Preparation of boronic acid β-lactamase inhibitor and use thereof

Abstract

The present invention relates to the field of pharmaceuticals, and provides a boronic acid β-lactamase inhibitor or a use thereof. The boronic acid β-lactamase inhibitor is a compound represented by formula (I) or an optical isomer thereof: (I); the β-lactamase inhibitor has favorable pharmacokinetic properties and good druggability; the ultra-broad-spectrum boronic acid β-lactamase inhibitor exhibits activity against class A, B, C and D enzymes, and also has inhibitory effects on carbapenem-resistant bacteria such as Klebsiella pneumoniae, Enterobacter, Enterobacter cloacae, Acinetobacter baumannii, and Pseudomonas aeruginosa.

Description

Preparation of a boronic acid-based beta-lactamase inhibitor and use thereof TECHNICAL FIELD

[0001] The present application provides a novel compound having an excellent beta-lactamase inhibitory effect. The present application provides a compound represented by formula (I) or an optical isomer thereof, which has an excellent beta-lactamase inhibitory effect. The compound is used in combination with a beta-lactam drug, and provides a prophylactic or therapeutic agent useful for a bacterial infectious disease. The present application also provides a prophylactic or therapeutic agent useful for treating various diseases by the use in combination with a beta-lactam drug. BACKGROUND

[0002] With the widespread use of antibiotics, the problem of bacterial drug resistance is becoming increasingly serious, and the WHO's priority pathogen list mainly includes multi-drug resistant gram-negative bacteria, especially carbapenem-resistant Enterobacteriaceae, carbapenem-resistant Pseudomonas aeruginosa and extensively drug-resistant Acinetobacter baumannii. As one of the oldest, most widely used and most commonly used antibiotics in clinical practice, the problem of drug resistance of beta-lactam antibiotics has also come with it and is becoming increasingly serious.

[0003] Among various drug resistance mechanisms, the beta-lactamase produced by bacteria is the main mechanism leading to drug resistance of beta-lactam antibiotics. At present, more than 190 kinds of beta-lactamases have been reported worldwide, and these enzymes have many differences in source, substrate, inhibitor, structure, etc., which brings difficulties to the systematic classification of beta-lactamases and the research and development of inhibitors. Existing beta-lactamase inhibitors such as clavulanic acid, sulbactam and tazobactam have certain inhibitory effect, but there are some limitations in clinical application, such as poor inhibitory effect on certain specific types of beta-lactamase, more adverse reactions, etc. The increase of drug-resistant bacterial infections has brought great challenges to clinical treatment, and the research and development of new beta-lactamase inhibitors have urgent market demand and important social value.

[0004] The global beta-lactamase inhibitor market continues to grow, and is expected to remain stable in the next few years, providing a broad market prospect for the research and development of new beta-lactamase inhibitors. Existing beta-lactamase inhibitors have limitations in inhibitory effect and safety, and cannot meet the diversified needs of clinical treatment. The research and development of new beta-lactamase inhibitors need to solve the shortcomings of existing technology, improve the inhibitory effect, reduce adverse reactions, and expand the antibacterial spectrum. The purpose of the present application is to provide a new beta-lactamase inhibitor, which has stronger inhibitory effect, lower adverse reactions and wider antibacterial spectrum, and can effectively cope with the challenge of bacterial drug resistance, providing new drug options for the clinical treatment of drug-resistant bacterial infections.

[0005] The present application is a new type of beta-lactamase inhibitor, which can cope with multiple infections caused by multiple drug-resistant bacteria. The dual inhibitor can simultaneously inhibit the activity of serine beta-lactamase and metal beta-lactamase, has a wider antibacterial spectrum and stronger antibacterial effect, and the main antibacterial spectrum includes multiple drug-resistant gram-negative bacteria, especially carbapenem-resistant enterobacteriaceae, carbapenem-resistant pseudomonas aeruginosa and klebsiella pneumoniae, and extensively drug-resistant baumanii, etc. The inhibitory effect and safety are better than those of existing inhibitors, and have broad clinical application prospect and market potential. The present application provides a new solution for clinical treatment of drug-resistant bacterial infection. The development of the present application is of great significance to improve the sensitivity of beta-lactam antibiotics to drug-resistant bacteria, maintain or enhance the antibacterial activity, reduce the medical burden and social cost. SUMMARY

[0006] In view of the above technical status, the present application discloses a boronic acid beta-lactamase inhibitor, a preparation method and application thereof. Specifically, the beta-lactamase inhibitor is a compound represented by formula (I) or an optical isomer thereof:

[0007] wherein,

[0008] n is selected from 0 or 1;

[0009] m is selected from 0 or 1; wherein n and m are not simultaneously 1;

[0010] G1, G2 can be independently selected from -CH2-, -C(=O)-, -S(O)(O)-, wherein G1, G2 cannot be -CH2- at the same time;

[0011] R1, R2 are H or R1, R2 together with the atoms to which they are attached form a cycloalkyl group, preferably cyclopropane group; as an exemplary illustration, R1, R2 are each independently H, or R1, R2 together with the atoms to which they are attached form a cycloalkyl group, preferably cyclopropane group;

[0012] R3 can be selected from H, C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C1-6 Alkyl-aryl, -C 1-6 alkyl-heteroaryl, wherein C 1-6 Alkyl, aryl, heteroaryl, -C 1-6 Alkyl-NR k R j -C 1-6 Alkyl-C(=O)NR k R j -C 1-6 Alkyl-C 3-6 Cycloalkyl, -S(O)(O)-C 1-6 Alkyl, -C(=O)-C 1-6 Alkyl, -C 1-6 Alkyl-C 3-6 Heterocyclic alkyl, -C 1-6 Alkyl-aryl, -C 1-6 Alkyl-heteroaryl groups can be converted to one or more halogens, hydroxyl groups, cyano groups, nitro groups, amino groups, C6 groups, etc. 1-6 Alkyl, C 1-6 Alkoxy, C 3-6 cycloalkyl or C 3-6 Substituted with epoxy alkyl groups;

[0013] R k R j It can be independently selected from H and C. 1-6 Alkyl, C 1-6 Alkoxy, C 3-6 cycloalkyl, C 3-6 Epoxyalkyl, -(CH2) t -Aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 Alkyl group, wherein t is 0, 1, 2, 3, 4, 5, or 6, wherein the C 1-6 Alkyl, C 1-6 Alkoxy, C 3-6 cycloalkyl, C 3-6 Epoxyalkyl, -(CH2) t -Aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 Alkyl groups can be any one or more R n Replaced; R n It can be halogen, hydroxyl, cyano, nitro, amino, C 1-6 Alkyl, C 1-6 Alkoxy, C 3-6 cycloalkyl or C 3-6 Epoxyalkyl.

[0014] In this invention, as one embodiment, the compound represented by formula (I) or its optical isomer is:

[0015] wherein

[0016] when n is 0, m is 0,

[0017] G1, G2may be independently selected from -CH2-, -C(=O)-, -S(O)(O)-, wherein G1, G2cannot be -CH2- at the same time;

[0018] R1, R2are H or R1, R2together with the atoms to which they are attached form a cycloalkyl group, preferably cyclopropane group;

[0019] R3may be selected from H, C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl, wherein C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl can be substituted by one or more halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl;

[0020] R k , R j may be independently selected from H, C 1-6alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl, wherein t is 0, 1, 2, 3, 4, 5, 6, said C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl can be substituted by any one or more R n R n may be halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl.

[0021] In the present application, as one of the embodiments, in the compound of formula (I) or its optical isomer, when n is 0, m is 0, G1 is selected from -CH2-, G2 is selected from -C(=O)-, R3 is H; R1, R2 are R1, R2 together with the atoms to which they are attached form a cycloalkyl, preferably cyclopropyl.

[0022] In the present application, as one of the embodiments, in the compound of formula (I) or its optical isomer, when n is 0, m is 0, G1 is selected from -CH2-, G2 is selected from -C(=O)-, R3 is H; R1, R2 are each independently H.

[0023] In the present application, as one of the embodiments, the compound of formula (I) or its optical isomer:

[0024] wherein,

[0025] when n is 0, m is 1,

[0026] G1, G2 can be independently selected from -CH2-, -C(=O)-, -S(O)(O)-, wherein G1, G2 cannot be -CH2- at the same time;

[0027] R1, R2 are H or R1, R2 together with the atoms to which they are attached form a cycloalkyl, preferably cyclopropyl;

[0028] R3 can be selected from H, C 1-6alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl, wherein C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl can be substituted by one or more halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl;

[0029] R k , R j may be independently selected from H, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl, wherein t is 0, 1, 2, 3, 4, 5, 6, said C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2)t heteroaryl or -S(O)(O)-C 1-6 alkyl can be optionally substituted by one or more R n ; R n may be halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 cycloalkyl.

[0030] In the present application, as one of the embodiments, the compound represented by the formula (I) or its optical isomer:

[0031] wherein,

[0032] when n is 1 and m is 0,

[0033] G1, G2may be independently selected from -CH2-, -C(=O)-, -S(O)(O)-, wherein G1, G2cannot be -CH2- at the same time;

[0034] R1, R2are H or R1, R2together with the atom to which they are attached form a cycloalkyl, preferably cyclopropane;

[0035] R3may be selected from H, C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl, wherein C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl can be substituted with one or more halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, or C 3-6 epoxyalkyl;

[0036] R k , R j may be independently selected from H, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl, wherein t is 0, 1, 2, 3, 4, 5, 6, said C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl can be substituted with any one or more R n ; R n may be halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, or C 3-6 epoxyalkyl.

[0037] In the present application, as one of the embodiments, R3in the compound of formula (I) or its optical isomers is selected from H, -CH3, -CH2-CH2F, or -CH2-CH2NH2.

[0038] In the present application, the C 1-6 alkyl group, as an illustrative example, includes, but is not limited to, methyl, ethyl, propyl, isopropyl, cyclopropyl, isobutyl, n-butyl, sec-butyl, t-butyl, cyclobutyl, pentyl, isopentyl, cyclopentyl, hexyl, isohexyl, 3-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, or cyclohexyl, and the like.

[0039] In the present application, as one of the embodiments, the C 1-6Alkoxy, as illustrative examples, includes, but is not limited to, methoxy, ethoxy, propoxy, isopropoxy, cyclopropoxy, isobutoxy, n-butoxy, sec-butoxy, t-butoxy, cyclobutoxy, pentoxy, isopentoxy, cyclopentoxy, hexoxy, isohexoxy, 3-methylpentoxy, 2-ethylbutoxy, 2,2-dimethylbutoxy, 2,3-dimethylbutoxy, or cyclohexoxy, and the like.

[0040] In the present application, as one of the embodiments, the aryl group, the heteroaryl group can be phenyl, imidazolyl, furanyl, pyrazinyl, thiazolyl, thiophenyl, oxazolyl, pyrrolyl, thiophenyl, pyrimidinyl, pyrazolyl, thiadiazolyl, triazolyl, and the like.

[0041] In the present application, as one of the embodiments, the saturated or unsaturated C 3-6 Cycloalkyl, as illustrative examples, can be cyclopropane, cyclopropane, cyclobutane, cyclobutene, cyclopentane, cyclopentene, cyclohexane, cyclohexene, and the like, one, two or more than two carbon atoms in the ring are each independently substituted by O, N, S. 3-6 Heterocycloalkyl, as illustrative examples, can be cyclopropane, cyclopropane, cyclobutane, cyclobutene, cyclopentane, cyclopentene, cyclohexane, cyclohexene, and the like, one, two or more than two carbon atoms in the ring are each independently substituted by O, N, S.

[0042] In the present application, the halogen in the above, as illustrative examples, includes, but is not limited to, F, Cl, Br, or I, and the like.

[0043] In the present application, the solvent used can be commercially available. The following abbreviations are used in the present application: KMnO4 refers to potassium permanganate; tBuOH refers to t-butanol; H2SO4 refers to sulfuric acid; MeOH refers to methanol; Pd(OAc)2 refers to palladium acetate; CataCXium A refers to n-butyl bis(1-adamantyl)phosphine; Cs2CO3 refers to cesium carbonate; HCl refers to hydrochloric acid; EtOAc refers to ethyl acetate; LiOH refers to lithium hydroxide; THF refers to tetrahydrofuran; H2O refers to water; DMAP refers to 4-dimethylaminopyridine; Pd(tBu3P)2 refers to bis(tri-tert-butylphosphine)palladium; Ag2SO4 refers to silver sulfate; Boc2O refers to di-tert-butyl dicarbonate; TEA refers to triethylamine; Tol refers to toluene; Pinanediol refers to 2,3-pinane diol; ACN refers to acetonitrile; Conc. HCl refers to concentrated hydrochloric acid; BBr3 refers to boron tribromide; DCM refers to dichloromethane; NBS refers to N-bromosuccinimide; Pd / C refers to palladium on carbon catalyst; NAOH refers to sodium hydroxide; HBr refers to hydrogen bromide; LiBr refers to lithium bromide; MEI refers to methyl iodide; NAH refers to sodium hydride; MeB(OH)2 refers to methyl boronic acid; Ir(ppy)3 refers to (tris(2-phenylpyridine)iridium; TEA refers to triethylamine; DMF refers to N,N-dimethylformamide; and the like.

[0044] In the present application, as one of the embodiments, the compound of formula (I) or its optical isomers is selected from one of the following compounds:

[0045] In the present application, as one of the embodiments, the compound of formula (I) or its optical isomers is selected from one of the following compounds:

[0046] In the present application, as one of the embodiments, the pharmaceutical composition further comprises penicillins (penicillin, amoxicillin, ampicillin, piperacillin, azlocillin, mezlocillin, sulbactam, etc.), cephalosporins (cephalothin, cefazolin, ceftizoxime, cephalexin, cefamandole, cefuroxime, cefaclor, cefotaxime, ceftriaxone, ceftazidime, cefixime, cefpirome, cefepime, ceftaroline fosamil, etc.), carbapenems (meropenem, imipenem, biapenem, etc.), monobactams (aztreonam), or a combination of two or more thereof.

[0047] In the present application, as one of the embodiments, the present application also provides a use of the compound or its optical isomers or the pharmaceutical composition in the preparation of a drug for treating bacterial infection.

[0048] In the present application, as one of the embodiments, the bacterial infection includes, but is not limited to, infections caused by Klebsiella pneumoniae, Enterobacter, Enterobacter cloacae, Acinetobacter baumannii or Pseudomonas aeruginosa.

[0049] The present application is a new type of β-lactamase inhibitor obtained by screening and optimization, which can cope with multiple infections caused by multiple drug-resistant bacteria. This dual inhibitor can simultaneously inhibit the activity of serine β-lactamase and metal β-lactamase, has a wider antibacterial spectrum and a stronger antibacterial effect, and the main antibacterial spectrum includes multiple drug-resistant gram-negative bacteria, especially carbapenem-resistant Enterobacter, carbapenem-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae, and extensively drug-resistant Acinetobacter baumannii, etc. The inhibitory effect and safety are superior to those of existing inhibitors. The present application can improve the sensitivity of β-lactam antibiotics to drug-resistant bacteria, while maintaining or enhancing their antibacterial activity. The β-lactamase inhibitor of the present application has good pharmacokinetic properties and good drug properties. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1: Colony counts of meropenem alone and in combination with compound 1-P2 against Klebsiella pneumoniae ATCC-1705 in a neutropenic mouse thigh infection model;

[0051] Figure 2: Antimicrobial activity effect diagram of compound 2 combined with meropenem in a mouse urinary tract infection model. DETAILED DESCRIPTION

[0052] The present application is further illustrated in detail by the following examples. These examples are for illustrative purposes only and are not intended to limit the scope of the present application.

[0053] Example 1

[0054] Step 1: Synthesis of 3-bromo-6-methoxyphthalic acid (Compound 1-2)

[0055] To a solution of 1-bromo-4-methoxy-2,3-dimethylbenzene (Compound 1-1, 100 g, 0.465 mol) in tert-butanol (150 mL) and water (1200 mL) was added dropwise potassium permanganate (440.82 g, 2.789 mol) at room temperature. The reaction was stirred at 100 °C for 16 h. After the reaction was completed, the reaction mixture was filtered through celite. The filtrate was adjusted to pH = 1-2 and concentrated to give crude Compound 1-2 (150 g) which was used directly in the next step.

[0056] LCMS (ESI) m / z = 274.95 [M-H] + .

[0057] Step 2: Synthesis of dimethyl 3-bromo-6-methoxyphthalate (Compound 1-3)

[0058] To a solution of 3-bromo-6-methoxybenzene-1,2-dicarboxylic acid (75 g, crude Compound 1-2, 0.273 mol) in methanol (500 mL) was added concentrated sulfuric acid (50 mL). The reaction was stirred at 65 °C for 16 h. After the reaction was completed, the methanol was concentrated. The remaining solution was diluted with water and adjusted to pH = 7-8. The solution was extracted with ethyl acetate, washed, dried and concentrated. The crude product was slurried (petroleum ether / ethyl acetate = 10 / 1) to give the yellow solid product (Compound 1-3, 16.7 g, 20.21% yield).

[0059] 1 H NMR (400 MHz, DMSO-d6) d 7.81 (d, J = 9.2 Hz, 1H), 7.26 (d, J = 9.2 Hz, 1H), 3.84 (s, 3H), 3.82 (s, 3H), 3.77 (s, 3H).

[0060] Step 3: Synthesis of 2-tert-butyl-4-methyl-5-methoxy-3-oxoisoindoline-2,4-dicarboxylate (Compound 1-4)

[0061] To a solution of 3-bromo-6-methoxyphthalic acid dimethyl ester (compound 1-3, 19.9 g, 0.066 mol), potassium N-aminomethyltrifluoroborate (23.36 g, 0.99 mol), cesium carbonate (64.22 g, 0.197 mol), n-butylbis(1-adamantyl)phosphine (4.71 g, 0.013 mol) in 1,4-dioxane (250 mL) and water (50 mL) was added palladium acetate (1.48 g, 0.007 mol) and the reaction was stirred at 100 °C under nitrogen for 16 hours. The reaction mixture was filtered over celite, extracted with ethyl acetate, washed, dried, filtered and concentrated. The residue was triturated (petroleum ether / ethyl acetate = 10 / 1) to give the product as a yellow solid (compound 1-4, 17.2 g, 53.16% yield).

[0062] 1 H NMR (400 MHz, DMSO-d6) δ 8.63 (s, 1H), 7.60 (d, J = 8.8 Hz, 1H), 7.34 (d, J = 8.8 Hz, 1H), 4.31 (s, 2H), 3.83 (s, 3H), 3.79 (s, 3H).

[0063] Step 4: Synthesis of 5-methoxy-3-oxoisoindoline-4-carboxylic acid methyl ester (compound 1-5)

[0064] To a solution of 2-tert-butyl-4-methyl-5-methoxy-3-oxoisoindoline-2,4-dicarboxylate (compound 1-4, 17.2 g, 0.053 mol) was added hydrochloric acid / ethyl acetate solution (4 M, 100 mL) and the reaction was stirred at room temperature for 2 hours. After the reaction was completed, it was filtered to give the product as a yellow solid (compound 1-5, 11.7 g, 99.06% yield).

[0065] 1 H NMR (400 MHz, DMSO-d6) δ 8.63 (s, 1H), 7.60 (d, J = 8.8 Hz, 1H), 7.34 (d, J = 8.8 Hz, 1H), 4.31 (s, 2H), 3.83 (s, 3H), 3.79 (s, 3H).

[0066] Step 5: Synthesis of 5-methoxy-3-oxoisoindoline-4-carboxylic acid (compound 1-6)

[0067] To methyl 5-methoxy-3-oxoisoindoline-4-carboxylate (compound 1-5, 11.7 g, 0.053 mol) in tetrahydrofuran (100 mL) / methanol (100 mL) / water (100 mL) was added lithium hydroxide hydrate (6.64 g, 0.162 mol), the mixture was stirred at 65 °C for 16 hours. After the reaction was completed, it was concentrated, adjusted to pH = 2-3, filtered to obtain the yellow solid product (compound 1-6, 9.50 g, 86.77% yield).

[0068] 1 H NMR (400 MHz, DMSO-d6) δ 12.97 (s, 1H), 8.58 (s, 1H), 7.54 (d, J = 8.4 Hz, 1H), 7.31 (d, J = 8.4 Hz, 1H), 4.30 (s, 2H), 3.83 (s, 3H).

[0069] Step 6: Synthesis of 6-bromo-5-hydroxy-3-oxoisoindoline-4-carboxylic acid (compound 1-7)

[0070] To a solution of 5-methoxy-3-oxoisoindoline-4-carboxylic acid (compound 1-6, 9.5 g, 24.10 mmol) and silver sulfate (17.17 g, 55.01 mmol) in concentrated sulfuric acid (100 mL) was added dropwise bromine (22.01 g, 137.70 mmol), the reaction was stirred at 80 °C for 16 hours. After the reaction was completed, it was cooled to room temperature, the reaction was added to ice water, the solid was precipitated and filtered to obtain the crude product (compound 1-7, 36.0 g) which was used directly in the next step.

[0071] Step 7: Synthesis of 6-bromo-5-((tert-butoxycarbonyl)oxy)-3-oxoisoindoline-2,4- dicarboxylic acid di-tert-butyl ester (compound 1-8)

[0072] To a solution of crude 6-bromo-5-hydroxy-3-oxoisoindoline-4-carboxylic acid (compound 1-7, 36.0 g, 0.048 mol, 30% purity) and di-tert-butyl dicarbonate (93.89 g, 0.430 mol) in tert-butyl alcohol (150 mL) and tetrahydrofuran (150 mL) was added 4-dimethylaminopyridine (5.84 g, 0.048 mol), the reaction was stirred at 60 °C for 3 hours. The reaction was concentrated under vacuum, the residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 6 / 1) to obtain the white solid product (compound 1-8, 8.60 g, 33.89% yield).

[0073] 1H NMR (400 MHz, DMSO-d6) δ 8.14 (s, 1H), 4.79 (s, 2H), 1.53 (s, 9H), 1.52 (s, 9H), 1.49 (s, 9H).

[0074] Step 8-9: Synthesis of 5-((tert-butoxycarbonyl)oxy)-3-oxo-6-((E)-2-((3aR,4R,6R,7aS)- 3A,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)vinyl)isoindoline- 2,4-dicarboxylate (Compound 1-10)

[0075] To a solution of compound 1-8 (8.60 g, 0.016 mol), vinylboronic acid pinacol ester (2.99 g, 0.019 mol) and triethylamine (3.28 g, 0.032 mol) in toluene (130 mL) was added bis(triphenylphosphine)palladium (0.83 g, 0.002 mol) under nitrogen atmosphere. The reaction mixture was stirred at 80 °C for 3 h. The reaction mixture was filtered and the filtrate was concentrated to give the crude product (compound 1-9, 9.5 g). To a solution of the above crude (compound 1-9, 9.5 g, 0.016 mol) in tetrahydrofuran (100 mL) was added (1R,2R,3S,5R)-(-)-2,3-pinanediol (13.45 g, 0.079 mol) and the mixture was stirred at room temperature for 16 h. After the reaction was completed, the reaction mixture was concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 4 / 1) to give the yellow solid product (compound 1-10, 4.20 g, 40.51% yield).

[0076] 1 H NMR (400 MHz, DMSO-d6) δ 8.14 (s, 1H), 4.79 (s, 2H), 1.53 (s, 9H), 1.52 (s, 9H), 1.49 (s, 9H).

[0077] Step 10: Synthesis of di-tert-butyl 5-((tert-butoxy)oxy)-3-oxo-6-((Z)-2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)vinyl)isoindoline-2,4- dicarboxylate (Compound 1-11)

[0078] To a solution of di-tert-butyl 5-((tert-butoxy)oxy)-3-oxo-6-((E)-2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)vinyl)isoindoline-2,4- dicarboxylate (Compound 1-10, 2.40 g, 3.70 mmol) in acetonitrile (20 mL) was added tris(2- phenylpyridine)iridium (0.24 g, 0.37 mmol) under nitrogen atmosphere. The reaction mixture was placed under a blue LED lamp (450 nm) and stirred at room temperature for 16 hours. The reaction mixture was filtered and the filtrate was concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 4 / 1) to give the product (Compound 1-11, 0.90 g, 37.84% yield) as a yellow solid.

[0079] 1 H NMR (400 MHz, DMSO-d6) δ 7.69 (s, 1H), 7.13 (d, J = 14.8 Hz, 1H), 5.90 (d, J = 14.8 Hz, 1H), 4.70-4.82 (m, 2H), 4.29 (d, J = 8.0 Hz, 1H), 2.10-2.28 (m, 2H), 1.93 (t, J = 5.2 Hz, 1H), 1.80-1.87 (m, 1H), 1.65-1.73 (m, 1H), 1.53 (s, 9H), 1.52 (s, 9H), 1.42 (s, 9H), 1.32 (s, 3H), 1.24 (s, 3H), 1.14 (d, J = 10.8 Hz, 1H), 0.80 (s, 3H).

[0080] Step 11: Synthesis of di-tert-butyl 5-((tert-butoxy)oxy)-3-oxo-6-(2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)cyclopropyl)isoindoline- 2,4-dicarboxylate (Compound 1-12)

[0081] To a solution of di-tert-butyl 5-((tert-butoxycarbonyl)oxy)-3-oxo-6-((Z)-2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxaborol-2-yl)vinyl)isoindoline- 2,4-dicarboxylate (Compound 1-11, 0.5 g, 0.764 mmol) and Pd(OAc)2(17.15 mg, 0.076 mmol) in tetrahydrofuran (10 mL) was added freshly prepared diazomethane (7.64 mL, ~1 M in ether) dropwise at -40 °C under nitrogen. The solution was slowly warmed to room temperature and stirred for 16 h. The reaction mixture was concentrated to dryness and the residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 4 / 1) to give the product as a white solid (Compound 1-12, 0.40 g, 78.32% yield).

[0082] LCMS (ESI) m / z = 668.35 [M+H] + .

[0083] Step 12: Synthesis of di-tert-butyl 5-((tert-butoxycarbonyl)oxy)-3-oxo-6-((lS,2R)-2- ((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)cyclopropyl) isoindoline-2,4-dicarboxylate and di-tert-butyl 5-((tert-butoxycarbonyl)oxy)-3-oxo-6-((lR,2S)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)cyclopropyl)isoindoline-2,4-dicarboxylate (Compound 1-12A and 1-12B)

[0084] Di-tert-butyl 5-((tert-butoxycarbonyl)oxy)-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5- trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)cyclopropyl)isoindoline-2,4- dicarboxylate (Compound 1-12, 250 mg, 0.374 mmol) was dissolved in isopropanol (50 mg / mL), filtered and purified by HPLC prep (eluted with 95% n-hexane / 5% ethyl acetate at a flow rate of 25 mL / min) to give yellow oily liquid 1-12A (140 mg, tR= 8.54 min) and yellow oily liquid 1-12B (117 mg, tR= 6.82 min).

[0085] Step 13: Synthesis of (laR,8bS)-2-hydroxy-5-oxo-IA,2,5,6,7,8B-hexahydro-lH- cyclopropa[3,4][l,2]oxazepino[5,6-f]isoindole-4-carboxylic acid and (laR,8bS)-2- hydroxy-5-oxo-IA,2,5,6,7,8B-hexahydro-lH-cyclopropa[3,4][l,2]oxazepino[5,6- f]isoindole-4-carboxylic acid (Compound 1-P1 and 1-P2)

[0086] To a solution of compound 1-12A (140 mg, 0.209 mmol) and MeB(OH)2(25.14 mg, 0.419 mmol) in THF (2 mL) was added concentrated HCl (2 mL) and the reaction mixture was stirred at room temperature for 5 h. The reaction was filtered and purified by C 18 column purification (eluted with 5% - 95% MeCN / H2O with 0.1% TFA in water) to give the product 1-P1 (free acid, 14 mg, 24.79% yield) as a yellow solid.

[0087] LCMS (ESI) m / z = 260.00 [M+H] + .

[0088] 1 H NMR (400 MHz, MeOD) δ 7.47 (s, 1H), 4.41 - 4.51 (m, 2H), 2.40 - 2.56 (m, 1H), 1.10 - 1.25 (m, 2H), 0.65 - 0.77 (m, 1H).

[0089] To a solution of compound 1-12B (117 mg, 0.175 mmol) and MeB(OH)2(21.01 mg, 0.350 mmol) in THF (1.5 mL) was added concentrated HCl (1.5 mL) and the reaction mixture was stirred at room temperature for 5 h. The reaction was filtered and purified by C 18 column purification (eluted with 5% - 95% MeCN / H2O with 0.1% TFA in water) to give the product 1-P2 (free acid, 11 mg, 24.00% yield) as a yellow solid.

[0090] LCMS (ESI) m / z = 260.00 [M+H] + .

[0091] 1 H NMR (400 MHz, MeOD) δ 7.47 (s, 1H), 4.41 - 4.51 (m, 2H), 2.40 - 2.56 (m, 1H), 1.10 - 1.25 (m, 2H), 0.65 - 0.77 (m, 1H).

[0092] Example 2

[0093] Step 1: Synthesis of 5-((tert-butoxy carbonyl)oxy)-3-oxo-6-(2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)ethyl)isoindoline- 2,4-dicarboxylate (Compound 2-1)

[0094] To a solution of compound 1-10 (400 mg, 0.611 mmol) in methanol (10 mL) was added 10% palladium on carbon (65 mg), the mixture was stirred under hydrogen condition for 2 hours, then filtered, the filtrate was concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 4 / 1) to give yellow solid product (compound 2-1, 350 mg, 87.26% yield).

[0095] 1 H NMR (400 MHz, DMSO-d6) δ 7.65 (s, 1H), 4.75 (s, 2H), 4.31 (dd, J = 8.4 Hz, 1.2 Hz, 2H), 2.58-2.68 (m, 2H), 2.25-2.34 (m, 1H), 2.11-2.20 (m, 1H), 1.92-2.00 (t, J = 5.6 Hz, 1H), 1.82-1.89 (d, J = 2.6 Hz, 1H), 1.65-1.72 (m, 1H), 1.52 (s, 9H), 1.51 (s, 9H), 1.47 (s, 9H), 1.31 (s, 3H), 1.24 (s, 3H), 1.03-1.10 (m, 2H), 0.93 (d, J = 10.4 Hz, 1H), 0.81 (s, 3H).

[0096] Step 2: Synthesis of 2-hydroxy-8-oxo-2,3,4,6,7,8-hexahydro-[l,2]oxaborazinan[5,6- f]isoindole-9-carboxylic acid (Compound 2)

[0097] To a solution of compound 2-1 (150 mg, 0.229 mmol) and MeB(OH)2(27.44 mg, 0.457 mmol) in THF (1.5 mL) was added concentrated hydrochloric acid (1.5 mL), and the reaction mixture was stirred at room temperature for 5 h. The reaction was filtered and purified by C 18 column (eluted with 5% - 95% MeCN / H2O with 0.1% TFA in water) to give yellow solid compound 2 (10 mg, 17.37% yield).

[0098] LCMS (ESI) m / z = 248.00 [M+H] + .

[0099] 1 H NMR (400 MHz, MeOD) d 7.66 (s, 1H), 4.50 (s, 2H), 2.74 (s, 2H), 0.95 (s, 2H).

[0100] Example 3

[0101] Step 1: Synthesis of 3-bromo-6-methoxyphthalic acid (compound 3-1B)

[0102] To a mixture of 1-bromo-4-methoxy-2,3-dimethylbenzene (compound 3-1A, 60 g, 0.279 mol) in tert-butanol (100 mL) and water (600 mL) was added potassium permanganate (264.55 g, 1.674 mol) at room temperature. The reaction was stirred at 100 °C for 16 h. After the reaction was completed, the reaction mixture was filtered through celite. The filtrate was adjusted to pH = 1-2 and concentrated to give crude product 3-1B (90 g) which was used directly in the next step.

[0103] LCMS (ESI) m / z = 273, 275 [M-H] + .

[0104] Step 2: Synthesis of dimethyl 3-bromo-6-methoxyphthalate (compound 3-1)

[0105] To a solution of 3-bromo-6-methoxybenzene-1,2-dicarboxylic acid (compound 3-1B, 90 g, crude product from previous step) in methanol (500 mL) was added concentrated sulfuric acid (50 mL). The reaction was stirred at 65 °C for 16 h. After the reaction was completed, the methanol was concentrated. The remaining solution was diluted with water and adjusted to pH = 7-8. The solution was extracted with ethyl acetate, washed, dried, and concentrated. The crude product was slurried (petroleum ether / ethyl acetate = 10 / 1) to give yellow solid product 3-1 (15.0 g, 15.13% yield).

[0106] 1 H NMR (400 MHz, DMSO-d6) d 7.81 (d, J = 9.2 Hz, 1H), 7.26 (d, J = 9.2 Hz, 1H), 3.84 (s, 3H), 3.82 (s, 3H), 3.77 (s, 3H).

[0107] Step 3: Synthesis of 3-(2-((tert-butoxycarbonyl)amino)ethyl)-6-methoxyphthalic acid dimethyl ester (Compound 3-3)

[0108] To a solution of 3-bromo-6-methoxyphthalic acid dimethyl ester (Compound 3-1, 15.0 g, 0.050 mol), Compound 3-2 ((tert-butoxycarbonyl)amino)ethyl potassium trifluoroborate (18.72 g, 0.074 mol), cesium carbonate (48.38 g, 0.149 mol), n-butyl bis(1-adamantyl)phosphine (3.55 g, 0.010 mol) in 1,4-dioxane (150 mL) and water (30 mL) was added palladium acetate (1.11 g, 0.005 mol) under nitrogen atmosphere. The reaction was stirred at 100 °C for 16 hours under nitrogen atmosphere. The reaction mixture was filtered on celite, extracted with ethyl acetate, washed, dried, filtered and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 3 / 1) to give the product 3-3 (11 g, 60.40% yield) as yellow oil.

[0109] 1 H NMR (400 MHz, DMSO-d6) δ 7.37 (d, J = 8.8 Hz, 1H), 7.24 (d, J = 8.8 Hz, 1H), 6.87 (t, J = 5.6 Hz, 1H), 3.79 (s, 3H), 3.78 (s, 3H), 3.74 (s, 3H), 3.02-3.10 (m, 2H), 2.69-2.76 (m, 2H), 1.36 (s, 9H).

[0110] Step 4: Synthesis of 3-(2-aminoethyl)-6-methoxyphthalic acid dimethyl ester (Compound 3-4)

[0111] To a solution of 3-(2-((tert-butoxycarbonyl)amino)ethyl)-6-methoxyphthalic acid dimethyl ester (Compound 3-3, 28 g, 0.076 mol) was added hydrochloric acid / ethyl acetate solution (4 M, 150 mL) and stirred at room temperature for 2 hours. After the reaction was completed, the product Compound 3-4 (18 g, 88.32% yield) was obtained by filtration.

[0112] 1 H NMR (400 MHz, DMSO-d6) δ 8.16 (s, 3H), 7.49 (d, J = 8.8 Hz, 1H), 7.30 (d, J = 8.8 Hz, 1H), 3.81 (s, 6H), 3.76 (s, 3H), 2.94 (s, 4H).

[0113] Step 5: Synthesis of 7-methoxy-l-oxo-l,2,3,4-tetrahydroisoquinoline-8- carboxylic acid methyl ester (Compound 3-5)

[0114] To 3-(2-aminoethyl)-6-methoxydimethyl phthalate (Compound 3-4, 18 g, 0.067 mol) in methanol (180 mL) / tetrahydrofuran (180 mL) / water (180 mL) was added potassium hydroxide (18.88 g, 0.337 mol) and the mixture was stirred at 80 °C for 3 h. After completion of the reaction, the organic solvents were concentrated, filtered and dried to get the yellow solid product 3-5 (12.7 g, 80.24% yield).

[0115] 1 H NMR (400 MHz, DMSO-d6) δ 8.03 (s, 1H), 7.36 (d, J = 8.8 Hz, 1H), 7.23 (d, J = 8.8 Hz, 1H), 3.77 (s, 3H), 3.70 (s, 3H), 3.28-3.35 (m, 2H), 2.83 (t, J = 6.4 Hz, 2H).

[0116] Step 6-7: Synthesis of 7-hydroxy-l-oxo-l,2,3,4-tetrahydroisoquinoline-8- carboxylic acid methyl ester (Compound 3-6)

[0117] To a solution of 7-methoxy-l-oxo-l,2,3,4-tetrahydroisoquinoline-8-carboxylic acid methyl ester (Compound 3-5, 12.7 g, 0.054 mol) in dichloromethane (130 mL) was added 1 M boron tribromide solution (135 mL, 0.135 mol) dropwise at -78 °C and the reaction was stirred at -78 °C for 4 h. After completion of the reaction, it was quenched with methanol and the temperature was raised to 50 °C for 4 h. After completion of the reaction, it was concentrated, slurried with dichloromethane and filtered to get the yellow product 3-6 (11 g, 92% yield).

[0118] 1 H NMR (400 MHz, DMSO-d6) δ 7.93 (s, 1H), 7.18 (d, J = 8.4 Hz, 1H), 7.02 (d, J = 8.4 Hz, 1H), 3.68 (s, 3H), 3.30 (t, J = 6.0 Hz, 2H), 2.78 (t, J = 6.4 Hz, 2H).

[0119] Step 8: Synthesis of 6-bromo-7-hydroxy-l-oxo-l,2,3,4-tetrahydroisoquinoline-8- carboxylic acid methyl ester (Compound 3-7)

[0120] To a solution of 7-hydroxy-l-oxo-l,2,3,4-tetrahydroisoquinoline-8-carboxylic acid methyl ester (compound 3-6, 11 g, 0.050 mol) in N,N-dimethylformamide (40 mL) was added N-bromosuccinimide (11.50 g, 0.065 mol) and the reaction mixture was stirred at room temperature for 5 h. The reaction mixture was added to ice water and the yellow solid product 3-7 (11 g, 73.84% yield) was filtered.

[0121] 1 H NMR (400 MHz, DMSO-d6) δ 9.68 (s, 1H), 8.03 (s, 1H), 7.61 (s, 1H), 3.72 (s, 3H), 3.26-3.35 (m, 2H), 2.76-2.86 (m, 2H).

[0122] Step 9: Synthesis of 6-bromo-7-hydroxy-l-oxo-l,2,3,4-tetrahydroisoquinoline-8- carboxylic acid (compound 3-8)

[0123] To a solution of 7-hydroxy-l-oxo-l,2,3,4-tetrahydroisoquinoline-8-carboxylic acid methyl ester (compound 3-6, 11 g, 0.050 mol) in N,N-dimethylformamide (40 mL) was added N-bromosuccinimide (11.50 g, 0.065 mol) and the reaction mixture was stirred at room temperature for 5 h. The reaction mixture was added to ice water and the yellow solid product 3-7 (11 g, 73.84% yield) was filtered.

[0124] 1 H NMR (400 MHz, DMSO-d6) δ 9.68 (s, 1H), 8.03 (s, 1H), 7.61 (s, 1H), 3.72 (s, 3H), 3.26-3.35 (m, 2H), 2.76-2.86 (m, 2H).

[0125] Step 10: Synthesis of 6-bromo-7-((tert-butoxycarbonyl)oxy)-l-oxo-3,4- dihydroisoquinoline-2,8(lH)-dicarboxylic acid di-tert-butyl ester (compound 3-9)

[0126] To a solution of 6-bromo-7-hydroxy-l-oxo-l,2,3,4-tetrahydroisoquinoline-8- carboxylic acid (compound 3-8, 1.7 g, 5.900 mmol) and di-tert-butyl dicarbonate (6.44 g, 29.500 mmol) in tert-butanol (15 mL) and tetrahydrofuran (15 mL) was added 4-dimethylaminopyridine (0.07 g, 0.590 mmol) and the reaction was stirred at 60 °C for 3 h. The reaction was concentrated in vacuo and the residue was purified by column chromatography on silica gel (eluent: petroleum ether / ethyl acetate = 6 / 1) to give the product 3-9 (1.30 g, 40.68% yield) as a yellow solid.

[0127] 1 H NMR (400 MHz, DMSO-d6) δ 7.88 (s, 1H), 3.91 (t, J = 5.6 Hz, 2H), 3.04 (t, J = 6.0 Hz, 2H), 1.51 (s, 9H), 1.49 (s, 18H).

[0128] Step 11: Synthesis of (E)-7-((tert-butoxycarbonyl)oxy)-l-oxo-6-(2-(4,4,5,5- tetramethyl-l,3,2-dioxaborolan-2-yl)vinyl)-3,4-dihydroisoquinoline-2,8(lH)-dicarboxylic acid di-tert-butyl ester (compound 3-10)

[0129] To a solution of 6-bromo-7-((tert-butoxycarbonyl)oxy)-l-oxo-3,4- dihydroisoquinoline-2,8(lH)-dicarboxylic acid di-tert-butyl ester (compound 3-9, 400 mg, 0.737 mmol), and triethylamine (149.24 mg, 1.475 mol) and bis(triphenylphosphine)palladium (18.92 mg, 0.037 mmol) in toluene (5 mL) was added vinylboronic acid pinacol ester (124.92 mg, 0.811 mmol) at 110 °C under nitrogen atmosphere. The reaction was stirred at 110 °C for 15 min. After cooling to room temperature, it was filtered and the filtrate was concentrated. The residue was purified by C18 column (eluted with 5% - 95% MeCN / H2O with 0.1% FA in water) to give the product 3-10 (230 mg, 50.60% yield) as a yellow oil.

[0130] 1 H NMR (400 MHz, CDCl3) δ 7.42 (s, 1H), 7.36 (d, J = 18.4 Hz, 1H), 6.24 (d, J = 18.4 Hz, 1H), 3.92 - 4.02 (m, 2H), 2.93 - 3.02 (m, 2H), 1.62 (s, 9H), 1.54 (s, 9H), 1.52 (s, 9H), 1.27 (s, 9H).

[0131] Step 12: Synthesis of 7-((tert-butoxy carbonyl)oxy)-l-oxo-6-(2-(4,4,5,5-tetramethyl- 1,3,2-dioxaborolan-2-yl)ethyl)-3,4-dihydroisoquinoline-2,8(lH)-dicarboxylic acid di- tert-butyl ester (Compound 3-11)

[0132] To a solution of (E)-7-((tert-butoxy carbonyl)oxy)-l-oxo-6-(2-(4,4,5,5-tetramethyl- 1,3,2-dioxaborolan-2-yl)vinyl)-3,4-dihydroisoquinoline-2,8(lH)-dicarboxylic acid di- tert-butyl ester (Compound 3-10, 230 mg, 0.373 mmol) in methanol (5 mL) was added 10% palladium on carbon (19.85 mg) and palladium hydroxide on carbon (26.20 mg), the mixture was stirred under hydrogen atmosphere for 16 h, filtered, and the filtrate was concentrated to give the product 3-11 (180 mg, 78% yield) as a yellow oil.

[0133] 1 H NMR (400 MHz, DMSO-d6) δ 7.36 (s, 1H), 3.85-3.91 (m, 2H), 2.98 (t, J = 6.0 Hz, 2H), 1.50 (s, 9H), 1.48 (s, 9H), 1.48 (s, 9H), 1.17 (s, 12H).

[0134] Step 13: Synthesis of 2-hydroxy-9-oxo-3,4,6,7,8,9-hexahydro-2H- [l,2]oxaborazino[5,6-G]isoquinoline-10-carboxylic acid (Compound 3)

[0135] To a solution of 7-((tert-butoxy carbonyl)oxy)-l-oxo-6-(2-(4,4,5,5-tetramethyl- 1,3,2-dioxaborolan-2-yl)ethyl)-3,4-dihydroisoquinoline-2,8(lH)-dicarboxylic acid di- tert-butyl ester (180 mg, 0.291 mmol) and MeB(OH)2(34.94 mg, 0.582 mmol) in THF (2 mL) was added concentrated hydrochloric acid (2 mL), and the reaction mixture was stirred at room temperature for 5 h. The reaction was filtered and purified by C18 column (eluted with 5% - 95% MeCN / H2O with 0.1% TFA in water) to give the product 3 (free acid, 20 mg, 65% yield) as a white solid.

[0136] LCMS (ESI) m / z = 262.08 [M+H] + .

[0137] Step 14: Synthesis of 2-hydroxy-9-oxo-3,4,6,7,8,9-hexahydro-2H- [l,2]oxaborino[5,6-G]isoquinoline-10-carboxylic acid disodium salt (Compound 3-Na)

[0138] Compound 3 (20 mg, 0.077 mmol) was dissolved in acetonitrile solution (0.5 mL), sodium hydroxide (6.13 mg, 0.153 mmol) aqueous solution was added, stirred for 10 minutes and lyophilized to obtain yellow solid product 3-Na (20 mg, 75.20% disodium salt).

[0139] LCMS (ESI) m / z = 262.05 [M+H] + (free acid).

[0140] 1 H NMR (400 MHz, D20) δ 6.83 (s, 1H), 3.33 (t, J = 6.4 Hz, 2H), 2.73 (t, J = 6.8 Hz, 2H), 2.59 (t, J = 6.8 Hz, 2H), 0.33 (t, J = 6.8 Hz, 2H).

[0141] Example 4

[0142] Step 1: Synthesis of 7-((tert-butoxy carbonyl)oxy)-l-oxo-6-((E)-2-((3aR,4R,6R,7aS)- 3A,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxaborol-2-yl)vinyl)-3,4- dihydroisoquinoline-2,8(lH)-dicarboxylic acid di-tert-butyl ester (Compound 4-1)

[0143] To (E)-7-((tert-butoxy carbonyl)oxy)-l-oxo-6-(2-(4,4,5,5-tetramethyl-l,3,2- dioxaborolan-2-yl)vinyl)-3,4-dihydroisoquinoline-2,8(lH)-dicarboxylic acid di-tert-butyl ester (Compound 3-10, 1.3 g, 2.100 mmol) in tetrahydrofuran (5 mL) was added (lR,2R,3S,5R)-(-)-2,3-pinane diol (1.07 g, 6.300 mmol) at room temperature. The reaction was stirred at room temperature for 3 hours. After the reaction was completed, the solvent was concentrated. The residue was purified by C18 column (eluted with 5% - 95% MeCN / H20 with 0.1% TFA in water) to give white solid product 4-1 (0.55 g, 38.10% yield).

[0144] 1H NMR (400 MHz, DMSO-d6) δ 7.85 (s, 1H), 7.18 (d, J = 18.4 Hz, 1H), 6.41 (d, J = 18.4 Hz, 1H), 4.44 (dd, J = 8.4, 1.2 Hz, 1H), 3.91 (s, 2H), 3.04 (t, J = 6.0 Hz, 2H), 2.30-2.40 (m, 1H), 2.15-2.28 (m, 1H), 2.01 (t, J = 5.6 Hz, 1H), 1.85-1.90 (m, 1H), 1.70-1.78 (m, 1H), 1.51 (s, 9H), 1.49 (s, 9H), 1.46 (s, 9H), 1.38 (s, 3H), 1.26 (s, 3H), 1.00 (d, J = 10.8 Hz, 1H), 0.84 (s, 3H).

[0145] Step 2: Synthesis of di-tert-butyl 7-((tert-butoxycarbonyl)oxy)-l-oxo-6-((Z)-2-((3aR,4R,6R,7aS)-3A,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)vinyl)-3,4-dihydroisoquinoline-2,8(lH)-dicarboxylate (Compound 4-2)

[0146] To a solution of di-tert-butyl 7-((tert-butoxycarbonyl)oxy)-l-oxo-6-((E)-2-((3aR,4R,6R,7aS)-3A,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)vinyl)-3,4-dihydroisoquinoline-2,8(lH)-dicarboxylate (Compound 4-1, 520 mg, 0.779 mmol) in acetonitrile (10 mL) was added tris(2-phenylpyridine)iridium (51 mg, 0.078 mmol) under nitrogen atmosphere. The reaction mixture was placed under a blue LED lamp (450 nm) and stirred at room temperature for 16 hours. The reaction was filtered and the filtrate was concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 4 / 1) to give the product 4-2 (190 mg, 24.07% yield) as a yellow solid.

[0147] 1H NMR (400 MHz, DMSO-d6) δ 7.46 (s, 1H), 7.06 (d, J = 14.8 Hz, 1H), 5.88 (d, J = 14.8 Hz, 1H), 4.31 (dd, J = 8.8 Hz, 2.0 Hz, 1H), 3.84 - 3.95 (m, 2H), 3.00 (t, J = 6.0 Hz, 2H), 2.21 - 2.30 (m, 1H), 2.12 - 2.20 (m, 1H), 1.95 (t, J = 5.2 Hz, 1H), 1.82 - 1.89 (m, 1H), 1.67 - 1.73 (m, 1H), 1.51 (s, 9H), 1.49 (s, 9H), 1.43 (s, 9H), 1.33 (s, 3H), 1.24 (s, 3H), 1.13 (d, J = 10.8 Hz, 1H), 0.80 (s, 3H).

[0148] Step 3: Synthesis of di-tert-butyl 7-((tert-butoxycarbonyl)oxy)-l-oxo-6-(2-((3aR,4R,6R,7aS)- 3A,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)cyclopropyl)-3,4- dihydroisoquinoline-2,8(lH)-dicarboxylate (Compound 4-3)

[0149] To a solution of di-tert-butyl 7-((tert-butoxycarbonyl)oxy)-l-oxo-6-(2-((3aR,4R,6R,7aS)- 3A,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)cyclopropyl)-3,4- dihydroisoquinoline-2,8(lH)-dicarboxylate (Compound 4-2, 190 mg, 0.285 mmol) and Pd(OAc)2(6.39 mg, 0.028 mol) in tetrahydrofuran (5 mL) was added freshly prepared diazomethane (5.7 mL, about 1 M in ether) slowly dropwise under nitrogen at -40 °C. The solution was slowly warmed to room temperature and stirred for 3 hours. The reaction mixture was concentrated to dryness, and the residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 4 / 1) to give Compound 4-3 (160 mg, 82.47% yield) as a white solid.

[0150] LCMS (ESI) m / z = 426.10 [M-256] + .

[0151] Step 4-5: Synthesis of 2-hydroxy-5-oxo-l,IA,2,5,6,7,8,9b-octahydropyrrolo[3,4][l,2]oxazaborino[5,6- b]isoquinoline-4-carboxylic acid disodium salt (Compound 4-Na)

[0152] To a solution of 7-((tert-butoxycarbonyl)oxy)-l-oxo-6-(2-((3aR,4R,6R,7aS)- 3A,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)cyclopropyl)- 3,4-dihydroisoquinoline-2,8(lH)-dicarboxylate (compound 4-3, 160 mg, 0.235 mmol) and MeB(OH)2(28.18 mg, 0.469 mmol) in tetrahydrofuran (3 mL) was added concentrated hydrochloric acid (3 mL) and the reaction mixture was stirred at room temperature for 3 h. The reaction was filtered and purified by C18 column (eluted with 5% - 95% MeCN / H2O with 0.1% TFA in water) to give the product 4 (free acid, 47.10 mg, 73.50% yield) as a yellow solid.

[0153] Compound 4 (47.10 mg, 0.173 mmol) was dissolved in acetonitrile solution (0.5 mL), added aqueous sodium hydroxide (13.80 mg, 0.345 mmol) stirred for 10 min and lyophilized to give the product 4-Na (45 mg, 73.48%, disodium salt) as a yellow solid.

[0154] LCMS (ESI) m / z = 274.00 [M+H] + (free acid).

[0155] 1 H NMR (400 MHz, D2O) δ 7.08 (s, 1H), 3.43 (t, J = 6.4 Hz, 2H), 2.85 (t, J = 6.4 Hz, 2H), 1.89 (td, J = 8.8, 3.6 Hz, 1H), 0.90 - 0.99 (m, 1H), 0.43 - 0.50 (m, 1H), 0.31 - 0.40 (m, 1H).

[0156] Example 5

[0157] Step 1: Synthesis of 2-bromo-4-methoxy-l,3-dimethylbenzene (compound 5-2)

[0158] Hydrobromic acid (48% in water, 30 mL) was dissolved in tetrahydrofuran (60 mL), lithium bromide (11.2 g, 129.0 mmol) and cuprous bromide (22.8 g, 158.7 mmol) were added and the solution was cooled to 0 °C before sodium nitrite (9.9 g, 143.8 mmol) was added. 3-Methoxy-2,6-dimethylaniline (5-1, 3.0 g, 19.8 mmol) was added portionwise to the solution and the reaction mixture was stirred at 20 °C for 1 h under nitrogen. After completion of the reaction, the mixture was diluted with water and extracted with ethyl acetate. The organic phases were combined and concentrated under reduced pressure before purification by column chromatography on silica gel (eluting with 0-2% ethyl acetate in petroleum ether) to give the product 5-2 as a colourless oil (2.9 g, 67%).

[0159] 1 H NMR (400 MHz, DMSO-d6) d 7.21 - 7.11 (m, 1H), 6.89 (d, J = 8.4 Hz, 1H), 3.77 (s, 3H), 2.29 (d, J = 0.7 Hz, 3H), 2.24 (s, 3H).

[0160] Step 2: Synthesis of 2-bromo-4-methoxyisophthalic acid (compound 5-3)

[0161] 2-Bromo-4-methoxy-1,3-dimethylbenzene (compound 5-2, 2.9 g, 13.3 mmol) and potassium permanganate (12.6 g, 79.8 mmol) were dissolved in tert-butanol / water (1 :1, 120 mL) and stirred at 100 °C for 2 h. After completion of the reaction, the reaction was filtered through celite and the filtrate was concentrated under reduced pressure. The solution was adjusted to pH 3 and extracted with ethyl acetate, dried and concentrated to give the product 5-3 as a white solid (2.7 g, 72%).

[0162] 1 H NMR (400 MHz, DMSO-d6) d 13.34 (s, 2H), 7.84 (d, J = 8.8 Hz, 1H), 7.19 (d, J = 8.8 Hz, 1H), 3.86 (s, 3H).

[0163] Step 3: Synthesis of 2-bromo-6-methoxy-3-(methoxycarbonyl)benzoic acid (compound 5-4)

[0164] To a solution of 2-bromo-4-methoxybenzoic acid (compound 5-1, 2.0 g, 8.4 mmol) in methanol (20 mL) was added sodium methoxide (1.0 M in methanol, 8.4 mL, 8.4 mmol) at room temperature. The reaction mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure and diluted with water. The resulting mixture was extracted with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure to give the target product 5-2 (1.8 g, 89%) as a white solid.

[0165] 1 H NMR (400 MHz, DMSO-d6) δ 13.55 (s, 1H), 7.85 (d, J = 8.8 Hz, 1H), 7.22 (d, J = 8.8 Hz, 1H), 3.88 (s, 3H), 3.83 (s, 3H).

[0166] Step 4: Synthesis of 3-(tert-butyl)-2-bromo-4-methoxyisophthalic acid 1-methyl ester (compound 5-5)

[0167] To a solution of 2-bromo-6-methoxy-3-(methoxycarbonyl)benzoic acid (5-4, 7.0 g, 24.2 mmol) and di-tert-butyl dicarbonate (26.4 g, 121.1 mmol) in tert-butanol (80 mL) was added 4-dimethylaminopyridine (0.3 g, 2.4 mmol) and the reaction mixture was stirred at 60 °C for 2 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure and purified by silica gel column (eluted with 0-10% ethyl acetate / petroleum ether) to give the target product 5-5 (8.1 g, 97%) as a white solid.

[0168] 1 H NMR (400 MHz, DMSO-d6) δ 7.86 (d, J = 8.7 Hz, 1H), 7.22 (d, J = 8.8 Hz, 1H), 3.87 (s, 3H), 3.83 (s, 3H), 1.53 (s, 9H).

[0169] Step 5: Synthesis of 5-methoxy-1-oxoisoindole-2,4-dicarboxylic acid di-tert-butyl ester (compound 5-6)

[0170] To a solution of 3-tert-butyl 1-methyl 2-bromo-4-methoxybenzene-1,3-dicarboxylate (compound 5-5, 8.1 g, 23.5 mmol), potassium (((tert-butoxycarbonyl)amino)methyl)trifluoroborate (8.3 g, 35.2 mmol), bis(1-adamantyl)n-butylphosphine (1.7 g, 4.7 mmol) and cesium carbonate (22.9 g, 70.4 mmol) in 1,4-dioxane / water (5:1, 80 mL) was added palladium acetate (0.5 g, 2.3 mmol) and the reaction mixture was stirred at 100 °C for 16 h. After completion of the reaction, it was cooled to room temperature and filtered through celite. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography (eluting with 0-25% ethyl acetate in petroleum ether) to afford the product 5-6 (7.1 g, 83%) as a white solid.

[0171] 1 H NMR (400 MHz, DMSO-d6) d 7.87 (d, J = 8.6 Hz, 1H), 7.31 (d, J = 8.6 Hz, 1H), 4.82 (s, 2H), 3.93 (s, 3H), 1.56 (s, 9H), 1.52 (s, 9H).

[0172] Step 6-8: Synthesis of 6-bromo-5-((tert-butoxycarbonyl)oxy)-1-oxoisoindoline- 2,4-dicarboxylic acid di-tert-butyl ester (compound 5-9)

[0173] To a solution of 2,4-di-tert-butyl 5-methoxy-1-oxo-3H-isoindole-2,4-dicarboxylate (compound 5-6, 4.0 g, 11.01 mmol) in dichloromethane (40 mL) was added trifluoroacetic acid (8 mL) and stirred at room temperature for 2 h. The reaction mixture was concentrated and dissolved in sulfuric acid (20 mL), silver sulfate (4.10 g, 13.21 mmol) and bromine (5.3 g, 33.02 mmol) were added successively and stirred at 80 °C for 16 h. After completion of the reaction, it was quenched with ice water and filtered. The filter cake was dissolved in tert-butanol (40 mL), di-tert-butyl dicarbonate (12.01 g, 55.04 mmol) and 4-dimethylaminopyridine (672 mg, 5.50 mmol) were added and the reaction mixture was filtered through celite. The filtrate was concentrated and purified by silica gel column chromatography (eluting with 0-10% ethyl acetate in petroleum ether) to afford the product 5-9 (1.1 g, 19%) as a white solid.

[0174] 1 H NMR (400 MHz, Chloroform-d) d 8.18 (s, 1H), 4.77 (s, 2H), 1.62 (s, 9H), 1.60 (s, 9H), 1.44 (s, 9H).

[0175] Step 9-10: Synthesis of di-tert-butyl 5-(((tert-butoxycarbonyl)oxy)-l-oxo-6-((E)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)vinyl)isoindoline-2,4-dicarboxylate (Compound 5-11)

[0176] Di-tert-butyl 6-bromo-5-((tert-butoxycarbonyl)oxy)-l-oxoisoindoline-2,4- dicarboxylate (Compound 5-9, 300 mg, 0.57 mmol), 2-vinyl-4,4,5,5-tetramethyl-l,3,2- dioxaborolane (105 mg, 0.68 mmol) and triethylamine (115 mg, 1.14 mmol) were dissolved in toluene (5 mL), and bis(triphenylphosphine)palladium (29 mg, 0.06 mmol) was added. The reaction was stirred at 80 °C for 2 h. The reaction was filtered through celite and concentrated under reduced pressure. The residue was dissolved in tetrahydrofuran (10 mL), and (lR,2R,3S,5R)-(-)-2,3-pinanediol (483 mg, 2.84 mmol) was added. The reaction was stirred at room temperature for 16 h. The reaction was concentrated under reduced pressure and purified by column chromatography on silica gel (eluted with 0-25% ethyl acetate in petroleum ether) to give the product 5-11 (300 mg, 81%) as a white solid.

[0177] 1 H NMR (400 MHz, Chloroform-d) δ 8.21 (s, 1H), 7.80 (d, J = 18.6 Hz, 1H), 6.21 (d, J = 18.6 Hz, 1H), 4.83 (s, 2H), 4.36 (dd, J = 8.7, 1.8 Hz, 1H), 2.42 - 2.34 (m, 1H), 2.23 (dt, J = 10.9, 6.0 Hz, 1H), 2.10 (t, J = 5.4 Hz, 1H), 1.95 - 1.87 (m, 2H), 1.62 (s, 9H), 1.60 (s, 9H), 1.44 (s, 3H), 1.33 (s, 9H), 1.30 (s, 3H), 1.26 (d, J = 1.9 Hz, 1H), 0.87 (s, 3H).

[0178] Step 11: Synthesis of di-tert-butyl 5-((tert-butoxycarbonyl)oxy)-l-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)ethyl)isoindoline-2,4-dicarboxylate (Compound 5-12)

[0179] Di-tert-butyl 5-((tert-butoxycarbonyl)oxy)-l-oxo-6-((E)-2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)vinyl)isoindoline- 2,4-dicarboxylate (compound 5-11, 90 mg, 0.14 mmol) was dissolved in methanol (2 mL), palladium on carbon (10 mg) was added, and the reaction was stirred at room temperature under a hydrogen atmosphere for 5 hours. The reaction was filtered through celite, concentrated under reduced pressure, and purified by silica gel column chromatography (eluting with 0-25% ethyl acetate in petroleum ether) to give the product 5-12 (75 mg, 83%) as a colorless oil.

[0180] 1 H NMR (400 MHz, Chloroform-d) δ 7.90 (s, 1H), 4.78 (s, 2H), 4.25 (dd, J = 8.7, 1.9 Hz, 1H), 2.92 - 2.86 (m, 2H), 2.31 (ddt, J = 14.5, 8.7, 2.4 Hz, 1H), 2.21 - 2.15 (m, 1H), 2.05 - 2.01 (m, 1H), 1.89 (tt, J = 5.7, 2.9 Hz, 1H), 1.82 (ddd, J = 14.6, 3.4, 2.0 Hz, 1H), 1.61 (s, 9H), 1.59 (s, 9H), 1.37 (s, 3H), 1.34 (s, 9H), 1.28 (s, 3H), 1.17 - 1.11 (m, 2H), 1.04 (d, J = 10.9 Hz, 1H), 0.83 (s, 3H).

[0181] Step 12: Synthesis of 5-hydroxy-l-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5- trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)ethyl)isoindole-4- carboxylic acid (compound 5-13)

[0182] Di-tert-butyl 5-((tert-butoxycarbonyl)oxy)-l-oxo-6-((E)-2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxol-2-yl)vinyl)isoindoline- 2,4-dicarboxylate (compound 5-11, 90 mg, 0.14 mmol) was dissolved in methanol (2 mL), palladium on carbon (10 mg) was added, and the reaction was stirred at room temperature under a hydrogen atmosphere for 5 hours. The reaction was filtered through celite, concentrated under reduced pressure, and purified by silica gel column chromatography (eluting with 0-25% ethyl acetate in petroleum ether) to give the product 5-12 (75 mg, 83%) as a colorless oil.

[0183] 1H NMR (400 MHz, DMSO-d6) δ 12.38 (s, 1H), 8.35 (s, 1H), 7.64 (s, 1H), 4.46 (s, 2H), 4.27 (dd, J = 8.7, 1.9 Hz, 1H), 2.73 (t, J = 7.8 Hz, 2H), 2.27 (ddt, J = 13.9, 8.8, 2.5 Hz, 1H), 2.08 (ddd, J = 10.7, 6.3, 2.1 Hz, 1H), 1.94 (t, J = 5.5 Hz, 1H), 1.81 (dq, J = 5.6, 2.9 Hz, 1H), 1.68 (ddd, J = 14.5, 3.4, 1.9 Hz, 1H), 1.29 (s, 3H), 1.23 (s, 3H), 1.09 (dd, J = 8.5, 7.1 Hz, 2H), 0.87 (d, J = 10.7 Hz, 1H), 0.80 (s, 3H).

[0184] Step 13-14: Synthesis of 2-hydroxy-6-oxo-2,3,4,6,7,8-hexahydro-[l,2]oxaborinan[5,6- f]isoindole-9-carboxylic acid disodium salt (Compound 5-Na)

[0185] Dissolve 5-hydroxy-l-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6- methanobenzo[d][l,3,2]dioxaborol-2-yl)ethyl)isoindoline-4-carboxylic acid (Compound 5-13, 35 mg, 0.07 mmol) and methylboronic acid (22 mg, 0.36 mmol) in tetrahydrofuran (1 mL), add hydrochloric acid (1 mL), stir at room temperature for 2 hours. The reaction solution is washed with petroleum ether and then freeze-dried to obtain the crude intermediate Compound 5. Dissolve the intermediate in 1 M sodium hydroxide solution and heat with acetone to obtain the yellow solid product 5-Na (21 mg, 95%).

[0186] LCMS (ESI) m / z = 248.0 [M+H] + (free acid).

[0187] 1 H NMR (400 MHz, Deuterium Oxide) δ 7.35 (s, 1H), 4.31 (s, 2H), 2.69 (t, J = 7.0 Hz, 2H), 0.37 (t, J = 7.0 Hz, 2H).

[0188] Example 6

[0189] Step 1: Synthesis of methyl 5-methoxy-2-methyl-3-oxoisoindoline-4-carboxylate (Compound 6-2)

[0190] Methyl 5-methoxy-3-oxoisoindoline-4-carboxylate (Compound 1-5, 10 g, 45.2 mmol) was dissolved in DMF (100 mL) under nitrogen atmosphere, cooled to 0 °C, then 60% sodium hydride (2.17 g, 54.2 mmol) was added portionwise, stirred at 0 °C for 0.5 h, then iodomethane (32.09 g, 226.0 mmol) was added. The reaction was slowly warmed to room temperature under nitrogen atmosphere for 1.5 h. After the reaction was completed, quenched with water, extracted with ethyl acetate, washed, dried, filtered, concentrated. The crude was purified by silica gel column chromatography (eluent: dichloromethane:methanol = 10:1) to give the target compound 6-2 (7.7 g, 68.81% yield) as a light yellow solid.

[0191] LCMS (ESI) m / z = 236.0 [M+H] + .

[0192] Step 2: Synthesis of 5-methoxy-2-methyl-3-oxoisoindoline-4-carboxylic acid (Compound 6-3)

[0193] To methyl 5-methoxy-2-methyl-3-oxoisoindoline-4-carboxylate (Compound 6-2, 7.7 g, 32.7 mmol) in tetrahydrofuran (35 mL) / methanol (35 mL) / water (35 mL) was added lithium hydroxide monohydrate (4.12 g, 98.1 mmol), the mixture was stirred at 60 °C for 16 h. After the reaction was completed, concentrated, adjusted pH = 2-3 with 6N hydrochloric acid, filtered, collected the filter cake to give the white product 6-3 (4.85 g, 63.61% yield).

[0194] LCMS (ESI) m / z = 222.0 [M+H] + .

[0195] Step 3: Synthesis of 6-bromo-5-hydroxy-2-methyl-3-oxoisoindoline-4-carboxylic acid (Compound 6-4)

[0196] To a solution of 5-methoxy-2-methyl-3-oxoisoindoline-4-carboxylic acid (compound 6-3, 4.85 g, 21.9 mmol) and silver sulfate (8.19 g, 26.28 mmol) in concentrated sulfuric acid (40 mL) was added dropwise liquid bromine (10.5 g, 65.7 mmol) and the reaction was stirred at 80 °C for 16 h. After the reaction was completed, it was cooled to room temperature and added to ice water. The solid was precipitated and filtered, washed with water and dried to give crude 6-4 (10.0 g) which was used directly in the next step.

[0197] LCMS (ESI) m / z = 283.8 [M-H] + .

[0198] Step 4: Synthesis of tert-butyl 6-bromo-5-((tert-butoxycarbonyl)oxy)-2-methyl-3- oxoisoindoline-4-carboxylate (compound 6-5)

[0199] To a solution of crude 6-bromo-5-hydroxy-2-methyl-3-oxoisoindoline-4-carboxylic acid (compound 6-4, 10.0 g, 21 mmol, 60% purity) and di-tert-butyl dicarbonate (27.5 g, 126 mmol) in tert-butanol (60 mL) and tetrahydrofuran (60 mL) was added 4-dimethylaminopyridine (2.57 g, 21.0 mol) and the reaction was stirred at 60 °C for 0.5 h. The reaction was concentrated in vacuo and the residue was purified by silica gel column chromatography (eluent: dichloromethane:methanol = 10:1) to give the light yellow target product 6-5 (5.7 g, 55.24% yield).

[0200] 1 H NMR (400 MHz, CDC13) δ 7.69 (s, 1H), 4.33 (s, 2H), 3.16 (s, 3H), 1.63 (s, 9H), 1.56 (s, 9H).

[0201] Step 5: Synthesis of tert-butyl (E)-5-((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-(2- (4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)vinyl)isoindoline-4-carboxylate (compound 6-6)

[0202] Under nitrogen atmosphere, 6-bromo-5-((tert-butoxycarbonyl)oxy)-2-methyl-3- oxoisoindoline-4-carboxylic acid tert-butyl ester (compound 6-5, 5.7 g, 12.9 mmol), 2- vinyl-4,4,5,5-tetramethyl-l,3,2-dioxaborolane (2.58 g, 16.78 mmol), triethylamine (2.61 g, 25.8 mmol) and bis(triphenylphosphine)palladium (0.73 g, 1.41 mmol) were dissolved in super dry toluene (150 mL), the reaction was stirred at 80 °C for 3 hours. After the reaction was completed, the reaction solution was filtered, and the filtrate was concentrated under vacuum to obtain the crude target compound 6-6 (8 g), which was directly used in the next step reaction.

[0203] LCMS (ESI) m / z = 516.2 [M-H] + .

[0204] Step 6: Synthesis of 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-((E)-2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanofuranodiazepine-2-yl)vinyl)isoindoline-4-carboxylic acid tert-butyl ester (compound 6-7)

[0205] The crude (E)-5-((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-(2-(4,4,5,5-tetramethyl- 1,3,2-dioxaborolan-2-yl)vinyl)isoindoline-4-carboxylic acid tert-butyl ester (compound 6-6, 6.65 g, 12.9 mmol) and (1R,2R,3S,5R)-(-)-2,3-pinane diol (10.95 g, 64.5 mmol) were dissolved in tetrahydrofuran solution (65 mL), the reaction solution was stirred at 25 °C for 16 hours. The reaction solution was concentrated under vacuum, and the crude product was purified by C18 reverse column (eluent: acetonitrile / water (0.1% trifluoroacetic acid)) to obtain the yellow target compound 6-7 (2.8 g, 36.43% yield).

[0206] 1H NMR (400 MHz, CDC13) δ 7.58 (s, 1H), 7.38 (d, J = 18.4 Hz, 1H), 6.19 (d, J = 18.4 Hz, 1H), 4.35 - 4.25 (m, 3H), 3.09 (s, 3H), 2.37 - 2.24 (m, 1H), 2.19 - 2.09 (m, 1H), 2.00 (t, J = 5.2 Hz, 1H), 1.90 - 1.84 (m, 1H), 1.84 - 1.76 (m, 1H), 1.57 (s, 10H), 1.46 (s, 9H), 1.35 (s, 3H), 1.23 (s, 3H), 0.80 (s, 3H).

[0207] Step 7: Synthesis of tert-butyl 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-((Z)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanofuran-2-yl)vinyl)isoindoline-4-carboxylate (Compound 6-8)

[0208] At room temperature, tert-butyl 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-((E)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanofuran-2-yl)vinyl)isoindoline-4-carboxylate (Compound 6-7, 2.8 g, 4.93 mmol) was dissolved in acetonitrile (55 mL), and Ir(ppy)3 (323.08 mg, 0.49 mmol) was added. The reaction was stirred at 25 °C for 5 hours under blue light (450 nm) irradiation with nitrogen protection. After the reaction was completed, the reaction was filtered, and the filtrate was concentrated. The crude product was purified by silica gel column chromatography (eluent: petroleum ether: ethyl acetate = 2: 1) to obtain the yellow target compound 6-8 (0.9 g, 30.54% yield).

[0209] 1H NMR (400 MHz, CDC13) δ 7.61 (s, 1H), 7.20 (d, J = 14.8 Hz, 1H), 5.86 (d, J = 14.8 Hz, 1H), 4.30 (s, 2H), 4.25 (dd, J = 8.8, 1.6 Hz, 1H), 3.16 (s, 3H), 2.33 - 2.25 (m, 1H), 2.22 - 2.15 (m, 1H), 2.01 (t, J = 5.2 Hz, 1H), 1.95 - 1.86 (m, 1H), 1.84 - 1.76 (m, 1H), 1.63 (s, 10H), 1.49 (s, 9H), 1.37 (s, 3H), 1.28 (s, 3H), 0.83 (s, 3H).

[0210] Step 9: Synthesis of tert-butyl 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)cyclopropyl)isoindoline-4-carboxylate (Compound 6-9)

[0211] Step 9: Synthesis of tert-butyl 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)cyclopropyl)isoindoline-4-carboxylate (Compound 6-9)

[0212] LCMS (ESI) m / z = 592.3 [M-H] + .

[0213] Step 9: Synthesis of tert-butyl 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methano-benzo[d][l,3,2]dioxaborol-2-yl)cyclopropyl)isoindoline-4-carboxylate (Compound 6-9)

[0214] Tert-butyl 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-(2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanofuro[3,2-b]pyrrol-2-yl)cyclopropyl)isoindoline-4- carboxylate (Compound 6-9, 220 mg, 0.38 mmol) was dissolved in tetrahydrofuran (2 mL), concentrated hydrochloric acid (2 mL) and methylboronic acid (68.14 mg, 1.13 mmol) were added. The reaction was stirred at 25 °C for 2 hours. The crude product was purified by high performance liquid chromatography (C18, acetonitrile and water as mobile phase, with 0.1% trifluoroacetic acid) to give the white target compound 6 (62.38 mg, 57.36% yield).

[0215] 1 H NMR (400 MHz, MeOD) d 7.46 (s, 1H), 4.49 (s, 2H), 3.23 (s, 3H), 2.47 (dd, J = 14.8, 6.0 Hz, 1H), 1.32 - 1.15 (m, 1H), 1.12 (s, 1H), 0.71 (td, J = 9.6, 7.0 Hz, 1H).

[0216] Step 10: Synthesis of 2-hydroxy-6-methyl-5-oxo-1a,2,5,6,7,8b-hexahydro-1H- cyclopropano[3,4][1,2]oxazaborino[5,6-f]isoindole-4-carboxylic acid disodium salt (Compound 6-Na)

[0217] 2-hydroxy-6-methyl-5-oxo-1a,2,5,6,7,8b-hexahydro-1H-cyclopropano[3,4][1,2]oxazaborino[5,6-f]isoindole-4-carboxylic acid (Compound 6, 63 mg, 0.23 mmol) was dissolved in 1 M NaOH in acetonitrile water solution (0.48 mL) and stirred for 0.5 hours, lyophilized to give the target compound 6-Na (75.27 mg, 92.92%, disodium salt).

[0218] LCMS (ESI) m / z = 273.6 [M+H] (free acid).

[0219] 1 H NMR (400 MHz, D2O) d 7.28 (s, 1H), 4.35 (s, 2H), 3.11 (s, 3H), 1.94 (td, J = 8.4, 3.6 Hz, 1H), 0.97 - 0.90 (m, 1H), 0.48 (dt, J = 6.4, 3.2 Hz, 1H), 0.36 (td, J = 9.2, 6.8 Hz, 1H).

[0220] Example 7

[0221] Step 1: Synthesis of tert-butyl 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanofuran-2-yl)ethyl)isoindoline-4-carboxylate (Compound 7-2)

[0222] To a solution of tert-butyl 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-((E)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanofuran-2-yl)vinyl)isoindoline-4-carboxylate (Compound 6-7, 140 mg, 0.25 mmol) in methanol (3 mL) and dichloromethane (1 mL) was added 10% palladium on carbon (15 mg), palladium hydroxide on carbon (15 mg), the mixture was stirred under hydrogen atmosphere for 17 hours, then filtered, the filtrate was concentrated. The crude was purified by C18 column (eluent: acetonitrile / water (0.1% formic acid)) to give the target product 7-2 (45 mg, 30.42% yield) as a white solid.

[0223] 1 H NMR (400 MHz, CDC13) δ 7.37 (s, 1H), 4.29 (s, 2H), 4.25 (dd, J = 8.8, 1.6 Hz, 1H), 3.15 (s, 3H), 2.80 - 2.65 (m, 2H), 2.40 - 2.27 (m, 1H), 2.22 - 2.13 (m, 1H), 2.02 (t, J = 5.6 Hz, 1H), 1.90 (tt, J = 5.4, 2.6 Hz, 1H), 1.86 - 1.75 (m, 1H), 1.67 (s, 1H), 1.64 (s, 9H), 1.54 (s, 9H), 1.36 (s, 3H), 1.28 (s, 3H), 1.20 - 1.12 (m, 2H), 0.84 (s, 3H).

[0224] Step 2: Synthesis of 2-hydroxy-7-methyl-8-oxo-2,3,4,6,7,8-hexahydro-[l,2]oxazaborinan[5,6- f]isoindole-9-carboxylic acid (Compound 7)

[0225] To a solution of 5-(((tert-butoxycarbonyl)oxy)-2-methyl-3-oxo-6-(2-((3aR,4R,6R,7aS)- 3a,5,5-trimethylhexahydro-4,6-methanofuran-2-yl)ethyl)isoindoline-4-carboxylic acid tert-butyl ester (Compound 7-2, 40 mg, 0.07 mmol) and MeB(OH)2(8.43 mg, 0.14 mmol) in THF (2 mL) was added concentrated hydrochloric acid (2 mL) and the reaction mixture was stirred at room temperature for 2 h. The reaction was filtered and purified by C18 column (eluent: acetonitrile / water (0.1% trifluoroacetic acid)) to give the white target product 7 (8.59 mg, 44.59% yield).

[0226] LCMS (ESI) m / z = 261.6 [M+H] + .

[0227] 1 H NMR (400 MHz, DMSO-d6) δ 7.66 (s, 1H), 4.59 (s, 2H), 3.20 (s, 3H), 2.84 - 2.63 (m, 2H), 1.07 - 0.90 (m, 2H).

[0228] Example 8

[0229] Step 1: Synthesis of methyl 2-(2-fluoroethyl)-5-methoxy-3-oxoisoindoline-4-carboxylate (Compound 8-2)

[0230] Under ice-bath nitrogen protection, to a solution of methyl 5-methoxy-3-oxoisoindoline-4- carboxylate (Compound 1-5, 8 g, 36.20 mmol) in DMF (80 mL) was added sodium hydride (1.74 g, 43.44 mmol), the reaction was stirred at 0 °C for 0.5 h, then 1-fluoro-2- iodoethane (9.45 g, 54.30 mmol) was added, the reaction was stirred at room temperature for another hour. After the reaction was completed, the reaction was quenched with water, extracted with ethyl acetate, the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 1 / 1) to give the yellow solid product 8-2 (6.50 g, 67.17% yield).

[0231] 1H NMR (400 MHz, CDC13) δ 7.43 (d, J = 8.4 Hz, 1H), 7.13 (d, J = 8.4 Hz, 1H), 4.72 (t, J = 4.6 Hz, 1H), 4.60 (t, J = 4.6 Hz, 1H), 4.48 (s, 2H), 4.01 (s, 3H), 3.94 - 3.90 (m, 1H), 3.89 (s, 3H), 3.84 (t, J = 4.6 Hz, 1H).

[0232] Step 2: Synthesis of 2-(2-fluoroethyl)-5-methoxy-3-oxoisoindoline-4-carboxylic acid (Compound 8-3)

[0233] To methyl 2-(2-fluoroethyl)-5-methoxy-3-oxoisoindoline-4-carboxylate (Compound 8-2, 5 g, 18.70 mmol) in tetrahydrofuran (10 mL) / methanol (10 mL) / water (10 mL) was added lithium hydroxide hydrate (2.35 g, 56.10 mmol), the mixture was stirred at 60 °C for 16 hours. After the reaction was completed, it was concentrated, adjusted to pH = 2-3, filtered to give yellow solid product 8-3 (4.60 g, 97.38% yield).

[0234] LCMS (ESI) m / z = 254.00 [M+H] +

[0235] Step 3: Synthesis of 6-bromo-2-(2-fluoroethyl)-5-hydroxy-3-oxoisoindoline-4- carboxylic acid (Compound 8-4)

[0236] To a solution of 2-(2-fluoroethyl)-5-methoxy-3-oxoisoindoline-4-carboxylic acid (Compound 8-4, 4.60 g, 18.20 mmol) and silver sulfate (6.81 g, 21.84 mmol) in concentrated sulfuric acid (40 mL) was added dropwise bromine (8.73 g, 54.60 mmol), the reaction was stirred at 80 °C for 16 hours. After the reaction was completed, it was cooled to room temperature, the reaction was added to ice water, the solid was precipitated and filtered to give crude product 8-4 (6.0 g) which was used directly in the next step.

[0237] LCMS (ESI) m / z = 317.90 [M+H] + .

[0238] Step 4: Synthesis of tert-butyl 6-bromo-5-((tert-butoxycarbonyl)oxy)-2-(2- fluoroethyl)-3-oxoisoindoline-4-carboxylate (Compound 8-5)

[0239] To a solution of crude 6-bromo-2-(2-fluoroethyl)-5-hydroxy-3-oxoisoindoline-4- carboxylic acid (compound 8-4, 6.0 g, 18.90 mmol) and di-tert-butyl dicarbonate (24.75 g, 113.40 mmol) in tert-butanol (40 mL) and tetrahydrofuran (40 mL) was added 4-dimethylaminopyridine (2.31 g, 18.90 mmol) and the reaction was stirred at 60 °C for 3 h. The reaction was concentrated in vacuo and the residue was purified by column chromatography on silica gel (eluent: petroleum ether / ethyl acetate = 3 / 1) to give the product 8-5 (2.70 g) as a white solid.

[0240] 1 H NMR (400 MHz, CDC13) δ 7.70 (s, 1H), 4.75 - 4.68 (m, 1H), 4.63 - 4.56 (m, 1H), 4.50 (s, 2H), 3.91 (t, J = 4.6 Hz, 1H), 3.83 (t, J = 4.6 Hz, 1H), 1.63 (s, 9H), 1.56 (s, 9H).

[0241] Step 5: Synthesis of tert-butyl (E)-5-((tert-butoxycarbonyl)oxy)-2-(2- fluoroethyl)-3-oxo-6-(2-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)vinyl)isoindoline- 4-carboxylate (compound 8-6)

[0242] To a solution of tert-butyl 6-bromo-5-((tert-butoxycarbonyl)oxy)-2-(2- fluoroethyl)-3-oxoisoindoline-4-carboxylate (compound 8-5, 2.70 g, 5.70 mmol), vinylboronic acid pinacol ester (1.05 g, 6.84 mmol) and triethylamine (1.15 g, 11.40 mmol) in toluene (30 mL) was added bis(triphenylphosphine)palladium (0.17 g, 0.34 mmol) and the reaction was stirred at 80 °C for 3 h. After the reaction was completed, the reaction was filtered and the filtrate was concentrated to give crude 8-6 (3 g) which was used directly in the next step without purification.

[0243] Step 6: Synthesis of tert-butyl 5-((tert-butoxycarbonyl)oxy)-2-(2-fluoroethyl)-3- oxo-6-((E)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2] dioxaborol-2-yl)vinyl)isoindoline-4-carboxylate (compound 8-7)

[0244] To a solution of the above crude 8-6 (3 g, 5.50 mmol) in tetrahydrofuran (40 mL) was added (1R,2R,3S,5R)-(-)-2,3-pinnanol (4.68 g, 27.50 mmol), and the reaction was stirred at room temperature for 16 hours. After the reaction was completed, the reaction was concentrated. The residue was purified by column chromatography on silica gel (eluent: petroleum ether / ethyl acetate = 4 / 1) to give the product 8-7 (1.80 g, 55.50% yield) as a white solid.

[0245] LCMS (ESI) m / z = 600.20 [M+H] + .

[0246] Step 7: Synthesis of tert-butyl 5-((tert-butoxycarbonyl)oxy)-2-(2- fluoroethyl)-3-oxo-6-((Z)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6- methanobenzo[d][1,3,2]dioxaborol-2-yl)vinyl)isoindoline-4-carboxylate (Compound 8-8)

[0247] To a solution of tert-butyl 5-((tert-butoxycarbonyl)oxy)-2-(2-fluoroethyl)-3-oxo-6- ((E)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][1,3,2]dioxaborol- 2-yl)vinyl)isoindoline-4-carboxylate (Compound 8-7, 0.80 g, 1.33 mmol) in acetonitrile (15 mL) was added tris(2-phenylpyridine)iridium (87.38 mg, 0.13 mmol) under nitrogen atmosphere, and the reaction mixture was placed under a blue LED lamp (450 nm) and stirred at room temperature for 16 hours. The reaction was filtered, and the filtrate was concentrated. The residue was purified by column chromatography on silica gel (eluent: petroleum ether / ethyl acetate = 4 / 1) to give the product 8-8 (0.42 g, 52.50% yield) as a yellow solid.

[0248] 1H NMR (400 MHz, CDC13) δ 7.64 (s, 1H), 7.20 (d, J = 14.8 Hz, 1H), 5.88 (d, J = 14.8 Hz, 1H), 4.72 (s, 1H), 4.60 (d, J = 4.8 Hz, 1H), 4.48 (s, 2H), 4.27 - 4.23 (m, 1H), 3.92 (t, J = 4.6 Hz, 1H), 3.84 (t, J = 4.6 Hz, 1H), 2.34 - 2.26 (m, 1H), 2.21 - 2.15 (m, 1H), 2.02 (s, 1H), 1.90 (d, J = 2.6 Hz, 1H), 1.86 - 1.76 (m, 3H), 1.63 (s, 9H), 1.50 (s, 9H), 1.37 (s, 3H), 1.28 (d, J = 1.8 Hz, 3H), 1.24 (s, 9H), 0.83 (s, 3H).

[0249] Step 8: Synthesis of tert-butyl 5-((tert-butoxycarbonyl)oxy)-2-(2- fluoroethyl)-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6- methanobenzo[d][l,3,2]dioxaborolan-2-yl)cyclopropyl)isoindoline-4-carboxylate (Compound 8-9)

[0250] To a solution of tert-butyl 5-((tert-butoxycarbonyl)oxy)-2-(2-fluoroethyl)-3-oxo-6- ((Z)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxabn-2- yl)vinyl)isoindoline-4-carboxylate (Compound 8-8, 0.32 g, 0.53 mmol) and Pd(OAc)2(6 mg, 0.03 mmol) in tetrahydrofuran (8 mL) was added freshly prepared diazomethane (6 mL, about 1 M in ether) dropwise at -30 °C under nitrogen protection. The solution was slowly warmed to room temperature and stirred for 16 hours. The reaction mixture was concentrated to dryness, and the residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 4 / 1) to give the product 8-9 (0.20 g, 61.05% yield) as a white solid.

[0251] LCMS (ESI) m / z = 614.20 [M+H] + .

[0252] Step 9: Synthesis of 6-(2-fluoroethyl)-2-hydroxy-5-oxo-la,2,5,6,7,8b-hexahydro-lH- cyclopropyl[3,4][l,2]oxaborinan[5,6-f]isoindole-4-carboxylic acid (Compound 8)

[0253] To a solution of tert-butyl 5-((tert-butoxycarbonyl)oxy)-2-(2- fluoroethyl)-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6- methanobenzo[d][l,3,2]dioxaborol an-2-yl)cyclopropyl)isoindoline-4-carboxylate (Compound 8-9, 180 mg, 0.29 mmol) and MeB(OH)2(33.80 mg, 0.58 mmol) in THF (2 mL) was added concentrated HCl (2 mL) and the reaction mixture was stirred at room temperature for 2 h. The reaction was filtered and purified by C18 column (eluted with 10% - 40% MeCN / H2O with 0.1% TFA in water) to give the product 8 (free acid, 25 mg, 27.95% yield) as a white solid.

[0254] 1 H NMR (400 MHz, MeOD) δ 7.49 (s, 1H), 4.75 (t, J = 4.8 Hz, 1H), 4.64 (t, J = 4.8 Hz, 1H), 4.60 (d, J = 4.0 Hz, 2H), 3.99 (td, J = 4.6, 2.0 Hz, 1H), 3.92 (td, J = 4.6, 1.8 Hz, 1H), 2.53 - 2.39 (m, 1H), 1.22 (td, J = 9.4, 3.8 Hz, 1H), 1.07 (s, 1H), 0.71 (td, J = 9.4, 7.0 Hz, 1H).

[0255] Step 10: Synthesis of 6-(2-fluoroethyl)-2-hydroxy-5-oxo-la,2,5,6,7,8b- hexahydro-lH-cyclopropyl[3,4][l,2]oxaborinan[5,6-f]isoindole-4-carboxylic acid disodium salt (Compound 8-Na)

[0256] To a solution of 6-(2-fluoroethyl)-2-hydroxy-5-oxo-la,2,5,6,7,8b- hexahydro-lH-cyclopropyl[3,4][l,2]oxaborinan[5,6-f]isoindole-4-carboxylic acid (Compound 8, 25 mg, 0.08 mmol) in acetonitrile water (5 mL) was added NaOH (6.60 mg, 0.16 mmol) and stirred at room temperature for 5 min before lyophilized to give the target product 8-Na (30 mg, disodium salt) as a yellow solid.

[0257] LCMS (ESI) m / z = 306.0 [M+H] + .

[0258] 1H NMR (400 MHz, MeOD) δ 7.12 (s, 1H), 4.67 (t, J = 4.8 Hz, 1H), 4.55 (t, J = 4.8 Hz, 1H), 4.35 (s, 2H), 3.84 (t, J = 4.8 Hz, 1H), 3.77 (t, J = 4.8 Hz, 1H), 1.85 (td, J = 8.2, 3.6 Hz, 1H), 0.92 - 0.77 (m, 1H), 0.49 (dt, J = 6.4, 3.2 Hz, 1H), 0.41 - 0.35 (m, 1H).

[0259] Example 9

[0260] Step 1: Synthesis of tert-butyl 5-((tert-butoxycarbonyl)oxy)-2-(2- fluoroethyl)-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6- methanobenzo[d][l,3,2]dioxaborol-2-yl)ethyl)isoindoline-4-carboxylate (Compound 9-2)

[0261] To a solution of tert-butyl 5-((tert-butoxycarbonyl)oxy)-2-(2-fluoroethyl)-3-oxo-6- ((E)-2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][l,3,2]dioxaborol- 2-yl)vinyl)isoindoline-4-carboxylate (Compound 8-7, 0.18 g, 0.30 mmol) in methanol (4 mL) was added palladium on carbon (30 mg) and the reaction was stirred at room temperature under hydrogen atmosphere (30 psi) for 12 h. After completion of the reaction, the reaction was filtered over celite and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: 0-35% EtOAc in PE) to afford the product 9-2 (0.12 g, 66.42% yield) as a colorless oily liquid.

[0262] LCMS (ESI) m / z = 602.30 [M+H] +

[0263] Step 2: Synthesis of 7-(2-fluoroethyl)-2-hydroxy-8-oxo-2,3,4,6,7,8-hexahydro- [l,2]oxaboro[5,6-f]isoindole-9-carboxylic acid (Compound 9)

[0264] To a solution of 5-((tert-butoxycarbonyl)oxy)-2-(2-fluoroethyl)-3-oxo-6-(2-((3aR,4R,6R,7aS)-3a,5,5-trimethylhexahydro-4,6-methanobenzo[d][1,3,2]dioxepin-2- yl)ethyl)isoindoline-4-carboxylic acid tert-butyl ester (0.12 g, 0.20 mmol) and isobutylboronic acid (compound 9-2, 40.67 mg, 0.40 mmol) in tetrahydrofuran (1 mL) was added concentrated hydrochloric acid (1 mL), the reaction was stirred at room temperature for 2 hours, after the reaction was completed by C18 column purification (eluted with 0% - 45% MeCN / H2O with 0.1% TFA in water) to give the product 9 (30 mg, 51.33% yield) as a white solid.

[0265] LCMS (ESI) m / z = 294.00 [M+H] + .

[0266] 1 H NMR (400 MHz, DMSO-d6) δ 7.69 (s, 1H), 4.79 (t, J = 4.6 Hz, 1H), 4.67 (s, 3H), 3.99 (t, J = 4.6 Hz, 1H), 3.92 (d, J = 4.4 Hz, 1H), 2.83 - 2.68 (m, 2H), 1.05 - 0.88 (m, 2H).

[0267] Biological activity test

[0268] Experimental Example 1 Test of minimum inhibitory concentration of antibiotic in combination with compound

[0269] 1. Preparation of strains

[0270] Strains stored in glycerol at -80°C were inoculated into CAMHA, Mueller Hinton II Agar (cation-adjusted), trademark name BD-212322 solid agar medium, and placed in an incubator at 35 ± 2°C for 18-24 h.

[0271] 2. Preparation of compound plates

[0272] Meropenem and compound were respectively configured into stock solutions with concentrations of 12.8 mg / mL and 1.6 mg / mL using DMSO, and stored in a -80°C refrigerator if not used on the same day.

[0273] On the day of the experiment, the meropenem stock solution was prepared in 96-well plates with test medium CAMHB into 11 two-fold serial dilutions of 4-fold working solution (128, 64, 32, 16, 8, 4, 2, 1, 0.5, 0.25, 0.125, 0 μg / mL). The compound stock solution was diluted in a centrifuge tube with test medium CAMHB into 4-fold working solution (32 μg / mL). Then 25 μL of the 4-fold working solution of meropenem and 25 μL of the 4-fold working solution of the compound were transferred into a U-bottom 96-well plate, mixed, and this was the compound plate.

[0274] 3. Preparation of inoculum

[0275] An appropriate amount of solid plate culture (step 1) was resuspended in physiological saline, mixed, and the concentration of the bacterial suspension was adjusted to ~1 x 10 8 cfu / mL using a turbidimeter. Then the bacterial suspension was diluted with test medium CAMHB to ~1 x 10 6 cfu / mL as the inoculum.

[0276] 4. Minimum inhibitory concentration (MIC) detection

[0277] 50 μL of the bacterial inoculum (step 3) was transferred into the compound plate (step 2) to obtain the test plate. The total volume of each well of the test plate was 100 μL, containing ~5 x 10 5 cfu / mL of bacteria.

[0278] The test concentration of meropenem was (unit: μg / mL): 32, 16, 8, 4, 2, 1, 0.5, 0.25, 0.125, 0.06, 0.03, 0; and the test concentration of the compound was 8 μg / mL. Finally, all the test plates were placed in an incubator at 35±2°C for 20 h.

[0279] Minimum inhibitory concentration (MIC) detection plate reading: After incubation, the test plate was observed by naked eye, and the lowest drug concentration that completely inhibited the growth of bacteria was the minimum inhibitory concentration of the compound. The lowest drug concentration that inhibited the growth of bacteria was defined as MIC. The results are shown in Table 1.

[0280] Table 1. Data of the antibacterial effect (MIC) of the compound of the present application combined with antibiotics on different strains Note: "NA" means not detected; MEM is meropenem.

[0281] As shown in Table 1, the compounds of the present application combined with meropenem are effective against all multi-drug resistant gram-negative bacterial strains, and the inhibitory effect is better than that of the existing inhibitors. In particular, the compounds have a high bacteriostatic effect and a wider antibacterial spectrum against carbapenem-resistant Klebsiella pneumoniae and extensively drug-resistant Acinetobacter baumannii, etc. In particular, the effect of compound 1-P2 is the most significant, and the MIC is ≤0.25 mg / L.

[0282] Experimental Example 2 Rat pharmacokinetic experiment

[0283] Reagents and samples: compound 1-P1, compound 1-P2, compound 2, compound 3-Na, compound 4-Na, physiological saline, EDTA-2K

[0284] Animals: SD rats, SPF level

[0285] Test method:

[0286] The pharmacokinetic characteristics of the compounds after intravenous injection were tested by the following method. In the experiment, the non-fasted SD rats were intravenously injected with a clear physiological saline solution of the candidate compound at a concentration of 0.2 mg / mL, and 3 rats were bled at time points of 5 min, 15 min, 30 min, 1 h, 2 h, 4 h, 8 h, and 24 h. 0.1 mL of blood was collected in a labeled EDTA-2K anticoagulant tube, and the anticoagulant (EDTA-2K) was mixed with the blood by gently inverting the tube. The blood was immediately placed on wet ice, and the plasma was separated by centrifugation within 1 h after blood collection. The separated plasma was placed in a labeled EP tube, and the plasma samples were analyzed by LC-MS / MS method. The pharmacokinetic parameters of the tested compounds are shown in Table 2.

[0287] Table 2 Rat pharmacokinetic data of the compounds of the present application

[0288] The experimental results show that the series of compounds 1-P1, compound 1-P2, compound 2, compound 3-Na, and compound 4-Na of the present application have good exposure under intravenous administration, and have no obvious toxic side effects and good safety at a dose of 1 mg / kg by intravenous injection. The pharmacokinetic properties are excellent.

[0289] Experimental Example 3 Beagle dog pharmacokinetic experiment

[0290] Reagents and samples: compound 1-P1, compound 1-P2, compound 2, physiological saline, EDTA-2K

[0291] Animals: beagle dogs, ordinary level

[0292] Test method:

[0293] The non-rodent pharmacokinetic characteristics of the compound after intravenous administration were tested by the following method. In the experiment, the unfed beagle dogs were intravenously injected with a clear saline solution of the candidate compound at a concentration of 0.4 mg / mL. Blood samples of 1 mL were collected from 3 beagle dogs at time points of 5 min, 15 min, 30 min, 1 h, 2 h, 4 h, 8 h, 24 h, and 48 h and placed in labeled EDTA-2K anticoagulant tubes. The anticoagulant (EDTA-2K) was mixed with the blood by gently inverting the tubes. The blood was immediately placed on wet ice, and the plasma was separated by centrifugation within 1 h after blood collection. The separated plasma was placed in labeled EP tubes. The plasma samples were analyzed by LC-MS / MS method, and the pharmacokinetic parameters were calculated. The pharmacokinetic parameters of the tested compounds are shown in Table 3.

[0294] Table 3 Pharmacokinetic data of beagle dogs of the compounds of the present application

[0295] The experimental results show that the series of compounds 1-P1, compound 1-P2, and compound 2 of the present application have good exposure under intravenous administration, no obvious toxic side effects when intravenously injected at 1 mg / kg, good safety, and excellent pharmacokinetic properties.

[0296] Experimental Example 4 Pharmacodynamic study of the test compound combined with meropenem in a thigh muscle infection model in mice

[0297] The present study aims to evaluate the in vivo antibacterial efficacy of compound 1-P2 combined with meropenem using a Klebsiella pneumoniae ATCC BAA-1705 thigh muscle infection model in mice.

[0298] Animal information: SPF level 6-8 week old female CD-1 mice were prepared for the experiment, and the adaptation period was at least 3 days.

[0299] Drug preparation:

[0300] Vehicle: normal saline

[0301] MEM 10 mg / mL: an appropriate amount of MEM was weighed and added to normal saline, vortexed to mix, and prepared into a solution with a concentration of 10 mg / mL for administration. Each time, the solution was prepared fresh.

[0302] MEM / compound 1-P2: an appropriate amount of compound 1-P2 was taken and added to a 10 mg / mL MEM solution to prepare a solution with a compound 1-P2 concentration of 10 mg / mL, 2.5 mg / mL, and 0.625 mg / mL for groups 4, 5, and 6, respectively. Each time, the solution was prepared fresh.

[0303] Bacterial culture and preparation: The bacteria in the glycerol stock of Klebsiella pneumoniae ATCC BAA-1705 were inoculated into MHA plates by using a sterile inoculation loop to streak the bacteria onto the plates, and then the plates were incubated in an incubator at 35±2°C for about 17 hours. A single colony from the overnight culture was suspended in 6 mL of sterile saline, and then vortexed to obtain a homogeneous suspension. The OD 600 The day of bacterial inoculation was designated as Day 0. Day-4 was intraperitoneally injected with cyclophosphamide at a dose of 150 mpk, once a day. Day-1 was intraperitoneally injected with cyclophosphamide at a dose of 100 mpk, once a day. Inoculation: The experimental animals were inoculated with the bacteria on the day of inoculation (Day 0) by injecting the bacteria into the right thigh muscle of the mice, and the infection amount was as shown in Table 4, and the infection volume was 100 μL. Drug administration: The drug administration and treatment of each group were as shown in Table 4:

[0304] Table 4: Modeling, grouping and drug administration Note: 1. Day-4: The day of bacterial infection was designated as Day 0, and the 4 days before the infection were designated as Day-4, and so on; 2. Vehicle: saline. 3. MEM: Meropenem.

[0305] Scheduled euthanasia and endpoint procedures

[0306] The mice in Group 1 were euthanized by CO2 2 hours after infection on Day 0, and the right thigh muscle was collected. The mice in Groups 2-6 were euthanized by CO2 12 hours after infection on Day 0, and the right thigh muscle was collected. After the thigh muscle was weighed, it was placed in a 50 mL centrifuge tube containing 10 mL of sterile saline, and then homogenized using a homogenizer and inoculated for bacterial colony counting, and the data were statistically analyzed.

[0307] Experimental results: The activity of Meropenem alone and Meropenem combined with Compound 1-P2 against Klebsiella pneumoniae strain ATCC BAA-1705 is shown in Figure 1. Compared with the Meropenem alone control group, the thigh bacterial count was reduced by 2.73, 2.23 and 2.04 log CFU in the Meropenem combined with 100 mg / kg, 25 mg / kg and 6.25 mg / kg of Compound 1-P2 treatment groups, respectively. The bacterial count observed in the combination therapy was significantly greater than that observed in the Meropenem alone group at all doses of Compound 1-P2 combined with Meropenem (P<0.001).

[0308] Experimental Example 5: Efficacy study of the test compound combined with Meropenem in a mouse urinary tract infection model

[0309] Evaluation of the antibacterial effect of Compound 2 in combination with the carbapenem antibiotic meropenem in a mouse urinary tract infection model Animal information: SPF level 15-18 g female C3H / He mice were used, and the acclimation period was at least 3 days.

[0310] Drug preparation:

[0311] Vehicle: normal saline

[0312] MEM 2.5 mg / mL: an appropriate amount of MEM was weighed into normal saline, vortexed, and mixed to prepare a solution with a concentration of 2.5 mg / mL for administration. Each time, it was prepared fresh.

[0313] MEM / Compound 2: An appropriate amount of Compound 2 powder was accurately weighed into a reagent bottle of appropriate volume, and a 2.5 mg / mL meropenem solution was added with a pipette. A 2.5 mg / mL MEM solution was added to prepare a solution with a concentration of 2.5 mg / mL, 0.625 mg / mL, and 0.3125 mg / mL of Compound 2 for Groups 4, 5, and 6, respectively. Each time, it was prepared fresh.

[0314] Modeling: The day of infection was defined as Day 0 or hour 0. On Day -4 and Day -1 before infection, the mice were given 150 mg / kg and 100 mg / kg of cyclophosphamide intraperitoneally to induce an immunosuppressed state. The volume of administration was 10 mL / kg. On Day 0, after anesthesia with Xylazine and Selamectin, the animals in Groups 1-11 were inoculated with K. pneumoniae ATCC BAA-2343 via the urethral injection method at a dose of ~3.00E+09 CFU / mouse and a volume of 50 μL.

[0315] Administration: According to the Compound treatment plan in Table 5 of the experimental test scheme, the animals were given the corresponding treatment, and the volume of administration was 10 mL / kg / dose. The administration method was subcutaneous injection.

[0316] Table 5. Experimental test scheme

[0317] Scheduled euthanasia and endpoint operations: Group 1 animals were euthanized 14 hours after infection, and Group 2-6 animals were euthanized 2 hours after the last administration (i.e., 48 hours after infection). The mouse kidney and bladder tissues were removed under sterile conditions and placed in 1 mL of sterile normal saline for tissue homogenization and gradient dilution of the tissue homogenate, followed by plate counting.

[0318] Experimental results: The effects of meropenem alone and meropenem in combination with Compound 2 against K. pneumoniae strain ATCC BAA-2343 are shown in Figure 2. The meropenem alone group was not effective in reducing bacterial load at the urinary tract infection site; compared to the meropenem alone group, meropenem in combination with 25 mg / kg, 6.25 mg / kg, 3.125 mg / kg of Compound 2, respectively, were able to reduce the bacterial load in the bladder and kidney by >1 log CFU (P < 0.001). That is, the observed reduction in bacterial counts with combination Compound 2 treatment was significantly greater than that observed with meropenem alone.

Claims

1. A borate β-lactamase inhibitor, which is a compound of formula (I) or its optical isomer: wherein, n is selected from 0 or 1; m is selected from 0 or 1; wherein n and m are not simultaneously 1; G1, G2may be independently selected from -CH2-, -C(=O)-, -S(O)(O)-, wherein G1, G2cannot be -CH2- simultaneously; R1, R2are H or R1, R2together with the atoms to which they are attached form a cycloalkyl group, preferably cyclopropane group; R3may be selected from H, C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl, wherein C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl can be substituted by one or more halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl; R k , R j may be independently selected from H, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl, wherein t is 0, 1, 2, 3, 4, 5, 6, said C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl may be substituted with any one or more R n ; R n may be halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl.

2. The boronic acid beta-lactamase inhibitor according to claim 1, which is a compound represented by formula (I) or an optical isomer thereof: wherein, when n is 0, and m is 0, G1, G2may be independently selected from -CH2-, -C(=O)-, -S(O)(O)-, wherein G1, G2cannot be -CH2- simultaneously; R1, R2are H or R1, R2together with the atoms to which they are attached form a cycloalkyl group, preferably cyclopropane group; R3may be selected from H, C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl, wherein C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl can be substituted by one or more halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl; R k , R j may be independently selected from H, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl, wherein t is 0, 1, 2, 3, 4, 5, 6, said C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl can be substituted with any one or more R n ; R n may be halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl.

3. The boronic acid-based beta-lactamase inhibitor according to claim 2, characterized in that, in the compound of formula (I) or optical isomers thereof, when n is 0, m is 0, G1is selected from -CH2-, G2is selected from -C(=O)-, R3is H; R1, R2are H or R1, R2together with the atoms to which they are attached form a cycloalkyl group, preferably cyclopropane group.

4. The boronic acid-based beta-lactamase inhibitor of claim 2, wherein, in the compound of formula (I) or optical isomers thereof, when n is 0, m is 0, G1is selected from -CH2-, G2is selected from -C(=O)-, R3is H; R1, R2are each independently H.

5. The borate β-lactamase inhibitor according to claim 1, wherein it is a compound of formula (I) or an optical isomer thereof: wherein, when n is 0, m is 1, G1, G2may be independently selected from -CH2-, -C(=O)-, -S(O)(O)-, wherein G1, G2cannot be -CH2- simultaneously; R1, R2are H or R1, R2together with the atoms to which they are attached form a cycloalkyl group, preferably cyclopropane group; R3may be selected from H, C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl, wherein C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl can be substituted by one or more halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl; R k , R j may be independently selected from H, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl, wherein t is 0, 1, 2, 3, 4, 5, 6, said C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl can be substituted with any one or more R n ; R n may be halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl.

6. The boronic acid beta-lactamase inhibitor of claim 1, which is a compound represented by Formula (I) or an optical isomer thereof: wherein, when n is 1, m is 0, G1, G2may be independently selected from -CH2-, -C(=O)-, -S(O)(O)-, wherein G1, G2cannot be -CH2- simultaneously; R1, R2are H or R1, R2together with the atoms to which they are attached form a cycloalkyl group, preferably cyclopropane group; R3may be selected from H, C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl, wherein C 1-6 alkyl, aryl, heteroaryl, -C 1-6 alkyl-NR k R j , -C 1-6 alkyl-C(=O)NR k R j , -C 1-6 alkyl-C 3-6 cycloalkyl, -S(O)(O)-C 1-6 alkyl, -C(=O)-C 1-6 alkyl, -C 1-6 alkyl-C 3-6 heterocycloalkyl, -C 1-6 alkyl-aryl, -C 1-6 alkyl-heteroaryl can be substituted by one or more halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl; R k , R j may be independently selected from H, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl, wherein t is 0, 1, 2, 3, 4, 5, 6, said C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl, C 3-6 epoxyalkyl, -(CH2) t -aryl, -(CH2) t -heteroaryl or -S(O)(O)-C 1-6 alkyl may be substituted with any one or more R n ; R n may be halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl, C 1-6 alkoxy, C 3-6 cycloalkyl or C 3-6 epoxyalkyl.

7. The boronic acid beta-lactamase inhibitor according to claim 1, in the compound of formula (I) or optical isomers thereof, R3is selected from H, -CH3, -CH2-CH2F, or -CH2-CH2NH2.

8. The boronic acid beta-lactamase inhibitor of claim 1, the compound of Formula (I) is selected from the following compounds or optical isomers thereof:

9. The boronic acid beta-lactamase inhibitor of claim 1, the compound of Formula (I) is selected from the following compounds or optical isomers thereof:

10. A pharmaceutical composition, characterized by, The pharmaceutical composition further comprises penicillins (penicillin, amoxicillin, ampicillin, piperacillin, azlocillin, mezlocillin, sulbactam), cephalosporins (cephalothin, cefazolin, cefradine, cephalexin, cefamandole, cefuroxime, cefaclor, cefotaxime, ceftriaxone, ceftazidime, cefixime, cefpirome, cefepime, ceftaroline fosamil), carbapenems (meropenem, imipenem, biapenem), monobactams (aztreonam), or two or more combinations thereof.

11. Use of the compound according to any one of claims 1-9 or optical isomers thereof or the pharmaceutical composition according to any one of claims 10 in the manufacture of a medicament for the treatment of bacterial infection.

12. The use according to claim 11, wherein the infection comprises an infection caused by Klebsiella pneumoniae, Enterobacter, Enterobacter cloacae, Acinetobacter baumannii or Pseudomonas aeruginosa.

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