was also withdrawn from the market by the FDA in 2008 due to its potential to induce renal failure, myocardial infarction, and heart failure.

[0006] Hemostatic drugs with other mechanisms, such as Carbacola, which acts on blood vessels, may induce epilepsy if used repeatedly; thrombin, a hemostatic drug that accelerates the blood clotting process, is only applicable to gastrointestinal or local bleeding.

[0007] Considering the fact that clinically available hemostatic drug options are very limited, and there are certain deficiencies in terms of dosage, clinical indications, etc., and existing drugs of the same type have problems such as high dosage, many side effects, and are prone to complications such as epilepsy, it is necessary to develop new hemostatic drugs that can better meet clinical needs. Summary of the Invention

[0008] In a first aspect, the present invention aims to overcome the drawbacks of the prior art mentioned above and to provide novel compounds having blood coagulation and hemostatic activity.

[0009] In particular, the present invention provides compounds represented by the structure of Formula I, pharmaceutically acceptable salts, hydrates, isomers, prodrugs, and mixtures thereof: [ka] [In the formula, R1 is selected from the group consisting of hydrogen, hydroxy, amino, alkyl, alkoxy, -NH-alkyl, cycloalkyl, aryl, aliphatic heterocyclyl, and aromatic heterocyclyl; said R1 is optionally substituted with 1 to 2 groups selected from hydroxy, alkyl, arylalkyl, halogen, aryl, and cycloalkyl; R2 is independently selected from the group consisting of hydrogen, carboxyl, amido, alkyl, -NH-alkyl, -CHO-alkyl, -CHNH-alkyl, -COO-alkyl, -CONH-alkyl, cycloalkyl, aryl, aliphatic heterocyclyl, aromatic heterocyclyl, arylalkyl, and cycloalkylalkyl; R2 may be substituted with 1 to 2 groups selected from hydroxy, alkyl, and alkoxy; or two R2, together with the carbon atoms to which they are attached, form a cycloalkyl or an aliphatic heterocyclyl; R3 is selected from hydrogen and halogen, specifically R3 is selected from hydrogen, fluorine, chlorine and bromine.

[0010] In one embodiment, the present invention provides a compound represented by the structure of Formula I', pharmaceutically acceptable salts, hydrates, isomers, prodrugs, and mixtures thereof: [ka] [In the formula, R1 is selected from the group consisting of hydrogen, hydroxy, amino, alkyl, alkoxy, -NH-alkyl, cycloalkyl, aryl, aliphatic heterocyclyl, and aromatic heterocyclyl; said R1 is optionally substituted with 1 to 2 groups selected from hydroxy, alkyl, halogen, aryl, and cycloalkyl; R2 is selected from the group consisting of hydrogen, carboxyl, amido, alkyl, -NH-alkyl, -CHO-alkyl, -CHNH-alkyl, -COO-alkyl, -CONH-alkyl, cycloalkyl, aryl, aliphatic heterocyclyl, and aromatic heterocyclyl; said R2 is optionally substituted with 1 to 2 groups selected from hydroxy and alkyl; R3 is selected from hydrogen and halogen, specifically R3 is selected from hydrogen, fluorine, chlorine and bromine.

[0011] In certain embodiments, R1 is selected from the group consisting of hydrogen, hydroxy, amino, C1-C6 alkyl, C1-C6 alkoxy, —NH—(C1-C6) alkyl, C3-C6 cycloalkyl, 6- to 10-membered aryl, 4- to 10-membered aliphatic heterocyclyl, and 5- to 10-membered aromatic heterocyclyl; and R1 is optionally substituted with 1 to 2 groups selected from hydroxy, C1-C4 alkyl, halogen, 6- to 10-membered aryl or aromatic heterocyclyl, and C3-C6 cycloalkyl.

[0012] In certain embodiments, R1 is selected from the group consisting of hydrogen, hydroxy, amino, phenyl, pyridyl, C1-C6 alkyl, C1-C6 alkoxy, —NH—(C1-C6) alkyl, C3-C6 cycloalkyl, and 4- to 7-membered aliphatic heterocyclyl; said R1 is optionally substituted with 1 to 2 groups selected from hydroxy, C1-C4 alkyl, F, Cl, Br, phenyl, benzyl, and cyclopropyl.

[0013] In certain embodiments, R1 is selected from the group consisting of hydrogen, hydroxy, amino, phenyl, benzyl, pyridyl, methyl, ethyl, propyl, isopropyl, butyl, methoxy, ethoxy, propoxy, -NHCH3, -NHCH2CH3, -NHCH2CH2CH3, cyclopropyl, cyclobutyl, cyclopentyl, piperidinyl, morpholinyl, piperazinyl, thiomorpholinyl, 1-oxide-4-thiomorpholinyl, and 1,1-dioxide-4-thiomorpholinyl; wherein R1 is optionally substituted with 1 to 2 groups selected from hydroxy, F, Cl, Br, methyl, ethyl, propyl, isopropyl, phenyl, benzyl, and cyclopropyl.

[0014] In certain embodiments, R1 is selected from the group consisting of hydrogen, C1-C4 alkoxy, morpholinyl, piperazinyl, thiomorpholinyl, 1-oxide-4-thiomorpholinyl, and 1,1-dioxide-4-thiomorpholinyl, wherein R1 is optionally substituted with 1 to 2 groups selected from hydroxy and benzyl.

[0015] In certain embodiments, R2 is selected from the group consisting of hydrogen, carboxyl, amido, C1-C6 alkyl, -CHO-(C1-C6)alkyl, -CHNH-(C1-C6)alkyl, -COO-(C1-C6)alkyl, -CONH-(C1-C6)alkyl, C3-C8 cycloalkyl, 6-10 membered aryl, 4-10 membered aliphatic heterocyclyl, and 5-10 membered aromatic heterocyclyl; said R2 is optionally substituted with 1 to 2 groups selected from hydroxy and C1-C4 alkyl.

[0016] In certain embodiments, R2 is selected from the group consisting of hydrogen, carboxyl, amido, C1-C6 alkyl, -CHO-(C1-C6)alkyl, -CHNH-(C1-C6)alkyl, -COO-(C1-C6)alkyl, -CONH-(C1-C6)alkyl, C3-C6 cycloalkyl, 6-membered aryl, 4- to 7-membered aliphatic heterocyclyl, and 6-membered aromatic heterocyclyl; said R2 is optionally substituted with 1 to 2 groups selected from hydroxy and C1-C4 alkyl.

[0017] In certain embodiments, R2 is selected from the group consisting of hydrogen, carboxyl, amido, methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, pentyl, -CHOCH3, -CHOCHCH3, -CHOCHCH2CH3, -CHNHCH3, -CHNHCH2CH3, -CHNHCH2CH2CH3, -COOCH3, -COOCH2CH3, -COOCH2CH2CH3, -CONHCH3, -CONHCH2CH3, -CONHCH2CH2CH3, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, benzyl, pyridyl, piperidinyl, morpholinyl, thiomorpholinyl, 1-oxide-thiomorpholinyl, 1,1-dioxide-4-thiomorpholinyl, wherein said R2 is optionally substituted with 1 to 2 groups selected from hydroxy, methyl, ethyl, propyl, and isopropyl.

[0018] In certain embodiments, R2 is independently selected from the group consisting of hydrogen, carboxyl, C1-C6 alkyl, -CHO-(C1-C6)alkyl, -COO-(C1-C6)alkyl, C3-C6 cycloalkyl, phenyl-(C1-C4)alkyl, and (C3-C6)cycloalkyl-(C1-C4)alkyl, wherein said alkyl, cycloalkyl, and phenyl are optionally substituted with 1 to 2 groups selected from hydroxy and C1-C4 alkoxy; or two R2, together with the carbon atoms to which they are attached, form C3-C6 cycloalkyl or tetrahydropyranyl.

[0019] In certain embodiments, one of R2 is hydrogen. In certain embodiments, R3 is selected from hydrogen and fluorine.

[0020] In certain embodiments, R1 and R2 are not simultaneously hydrogen.

[0021] In certain embodiments, R1, R2, and R3 are not simultaneously hydrogen.

[0022] In certain embodiments, the compound of formula I of the present invention has the following structure: [ka] JPEG0007749679000004.jpg229170

[0023] Another object of the present invention is to provide pharmaceutical compositions comprising at least one compound as described above, or a pharmaceutically acceptable salt, hydrate, isomer, prodrug, or mixture thereof, and at least one pharmaceutically acceptable excipient.

[0024] Another object of the present invention is to provide use of the above-mentioned compound or a pharmaceutically acceptable salt, hydrate, isomer, prodrug, mixture, or pharmaceutical composition thereof for the manufacture of a medicament, which has therapeutic activity in blood coagulation and hemostasis, and can be used for abnormal bleeding due to hyperfibrinolysis, surgical and postoperative bleeding, etc.

[0025] Another object of the present invention is to provide a method for treating and / or alleviating a bleeding disease or condition, comprising administering to a patient in need thereof one or more of the pharmaceutical compositions described above, or a compound of formula I or a pharmaceutically acceptable salt, hydrate, isomer, prodrug or mixture thereof.

[0026] definition Unless otherwise specified, the following terms and phrases used herein shall have the following meanings: Certain terms and phrases, if not specifically defined, should not be considered indefinite or unclear but should be understood according to their ordinary meaning. When trade names are mentioned herein, they are intended to refer to the corresponding commercially available product or its active ingredient.

[0027] As used herein, the term "pharmaceutically acceptable" means suitable for use in contact with the tissues of humans and animals without excessive toxicity, irritation, allergic response or other problem or complication, and with a reasonable benefit / risk ratio.

[0028] The term "pharmaceutically acceptable salt" refers to a salt of a compound of the present invention prepared from a compound of the present invention having a specific substituent and a relatively non-toxic acid or base. When a compound of the present invention contains a relatively acidic functional group, a base addition salt can be obtained by contacting the neutral form of such a compound with a sufficient amount of base, either neat or in a suitable inert solvent. When a compound of the present invention contains a relatively basic functional group, an acid addition salt can be obtained by contacting the neutral form of such a compound with a sufficient amount of acid, either neat or in a suitable inert solvent.

[0029] The compounds of the present invention may exist in particular geometric or stereoisomeric forms. The present invention contemplates all such compounds, including cis and trans isomers, (-)- and (+)-enantiomers, (R)- and (S)-enantiomers, diastereomers, (D)-isomers, (L)-isomers, and racemic and other mixtures thereof, all of which are within the scope of the present invention.

[0030] "Alkyl" refers to a straight-chain or branched saturated aliphatic hydrocarbon group, for example, C1-C4 alkyl and C1-C6 alkyl refer to saturated aliphatic hydrocarbon groups containing 1 to 4 carbon atoms and 1 to 6 carbon atoms, respectively, including, but not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, 3,3-dimethylbutyl, and the like, and various isomers thereof.

[0031] "Alkoxy" refers to -O-alkyl; for example, C1-C6 alkoxy refers to a straight or branched chain alkoxy containing 1 to 6 carbon atoms, and C1-C3 alkoxy refers to a straight or branched chain alkoxy containing 1 to 3 carbon atoms. Typical alkoxy groups include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, and the like.

[0032] "Cycloalkyl" refers to a saturated or partially unsaturated monocyclic or polycyclic cyclic hydrocarbon substituent. For example, "C3-C6 cycloalkyl" refers to a cycloalkyl group containing from 3 to 6 carbon atoms. Typical cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, and the like.

[0033] "Aliphatic heterocyclyl" refers to a saturated monocyclic hydrocarbon substituent in which one or more ring atoms are replaced with a heteroatom selected from N, O, and S, the remaining ring atoms are carbon, and the S heteroatom is optionally oxidized. For example, "3- to 8-membered aliphatic heterocyclyl" refers to a saturated cyclic hydrocarbon substituent containing 3 to 8 ring atoms in which one or more ring atoms are replaced with a heteroatom selected from N, O, and S, the remaining ring atoms are carbon, and the S heteroatom is optionally oxidized. Specific examples of aliphatic heterocyclyl in the present invention include, but are not limited to, oxetanyl, pyrrolidinyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydrothiophenyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, 1-oxide-4-thiomorpholinyl, and 1,1-dioxide-4-thiomorpholinyl.

[0034] "Aromatic heterocyclyl" refers to an aromatic ring substituent in which one or more ring atoms are replaced with a heteroatom selected from N, O, and S, and the remaining ring atoms are carbon. For example, "5- to 6-membered aromatic heterocyclyl" refers to an aromatic heterocyclyl containing 5 to 6 ring atoms. Specific examples of aromatic heterocyclyls described herein include, but are not limited to, pyridyl, pyrimidinyl, imidazolyl, pyridazinyl, pyrazolyl, thiazolyl, oxazolyl, isoxazolyl, and 1,2,4-oxadiazolyl.

[0035] "Aryl" refers to an aromatic cyclic group, for example, a "6- to 10-membered aryl" refers to an aromatic cyclic group containing 6 to 10 carbon ring atoms. Examples of aryl as described herein include, but are not limited to, phenyl, naphthyl, and the like.

[0036] "Halogen" includes fluorine, chlorine, bromine and iodine.

[0037] "Optionally" means that the subsequently described event or circumstance may occur, but need not occur.

[0038] The abbreviations used herein are known to those skilled in the art and are intended to have the meaning known in the art unless otherwise specified. For example, DMF stands for N,N-dimethylformamide; THF stands for tetrahydrofuran; and Me stands for methyl.

[0039] The test has demonstrated that the compounds of the present invention have excellent blood coagulation activity and hemostatic activity, which are clearly superior to tranexamic acid, the most widely used hemostatic drug in clinical practice, and have great value in clinical application.

[0040] Detailed Description The following examples are for illustrative purposes only and should not be construed as limiting the scope of the present invention. Unless otherwise specified, the raw materials and reagents according to the present invention can be obtained from commercial sources, and the specific source does not affect the implementation of the technical solution of the present invention.

[0041] Preparation 1: Preparation of tert-butyl 2-chloro-8-hydroxy-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate [ka]

[0042] Step 1: Preparation of tert-butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 2-Chloro-5,6,7,8-tetrahydro-1,6-naphthyridine hydrochloride (5 g) was dissolved in dichloromethane (50 ml), triethylamine (10 ml) was added, and di-tert-butyl dicarbonate (6.7 ml) was slowly added dropwise. After the addition was complete, the reaction was carried out at room temperature for 1 hour, and LC-MS showed that the reaction was complete. The system was concentrated to give a crude oil, which was separated by chromatography to give the title compound (6 g). [ka]

[0043] Step 2: Preparation of 6-(tert-butoxycarbonyl)-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine 1-oxide tert-Butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (9 g) was weighed and dissolved in dichloromethane (100 ml). m-Chloroperbenzoic acid (11.7 g) was added portionwise while cooling in an ice bath. The reaction was carried out at room temperature for 1 hour, and LC-MS showed that the reaction was complete. Dichloromethane and water were added, the layers were separated, the aqueous layer was extracted, and the organic phase was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (7.0 g). [ka]

[0044] Step 3: Preparation of tert-butyl 8-acetoxy-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 6-(tert-Butyloxycarbonyl)-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine 1-oxide (7 g) was weighed and dissolved in acetic anhydride (80 mL). The system was evacuated and refilled with nitrogen (three times), then heated to 70 °C and reacted overnight. LC-MS showed the reaction was complete. The reaction was concentrated under reduced pressure to remove most of the acetic anhydride, and ethyl acetate and water were added. The aqueous phase was extracted three times with ethyl acetate, and the extract was washed twice with saturated sodium bicarbonate solution. The organic phase was dried and concentrated, and the residue was separated and purified by chromatography column to give the title compound (5 g). [ka]

[0045] Step 4: Preparation of tert-butyl 2-chloro-8-hydroxy-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 8-acetoxy-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (3 g) was weighed and dissolved in methanol (30 ml), and potassium carbonate (635 mg) was added. After the addition was complete, the reaction was carried out at room temperature for 0.5 hours, and LC-MS showed the reaction was complete. Ethyl acetate and water were added, and the aqueous layer was extracted three times with ethyl acetate. The organic phase was dried and concentrated to give an oily crude product, which was separated and purified by column chromatography to give the title compound (1.9 g). [ka]

[0046] Preparation 2: Preparation of 6-(tert-butyl) 7-methyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6,7(5H)-dicarboxylate [ka]

[0047] Step 1: Preparation of 2,3-bis(methoxycarbonyl)pyridine 1-oxide Dimethyl pyridine-2,3-dicarboxylate (4.90 g) was weighed and dissolved in acetonitrile (60 mL). Carbamide peroxide (4.71 g) was added while cooling in an ice bath, and trifluoroacetic anhydride (10.5 g) was slowly added dropwise. After the addition was complete, the system became a clear solution, and the temperature was raised to room temperature and the reaction was continued for 4 hours. TLC showed that the reaction was essentially complete. The reaction was quenched by adding aqueous sodium metabisulfite solution. Dichloromethane and water were added, the layers were separated, and the aqueous layer was extracted with a mixed solvent (DCM / MeOH = 10 / 1). The organic phase was dried over anhydrous sodium sulfate and filtered under suction. The filtrate was concentrated to dryness to give the title compound (5.15 g). [ka]

[0048] Step 2: Preparation of dimethyl 6-chloropyridine-2,3-dicarboxylate Phosphorus oxychloride (30 mL) was added to 2,3-bis(methoxycarbonyl)pyridine 1-oxide (5.15 g) under ice-cooling, and the mixture was heated to 105°C and reacted for 4 hours. TLC showed that the reaction was complete. The reaction mixture was concentrated under reduced pressure, diluted with ethyl acetate, added dropwise to crushed ice, and adjusted to pH 10 by adding aqueous sodium carbonate. The mixture was extracted with ethyl acetate, and the organic phase was washed with aqueous sodium chloride. The organic phase was concentrated to dryness, and the crude product was purified by column chromatography to give the title compound (3.52 g). [ka]

[0049] Step 3: Preparation of (6-chloropyridine-2,3-diyl)dimethanol Dimethyl 6-chloropyridine-2,3-dicarboxylate (3.50 g) was weighed and dissolved in tetrahydrofuran (72 mL) and methanol (1.5 mL). Lithium borohydride (0.84 g) was added portionwise while cooling in an ice bath. The mixture was warmed to room temperature and reacted for 3 hours. TLC showed the reaction was complete. The reaction mixture was poured into aqueous sodium bicarbonate, ethyl acetate was added, the aqueous layer was separated and extracted, the organic layer was dried over anhydrous sodium sulfate, suction filtered, and the filtrate was concentrated to give the title compound (2.63 g). [ka]

[0050] Step 4: Preparation of 6-chloro-2,3-bis(chloromethyl)pyridine Thionyl chloride (40 mL) was added to (6-chloropyridine-2,3-diyl)dimethanol (2.63 g) under ice cooling and allowed to react at room temperature for 3 hours. Due to the presence of a monochlorinated intermediate, the temperature was raised to 35°C and the reaction was allowed to proceed for 3 hours, after which TLC showed the reaction was complete. The system was concentrated under reduced pressure, diluted with ethyl acetate, added dropwise to crushed ice, and adjusted to pH 10 by adding aqueous sodium carbonate. Extraction was performed with ethyl acetate, and the organic phase was washed with aqueous sodium chloride. The organic phase was concentrated to dryness, and the crude product was purified by column chromatography to give the title compound (2.1 g). [ka]

[0051] Step 5: Preparation of dimethyl 6-acetyl-2-chloro-5,6-dihydro-1,6-naphthyridine-7,7(8H)-dicarboxylate 6-Chloro-2,3-bis(chloromethyl)pyridine (2.10 g) was weighed and dissolved in N,N-dimethylformamide (15 mL). Dimethyl acetylaminomalonate (2.17 g) and sodium hydride (0.40 g) were added successively while cooling in an ice bath. The reaction was carried out at room temperature for 1 hour, and then sodium hydride (0.40 g) was added while cooling in an ice bath, followed by reaction at room temperature overnight. TLC showed that the reaction was complete. Ethyl acetate and water were added, and the aqueous layer was separated and extracted. The organic phase was concentrated to dryness, and the crude product was purified by column chromatography to obtain the title compound (1.74 g). [ka]

[0052] Step 6: Preparation of 2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-7-carboxylic acid hydrochloride 6M hydrochloric acid (15 mL) was added to dimethyl 6-acetyl-2-chloro-5,6-dihydro-1,6-naphthyridine-7,7(8H)-dicarboxylate (1.74 g) and the mixture was reacted at 100° C. for 4 hours under sealed conditions. TLC showed that the reaction was complete. The mixture was concentrated to dryness under reduced pressure to give the title compound (1.16 g). [ka]

[0053] Step 7: Preparation of methyl 2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-7-carboxylate hydrochloride 2-Chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-7-carboxylic acid hydrochloride (1.16 g) was weighed and dissolved in methanol (20 mL). Thionyl chloride (1.67 g) was added dropwise slowly while cooling in an ice bath. The reaction was refluxed at 70° C. for 2 hours, and TLC showed the reaction was complete. The system was concentrated to dryness under reduced pressure to give the title compound (1.23 g). [ka]

[0054] Step 8: 2-Chloro-7,8-dihydro-1,6-naphthyridine-6,7(5H)-dicarboxylic acid 6-(tert-butyl) 7-methyl ester Methyl 2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-7-carboxylate hydrochloride (1.23 g) was weighed and dissolved in dichloromethane (25 mL), and triethylamine (1.89 g) and di-tert-butyl carboxylate (1.53 g) were added successively. The reaction mixture was allowed to react at room temperature for 2 hours, after which TLC showed the reaction was complete. Dichloromethane and water were added, the aqueous layer was separated and extracted, and the organic layer was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (1.19 g). [ka]

[0055] Example 1: Preparation of 5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0056] Step 1: Preparation of tert-butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 2-Chloro-5,6,7,8-tetrahydro-1,6-naphthyridine hydrochloride (0.9 g) was weighed and suspended in dichloromethane (15 mL). N,N-diisopropylethylamine (1.4 g) was added to release the free base, followed by di-tert-butyl dicarbonate (1.15 g) and the reaction was allowed to proceed at room temperature for 1 hour. TLC showed that the starting material was completely consumed. Purification by column chromatography afforded the title compound (1.12 g). [ka]

[0057] Step 2: Preparation of tert-butyl 2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate Chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-tert-butyl carboxylate (1.12 g) was weighed and dissolved in N,N-dimethylformamide (20 mL). Zinc cyanide (2.44 g) and tetrakis(triphenylphosphine)palladium (483 mg) were added. The system was evacuated and backfilled with argon (three times), and then reacted at 120 °C for 3 h. TLC showed complete consumption of the starting material. The mixture was diluted with ethyl acetate, filtered through Celite, and extracted twice with ethyl acetate. The organic phase was washed once with saturated brine, dried over anhydrous sodium sulfate, and concentrated. The residue was purified by column chromatography to give the title compound (1.1 g). [ka]

[0058] Step 3: Preparation of 5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride tert-Butyl 2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (1.1 g) was weighed and dissolved in 6 M aqueous hydrochloric acid (25 mL) and reacted at 120 °C overnight. LCMS showed that the starting material was completely consumed, so the reaction was concentrated to dryness. The residue was separated by pre-HPLC to give a pale yellow solid (726 mg). [ka]

[0059] Example 2: Preparation of 8-hydroxy-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0060] Step 1: Preparation of tert-butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 2-Chloro-5,6,7,8-tetrahydro-1,6-naphthyridine hydrochloride (5 g) was dissolved in dichloromethane (50 ml), triethylamine (10 ml) was added, and then di-tert-butyl dicarbonate (6.7 ml) was added dropwise slowly. After the addition was complete, the reaction was carried out at room temperature for 1 hour, and LC-MS showed that the reaction was complete. The system was concentrated to give a crude oil, which was purified by column chromatography to give the title compound (5.5 g). [ka]

[0061] Step 2: Preparation of 6-(tert-butoxycarbonyl)-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-1-oxide 2 g of tert-butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (2 g) was weighed and dissolved in 50 ml of dichloromethane. While cooling in an ice bath, 2.6 g of m-chloroperoxybenzoic acid was added portionwise. The reaction was carried out at room temperature overnight, and LC-MS showed that the reaction was complete. Dichloromethane and water were added, the aqueous layer was separated and extracted, and the organic layer was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (1.5 g). [ka]

[0062] Step 3: Preparation of tert-butyl 8-acetoxy-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 6-(tert-Butyloxycarbonyl)-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-1-oxide (300 mg) was weighed and dissolved in acetic anhydride (5 mL). The system was evacuated and refilled with nitrogen (three times), then heated to 70 °C and reacted overnight. LC-MS showed the reaction was complete. The reaction mixture was concentrated under reduced pressure to remove most of the acetic anhydride, and ethyl acetate and water were added. The aqueous layer was extracted three times, and the organic phase was washed twice with saturated sodium bicarbonate solution, dried, and concentrated. The residue was purified by column chromatography to give the title compound (280 mg). [ka]

[0063] Step 4: Preparation of tert-butyl 8-acetoxy-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 8-acetoxy-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (150 mg) was weighed and dissolved in N,N-dimethylformamide (6 mL), and zinc cyanide (270 mg) and tetrakis(triphenylphosphine)palladium (105.9 mg) were added. The system was evacuated and refilled with nitrogen (three times), then heated to 120 °C and reacted for 3 hours. LC-MS showed the reaction was complete. Ethyl acetate and water were added, and the aqueous phase was extracted three times with ethyl acetate. The organic phase was dried and concentrated. The residue was purified by column chromatography to give the title compound (60 mg). [ka]

[0064] Step 5: Preparation of tert-butyl 8-hydroxy-2-(imino(methoxy)methyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate Tert-butyl 8-acetoxy-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (60 mg) was weighed and dissolved in a solution of methanol (1 mL), tetrahydrofuran (1 mL), and water (1 mL). Lithium hydroxide monohydrate (32 mg) was added and the mixture was allowed to react at room temperature for 1 hour. LC-MS showed the reaction was complete. Ethyl acetate and water were added, and the aqueous phase was extracted three times with ethyl acetate. The organic phase was dried and concentrated to give the title compound (50 mg). [ka]

[0065] Step 6: Preparation of 8-hydroxy-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride tert-Butyl 8-hydroxy-2-(imino(methoxy)methyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (50 mg) was weighed and dissolved in 6 M aqueous hydrochloric acid (4 mL). The system was heated to 120 °C and reacted for 5 hours. LC-MS showed that the reaction was complete. The reaction was concentrated, and the residue was purified by pre-HPLC to give the title compound (35 mg). [ka]

[0066] Example 3: Preparation of 8-amino-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid dihydrochloride [ka]

[0067] Step 1: Preparation of tert-butyl 2-chloro-8-((methylsulfonyl)oxy)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-hydroxy-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (100 mg) was weighed and dissolved in dichloromethane (4 ml). Triethylamine (106 mg) was added while cooling in an ice bath. The system was evacuated and refilled with nitrogen (three times). Methanesulfonyl chloride (80 mg) was then added dropwise, and the reaction was allowed to proceed at room temperature for 1 hour. LC-MS showed the reaction was complete. Dichloromethane and water were added, the aqueous layer was separated and extracted, and the organic phase was concentrated to dryness to give the title compound (126.7 mg). [ka]

[0068] Step 2: Preparation of tert-butyl 8-azido-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-((methanesulfonyl)oxy)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (126 mg) was weighed and dissolved in N,N-dimethylformamide (4 ml), and sodium azide (30 mg) was added while cooling in an ice bath. The reaction was heated at 85° C. for 1 hour, and TLC showed the reaction was complete. Ethyl acetate and water were added, the aqueous layer was separated and extracted, and the organic phase was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (90 mg). [ka]

[0069] Step 3: Preparation of tert-butyl 8-amino-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 8-azido-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (90 mg) was weighed and dissolved in tetrahydrofuran (3 mL) and water (0.3 mL). Triphenylphosphine (152 mg) was added, and the reaction was carried out at room temperature for 18 hours. LC-MS showed the reaction was complete. Ethyl acetate and water were added, and the aqueous layer was extracted with ethyl acetate (3 times). The organic layer was dried and concentrated, and the residue was purified by column chromatography to give the title compound (70 mg). [ka]

[0070] Step 4: Preparation of tert-butyl 8-((tert-butoxycarbonyl)amino)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 8-amino-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (70 mg) was weighed and dissolved in methylene chloride (6 mL), and triethylamine (37 mg) was added, followed by the slow dropwise addition of di-tert-butyl dicarbonate (80 mg). The reaction was carried out at room temperature for 2 hours. LC-MS showed the reaction was complete. The system was concentrated, and the residue was purified by column chromatography to give the title compound (70 mg). [ka]

[0071] Step 5: Preparation of tert-butyl 8-((tert-butoxycarbonyl)amino)-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 8-((tert-butoxycarbonyl)amino)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (30 mg) was dissolved in N,N-dimethylformamide (3 mL), zinc cyanide (90 mg) and tetrakis(triphenylphosphine)palladium (72 mg) were added, the system was evacuated and refilled with nitrogen (3 times), and the mixture was heated at 120° C. for 2 hours. LC-MS showed the reaction was complete. Ethyl acetate and water were added, the aqueous layer was extracted with ethyl acetate (3 times), the organic phase was dried and concentrated, and the residue was purified by column chromatography to give the title compound (25 mg). [ka]

[0072] Step 6: Preparation of 8-amino-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid dihydrochloride tert-Butyl 8-((tert-butoxycarbonyl)amino)-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (25 mg) was weighed and dissolved in 6 M aqueous hydrochloric acid (4 mL). The system was heated to 120° C. and reacted for 5 hours. LC-MS showed that the reaction was complete. The reaction was concentrated, and the residue was purified by pre-HPLC to give the title compound (13 mg). [ka]

[0073] Example 4: Preparation of 8-((2-hydroxyethyl)amino)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid dihydrochloride [ka]

[0074] Step 1: Preparation of tert-butyl 2-chloro-8-((2-hydroxyethyl)amino)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-((methanesulfonyl)oxy)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (100 mg) was dissolved in acetonitrile (4 mL) at room temperature, and N,N-diisopropylethylamine (0.23 mL) and ethanolamine (34 mg) were added. The reaction was heated at 60° C. overnight, and TLC showed the reaction was complete. Dichloromethane and water were added, the layers were separated, the aqueous layer was extracted with dichloromethane, and the organic phase was concentrated to dryness. The resulting crude product was purified by silica gel column chromatography to give the title compound (54 mg). [ka]

[0075] Step 2: Preparation of tert-butyl 8-((tert-butoxycarbonyl)(2-hydroxyethyl)amino)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-((2-hydroxyethyl)amino)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (53 mg) was dissolved in methylene chloride (4 mL) at room temperature, triethylamine (32 mg) and di-tert-butyl dicarbonate (53 mg) were added, and the reaction was stirred overnight. LC-MS showed the reaction was complete. Dichloromethane and water were added, the layers were separated, the aqueous layer was extracted with dichloromethane, and the organic phase was concentrated to dryness. The resulting crude product was purified by silica gel column chromatography to give the title compound (60 mg). [ka]

[0076] Step 3: Preparation of tert-butyl 8-((tert-butoxycarbonyl)(2-hydroxyethyl)amino)-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 8-((tert-butoxycarbonyl)(2-hydroxyethyl)amino)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (43 mg) was dissolved in N,N-dimethylformamide (5 mL) at room temperature, zinc cyanide (246 mg) and tetrakis(triphenylphosphine)palladium (808 mg) were added, the system was evacuated and refilled with nitrogen (three times), and the mixture was heated at 120° C. and stirred overnight. LC-MS showed the reaction was complete. The mixture was filtered, ethyl acetate and water were added, the layers were separated, the aqueous layer was extracted three times with ethyl acetate, the organic phase was dried and concentrated, and the resulting crude product was purified by pre-TLC to give the title compound (30 mg). [ka]

[0077] Step 4: Preparation of 8-((2-hydroxyethyl)amino)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid dihydrochloride tert-Butyl 8-((tert-butoxycarbonyl)(2-hydroxyethyl)amino)-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (30 mg) was weighed and dissolved in 6 M aqueous hydrochloric acid (5 mL). The system was heated at 120° C. for 5 hours. LC-MS showed the reaction was complete. The reaction was concentrated, and the residue was purified by pre-HPLC to give the title compound (15.8 mg). [ka]

[0078] Example 5: Preparation of 8-morpholino-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0079] Step 1: Preparation of tert-butyl 2-chloro-8-((methylsulfonyl)oxy)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-hydroxy-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (270 mg) was weighed and dissolved in dichloromethane (8 ml). Triethylamine (300 mg) was added while cooling in an ice bath. The system was evacuated and refilled with nitrogen (three times), and methanesulfonyl chloride (230 mg) was added dropwise. The reaction was allowed to proceed at room temperature for 1 hour, at which time LC-MS showed the reaction was complete. Dichloromethane and water were added, the layers were separated, the aqueous layer was extracted, and the organic phase was concentrated to dryness to give the title compound (310 mg). [ka]

[0080] Step 2: Preparation of tert-butyl 2-chloro-8-morpholino-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-((methanesulfonyl)oxy)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (150 mg) was weighed and dissolved in N,N-dimethylformamide (2 ml) and acetonitrile (2 ml), and potassium carbonate (138 mg) and morpholine (174 mg) were added. The reaction was heated at 60° C. overnight, after which TLC showed the reaction was complete. Ethyl acetate and water were added, the layers were separated, the aqueous layer was extracted, and the organic phase was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (120 mg). [ka]

[0081] Step 3: Preparation of tert-butyl 2-cyano-8-morpholino-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-morpholino-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (120 mg) was weighed and dissolved in N,N-dimethylformamide (5 mL). Zinc cyanide (318 mg) and tetrakis(triphenylphosphine)palladium (196 mg) were added. The system was evacuated and refilled with nitrogen (three times), and the mixture was heated at 120 °C for 2 h. LC-MS indicated the reaction was complete. Ethyl acetate and water were added, and the aqueous layer was extracted three times with ethyl acetate. The organic phase was dried and concentrated to dryness. The residue was purified by column chromatography to give the title compound (100 mg). [ka]

[0082] Step 4: Preparation of 8-morpholino-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride tert-Butyl 2-cyano-8-morpholino-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (42 mg) was weighed and dissolved in 6 M aqueous hydrochloric acid (4 mL). The system was heated at 120 °C for 5 hours. LC-MS showed the reaction was complete. The reaction was concentrated, and the residue was purified by pre-HPLC to give the title compound (31 mg). [ka]

[0083] Example 6: Preparation of 8-(1,1-dioxide-thiomorpholino)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0084] Step 1: Preparation of tert-butyl 2-chloro-8-(1,1-dioxide-thiomorpholino)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-((methanesulfonyl)oxy)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (65 mg) was weighed and dissolved in acetonitrile (5 mL), and thiomorpholine 1,1-dioxide (540 mg) and potassium carbonate (550 mg) were added sequentially. The temperature was raised to 75°C overnight, at which point TLC indicated that the reaction was essentially complete. Ethyl acetate and water were added, the layers were separated, the aqueous layer was extracted, and the organic phase was concentrated to dryness. The resulting crude product was purified by column chromatography to provide the title compound (28 mg). [ka]

[0085] Step 2: Preparation of tert-butyl 2-cyano-8-(1,1-dioxide-thiomorpholino)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 2-Chloro-8-(1,1-dioxide-thiomorpholino)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (28 mg) was weighed and dissolved in N,N-dimethylformamide (2.5 mL), and zinc cyanide (82 mg) and tetrakis(triphenylphosphine)palladium (81 mg) were added sequentially. The system was evacuated and refilled with nitrogen (three times), and the reaction was carried out at 120 °C for 6 hours. TLC showed that the reaction was essentially complete. Ethyl acetate was added, the mixture was suction filtered, the filtrate was washed with aqueous ammonium chloride, and the organic phase was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (25 mg). [ka]

[0086] Step 3: Preparation of 8-(1,1-dioxide-thiomorpholino)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride tert-Butyl 2-cyano-8-(1,1-dioxide-thiomorpholino)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (25 mg) was weighed, and 6 M hydrochloric acid (2.5 mL) was added. The reaction was carried out under sealed conditions at 120 °C for 4 hours, at which time TLC showed that the reaction was essentially complete. The system was concentrated to dryness, and the residue was purified by pre-HPLC to give the title compound (4.5 mg). [ka]

[0087] Example 7: Preparation of 7-((3-hydroxypropoxy)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0088] Step 1: Preparation of tert-butyl 2-chloro-7-(hydroxymethyl)-7,8-dihydro-1,6-naphthyridine-6-(5H)-carboxylate 6-(tert-butyl) 7-methyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6,7(5H)-dicarboxylate (1.00 g) was dissolved in tetrahydrofuran (20 mL) / methanol (1 mL) at room temperature. With cooling in an ice bath, lithium borohydride (0.340 g) was added, and the reaction was stirred for 2 hours. LCMS showed the reaction was complete. The reaction was quenched with the dropwise addition of saturated ammonium chloride solution with cooling in an ice bath. Ethyl acetate and water were added, the layers were separated, and the aqueous layer was extracted with ethyl acetate. The combined organic phases were dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the title compound (0.90 g). [ka]

[0089] Step 2: Preparation of tert-butyl 7-((3-((tert-butyldimethylsilyl)oxy)propoxy)methyl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate Sodium hydride (0.024 g) was placed in a reaction flask at room temperature, and N,N-dimethylformamide (2 mL) was added under a nitrogen atmosphere. The system was cooled in an ice bath for 10 minutes. 3-Bromopropoxytert-butyldimethylsilane (1.77 g) was added, followed by tert-butyl 2-chloro-7-(hydroxymethyl)-7,8-dihydro-1,6-naphthyridine-6-(5H)-carboxylate (208 mg) and tetrabutylammonium iodide (26 mg). After the addition was complete, the mixture was heated to 40°C and stirred for 1 hour, at which point TLC indicated the reaction was complete. The reaction was quenched by dropwise addition of saturated ammonium chloride solution while cooling in an ice bath. Ethyl acetate and water were added, the layers were separated, and the aqueous layer was extracted with ethyl acetate. The organic phase was washed with saturated ammonium chloride solution. The combined organic phases were dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the title compound (40 mg). [ka]

[0090] Step 3: Preparation of 6-(tert-butyl) 2-methyl 7-((3-((tert-butyldimethylsilyl)oxy)propoxy)methyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate tert-Butyl 7-((3-((tert-butyldimethylsilyl)oxy)propoxy)methyl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (37 mg) was dissolved in methanol (20 mL) at room temperature, and palladium acetate (9 mg), 1',1-bis(diphenylphosphino)ferrocene (44 mg), and triethylamine (8 mg) were added. After the addition was complete, the system was charged with carbon monoxide and then heated to 65°C and stirred under a carbon monoxide atmosphere overnight. LCMS showed the reaction was complete, and the solvent was removed under reduced pressure. The resulting crude product was purified by pre-TLC to give the title compound (33 mg). [ka]

[0091] Step 4: Preparation of 6-(tert-butoxycarbonyl)-7-((3-((tert-butyldimethylsilyl)oxy)propoxy)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid 6-(tert-butyl) 2-methyl 7-((3-((tert-butyldimethylsilyl)oxy)propoxy)methyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate (58 mg) was dissolved in a tetrahydrofuran (1 mL) / methanol (1 mL) / water (1 mL) system at room temperature, lithium hydroxide monohydrate (10 mg) was added, and the system was stirred for 30 minutes. LCMS showed that the reaction was complete. The reaction mixture was made weakly acidic with hydrogen chloride in 1,4-dioxane (4 M) and concentrated under reduced pressure. The crude title compound was obtained and used directly in the next step. [ka]

[0092] Step 5: Preparation of 7-((3-hydroxypropoxy)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride The crude 6-(tert-butoxycarbonyl)-7-((3-((tert-butyldimethylsilyl)oxy)propoxy)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid obtained in step 4 was added to a solution of hydrogen chloride in 1,4-dioxane (4 M, 2 mL) at room temperature and stirred for 30 minutes. LCMS showed that the reaction was complete. The reaction mixture was concentrated under reduced pressure, and the residue was purified by pre-HPLC to give the title compound (28.3 mg). [ka]

[0093] Example 8: Preparation of 7-carbamoyl-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0094] Step 1: Preparation of tert-butyl 7-carbamoyl-2-chloro-7,8-dihydro-1,6-naphthyridine-6-(5H)-carboxylate 6-(tert-Butoxycarbonyl)-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-7-carboxylic acid (86 mg) was dissolved in N,N-dimethylformamide (4 mL) at room temperature. 2-(7-azobenzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (157 mg), ammonium chloride (87 mg), and N,N-diisopropylethylamine (356 mg) were added sequentially while cooling in an ice bath. After the addition was complete, the reaction was stirred overnight at room temperature, and LCMS indicated the reaction was complete. Sodium bicarbonate solution was added, the mixture was extracted with ethyl acetate, and the extract was washed with saturated ammonium chloride solution. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The resulting crude product was purified by pre-TLC to give the title compound (46 mg). [ka]

[0095] Step 2: Preparation of 6-(tert-butyl) 2-methyl 7-carbamoyl-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate tert-Butyl 7-carbamoyl-2-chloro-7,8-dihydro-1,6-naphthyridine-6-(5H)-carboxylate (40 mg) was dissolved in methanol (20 mL) at room temperature, and palladium acetate (15 mg), 1,1'-bis(diphenylphosphino)ferrocene (72 mg), and triethylamine (65 mg) were added. After the addition was complete, the system was charged with carbon monoxide and then heated to 65°C and stirred overnight under a carbon monoxide atmosphere. The reaction was detected to be complete by LCMS, and the reaction mixture was concentrated under reduced pressure. The crude product was purified by pre-TLC to give the title compound (39 mg). [ka]

[0096] Step 3:Preparation of 6-(tert-butoxycarbonyl)-7-carbamoyl-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid 2-Methyl 7-carbamoyl-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate 6-(tert-butyl) (39 mg) was dissolved in tetrahydrofuran (1 mL) / methanol (1 mL) / water (1 mL) at room temperature, lithium hydroxide monohydrate (10 mg) was added, and the mixture was stirred for 3 minutes. The reaction was detected to be complete by LCMS, and the reaction mixture was concentrated under reduced pressure to give the crude title compound. [ka]

[0097] Step 4: Preparation of 7-carbamoyl-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride The crude 6-(tert-butoxycarbonyl)-7-carbamoyl-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid obtained in step 3 was added to a solution of hydrogen chloride in 1,4-dioxane (4 M, 2 mL) at room temperature and stirred for 30 minutes. LCMS showed the reaction was complete. The reaction mixture was concentrated under reduced pressure, and the residue was purified by pre-HPLC to give the title compound (10 mg). [ka]

[0098] Example 9: Preparation of 7-(1-hydroxycyclopropyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0099] Step 1: Preparation of tert-butyl 2-chloro-7-(1-hydroxycyclopropyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 6-(tert-butyl) 7-methyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6,7(5H)-dicarboxylate (98 mg) and tetraisopropyl titanate (85 mg) were placed in a dry reaction flask. The system was evacuated and refilled with nitrogen (three times), and tetrahydrofuran (2.5 mL) was added. While cooling in an ice bath, a solution of ethylmagnesium bromide in tetrahydrofuran (1.2 mL, 1.0 M) was slowly added dropwise. The mixture was allowed to warm slowly to room temperature and react for 2 hours. TLC showed the reaction was complete. The reaction was quenched by the addition of saturated aqueous ammonium chloride solution. Ethyl acetate and water were added. The aqueous layer was separated and extracted, and the organic layer was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (50 mg). [ka]

[0100] Step 2: Preparation of 2-methyl 7-(1-hydroxycyclopropyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate 6-(tert-butyl ester) 2-Chloro-7-(1-hydroxycyclopropyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-tert-butyl carboxylate (50 mg) was weighed and dissolved in methanol (8 mL), followed by the sequential addition of palladium acetate (17 mg), 1,1'-bis(diphenylphosphino)ferrocene (83 mg), and triethylamine (76 mg). The system was charged with carbon monoxide and reacted overnight at 65°C under a carbon monoxide atmosphere. TLC indicated that the reaction was essentially complete. The reaction mixture was concentrated to dryness under reduced pressure, and the resulting crude product was purified by column chromatography to yield the title compound (40 mg). [ka]

[0101] Step 3:Preparation of 7-(1-hydroxycyclopropyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride 6-(tert-butyl) 2-methyl 7-(1-hydroxycyclopropyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate (40 mg) was weighed and dissolved in a mixture of methanol (2 mL), tetrahydrofuran (2 mL), and water (2 mL), and lithium hydroxide monohydrate (10 mg) was added. The reaction was allowed to proceed at room temperature for 1 hour, at which time TLC indicated that the reaction was essentially complete. The system was concentrated to dryness, and methylene chloride (3 mL) and hydrogen chloride in 1,4-dioxane (1 mL, 4.0 M) were added. The reaction was allowed to proceed at room temperature for 1 hour, at which time TLC indicated that the reaction was essentially complete. The system was concentrated to dryness and purified by pre-HPLC to provide the title compound (14.8 mg). [ka]

[0102] Example 10: Preparation of 7-(4-hydroxybutyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0103] Step 1: Preparation of (3-((tert-butyldimethylsilyl)oxy)propyl)triphenylphosphonium bromide 3-Bromopropoxytert-butyldimethylsilane (1.012 g) and triphenylphosphine (1.048 g) were dissolved in acetonitrile (15 mL) at room temperature, and the reaction mixture was heated to 80 °C and stirred overnight. LCMS showed the reaction was complete, and the reaction mixture was concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the title compound (1.176 g). [ka]

[0104] Step 2:Preparation of tert-butyl 7-(4-((tert-butyldimethylsilyl)oxy)but-1-en-1-yl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (3-((tert-Butyldimethylsilyloxy)propyl)triphenylphosphonium bromide (178 mg) was dissolved in tetrahydrofuran under a nitrogen atmosphere, and sodium hydride (8 mg) was added while cooling in an ice bath and stirred for 30 minutes. tert-Butyl 2-chloro-7-formyl-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (96 mg) was added, and completion of the reaction was confirmed by LCMS. The reaction was placed in an ice bath and quenched by dropwise addition of water, followed by extraction with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the title compound (38 mg). [ka]

[0105] Step 3: Preparation of 6-(tert-butyl)2-methyl 7-(4-((tert-butyldimethylsilyl)oxy)but-1-en-1-yl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate Tert-butyl 7-(4-((tert-butyldimethylsilyl)oxy)but-1-en-1-yl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (36 mg) was dissolved in methanol (20 mL) at room temperature, and palladium acetate (9 mg), 1,1'-bis(diphenylphosphino)ferrocene (44 mg), and triethylamine (16 mg) were added. After the addition was complete, the system was charged with carbon monoxide and then heated to 65°C and stirred overnight under a carbon monoxide atmosphere. LCMS showed the reaction was complete, and the reaction mixture was concentrated under reduced pressure. The resulting crude product was purified by pre-TLC to give the title compound (26 mg). [ka]

[0106] Step 4: Preparation of 6-(tert-butyl)2-methyl 7-(4-((tert-butyldimethylsilyl)oxy)butyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate 6-(tert-butyl)2-methyl 7-(4-((tert-butyldimethylsilyl)oxy)but-1-en-1-yl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate (26 mg) was dissolved in ethyl acetate (20 mL) at room temperature, palladium on carbon (5 mg) was added, the system was charged with hydrogen, and stirred under a hydrogen atmosphere for 3 hours. LCMS showed the reaction was complete, and the mixture was filtered and concentrated under reduced pressure to give the crude title compound (25 mg). [ka]

[0107] Step 5: Preparation of 6-(tert-butoxycarbonyl)-7-(4-((tert-butyldimethylsilyl)oxy)butyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid At room temperature, 6-(tert-butyl)2-methyl 7-(4-((tert-butyldimethylsilyl)oxy)butyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate (25 mg) was dissolved in a system of tetrahydrofuran (1 mL) / methanol (1 mL) / water (1 mL), lithium hydroxide monohydrate (21 mg) was added, and the reaction was stirred for 1 hour. LC-MS showed that the reaction was complete. The system was adjusted to weak acidity with hydrogen chloride in 1,4-dioxane (4 M) and concentrated under reduced pressure to give the crude title compound. [ka]

[0108] Step 6: Preparation of 7-(4-hydroxybutyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride The crude 6-(tert-butoxycarbonyl)-7-(4-((tert-butyldimethylsilyl)oxy)butyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid obtained in step 5 was added to hydrogen chloride in 1,4-dioxane (4 M, 2 mL) at room temperature and stirred for 30 minutes. LCMS showed that the reaction was complete. The reaction mixture was concentrated under reduced pressure, and the residue was purified by pre-HPLC to give the title compound (2.3 mg). [ka]

[0109] Example 11: Preparation of 7-(((3-hydroxypropyl)amino)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid dihydrochloride [ka]

[0110] Step 1: Preparation of tert-butyl 2-chloro-7-(((3-hydroxypropyl)amino)methyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-7-formyl-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (97 mg) was dissolved in 1,2-dichloroethane (5 mL) at room temperature, 3-amino-1-propanol (34 mg) was added, and the mixture was stirred for 30 minutes. Sodium triacetoxyborohydride (254 mg) was then added, and the mixture was stirred overnight. LCMS showed the reaction was complete. The reaction mixture was diluted with water and dichloromethane (20 mL), washed with water, and extracted with dichloromethane. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to give the crude title compound, which was used directly in the next reaction. [ka]

[0111] Step 2:Preparation of tert-butyl 7-(((tert-butoxycarbonyl)(3-hydroxypropyl)amino)methyl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate The tert-butyl 2-chloro-7-(((3-hydroxypropyl)amino)methyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate obtained in Step 1 was dissolved in methanol (5 mL) at room temperature, and di-tert-butyl dicarbonate (87 mg) was added and stirred for 1 hour. LCMS showed that the reaction was complete. The reaction mixture was concentrated under reduced pressure, and the obtained crude product was purified by silica gel column chromatography to give the title compound (67 mg). [ka]

[0112] Step 3: Preparation of 6-(tert-butyl)2-methyl 7-(((tert-butoxycarbonyl)(3-hydroxypropyl)amino)methyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate At room temperature, tert-butyl 7-(((tert-butoxycarbonyl)(3-hydroxypropyl)amino)methyl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (67 mg) was dissolved in methanol (20 mL), and palladium acetate (17 mg), 1,1'-bis(diphenylphosphino)ferrocene (81 mg), and triethylamine (30 mg) were added. After the addition was complete, the system was charged with carbon monoxide and stirred under a carbon monoxide atmosphere at 65°C overnight. LCMS showed the reaction was complete, and the reaction mixture was concentrated under reduced pressure. The resulting crude product was purified by pre-TLC to give the title compound (43 mg). [ka]

[0113] Step 4:Preparation of methyl 7-(((3-hydroxypropyl)amino)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylate 2-Methyl 7-(((tert-butoxycarbonyl)(3-hydroxypropyl)amino)methyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate 6-(tert-butyl) (43 mg) was added to hydrogen chloride in 1,4-dioxane (4 M, 2 mL) at room temperature and stirred for 30 minutes. LCMS showed the reaction was complete, and the reaction mixture was concentrated under reduced pressure to give the crude title compound. [ka]

[0114] Step 5: Preparation of 7-(((3-hydroxypropyl)amino)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride The crude methyl 7-(((3-hydroxypropyl)amino)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylate obtained in Step 4 was dissolved in a system of tetrahydrofuran (1 mL) / methanol (1 mL) / water (1 mL), and lithium hydroxide monohydrate (38 mg) was added and stirred for 30 minutes. LCMS showed that the reaction was complete, and the reaction mixture was made weakly acidic with hydrogen chloride in 1,4-dioxane (4 M), the solvent was removed under reduced pressure, and the residue was purified by pre-HPLC to give the title compound (21.8 mg). [ka]

[0115] Example 12: Preparation of 7-(hydroxy(phenyl)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0116] Step 1:Preparation of tert-butyl 2-chloro-7-(hydroxy(phenyl)methyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate Tert-butyl 2-chloro-7-formyl-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (97 mg) was dissolved in tetrahydrofuran (10 mL) under a nitrogen atmosphere. Phenylmagnesium bromide (0.42 mL) was added dropwise while cooling in an ice bath, and the mixture was stirred for 1.5 hours. LCMS showed the reaction was complete. The reaction was quenched by the addition of ammonium chloride solution, partitioned between water and ethyl acetate, and the aqueous layer was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the title compound (86 mg). [ka]

[0117] Step 2: Preparation of 2-methyl 7-(hydroxy(phenyl)methyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate 6-(tert-butyl ester) tert-Butyl 2-chloro-7-(hydroxy(phenyl)methyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (86 mg) was dissolved in methanol (20 mL) at room temperature, and palladium acetate (23 mg), 1,1'-bis(diphenylphosphino)ferrocene (127 mg), and triethylamine (47 mg) were added. After the addition was complete, the system was charged with carbon monoxide and stirred overnight at 65 °C under a carbon monoxide atmosphere. LCMS showed the reaction was complete, and the reaction mixture was concentrated under reduced pressure. The resulting crude product was purified by pre-TLC to give the title compound (67 mg). [ka]

[0118] Step 3:Preparation of methyl 7-(hydroxy(phenyl)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylate 2-Methyl 7-(hydroxy(phenyl)methyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate 6-(tert-butyl) (40 mg) was added to hydrogen chloride in 1,4-dioxane (4 M, 2 mL) at room temperature and stirred for 30 minutes. LCMS showed the reaction was complete, and the reaction mixture was concentrated under reduced pressure to give the crude title compound. [ka]

[0119] Step 4: Preparation of 7-(hydroxy(phenyl)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride The crude 7-(hydroxy(phenyl)methyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylate obtained in Step 3 was dissolved in a system of tetrahydrofuran (1 mL) / methanol (1 mL) / water (1 mL), and lithium hydroxide monohydrate (42 mg) was added and stirred for 30 minutes. LCMS showed that the reaction was complete, and the reaction mixture was made weakly acidic with hydrogen chloride in 1,4-dioxane (4 M), concentrated under reduced pressure, and the residue was purified by pre-HPLC to give the title compound (17.2 mg). [ka]

[0120] Example 13: Preparation of 7-(1,4-dihydroxybutyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0121] Step 1: Preparation of 6-(tert-butoxycarbonyl)-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-7-carboxylic acid 6-(tert-butyl) 7-methyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6,7(5H)-dicarboxylate (1 g) was dissolved in tetrahydrofuran (3 mL), methanol (3 mL), and water (3 mL) at room temperature. Lithium hydroxide hydrate (0.257 g) was added, and the reaction was stirred for 30 minutes, at which point LCMS showed the reaction was complete. The pH was adjusted to 4-5 with dilute hydrochloric acid (1 M) while cooling in an ice bath. Ethyl acetate and water were added, and the layers were separated. The aqueous layer was extracted with ethyl acetate, and the organic layers were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to give the title compound (0.95 g). [ka]

[0122] Step 2: Preparation of tert-butyl 2-chloro-7-(methoxy(methyl)carbamoyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 6-(tert-Butoxycarbonyl)-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-7-carboxylic acid (0.95 g) was dissolved in dichloromethane (20 mL) at room temperature, and N,N-diisopropylethylamine (3.0 mL), 2-(7-azabenzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (1.28 g), and methoxymethylamine hydrochloride (0.6 g) were added successively. The mixture was stirred overnight, and TLC indicated the reaction was complete. Dichloromethane and water were added, and the layers were separated. The aqueous layer was extracted with dichloromethane, and the extract was washed with saturated brine. The organic layers were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the title compound (900 mg). [ka]

[0123] Step 3:Preparation of tert-butyl 2-chloro-7-formyl-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-7-(methoxy(methyl)carbamoyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (0.9 g) was dissolved in anhydrous tetrahydrofuran (20 mL). The system was cooled to −78° C. under a nitrogen atmosphere, and diisobutylaluminum hydride solution (7.6 mL) was added. After the addition was complete, the system was slowly warmed to room temperature and stirred for 3 hours. LCMS showed the reaction was complete. The reaction was placed in an ice bath and quenched by the dropwise addition of water over 10 minutes. Saturated potassium sodium tartrate solution (20 mL) was then added and stirred for 20 minutes. Extraction with ethyl acetate was performed, and the organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the title compound (0.54 g). [ka]

[0124] Step 4: Preparation of tert-butyl 7-(4-((tert-butyldimethylsilyl)oxy)-1-hydroxybutyl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl chloro-7-formyl-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (128 mg) was dissolved in anhydrous tetrahydrofuran (20 mL). The system was evacuated and refilled with nitrogen (three times), cooled to 0 °C, and a 2 M solution of 3-(tert-butyldimethylsiloxy)propylmagnesium bromide (0.42 mL) was added dropwise. After the addition, the temperature was maintained and the reaction was allowed to proceed for 20 minutes. LCMS showed the reaction was complete. The reaction was placed in an ice bath and quenched by the dropwise addition of water over 10 minutes. After three extractions with ethyl acetate, the organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the title compound (70 mg). [ka]

[0125] Step 5: Preparation of 6-(tert-butyl) 2-methyl 7-(4-(((tert-butyldimethylsilyl)oxy)-1-hydroxybutyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate tert-Butyl 7-(4-((tert-butyldimethylsilyl)oxy)-1-hydroxybutyl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (70 mg) was weighed and dissolved in methanol (10 mL), and triethylamine (30.1 mg), palladium acetate (16.7 mg), and 1,1'-bis(diphenylphosphino)ferrocene (82.5 mg) were added. Carbon monoxide gas was introduced into the reaction system, and the reaction was heated to 65°C and reacted overnight. LC-MS showed the reaction was complete, and the system was concentrated, and the residue was purified by column chromatography to give the title compound (80 mg). [ka]

[0126] Step 6: Preparation of methyl 7-(1,4-dihydroxybutyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylate 2-Methyl 7-(4-(((tert-butyldimethylsilyl)oxy)-1-hydroxybutyl)-7,8-dihydro-1,6-naphthyridine-2,6(5H)-6-dicarboxylate (tert-butyl) (80 mg) was weighed and dissolved in dichloromethane (3 mL). 4 M hydrogen chloride in 1,4-dioxane (3 mL) was added dropwise while cooling in an ice bath, and the reaction was carried out for 30 minutes while maintaining the temperature. LC-MS showed that the reaction was complete, and the system was concentrated to give the crude title compound (50 mg). [ka]

[0127] Step 7: Preparation of 7-(1,4-dihydroxybutyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride Methyl 7-(1,4-dihydroxybutyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylate (70 mg) was weighed and dissolved in a solution of tetrahydrofuran (1 mL), water (1 mL), and methanol (1 mL). Lithium hydroxide monohydrate (13.44 mg) was added while cooling in an ice bath. The reaction was allowed to proceed at room temperature for 30 minutes. LC-MS showed the reaction was complete, and the reaction mixture was adjusted to pH 4-5 with hydrochloric acid solution. The system was concentrated to give the crude product, which was purified by pre-HPLC to give the title compound (7 mg). [ka]

[0128] Example 14: Preparation of 8-((3-isobutylpiperazin-1-yl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0129] Step 1: Preparation of tert-butyl 8-(4-(tert-butoxycarbonyl)-3-isobutylpiperazin-1-yl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-((methylsulfonyl)oxy)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (50 mg) was dissolved in a mixture of N,N-dimethylformamide (0.5 mL) and acetonitrile (0.5 mL), and tert-butyl 2-isobutylpiperazine-1-carboxylate (51 mg) and potassium carbonate (40 mg) were added. The reaction temperature was raised to 70 °C and allowed to react overnight, after which TLC showed the disappearance of the starting material. The reaction was cooled to room temperature, quenched with water, extracted with ethyl acetate, and the combined organic phase was washed once with saturated brine, dried over anhydrous sodium sulfate, and concentrated. The residue was purified by column chromatography to give the title compound (30 mg). [ka]

[0130] Step 2: Preparation of tert-butyl 8-(4-(tert-butoxycarbonyl)-3-isobutylpiperazin-1-yl)-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 8-(4-(tert-butoxycarbonyl)-3-isobutylpiperazin-1-yl)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (30 mg) was weighed and dissolved in a mixed solvent of 1,4-dioxane (1 mL) and water (0.5 mL), and potassium acetate (12 mg), potassium hexacyanoferrate trihydrate (13 mg), 2-(dicyclohexylphosphino)-2,4,6-triisopropylbiphenyl (3 mg), and (2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl)(2'-amino-1,1'-biphenyl-2-yl)palladium(II) methanesulfonate (3 mg) were successively added. The system was evacuated and refilled with nitrogen (three times), sealed, and reacted at 125°C for 1 hour. LC-MS showed the reaction was complete. The reaction was cooled to room temperature, filtered, and the filter cake was washed several times with ethyl acetate. Water was added to the filtrate, the organic layer was separated, and the aqueous phase was extracted three times with ethyl acetate. The organic layers were combined, dried over anhydrous sodium sulfate, and concentrated to dryness under reduced pressure. The residue was purified by column chromatography to give the title compound (20 mg). [ka]

[0131] Step 3: Preparation of 8-((3-isobutylpiperazin-1-yl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride tert-Butyl 8-(4-(tert-butoxycarbonyl)piperazin-1-yl)-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (20 mg) was weighed and dissolved in 6 M aqueous hydrochloric acid (2 mL). The reaction was carried out at 110° C. overnight and the completion of the reaction was monitored by LC-MS. Concentration under reduced pressure and purification by pre-HPLC gave the title compound (1.48 mg). [ka]

[0132] Example 15: Preparation of 8-(2-benzylmorpholino)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0133] Step 1: Preparation of tert-butyl 8-(2-benzylmorpholino)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-chloro-8-((methylsulfonyl)oxy)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (50 mg) was dissolved in a mixture of N,N-dimethylformamide (0.5 mL) and acetonitrile (0.5 mL), and 2-benzylmorpholine (38 mg) and potassium carbonate (40 mg) were added. The reaction temperature was raised to 70 °C and allowed to react overnight, after which TLC showed the disappearance of the starting material. The reaction was cooled to room temperature, quenched with water, extracted with ethyl acetate, and the combined organic phase was washed once with saturated brine, dried over anhydrous sodium sulfate, and concentrated. The residue was purified by column chromatography to give the title compound (25 mg). [ka]

[0134] Step 2: Preparation of tert-butyl 8-(2-benzylmorpholino)-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate 25 mg of tert-butyl 8-(2-benzylmorpholino)-2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate was weighed and dissolved in 1 mL of 1,4-dioxane and 0.5 mL of water. Potassium acetate (12 mg), potassium hexacyanoferrate trihydrate (13 mg), 2-(dicyclohexylphosphino)-2,4,6-triisopropylbiphenyl (3 mg), and (2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl)(2'-amino-1,1'-biphenyl-2-yl)palladium(II) methanesulfonate (3 mg) were added sequentially. The system was evacuated and refilled with nitrogen three times, sealed, and reacted at 125 °C for 2 hours. LC-MS analysis indicated the reaction was complete. The reaction mixture was cooled to room temperature, filtered, and the filter cake was washed several times with ethyl acetate. Water was added to the filtrate, the organic layer was separated, and the aqueous layer was extracted three times with ethyl acetate. The organic layers were combined, dried over anhydrous sodium sulfate, and concentrated to dryness under reduced pressure. The residue was purified by column chromatography to give the title compound (20 mg). [ka]

[0135] Step 3: Preparation of 8-(2-benzylmorpholino)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride tert-Butyl 8-(2-benzylmorpholino)-2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (20 mg) was weighed and dissolved in 6 M aqueous hydrochloric acid (2 mL). The reaction was carried out at 105 °C overnight, and the completion of the reaction was monitored by LC-MS. Concentration under reduced pressure and purification by pre-HPLC gave the title compound (10.34 mg). [ka]

[0136] Example 16: Preparation of 5,6,7,8-tetrahydro-1,6-naphthyridine-2,7-dicarboxylic acid hydrochloride [ka]

[0137] Step 1: Preparation of 6-(tert-butyl)2,7-dimethyl 7,8-dihydro-1,6-naphthyridine-2,6,7(5H)-tricarboxylate 6-(tert-butyl)-7-methyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6,7(5H)-dicarboxylate (100 mg) was weighed and dissolved in methanol (10 mL), and triethylamine (0.085 mL), palladium acetate (34.3 mg), and 1,1'-bis(diphenylphosphino)ferrocene (169.5 mg) were added. Carbon monoxide gas was introduced into the system, and the reaction mixture was heated at 65 °C overnight. LC-MS showed the reaction was complete, so the system was concentrated, and the residue was purified by column chromatography to give the title compound (70 mg). [ka]

[0138] Step 2: Preparation of 6-(tert-butoxycarbonyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2,7-dicarboxylic acid 6-(tert-butyl)-2,7-dimethyl 7,8-dihydro-1,6-naphthyridine-2,6,7(5H)-tricarboxylate (70 mg) was weighed and dissolved in a solution of tetrahydrofuran (3 mL), water (3 mL), and methanol (3 mL). Lithium hydroxide monohydrate (16.6 mg) was added while cooling in an ice bath. The reaction was allowed to proceed overnight at room temperature. LC-MS showed the reaction was complete. The pH of the reaction mixture was adjusted to slightly acidic with hydrochloric acid solution, and the mixture was concentrated to give the crude title compound (100 mg). [ka]

[0139] Step 3: Preparation of 5,6,7,8-tetrahydro-1,6-naphthyridine-2,7-dicarboxylic acid hydrochloride 6-(tert-Butoxycarbonyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2,7-dicarboxylic acid (63.4 mg) was weighed and dissolved in dichloromethane (3 mL). 4 M hydrogen chloride in 1,4-dioxane (3 mL) was added dropwise while cooling in an ice bath. The reaction was allowed to proceed for 30 minutes while maintaining the temperature. LC-MS showed the reaction was complete. The system was concentrated, and the residue was purified by pre-HPLC to give the title compound (35 mg). [ka]

[0140] Example 17: Preparation of 3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0141] Step 1: Preparation of 2-chloro-5-fluoro-6-((4-methoxybenzyl)oxy)nicotinonitrile [ka] 2,6-Dichloro-5-fluoronicotinonitrile (5.0 g) was weighed and dissolved in tetrahydrofuran (50 mL). The solution was cooled to -78 °C and stirred. Potassium tert-butoxide (3.5 g) was added under a nitrogen atmosphere. The system was cooled to -78 °C, and a solution of 4-methoxybenzyl chloride (3.95 g) in tetrahydrofuran (50 mL) was added dropwise. After the addition was complete, the reaction solution was warmed to room temperature and allowed to react overnight. TLC showed that the reaction was complete. The reaction solution was concentrated under reduced pressure, ethyl acetate and water were added, the aqueous layer was separated and extracted, and the organic layer was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (6.2 g). MS(ESI) m / z(M+H)+=293.1

[0142] Step 2: Preparation of 5-fluoro-6-((4-methoxybenzyl)oxy)-2-vinyl-nicotinonitrile [ka] 2-Chloro-5-fluoro-6-((4-methoxybenzyl)oxy)nicotinonitrile (6.0 g), potassium vinyltrifluoroborate (5.5 g), [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium (0.29 g), and cesium fluoride (6.23 g) were weighed into a reaction flask, and 1,4-dioxane (60 mL) and water (6 mL) were added. The system was evacuated and refilled with nitrogen, and the reaction was allowed to proceed at 90 °C overnight. TLC indicated that the reaction was essentially complete. The mixture was concentrated to dryness under reduced pressure, ethyl acetate and water were added, the aqueous layer was separated and extracted, and the organic layer was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (2.68 g). MS(ESI) m / z(M+H)+=285.1

[0143] Step 3: Preparation of 6-benzyl-3-fluoro-2-((4-methoxybenzyl)oxy)-7,8-dihydro-1,6-naphthyridin-5(6H)-one [ka] 5-Fluoro-6-((4-methoxybenzyl)oxy)-2-vinyl-nicotinonitrile (2.68 g) was weighed and dissolved in methanol (20 mL) and water (4 mL), and benzylamine (12.44 g) was added. The reaction was allowed to proceed at 80° C. overnight, after which TLC showed that the reaction was essentially complete. The mixture was concentrated under reduced pressure, dichloromethane and water were added, the aqueous layer was separated and extracted, and the organic phase was washed with 1 M dilute hydrochloric acid and then concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (2.37 g). MS(ESI) m / z(M+H)+=393.1

[0144] Step 4: Preparation of 6-benzyl-3-fluoro-2-((4-methoxybenzyl)oxy)-5,6,7,8-tetrahydro-1,6-naphthyridine [ka] 6-Benzyl-3-fluoro-2-((4-methoxybenzyl)oxy)-7,8-dihydro-1,6-naphthyridin-5(6H)-one (1.19 g) was weighed and dissolved in tetrahydrofuran (20 mL). Lithium aluminum hydride (0.29 g) was added portionwise while cooling in an ice bath, and the reaction was carried out at 70°C for 4 hours. TLC showed substantial completion of the reaction. While cooling in an ice bath, 0.5 mL of water, 0.5 mL of 15% aqueous sodium hydroxide solution, and 1.5 mL of water were added dropwise successively, and the mixture was stirred at room temperature for 15 minutes. Anhydrous magnesium sulfate was then added and stirred for 15 minutes. The mixture was filtered through Celite and anhydrous sodium sulfate. The filter residue was washed with ethyl acetate, and the filtrate was concentrated to dryness to give the title compound (1.15 g). MS(ESI) m / z(M+H)+=379.1

[0145] Step 5: Preparation of 6-benzyl-2-chloro-3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine [ka] 6-Benzyl-3-fluoro-2-((4-methoxybenzyl)oxy)-5,6,7,8-tetrahydro-1,6-naphthyridine (1.14 g) was weighed and, while cooling in an ice bath, phosphorus oxychloride (10 mL) was added. The reaction was allowed to proceed overnight at 100° C., and TLC showed that the reaction was essentially complete. The mixture was concentrated under reduced pressure, diluted with ethyl acetate, added dropwise to crushed ice, and the pH was adjusted to 10 by the addition of saturated sodium carbonate solution. The mixture was extracted with ethyl acetate, and the extract was washed with saturated brine. The organic phase was dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated to dryness to give the crude title compound (0.82 g). MS(ESI) m / z(M+H)+=277.1

[0146] Step 6: Preparation of 2-chloro-3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine [ka] 6-Benzyl-2-chloro-3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine (0.82 g) was weighed and dissolved in 1,2-dichloroethane (8 mL). N,N-diisopropylethylamine (1.93 g) and 1-chloroethyl chloroformate (2.57 g) were added successively while cooling in an ice bath. The reaction was carried out at 80°C for 1.5 hours, at which time TLC indicated that the reaction was essentially complete. The system was concentrated to dryness, dissolved in methanol, and reacted at 60°C for 1.5 hours. TLC indicated that the reaction was essentially complete. The system was concentrated to dryness under reduced pressure to give the crude title compound. MS(ESI) m / z(M+H)+=187.1

[0147] Step 7: Preparation of 6-(tert-butoxycarbonyl)-2-chloro-3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine [ka] 2-Chloro-3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine was weighed and dissolved in dichloroethane (10 mL). Triethylamine (0.91 g) and di-tert-butyl dicarbonate (0.98 g) were added while cooling in an ice bath, and the reaction was allowed to proceed at room temperature for 2 hours. TLC showed that the reaction was essentially complete. Dichloromethane and water were added, the aqueous layer was separated and extracted, and the organic layer was concentrated to dryness. The resulting crude product was purified by column chromatography to give the title compound (0.28 g). MS(ESI) m / z(M+H)+=287.1

[0148] Step 8: Preparation of 6-(tert-butyl) 2-methyl 3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine-2,6-dicarboxylate [ka] 6-(tert-Butoxycarbonyl)-2-chloro-3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine (100 mg) was weighed and dissolved in methanol (10 mL), and palladium acetate (40 mg), 1,1'-bis(diphenylphosphino)ferrocene (200 mg), and triethylamine (71 mg) were added sequentially. The system was evacuated and recharged with carbon monoxide (three times), and the reaction was carried out under a carbon monoxide atmosphere at 65 °C overnight. TLC indicated that the reaction was essentially complete. The mixture was concentrated to dryness under reduced pressure, and the resulting crude product was purified by column chromatography to give the title compound (100 mg). MS(ESI) m / z(M+H)+=311.1

[0149] Step 9: Preparation of 6-(tert-butoxycarbonyl)-3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid [ka] 6-(tert-butyl)2-methyl 3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine-2,6-dicarboxylate (100 mg) was weighed and dissolved in a system of methanol (2 mL), tetrahydrofuran (2 mL), and water (2 mL), and lithium hydroxide monohydrate (27 mg) was added. The reaction was allowed to proceed at room temperature for 1 hour, at which point TLC showed that the reaction was essentially complete. The system was concentrated to dryness to give the crude product, which was used directly in the next reaction. MS(ESI) m / z(M+H)+=297.1

[0150] Step 10: Preparation of 3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka] To 6-(tert-butoxycarbonyl)-3-fluoro-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid (94 mg), dichloromethane (3 mL), and hydrogen chloride in 1,4-dioxane (2 mL, 4.0 M) were added, and the reaction was allowed to proceed at room temperature for 1 hour, at which time TLC showed that the reaction was essentially complete. The system was concentrated to dryness, and the residue was purified by reverse-phase preparative column chromatography to give the title compound (62.6 mg). MS(ESI) m / z(M+H)+=197.1 1 H NMR (400 MHz, Deuterium Oxide) δ 7.64 (d, J = 10.2 Hz, 1H), 4.47 (s, 2H), 3.61 (t, J = 6.4 Hz, 2H), 3.18 (t, J = 6.5 Hz, 2H)

[0151] Example 45: Preparation of 7,7-diethyl-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride [ka]

[0152] Step 1: Preparation of 2-methyl-N-(pentan-3-ylidene)propane-2-sulfinamide Pentan-3-one (10.73 g) was weighed and dissolved in tetrahydrofuran (300 mL), and tetraethyl titanate (46 g) and 2-methylpropane-2-sulfinamide (12 g) were added. After the addition was complete, the system was evacuated and refilled with nitrogen (three times). The reaction was heated to 65°C and reacted for 20 hours. LC-MS showed the reaction was complete. Water (30 mL) was added to the system to precipitate a large amount of solid, the mixture was suction filtered, the organic phase was dried and concentrated to dryness, and the residue was purified by column chromatography to give the title compound (10.8 g). [ka]

[0153] Step 2:Preparation of N-(3-((3-bromo-6-methoxypyridin-2-yl)methyl)pent-3-yl)-2-methylpropane-2-sulfinamide Tetrahydrofuran (50 mL) was added to a dry reaction flask, the system was evacuated and refilled with nitrogen (three times), 2 M lithium diisopropylamide (25 mL) was added, and the temperature was reduced to -78 °C. A solution of 3-bromo-6-methoxy-2-methylpyridine (9.4 g) in tetrahydrofuran (50 mL) was added, and the mixture was stirred at -78 °C for 1 hour. A solution of 2-methyl-N-(pentan-3-ylidene)propane-2-sulfinamide (8 g) in tetrahydrofuran (50 mL) was added, and the temperature was slowly increased from -78 °C to -30 °C. The mixture was stirred for 2 hours, at which point LC-MS indicated the reaction was complete. The reaction was quenched with saturated ammonium chloride solution and extracted three times with ethyl acetate. The organic phase was dried and concentrated to dryness, and the residue was purified by column chromatography to give the title compound (11.3 g). [ka]

[0154] Step 3: Preparation of ethyl 2-(2-((tert-butylsulfinyl)amino)-2-ethylbutyl)-6-methoxynicotinate N-(3-((3-bromo-6-methoxypyridin-2-yl)methyl)pent-3-yl)-2-methylpropane-2-sulfinamide (11.3 g) was placed in a dry reaction flask and dissolved in ethanol (10 mL), and 1,1'-bis(diphenylphosphino)ferrocene-palladium(II) dichloride dichloromethane complex (4.73 g) and triethylamine (9.6 mL) were added. The system was evacuated and recharged with carbon monoxide (3 times), then heated to reflux for 6 hours. LC-MS showed the reaction was complete. The system was concentrated to dryness. Purification by column chromatography gave the title compound (9.3 g). [ka]

[0155] Step 4: Preparation of 7,7-diethyl-2-methoxy-7,8-dihydro-1,6-naphthyridin-5(6H)-one Ethyl 2-(2-((tert-butylsulfinyl)amino)-2-ethylbutyl)-6-methoxynicotinate (9.3 g) was placed in a dry reaction flask and dissolved in dioxane (10 mL), sodium hydroxide (4.8 g) was added, and the reaction was heated at 100° C. for 6 hours. LC-MS showed the reaction was complete. The system was filtered through Celite, and the filtrate was concentrated to dryness. Purification by column chromatography gave the title compound (4.6 g). [ka]

[0156] Step 5: Preparation of 7,7-diethyl-2-methoxy-5,6,7,8-tetrahydro-1,6-naphthyridine 7,7-Diethyl-2-methoxy-7,8-dihydro-1,6-naphthyridin-5(6H)-one (3 g) was weighed and dissolved in tetrahydrofuran (100 mL). Lithium aluminum hydride (1.9 g) was added portionwise while cooling in an ice bath. The reaction was heated to reflux and stirred overnight. LC-MS showed the reaction was complete. The mixture was concentrated to dryness. Purification by silica gel column chromatography gave the title compound (2.8 g). [ka]

[0157] Step 6: Preparation of 7,7-diethyl-5,6,7,8-tetrahydro-1,6-naphthyridin-2-ol 7,7-Diethyl-2-methoxy-5,6,7,8-tetrahydro-1,6-naphthyridine (2.8 g) was weighed and dissolved in 33% hydrogen bromide in acetic acid (w / w, 20 mL). The reaction was heated to 80° C. and stirred overnight. LC-MS showed the reaction was complete. The mixture was concentrated to dryness. The resulting crude product was slurried with acetonitrile to give the title compound (4.3 g). [ka]

[0158] Step 7: Preparation of 2-chloro-7,7-diethyl-5,6,7,8-tetrahydro-1,6-naphthyridine 7,7-Diethyl-5,6,7,8-tetrahydro-1,6-naphthyridin-2-ol (2.8 g) was weighed and dissolved in phosphorus oxychloride (40 mL). The reaction was heated to 120 °C and allowed to react overnight. LC-MS showed the reaction was complete, and the mixture was concentrated to dryness under reduced pressure. Diluted with dichloromethane, water was added, and the pH was adjusted to 9-10 with sodium carbonate. The resulting crude title compound was used directly in the next reaction without purification. [ka]

[0159] Step 8: Preparation of tert-butyl 2-chloro-7,7-diethyl-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate The crude product from the previous step was dissolved in THF / HO, the system was treated with sodium carbonate, di-tert-butyl dicarbonate (4.67 mL) was added, and the mixture was stirred at room temperature overnight. LC-MS showed the reaction was complete. The mixture was extracted three times with dichloromethane, and the organic phase was dried and concentrated. Purification by silica gel column chromatography gave the title compound (1.5 g). [ka]

[0160] Step 9: Preparation of 6-(tert-butyl) 2-ethyl 7,7-diethyl-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate tert-Butyl 2-chloro-7,7-diethyl-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (100 mg) was placed in a dry reaction flask and dissolved in ethanol (10 mL). 1,1'-bis(diphenylphosphino)ferrocene palladium dichloride dichloromethane complex (50.3 mg) and N,N-diisopropylethylamine (0.11 mL) were added. Carbon monoxide gas was introduced into the system and heated to 100 °C. The reaction was allowed to proceed overnight. LC-MS showed the reaction was complete, and the system was concentrated to dryness. Purification by column chromatography afforded the title compound (80 mg). [ka]

[0161] Step 10: Preparation of 6-(tert-butoxycarbonyl)-7,7-diethyl-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid 6-(tert-butyl)2-ethyl 7,7-diethyl-7,8-dihydro-1,6-naphthyridine-2,6(5H)-dicarboxylate (45 mg) was weighed and dissolved in a solution of tetrahydrofuran (1 mL), water (1 mL), and methanol (1 mL), and lithium hydroxide hydrate (10.6 mg) was added at room temperature. The reaction was allowed to proceed at room temperature for 1 hour. LC-MS showed the reaction was complete, and the system was concentrated to give the crude product as a white solid. [ka]

[0162] Step 11: Preparation of 7,7-diethyl-5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride The crude solid obtained in the previous step was dissolved in dichloromethane (1.5 mL) and cooled in an ice bath to which 4 M hydrogen chloride in 1,4-dioxane (1.5 mL) was added dropwise. After the addition was complete, the reaction was allowed to proceed at room temperature for 1 hour. LC-MS showed the reaction was complete, and the system was concentrated to give the crude product, which was purified by pre-HPLC to give the title compound (5 mg). [ka]

[0163] The following compounds are prepared using conventional, commercially available starting materials and reagents, with reference to the preparation methods in the examples described above, in combination with conventional separation and purification methods in the art. [Table 1] JPEG0007749679000128.jpg210170JPEG0007749679000129.jpg222170JPEG00077496790 00130.jpg215170JPEG0007749679000131.jpg216170JPEG0007749679000132.jpg132170

[0164] Biological assays Test Example 1: Plasma clot lysis assay 1. Purpose The inhibitory effect of the compounds of the present invention on the breakdown of plasma clots is determined.

[0165] 2. Experimental materials and equipment [Table 2]

[0166] 3. Experimental Procedure 3.1 Fresh healthy human blood was collected, mixed with 1 part anticoagulant (0.109 M trisodium citrate) and 9 parts blood, centrifuged at 2000 × g for 20 minutes at room temperature, and the supernatant (plasma) was collected, sub-packaged, and stored at −80°C for later use.

[0167] 3.2 On the day of the experiment, plasma was thawed in a 37°C water bath and all reagents except tPA were preheated to 37°C.

[0168] 3.3 12.5 μL of 80 mM CaCl 2 (HEPES buffer, pH 7.4) was placed in a 96-well plate, and then 25 μL of test compounds diluted with saline at different concentrations were added, and the negative control wells were filled with an equal amount of saline.

[0169] 3.4 50 μL of preheated plasma was mixed with 12.5 μL of 4 nM tPA (HEPES buffer, pH 7.4) and immediately added to a 96-well plate. The absorbance at 405 nm was measured continuously every 2 minutes for 15 hours.

[0170] 3.5 The absorption value changed with time, first increasing and then decreasing. The time corresponding to the median of the absorption value in the decreasing section minus the time corresponding to the median of the absorption value in the increasing section was taken as the plasma clot lysis time (clot dissolution time). The plasma clot lysis time in the wells treated with different concentrations of the compound was calculated relative to the plasma clot lysis time in the negative control well to obtain the inhibition rate: Inhibition %=(1-clot lysis time of negative control wells / clot lysis time of compound-treated wells)×100%

[0171] 3.6 Dose-response curve fitting The logarithm of compound concentration is plotted on the X-axis and the percentage of inhibition on the Y-axis. Dose-response curves are fitted using the software GraphPad Prism 5 using the log(inhibitor) vs. slope of the response variable to calculate the IC of compounds that inhibit plasma clot breakdown. 50 derived the value.

number

[0172] The inhibitory effect of the compounds of the present invention on plasma clot lysis was determined by the above-mentioned test and the calculated IC50 All values ​​are IC values ​​for tranexamic acid, a hemostatic agent commonly used in clinical practice. 50 For example, the inhibitory IC value of the compound of Example 1 of the present invention on plasma clot lysis was 50 is the IC of tranexamic acid 50 The relative in vitro clotting activity (IC 50 ratio=IC 50実施例 / I C 50トラネキサム酸 ) are shown in the table below. [Table 3]

[0173] Experimental data show that the compounds of the present invention can effectively inhibit the decomposition of coagulated plasma and exhibit excellent coagulation and hemostatic effects. The effective dose is much lower than that of the most frequently used hemostatic agents in clinical practice, which can effectively avoid side effects and complications caused by high-dose administration, making them highly promising for clinical application.

[0174] Test Example 2: PK data in monkeys 1.Animals Male cynomolgus monkeys, normal grade, 3 animals per group (N=3)

[0175] 2. Formulation and Administration The compound was weighed and dissolved in saline to prepare a 0.5 mg / mL clear solution for intravenous administration.

[0176] On the day of the experiment, animals were administered the drugs according to the scheme in the table below. At each post-administration time point, approximately 1 mL of blood was collected from a vein in the forearm and placed in a sodium heparin anticoagulant tube. Blood samples were placed on ice after collection, and plasma was separated by centrifugation within 1 hour (centrifugation conditions: 2200 g, 10 minutes, 2-8°C). Plasma samples were stored in a -80°C refrigerator until analysis.

[0177] [Table 4]

[0178] 3. Biological analysis The compound concentration in the plasma of cynomolgus monkeys was measured by the following method. Equipment and instruments: LC-MS / MS-19 (TQ5500, ABSCIEX, USA) Internal standard: warfarin Chromatography column: ACQUITY UPLCBEHC18, model 1.7 μm 2.1*50 mm, purchased from Shenzhen Novah Chemical Technology Co., Ltd. Flow rate: 0.60ml / min Column temperature: 40℃ Mobile phase A: 0.1% formic acid in water Mobile phase B: 0.1% formic acid in acetonitrile The elution gradient is shown in Table 3. [Table 5] MS detection conditions: electrospray ion source (ESI), positive ion mode, MRM scan

[0179] 30 μL of the plasma sample prepared in section 2 was collected, and 300 μL of MeOH containing 100 ng / mL of internal standard was added to precipitate proteins. The mixture was vortexed for 1 minute and centrifuged at 18,000 g for 7 minutes. The supernatant was transferred to a 96-well plate. 4 μL of the supernatant was injected into the LC-MS / MS for analysis.

[0180] Pharmacokinetic parameters were calculated according to the blood concentration data at various time points using Phoenix WinNonlin 7.0 software.

[0181] Compounds of the invention were tested using the experiments described above and the pharmacokinetic parameters measured in cynomolgus monkeys are shown in the table below. [Table 6]

[0182] Experiments have shown that the compounds of the present invention have the advantages of better hemostatic activity, lower effective doses, and longer duration of drug effect, which can avoid various side effects that may occur with high-dose clinical administration, thereby improving the safety and efficacy of the drug for patients.In addition, the compounds of the present invention are convenient for preparation and large-scale industrial production, which can effectively reduce the cost of pharmaceuticals.The compounds of the present invention have good distribution, metabolism, and excretion properties, have low potential for drug-drug interactions, and can meet the pharmacokinetic parameter requirements for therapeutic effect in the human body.

Claims

1. A compound represented by the structure of Formula I, a pharmaceutically acceptable salt or hydrate thereof: 【Chemical 1】 [In the formula, R １ is hydrogen, hydroxy, amino, phenyl, pyridyl, C １ -C ６ Alkyl, C １ -C ６ Alkoxy, —NH—(C １ -C ６ ) alkyl, C ３ -C ６ cycloalkyl, and 4- to 7-membered aliphatic heterocyclyl; １ is hydroxy, C １ -C ４ optionally substituted with 1 to 2 groups selected from alkyl, F, Cl, Br, phenyl, benzyl, cyclopropyl; R ２ are independently hydrogen, carboxyl, amide, C １ -C ６ Alkyl, —NH—C １ -C ６ Alkyl, —CH ２ O-C １ -C ６ Alkyl, —CH ２ NH-C １ -C ６ Alkyl, —COO—C １ -C ６ Alkyl, -CONH-C １ -C ６ Alkyl, C ３ -C ６ Cycloalkyl, phenyl, 4- to 7-membered aliphatic heterocyclyl, pyridyl, phenyl C １ -C ６ Alkyl, C ３ -C ６ Cycloalkyl-C １ -C ６ alkyl; ２ is hydroxy, C １ -C ６ Alkyl, C １ -C ６ alkoxy; or two R ２ together with the carbon atoms to which they are attached, form C ３ -C ６ forming a cycloalkyl or tetrahydropyranyl; R ３ is selected from hydrogen and halogen; The aliphatic heterocyclyl refers to a saturated monocyclic hydrocarbon substituent in which one or more ring atoms are replaced with a heteroatom selected from N, O, and S, the remaining ring atoms being carbon, and the S heteroatom(s) being optionally oxidized; and R １ , R ２ and R ３ is not hydrogen at the same time.

2. 2. The compound of claim 1 having the structure of Formula I', a pharmaceutically acceptable salt or hydrate thereof: 【Chemistry 2】 [In the formula, R １ is hydrogen, hydroxy, amino, C １ -C ６ Alkyl, C １ -C ６ Alkoxy, —NH—C １ -C ６ Alkyl, C ３ -C ６ is selected from the group consisting of cycloalkyl, phenyl, 4- to 7-membered aliphatic heterocyclyl, and pyridyl; １ is hydroxy, C １ -optionally substituted with 1 to 2 groups selected from C4 alkyl, F, Cl, Br, phenyl, and cyclopropyl; R ２ is hydrogen, carboxyl, amide, C １ -C ６ Alkyl, —NH—C １ -C ６ Alkyl, —CH ２ O-C １ -C ６ Alkyl, —CH ２ NH-C １ -C ６ Alkyl, —COO—C １ -C ６ Alkyl, -CONH-C １ -C ６ Alkyl, C ３ -C ６ is selected from the group consisting of cycloalkyl, phenyl, 4- to 7-membered aliphatic heterocyclyl, and pyridyl; ２ is hydroxy, C １ -C ６ optionally substituted with 1 to 2 groups selected from alkyl; R ３ is selected from hydrogen and halogen.

3. R １ is hydrogen, hydroxy, amino, phenyl, pyridyl, methyl, ethyl, propyl, isopropyl, butyl, methoxy, ethoxy, propoxy, -NHCH ３ , -NHCH ２ CH ３ , -NHCH ２ CH ２ CH ３ , cyclopropyl, cyclobutyl, cyclopentyl, piperidinyl, morpholinyl, piperazinyl, thiomorpholinyl, 1-oxide-4-thiomorpholinyl, 1,1-dioxide-4-thiomorpholinyl; １ is optionally substituted with 1 to 2 groups selected from hydroxy, F, Cl, Br, methyl, ethyl, propyl, isopropyl, phenyl, benzyl, and cyclopropyl, or a pharmaceutically acceptable salt or hydrate thereof.

4. R １ But hydrogen, C １ -C ４ is selected from the group consisting of alkoxy, morpholinyl, piperazinyl, thiomorpholinyl, 1-oxide-4-thiomorpholinyl, and 1,1-dioxide-4-thiomorpholinyl; １ is optionally substituted with 1 to 2 groups selected from hydroxy and benzyl, or a pharmaceutically acceptable salt or hydrate thereof, according to claim 1 or 2.

5. R ２ is hydrogen, carboxyl, amide, methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, pentyl, -CH ２ OCH ３ , -CH ２ OCH ２ CH ３ , -CH ２ OCH ２ CH ２ CH ３ , -CH ２ NHCH ３ , -CH ２ NHCH ２ CH ３ , -CH ２ NHCH ２ CH ２ CH ３ , -COOCH ３ , -COOCH ２ CH ３ , -COOCH ２ CH ２ CH ３ , -CONHCH ３ , -CONHCH ２ CH ３ , -CONHCH ２ CH ２ CH ３ , cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, benzyl, pyridyl, piperidinyl, morpholinyl, thiomorpholinyl, 1-oxide-thiomorpholinyl, 1,1-dioxide-4-thiomorpholinyl; ２ is optionally substituted with 1 to 2 groups selected from hydroxy, methyl, ethyl, propyl, and isopropyl, or a pharmaceutically acceptable salt or hydrate thereof.

6. R ２ is hydrogen, carboxyl, C １ -C ６ Alkyl, —CH ２ O-(C １ -C ６ ) alkyl, —COO—(C １ -C ６ ) alkyl, C ３ -C ６ Cycloalkyl, phenyl-(C １ -C ４ ) alkyl and (C ３ -C ６ ) cycloalkyl-(C １ -C ４ ) alkyl; wherein said alkyl, cycloalkyl and phenyl are independently selected from the group consisting of hydroxy and C １ -C ４ alkoxy; or two R ２ together with the carbon atoms to which they are attached, C ３ -C ６ The compound according to any one of claims 1 to 4, which forms a cycloalkyl or tetrahydropyranyl, or a pharmaceutically acceptable salt or hydrate thereof.

7. R ３ The compound according to any one of claims 1 to 6, or a pharmaceutically acceptable salt or hydrate thereof, wherein is selected from hydrogen, fluorine, chlorine and bromine.

8. R １ and R ２ The compound according to any one of claims 1 to 7, or a pharmaceutically acceptable salt or hydrate thereof, wherein is not simultaneously hydrogen.

9. structure: 【Chemistry 3】 【change】 【change】 2. The compound of claim 1, or a pharmaceutically acceptable salt or hydrate thereof, having the formula:

10. A pharmaceutical composition comprising at least one compound according to any one of claims 1 to 9, or a pharmaceutically acceptable salt or hydrate thereof, and at least one pharmaceutically acceptable excipient.

11. Use of a compound represented by the structure of Formula I, a pharmaceutically acceptable salt or hydrate thereof, for the manufacture of a medicament: 【Chemistry 4】 [In the formula, R １ is hydrogen, hydroxy, amino, phenyl, pyridyl, C １ -C ６ Alkyl, C １ -C ６ Alkoxy, —NH—(C １ -C ６ ) alkyl, C ３ -C ６ cycloalkyl, and 4- to 7-membered aliphatic heterocyclyl; １ is hydroxy, C １ -C ４ optionally substituted with 1 to 2 groups selected from alkyl, F, Cl, Br, phenyl, benzyl, cyclopropyl; R ２ are independently hydrogen, carboxyl, amide, C １ -C ６ Alkyl, —NH—C １ -C ６ Alkyl, —CH ２ O-C １ -C ６ Alkyl, —CH ２ NH-C １ -C ６ Alkyl, —COO—C １ -C ６ Alkyl, -CONH-C １ -C ６ Alkyl, C ３ -C ６ Cycloalkyl, phenyl, 4- to 7-membered aliphatic heterocyclyl, pyridyl, phenyl C １ -C ６ Alkyl, C ３ -C ６ Cycloalkyl-C １ -C ６ alkyl; ２ is hydroxy, C １ -C ６ Alkyl, C １ -C ６ alkoxy; or two R ２ together with the carbon atoms to which they are attached, form C ３ -C ６ forming a cycloalkyl or tetrahydropyranyl; R ３ is selected from hydrogen and halogen; The aliphatic heterocyclyl refers to a saturated monocyclic hydrocarbon substituent in which one or more ring atoms are replaced with a heteroatom selected from N, O and S, the remaining ring atoms being carbon, and the S heteroatom(s) being optionally oxidized.

12. The use according to claim 11, wherein the compound is a compound as defined in any one of claims 1 to 9.

13. 12. The use of claim 11, wherein the compound is a compound represented by the following structure: 【Chemistry 5】

14. The use according to any one of claims 11 to 13, wherein the medicament has therapeutic activity for blood coagulation and hemostasis, and can be used for abnormal bleeding due to hyperfibrinolysis, and surgical and postoperative bleeding.

15. 11. The pharmaceutical composition of claim 10 for treating and / or alleviating bleeding diseases or conditions.

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