Metal-Free and Solvent-Free Synthesis of Fused Pyridine Heterocycles and Their Biomedical Applications

Abstract

Embodiments herein provide fused pyridine heterocycles, such as azaindoles, carboline derivatives, furo[b]pyridines or furo[b]pyridine-isatin hybrids of formula I. Embodiments also relate to a method for synthesizing various complex pyridine heterocycles. The pyridine heterocycles can be used for treating cancer (cervical, kidney, lung, breast and epidermal skin) and multi-drug resistant tuberculosis. These heterocycles are also capable of being used as anti-biofilm agents to limit pathogenic strains, thereby minimizing the risk of secondary infections.

Description

Field of the Invention

[0001] The present invention relates to a metal-free and solvent-free synthesis method and system of fused pyridine heterocycles and application thereof in the treatment of cancer and tuberculosis. Background Art

[0002] Fused pyridines belong to the largest family of alkaloids and are widely distributed in nature, including plants, marine organisms, insects, mammals, and human tissues and fluids. These heterocyclic compounds have attracted much attention due to their diverse biological activities. They act as specific ligands for specific proteins, and by carefully regulating the expression of proteins with the help of these external ligands (agonists and antagonists), important biological functions can be manipulated. Therefore, finding suitable protein-ligand interactions for each newly discovered molecule is an important topic in the field of chemical biology. Structural analogies of newly synthesized molecules with existing (known) ligands may become an important tool to solve this mystery.

[0003] Azoindoles (pyrrolopyridines) are the closest bioisosteres of indoles and purines. Therefore, they play an indispensable role in mimicking natural ligand-target interactions. As a result, pyrrolopyridines have become an indispensable core unit in a variety of important drug candidates developed in recent years. However, their synthesis has always been a major challenge in the synthetic chemistry industry. Due to the electron-deficient nature of the pyridine ring, classical indole synthesis (including Fischer cyclization and Madelung cyclization) is often not effectively applied to the synthesis of the corresponding azoindoles. In addition, the pharmaceutical industry generally lacks conventionally developed protocols because any heavy metals in the synthetic strategy may cause harmful toxicity and inaccuracy in biological studies.

[0004] Indolepyridines (carbolines) have a wide range of DNA intercalation properties, enzyme inhibition properties (mainly CDKs, topoisomerases and monoamine oxidases) and interactions with benzodiazepine receptors and 5-hydroxyserotonin receptors. In addition, these compounds have shown a spectrum of pharmacological properties, including sedative, anxiolytic, hypnotic, anticonvulsant, antitumor, antiviral, antiparasitic and antibacterial activities. Despite this, the synthesis of tailor-made carboline derivatives remains an unsolved problem for the synthetic chemistry industry. An overall evaluation of existing approaches revealed the following serious problems: low yields, limited substrate scope (including the use of very specific starting materials), involvement of extreme thermal conditions, corrosive reagents and toxic heavy metal catalysts.

[0005] In the past two decades, furanopyridines have been extensively studied as bioisosteres of indoles. As a result, these heterocyclic compounds have emerged as useful pharmacophores in therapeutic areas such as cognitive or autoimmune diseases, migraine, irritable bowel syndrome, and asthma. Benzofuranopyridines, as another attractive member of the fused pyridine class, have also attracted attractive applications in the pharmaceutical and OLED industries. However, the further development of synthetic methods remains limited due to the limited substrate scope and the lack of innovative methods. Existing methods mainly rely on expensive heavy metal catalysts and are limited to the synthesis of furan rings on substituted pyridine derivatives. Alternative methods for the formation of pyridine cores on furan derivatives have not been thoroughly investigated.

[0006] To summarize the challenges of the prior art methods, standard indole and carbazole synthesis protocols are not applicable in this field due to inherent structural complexity. The pyridine ring is very electron deficient compared to its benzene counterpart. This limits the scope of the formation of five-membered rings on the pyridine ring. In addition, the formation of nitrogen-containing six-membered rings on pyrrole and indole has not been thoroughly studied due to the narrow substrate range. Similarly, the thermal stability of pyrrole and indole derivatives also limits their use as starting materials. In addition, methods with a narrow substrate range, expensive starting materials, heavy metal catalysts and cumbersome working procedures are difficult to commercialize because these elements are not cost-effective in large-scale production. In addition, conventional methods use metal catalysts, and organic solvents are widely used in organic synthesis and have attracted much attention due to their inherent toxicity and environmental hazards.

[0007] To overcome the above disadvantages, a versatile one-pot method has been designed and developed herein to synthesize a series of substituted nitrogen heterocycles. The novel synthetic scheme is a metal-free and solvent-free method that can obtain a variety of compounds by strategic design of starting materials. The synthesized compounds were carefully screened and found to have interesting biological activities or efficacy such as anticancer, antimycobacterial and antibiofilm compounds. The compounds synthesized by the present invention do not require complicated purification procedures or expensive precision equipment.

[0008] Purpose of the Invention

[0009] The main purpose of the examples herein is to provide fused pyridine heterocycles.

[0010] Another object of the present invention is to provide a metal-free and solvent-free method for synthesizing fused pyridine heterocycles.

[0011] Another object of the present invention is to synthesize compounds with anti-cancer and anti-multidrug resistant pathogen biological efficacy. Summary of the invention

[0012] Therefore, the embodiments herein provide fused pyridine heterocycles and methods for their preparation. The pyridine heterocycles of the present invention can be used to treat cancer (cervical, kidney, lung, breast and epidermal skin) and multi-drug resistant tuberculosis. These heterocycles can also be used as anti-biofilm agents to restrict pathogenic strains, thereby minimizing the risk of secondary infection.

[0013] In one embodiment, the fused pyridine heterocycle is, for example, a nitrogen indole of formula I, a carboline derivative, a furano[b]pyridine, or a furano[b]pyridine-isatin hybrid.

[0014]

[0015] and prodrugs, stereoisomers, racemates, salts, hydrates, hydrated salts, acid salt hydrates, solvates, isomorphous crystal forms and compositions thereof;

[0016] wherein 'X' is one of nitrogen or oxygen;

[0017] R 1 It is morpholine ketone, -CONH 2 , -CN, -CHO, -COOH, -ROH, -COOR, wherein R is an alkyl

[0018] R 2 and R 5 At least one selected independently from the group consisting of -H, -Boc, alkyl, p-toluenesulfonyl, phenylsulfonyl, aryloxy, benzyloxy, optionally substituted benzyl and optionally substituted aryl; R 3 , R 4 , R 6 and R 7 are independently selected from -H, alkyl, or R 3 and R 4 At least one of; and R 6 and R 7 Capable of being fused to form an optionally substituted benzene ring.

[0019] In another embodiment, the present invention also provides a method for preparing a pyrimidine fused heterocycle, the method comprising: contacting a reactant selected from the group consisting of N-substituted pyrrole-2-carboxaldehyde, N-substituted indole-carboxaldehyde, optionally substituted furan carboxaldehyde and benzofuran-2-pyrrole carboxaldehyde with an acidic salt of a glycine alkyl ester under alkaline conditions at a temperature range of 100 to 160° C. for 3 to 15 hours to obtain a compound of formula I.

[0020] These and other aspects of the embodiments described herein will be better appreciated and understood when considered in conjunction with the following description and accompanying drawings. However, it should be understood that the following description, while indicating the preferred embodiments and their numerous specific details, is given by way of illustration and not limitation. Various changes and modifications may be made within the scope of the embodiments described herein without departing from the subject matter thereof, and the embodiments described herein include all such changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The method and system are illustrated in the accompanying drawings, in which similar reference letters indicate corresponding parts in the various figures. The embodiments described herein may be better understood through the following description with reference to the accompanying drawings, in which:

[0022] Figure 1 A schematic diagram showing an invention according to an embodiment of the present disclosure is shown;

[0023] Figure 2 The synthesis of 5-azaindole 3aa-fa from N-substituted pyrrole-2-aldehydes 1a-i according to the embodiments described in the present disclosure is shown;

[0024] Figure 3 Demonstrating the role of various substituents at the 1,4,5-positions of 1-substituted-2-pyrrole aldehydes (1a-i) in the formation of 5-nitroindole 3aa-fa according to the embodiments described in the present disclosure;

[0025] Figure 4 The plausible formation mechanisms of 5-nitroindole (3aa-fa), carboline (18aa-fa), azabenzofuran (20aa-ba) and pyrrolebenzofuran (28aa-ac) according to the embodiments described in the present disclosure are demonstrated;

[0026] Figure 5 Demonstrating the formation of 5-regio monomers, but not 6-regioisomers, of various heterocycles according to the embodiments described in the present disclosure;

[0027] Figure 6 Shows the single crystal XRD analysis of 5-nitrogen indole derivative 3aa (CCDC 1836867) according to the examples described in the present disclosure;

[0028] Figure 7 The synthesis of novel 5-nitrogen indole derivatives (11 to 14) according to the embodiments described in the present disclosure is shown;

[0029] Figure 8 The synthesis of the proposed CB2 agonist (16) according to the embodiments described in the present disclosure is shown;

[0030] Fig. 9The synthesis of γ-carboline 18aa-fa according to the embodiments described in the present disclosure is shown;

[0031] Fig.10 The single crystal XRD analysis of the γ-carboline derivative 18ac (CCDC: 1897787) according to the embodiments of the present disclosure is shown;

[0032] Fig.11 The synthesis of furano[b]pyridine (20aa-ba) according to the embodiments described in the present disclosure is shown;

[0033] Fig.12 The synthesis of furanpyridine-isatin hybrid (26) for anti-tuberculosis activity according to the examples described in the present disclosure is shown;

[0034] Fig.13 The synthesis of benzofuranopyridine (28aa-ac) according to the embodiments described in the present disclosure is shown;

[0035] Fig.14 The synthesis of benzofuranopyridine (28aa-ac) according to the embodiments described in the present disclosure is shown;

[0036] Fig.15 The fluorescence decay curves of 18ac in DMSO (left side; λexc 360 nm) and 10-5M compound 18ac solution in four different solvents in a UV chamber (right side) are shown according to the embodiments described in the present disclosure;

[0037] Fig.16 Dose-response curves for carbolines 18ac, 18bc, 18da and 18fa in human cancer cell lines HeLa, MCF-7, HEK293, A431 and A549 are shown. According to the examples described in the present disclosure, IC50 values ​​were determined by standard crystal violet assay in triplicate;

[0038] Fig.17 Confocal microscopy studies (λex=405nm; collection range=420 to 470nm) for 18ac uptake in HeLa cells according to embodiments described in the present disclosure are shown;

[0039] Fig.18 The structural formulas of various compounds according to the embodiments described in the present disclosure are shown;

[0040] Fig.19 The key features of the invention that distinguish it from prior art approaches are demonstrated according to the embodiments described in this disclosure.

[0041] Fig. 20The in vitro anti-tuberculosis activity of furano[b]pyridine-isatin hybrid derivative 26 according to the examples described in the present disclosure is shown against Mycobacterium smegmatis (50 to 100 μM), SD (n=3); multidrug-resistant / opportunistic Mycobacterium bovis (70 to 100 μM) SD (n=3). DETAILED DESCRIPTION

[0042] The embodiments herein and their various features and advantageous details are explained more fully with reference to the non-limiting embodiments shown in the accompanying drawings and described in detail in the following description. The description of recognized components and processing techniques is omitted to clarify the embodiments herein. In addition, the various embodiments described herein are not necessarily mutually exclusive, because certain embodiments can be combined with one or more other embodiments to form new embodiments. Unless otherwise stated, the term "or" used herein refers to a non-exclusive or. The examples used herein are merely to facilitate understanding of the manner in which the embodiments described herein can be practiced, and further enable those skilled in the art to practice the embodiments described herein. Therefore, the examples should not be interpreted as limiting the scope of the embodiments described herein.

[0043] As used herein, the term "alkyl" includes a chain of carbon atoms, which chain is optionally branched.

[0044] As used herein, the term "aryl" includes molecular fragments or radicals comprising aromatic monocyclic or polycyclic rings of carbon atoms, for example, phenyl, naphthyl and the like.

[0045] As used herein, the term "substituted aryl" includes molecular fragments or free radicals comprising an aryl group having one or more substituents, such as alkyl, heteroalkyl, halogen, hydroxy, amino, alkyl or dialkylamino, alkoxy, alkylsulfonyl, aminosulfonyl, carboxylate, alkoxycarbonyl, aminocarbonyl, cyano, nitro, and the like. It should be understood that the alkyl group in such substituents may be optionally substituted with halogen.

[0046] The invention described herein relates to the discovery of pyridine fused heterocycles, such as substituted 5-nitrogen indoles, γ-carbolines, furano[b]pyridines, 5-nitrogen indoles or furano[b]pyridine-isatin hybrids, benzofuranopyridines and their thio-based counterparts. The compounds of the invention have application value in the treatment of cancer [HeLa (cervical cancer), MCF-7 (breast cancer), HEK293 (kidney), A431 (cervical squamous epithelial) and A549 cells (lung)] and multidrug-resistant pathogens, such as agents causing tuberculosis (Mycobacterium smegmatis, Mycobacterium bovis (BCG) and other tuberculogenic strains. The compounds of the invention can also be used for anti-biofilm activity against biofilm-forming bacteria or pathogen groups. The invention also provides a simple method for synthesizing pyridine fused heterocycles. The method is a simple one-pot, one-step method for obtaining a variety of heterocycles in a general manner. The product purification is simple and the yield is reproducible.

[0047] The method described in the present invention describes a simple one-pot synthesis of a library of pyridinium furan derivatives. In addition, a group of novel pyridinium furan-isatin hybrids have been developed in our laboratory and demonstrated to have anti-mycobacterial activity against both non-pathogenic and pathogenic mycobacteria that cause tuberculosis. In addition, several novel pyridinium furan molecules and their functional derivatives have been studied for their anti-TB properties and demonstrated to have anti-tuberculosis activity against multidrug-resistant mycobacterium strains.

[0048] The invented synthetic method has been successfully optimized to produce various heterocycles in respectable yields via a simplified one-pot process, which can otherwise only be prepared in very limited yields via multi-step syntheses.

[0049] In one embodiment of the present invention, the fused pyridine heterocycle, such as nitrogen indole, carboline derivative, furano[b]pyridine is a compound of formula I

[0050]

[0051] and prodrugs, stereoisomers, racemates, salts, hydrates, hydrated salts, acid salt hydrates, solvates, isomorphous crystal forms and compositions thereof;

[0052] wherein 'X' is one of nitrogen or oxygen;

[0053] R 1 It is morpholine ketone, -CONH 2 , -CN, -CHO, -COOH, -ROH, -COOR, wherein R is an alkyl

[0054] R 2 and R 5 At least one selected independently from the group consisting of -H, -Boc, alkyl, p-toluenesulfonyl, phenylsulfonyl, aryloxy, benzyloxy, optionally substituted benzyl and optionally substituted aryl; R 3 , R 4 , R 6 and R 7 are independently selected from -H, alkyl, or R 3 and R 4 At least one of; and R 6 and R 7 Capable of being fused to form an optionally substituted benzene ring.

[0055] In another embodiment, the present invention discloses a compound of formula I, wherein X is nitrogen; R 1 It is morpholine ketone, -CONH 2 , -CN, -CHO, -COOH, -ROH and -COOR, wherein R is selected from -Me, Et or tBu composed of an alkyl group; R 2 With R 5 are the same and are selected from the group consisting of hydrogen, methyl, benzyl, methoxybenzyl, p-toluenesulfonyl and benzenesulfonyl; R 3 , R 4 , R 6 and R 7 are independently selected from -H or -CH 3 One of a kind.

[0056] In another embodiment, the present invention discloses a compound of formula I, wherein X is nitrogen; R 1 It is morpholine ketone, -CONH 2 , -CN, -CHO, -COOH, -ROH and -COOR, wherein R is selected from -Me, Et or t Bu composed of an alkyl group; R 2 With R 5 are the same and are selected from hydrogen, methyl, benzyl, methoxybenzyl, p-toluenesulfonyl and benzenesulfonyl, R 3 and R 4 and R6 and R7 can be fused to form an optionally substituted benzene ring.

[0057] In another embodiment, the compound of formula I comprises

[0058]

[0059] Where R 1 is -COOR, wherein R is selected from -Me, Et or t Bu composed of an alkyl group; R 3 , R 4 , R 6 and R 7 are independently selected from -H, alkyl or R 3 and R 4 At least one of; and R 6 and R 7 Capable of being fused to form an optionally substituted benzene ring.

[0060] In another embodiment, the present invention discloses a compound of formula II

[0061]

[0062] and its prodrugs, stereoisomers, racemates, salts, hydrates, hydrated salts, acid salt hydrates, solvates, isomorphous crystals and compositions thereof; wherein R1 is an optionally substituted isatin; R3, R4, R6 and R7 are independently selected from -H, alkyl or at least one of R3 and R4; and R6 and R7 can be fused to form an optionally substituted benzene ring.

[0063] In one embodiment, the compound of formula II is

[0064]

[0065] The present invention also provides a simple method for preparing the compounds of formula I and II. In one embodiment, the compound of formula I can be prepared by the following steps: reacting a reactant selected from the group consisting of N-substituted pyrrole-2-carboxaldehyde, N-substituted indole-carboxaldehyde, optionally substituted furan carboxaldehyde and benzofuran-2-carboxaldehyde with an acidic salt of a glycine alkyl ester in the presence of a base (selected from N,N-diisopropylethylamine (DIPEA), triethylamine (Et 3 N), K 2 CO 3 ,NAH,Cs 2 CO 3 and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)) under the conditions of temperature range of 100 to 160° C. for 3 to 15 hours to obtain the compound of formula I. In the embodiment, the molar ratio of the reactant to the acid salt of glycine alkyl ester is in the range of 1:2 to 2:1, preferably 2:1, and the molar ratio of the reactant to the base is in the range of 1:1 to 1:15, preferably in the range of 1:1 to 1:2.

[0066] The present invention also discloses a method for preparing a compound of formula II. The method comprises the following steps: reacting an optionally substituted furfural with an acidic salt of a glycine alkyl ester in a base (selected from N,N-diisopropylethylamine (DIPEA), triethylamine (Et 3 N), K 2 CO 3 ,NAH,Cs 2 CO 3 and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)) under the conditions of 100 to 160° C. for 3 to 15 hours to obtain the compound of formula I; b) under the first reaction conditions (temperature range 0° C. to 30° C., for 10 to 30 minutes), in the presence of a reducing agent (LiAlH 4) under the presence of 2-4 hours, reacting the compound of formula I in THF to produce the corresponding alcohol; c) under the second reaction condition (2 to 4 hours), reacting the corresponding alcohol obtained in step a) with propargyl bromide and sodium hydride in the presence of a catalyst (tetrabutylammonium iodide (TBAI)) in refluxing anhydrous THF to obtain the corresponding alkyne derivative; d) under the third reaction condition (temperature range 20°C to 35°C, for 25 to 35 hours), causing the corresponding alkyne derivative obtained in step b) to undergo a copper-catalyzed click reaction with an azide to obtain the compound of formula II.

[0067] Referring now to the drawings, and more particularly to the attached Figures 1 to 20 Preferred embodiments are shown, with like reference characters indicating corresponding features consistently throughout the drawings.

[0068] Figure 1 The schematic diagram of the invention according to the embodiment described in the present disclosure is shown. The present invention relates to a newly developed process / method for the synthesis of heterocyclic compounds in organic chemistry and their anticancer and antituberculosis activities. The implementation of the system invention can be described as the following units

[0069] Elements, components or units of the present invention:

[0070] A. Discovery of a new cascade synthesis of pyridine-fused heterocycles

[0071] B. Synthesis of Substituted 5-Azoindole Derivatives

[0072] C. Synthesis of Substituted γ-Carboline Derivatives

[0073] D. Synthesis of Substituted Furano[b]pyridine, Benzofurano[b]pyridine Derivatives and Furano[b]pyridine-Isatin Hybrids

[0074] E. Optical performance evaluation

[0075] F. In vitro studies against tumor cell lines and multidrug-resistant pathogens

[0076] G. Antimycobacterial properties of novel 5-nitrogen indole, furanpyridine and their isatin hybrids

[0077] H. Test process or method

[0078] Function description of each unit:

[0079] 1. Brief introduction to the unexpected discovery and systematic development of optimized synthetic processes

[0080] 2. The synthesis method of the present invention and the substrate scope of the synthesis of 5-nitroindole derivatives, the mechanism of synthesis and regioselectivity, and the rational design and synthesis of novel CB2 agonist analogs

[0081] 3. Synthesis of γ-carboline and BET inhibitor analogs using a newly developed method

[0082] 4. Synthesis of furanopyridine and benzofuranopyridine

[0083] 5. Photophysical studies of new carbolines: UV absorption and fluorescence studies

[0084] 6. Cellular uptake (confocal microscopy) and cytotoxicity studies of typical carboline derivatives

[0085] 7. Antimycobacterial properties of novel 5-nitrogen indole and / or furano[b]pyridine and their indigo carmine hybrids

[0086] Discovery of a novel cascade synthesis of pyridine-fused heterocycles: Azaindoles are a class of potent heterocyclic motifs with a wide range of applications in pharmaceutical products. Their structural similarity to that of interesting biomolecules and limited availability in biological systems make them a promising candidate for modulating natural ligand-protein interactions. Pyrrologlycine may become a key structural component for developing a series of azaindole core molecules via heterocyclization strategies. While attempting to prepare pyrrologlycine via the imidization of N-benzylpyrrole-2-carboxaldehyde (1a) with glycine methyl ester hydrochloride (2a) in refluxing toluene in the presence of Hünig's base (DIPEA), we found that the product was not the corresponding imine but was later identified as 1-benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3aa).

[0087] A novel reaction for the synthesis of pyrrolopyridines (nitroindoles) was further analyzed to find the optimal reaction conditions. Various inorganic and organic bases were investigated for their effectiveness in obtaining the desired transformation (Table 1). By systematically varying the equivalents of N-substituted pyrrole-2-aldehyde and base, a suitable molar ratio was found that gave the best yield. Various solvent systems were investigated to improve the yield of the desired 5-nitroindole.

[0088]

[0089]

[0090] Table 15 - Optimization of reaction conditions for nitrogen indole synthesis

[0091] Figure 2The synthesis of 5-azaindole 3aa-fa from N-substituted pyrrole-2-aldehydes 1a-i according to the embodiments described in the present disclosure is demonstrated. A variety of reaction conditions were investigated, including neat reaction and microwave irradiation. From a series of experimental data in our hands, we concluded that by the newly discovered reaction, a mixture of 2.0 equivalents of N-benzylpyrrole-2-carboxaldehyde (1a) and 1.0 equivalent of glycine alkyl ester hydrochloride was heated at 150°C in a sealed tube, and the optimal yield of the desired 5-azaindole (3aa) was 58% (e.g. Figure 2 shown).

[0092] Synthesis of Substituted 5-Nitroindole Derivatives: In addition, for a series of N-substituted pyrrole-2-aldehydes (1b-j), it was observed that the conversion of nitrogen indoles proceeded smoothly when electron-rich N-substituents were present on the pyrrole-2-carboxaldehyde subunit, i.e., 4-methoxybenzyl (1b), methyl (1c) functional groups. Pyrrole-2-carboxaldehyde derivatives with mild electron-withdrawing groups such as p-toluenesulfonyl (1d) and benzenesulfonyl (1e) underwent similar heterocyclization to give the corresponding nitrogen indole derivatives, but with long reaction times and moderate yields. When N-Boc pyrrole-2-carboxaldehyde (1h) or 5H-pyrrolo[2,1-a]isoindole-3-aldehyde (1i) were reacted under similar reaction conditions, no trace of nitrogen indole products was generated due to the strong electron-withdrawing tendency of the Boc protecting group in 1h and the highly strained pyrrole-fused isoindole ring system in li. In summary, we conclude that the nucleophilicity of C-3 of the pyrrole heterocyclic unit plays a crucial role in heterocyclization.

[0093] Figure 3 The role of various substituents at the 1,4,5-positions of 1-substituted-2-pyrrole aldehydes (1a-i) in the formation of 5-azaindole 3aa-fa according to the embodiments described in the present disclosure is demonstrated. Substitution at C-4 on the pyrrole subunit is also not allowed in the methodology, most likely due to steric crowding. Although substituents with less steric requirements at C-5 (such as methyl groups (1f)) are well tolerated, bulky substituents at the C-5 position of the pyrrole unit (such as benzyl groups) do not form 5-azaindole products even when heated at 150°C for 48 hours.

[0094] Figure 4 The plausible formation mechanisms of 5-nitroindole (3aa-fa), carboline (18aa-fa), azabenzofuran (20aa-ba) and pyrrolobenzofuran (28aa-ac) according to the embodiments described in the present disclosure are shown. The possible mechanisms (e.g., the conversion of various heterocyclic or benzo-fused heterocyclic 2-aldehydes (1a-i, 17a-h, 19a-b and 27) to the corresponding fused pyridine heterocycles (3aa-fa, 18aa-fa, 20aa-ba and 28aa-ac) are shown. Figure 4 ) involves the initial formation of trans-imine 4 from a heterocyclic 2-aldehyde and a glycine alkyl ester (2a-c). In the presence of Hunig's base, imino nucleophile 5 is generated by abstraction of the active methylene proton from trans-imine 4, which further undergoes nucleophilic addition reaction with another heterocyclic-2-aldehyde molecule (1a-i, 17a-h, 19a-b, 27) to give intermediate imino alcohol 6. Imino alcohol 6 removes a water molecule under the reaction conditions to give iminoenamine intermediate 7. The imine double bond in intermediate 7 is activated by conjugate acid (+BH), electrophilic aromatic substitution is carried out at the 3-position of the heterocyclic unit, and imine intermediate 8 aromatizes due to proton loss to form a second CC bond to give intermediate 10. 10 is dehydrogenated in situ by autoxidation to give the desired pyridine-fused compounds (3aa-fa, 18aa-fa, 20aa-ba, and 28aa-ac).

[0095] Figure 5 Demonstration of the formation of 5-regio monomers, but not 6-regioisomers, of various heterocycles according to the embodiments described in the present disclosure is presented. Exclusive formation of the 5-regioisomer is explained by invoking the trans-imine nucleophile 5a to participate in the first CC bond formation process via nucleophilic addition to heterocyclic-2-aminoacetaldehyde 1 to afford the 5-regioisomer intermediate 8a, whereas formation of the 6-regioisomer intermediate 8b is not favored due to steric crowding of the nucleophilic reaction of the synthetic imine 5b with the heterocyclic-2-acetaldehyde 1 (e.g., Figure 5 The imine intermediate 8a undergoes nucleophilic substitution at the 3-position of the heterocycle or benzo-fused carboxaldehyde to form a second C-C bond, which is then closed by a heterocyclization reaction to afford the dihydro intermediate 9, which provides various heterocycles such as 5-nitroindole, γ-carboline, 5-nitrobenzofuran, and pyrrolebenzofuran during aromatization and autooxidation.

[0096] Figure 6 Single crystal XRD analysis of 5-nitrogen indole derivative 3aa (CCDC 1836867) according to the examples described in the present disclosure is shown. Further, ester 3aa reacts with ammonia in alkaline methanol solution to produce the corresponding amide derivative 11. Mild dehydration of 11 in phosphorus oxychloride provides cyano-nitrogen indole 12. Ester 3aa reacts rapidly with lithium aluminum hydride to produce the corresponding alcohol 13.

[0097] Figure 7 The synthesis of novel 5-nitrogen indole derivatives (11 to 14) according to the embodiments described in the present disclosure is shown. The introduction of a formyl moiety into the six-membered ring nitrogen indole while retaining the highly nucleophilic C-3 and C-2 positions of the indole can also be achieved by this method, because the alcohol 13 can be easily oxidized to the aldehyde 14 (such as 14) by treatment with manganese dioxide in refluxing dichloromethane. Figure 7 shown).

[0098] Figure 8 The synthesis of a proposed CB2 agonist (16) according to the embodiments described in the present disclosure is demonstrated. Cannabinoid receptors are a class of transmembrane proteins that belong to the G protein-coupled receptor superfamily. These receptors are of two types, namely CB1 and CB2. Cannabinoid-cannabinoid receptor interactions have been extensively studied for their anti-palliative effects, while CB2 receptors are used for selective targeted therapy of neuropathic pain. Recent literature suggests that CB2 can be an important target for the development of new anti-cancer molecules because CB2 agonists can modulate key cellular signaling pathways including cell survival, angiogenesis, and metastasis. It is speculated that compound 3ca has significant structural similarity to the selective CB2 agonist GSK554418A reported in the literature and is expected to exhibit similar biological activities. Therefore, the methyl ester of 3ca was hydrolyzed to the corresponding 5-nitroindole acid (15). Thereafter, 15 was coupled with morpholine to obtain 16 (such as Figure 8 In vitro studies are ongoing in our laboratory to confirm the CB2 agonist activity of 3ca and 16 in tumor cell lines.

[0099] Fig. 9 The synthesis of γ-carboline 18aa-fa according to the embodiments described in the present disclosure is demonstrated. Carboline is the olfactory domain, extra terminal (BET) protein has emerged as a new class of targets for the treatment of cancer. The human genome encodes 46 bromodomain-containing proteins, which can be roughly divided into 8 subfamilies. Existing studies have shown that the fine regulation of gene transcription through selective targeting of bromodomains may bring innovative changes to the way we treat cancer. BET inhibitors are rapidly entering clinical trials for various human cancers, such as IBET-762 (sponsored by GSK, for the treatment of epithelial cancer, currently in Phase I clinical trials) and OTX015 (sponsored by Onocethix, for the treatment of leukemia, currently in Phase I clinical trials). In recent years, some synthetic γ-carboline derivatives have shown selective bromodomain inhibition at low nanomolar concentrations.

[0100] Synthesis of substituted γ-carboline derivatives: As described in the proposed mechanism (eg Figure 4As shown in Scheme 6), it is envisioned that a library of pyridine-fused heterocycles can be prepared by the method of the present invention. To verify our hypothesis, we prepared a series of N-substituted indole-2-carboxaldehyde derivatives (17a-h) using standard reactions. N-methylindole-2-carboxaldehyde (2 equivalents) and glycine methyl ester hydrochloride (2a-c, 1 equivalent) were heated at 120°C with DIPEA (3.5 equivalents) in a sealed tube for 3 to 9 hours to obtain the corresponding γ-carboline derivatives (18aa-fa, Scheme 6). It is worth noting that under the standard reaction conditions of the scheme, the N-protected indole-2-carboxaldehyde derivatives are more active than the recent N-substituted pyrrole-2-carboxaldehyde derivatives (1a-i).

[0101] Fig.10 Single crystal XRD analysis of γ-carboline derivative 18ac (CCDC: 1897787) according to the examples described in the present disclosure is shown.

[0102] Fig.11 The synthesis of furano[b]pyridines (20aa-ba) according to the embodiments described in the present disclosure is demonstrated. Synthesis of Substituted Furo[b]pyridines, Benzofuranopyridine Derivatives and Furo[b]pyridine-Isatin Hybrids Furanaldehyde (19a) and 5-methylfuraldehyde (19b) were successfully converted to the corresponding furano[b]pyridines (20aa-ba) under standard reaction conditions established in the laboratory. Synthetic derivatives of this class of compounds were found to exhibit anti-tuberculosis properties against mycobacterium strains that cause tuberculosis. In addition, a furano[b]pyridine-isatin hybrid molecule (26) was synthesized to further enhance the anti-tuberculosis activity.

[0103] Fig.12 The synthesis of a furanopyridine-isatin hybrid (26) for anti-tuberculosis activity according to the embodiments described in the present disclosure is demonstrated. The novel furano[b]pyridine was found to be very promising through preliminary evaluation. The furano[b]pyridine 20ba was treated with LiAlH4 to give the corresponding alcohol 21. The alcohol was subjected to propargylation to give the alkyne derivative 22, and the indigo azido 25 was synthesized, and the indigo-azide 25 was synthesized according to literature reports. The click chemistry reaction of 22 and 25 was successfully converted into the novel furanopyridine-isatin hybrid 26 (e.g. Fig.10 All furanopyridine derivatives and isatin hybrids were screened for anti-mycobacterial activity against multidrug-resistant and broadly drug-resistant (MDR) strains of Mycobacterium tuberculosis and against a panel of biofilm-forming bacteria or pathogens and were found to have significant anti-tuberculosis activity.

[0104] Fig.13The synthesis of benzofuranopyridines (28aa-ac) according to the examples described in the present disclosure is demonstrated. The versatility of the discovery method is once again demonstrated by reacting benzofuran-2-carboxaldehyde 27 with glycine alkyl esters (2a-c) to obtain new benzofuranopyridine derivatives (28aa-ac). Fig.11 All heterocycles synthesized using this method are uniquely identifiable products of their respective reactions.

[0105] Fig.14 The synthesis of benzofuranopyridine (28aa-ac) according to the embodiments of the present disclosure is shown. Optical property evaluation: The photophysical properties of a synthesized carboline derivative 18ac were studied. 2 Cl 2 ), methanol (MeOH), dimethyl sulfoxide (DMSO) and n-hexane. It was found that the UV absorption characteristics of compound 18ac were independent of the solvent polarity. The maximum absorption peak (λmax) of the DMSO solution of 18ac was observed at 230nm. Subsequently, the fluorescence of 18ac was studied with the same four solutions. When the solvent was changed from non-polar hexane to medium-polar dichloromethane and then to high-polar DMSO, a red shift of nearly 40nm was observed (Table 2; Fig.14 The intrinsic fluorescence of 18ac is quenched in the polar protic solvent methanol, which may be due to the ultrafast photoinduced electron transfer between solute-solvent molecules promoted by hydrogen bonding interactions in highly polar solvents.

[0106]

[0107] Table 2 Measurement of the absorption rate (ε) and half-life (τ) of 18ac

[0108] Fig.15 Fluorescence decay curves of 18ac in DMSO (left; λexc 360nm) and 10 to 5M compound 18ac solutions in four different solvents in a UV chamber (right) are shown according to the embodiments described in the present disclosure. The fluorescence lifetime was determined using a time-correlated single photon counting (TCSPC) experiment. In general, the longer the fluorescence lifetime, the higher the quantum yield and the better the imaging contrast. Organic molecules are ideal for FRET studies because they are classified as "rigid dyes." Fortunately, 18ac has strong fluorescence in DMSO and DCM, with average fluorescence lifetimes of 8.35 nanoseconds (ns) and 4.73 ns, respectively (Table 2; Fig.15 ).

[0109] Fig.16Dose-response curves of carboline 18ac, 18bc, 18da and 18fa for 48 hours of incubation in HeLa, MCF-7, HEK293, A431 and A549 cell lines are shown. According to the embodiments described in the present disclosure, IC50 values ​​were determined by standard crystal violet assay in triplicate; In vitro studies: Cytotoxicity tests of novel carboline derivatives 18ac, 18bc, 18da and 18fa were performed on human malignant cell lines, such as HeLa, MCF-7, HEK293, A431 and A549, using standard crystal violet method. Cells were plated in 96-well plates (1800 cells per well) and incubated at 37°C, 5% CO 2 The cells were cultured for 48 hours under the same conditions. When 50% confluency was reached, the cells were incubated for 48 hours with a series of concentrations (0.1 μM, 0.25 μM, 0.5 μM, 1 μM, 2.5 μM, 5 μM, 10 μM, 25 μM, 50 μM and 100 μM) of carbolines 18ac, 18bc, 18da and 18fa. The results obtained from these tests (Table 3) show that micromolar concentrations of carbolines are cytotoxic.

[0110]

[0111] Table 3 IC values ​​of carbolines 18a, 18bc, 18da and 18fa as DNA intercalators in HeLa, MCF7, HEK293, A431 and A549 cells 50 Study (48 hours in culture).

[0112] Fig.17 Confocal microscopy studies (λex = 405 nm; collection range = 420 to 470 nm) for 18ac uptake in HeLa cells according to embodiments described in the present disclosure are shown.

[0113] a) Confocal fluorescence image of HeLa cells after incubation with 10 μM 18ac for 3 h (20x magnification, 2x zoom);

[0114] b) DIC image of HeLa cells

[0115] c) Overlapping graph of (a) and (b)

[0116] d) Confocal image of HeLa cells after incubation with 18ac at a concentration of 100 nM for 3 h (20x magnification, 2x zoom)

[0117] e) DIC image of HeLa cells

[0118] f) Overlapping graph of (d) and (e)

[0119] To further evaluate the cellular uptake of the novel carbolines, live cell imaging experiments were performed. Cells were plated in 4-well plates (cell count = 10 per well). 4 cells) and cultured at 37°C, 5% CO 2 The cells were cultured under the same conditions for 48 hours. After incubation with 18ac (10 nM, 100 nM, 1 μM, 10 μM and 100 μM) for 3 hours, cellular uptake and distribution were monitored using confocal microscopy (λex = 405 nm; collection range = 420 to 470 nm). When incubated with a concentration of 10 μM, appropriate cytoplasmic uptake of 18ac was observed in cancer cells, while nominal uptake was observed at a concentration of 100 nM.

[0120] Fig.18 The structural formulas of various compounds according to the embodiments described in the present disclosure are shown.

[0121] Fig.19 The key features of the invention that distinguish it from prior art approaches are demonstrated according to the embodiments described in this disclosure.

[0122] In vitro antimycobacterial activity of novel furano[b]pyridines and their isatin hybrids against nonpathogenic (Mycobacterium smegmatis) and pathogenic / opportunistic mycobacteria (Mycobacterium bovis)

[0123] The newly synthesized furano[b]pyridine-isatin hybrid derivative 26 (also labeled as CV-PD-PF-IST-HBD-001) was tested against nonpathogenic ( Mycobacterium smegmatis ) and BCG pathogenic ( Mycobacterium bovis ) multidrug-resistant strains. Fig. 20 As shown. It was observed that furano[b]pyridine-isatin hybrid drug 26 was active against non-pathogenic mycobacterium strains within 24 hours and pathogenic multidrug-resistant mycobacterium strains within 48 hours in the concentration range of 70 to 100 μM, respectively. The obtained results are exciting and strengthen the modification or change in drug design to develop new anti-tuberculosis drugs by India to end the death of millions of people in developing countries.

[0124] Fig. 20 The in vitro anti-tuberculosis activity of furano[b]pyridine-isatin hybrid derivative 26 according to the examples described in the present disclosure is shown against Mycobacterium smegmatis (50 to 100 μM), SD (n=3); multidrug-resistant / opportunistic Mycobacterium bovis (70 to 100 μM) SD (n=3).

[0125] Test method:

[0126] Cytotoxicity test method of carbolines in cancer cell lines: To this end, carbolines 18ac, 18bc, 18da and 18fa were subjected to standard cell viability studies (crystal violet assay) to test anticancer activity against various human tumor cell lines, such as HeLa, MCF-7, HEK293, A431 and A549. Crystal violet is a triarylmethane dye that stains adherent cells by binding to the ribose moiety in DNA. The amount of crystal violet staining in the experiment is proportional to the amount of viable cell biomass attached to the plate after repeated washing. The above human cancer cell lines were plated in 96-well tissue culture plates (1800 cells / well) and incubated with RPMI 1640 medium (volume ≥100 μL / well) at 37°C, 5% CO 2 The cells were cultured for 48 h under the conditions of 10% heat-inactivated fetal bovine serum (HIFBS) and 1% penicillin-streptomycin antibiotics. When the monolayer cells reached 50% confluence / well, the old medium was aspirated and replaced with ≥100 μL / well of fresh medium, and increasing concentrations of carbolines 18ac, 18bc, 18da, and 18fa (0.1 μM, 0.25 μM, 0.5 μM, 1 μM, 2.5 μM, 5 μM, 10 μM, 25 μM, 50 μM, and 100 μM) were added, respectively, and incubated at 37°C, 5% CO 2 48 hours under the same conditions. Positive control: 40% DMSO culture medium was added to three wells and cultured under the same conditions. Three wells of cells were treated with each concentration. After 48 hours, the culture medium / well was aspirated, the cells were rinsed twice with a gentle stream of tap water, and the plate was inverted on filter paper to remove residual liquid. To measure cell viability, 50 μL of 0.5% crystal violet staining solution (0.5 g crystal violet powder, 80 mL H 2 O, 20mL methanol) was added to each well and incubated on a shaker at room temperature for 20 minutes (frequency is approximately 20 shakes / minute). The plates were gently rinsed again as before and dried at room temperature for 2 hours. The crystal violet dye was then dissolved by adding 200 μL methanol / well and the plates were incubated at room temperature for 20 minutes. Finally, the optical density of each well was measured at 570nm (OD570) using a Synergy H1 multimode plate reader (BioTek Instruments, Inc., Winooski, VT, USA). The average background of OD570 of the blank wells was measured and subtracted from the OD570 / well of the plate. The percentage of viable cells after treatment was determined, and dose-response curves were plotted as semi-log [concentration] versus normalized cell viability percentage curves using GraphPad Prism v.6.02 (GraphPad Software, San Diego, CA). The effects of carbolines 18ac, 18bc, 18da, and 18fa on different human tumor cell lines ( Fig.16 ) with a half maximal inhibitory concentration (IC50), as shown in Table 3.

[0127] Fig.17 Confocal microscopy studies (λex=405nm; collection range=420 to 470nm) for 18ac uptake in HeLa cells according to embodiments described in the present disclosure are shown;

[0128] Fig.18 The structural formulas of various compounds according to the embodiments described in the present disclosure are shown;

[0129] Fig.19 The key features of the invention that distinguish it from prior art approaches are demonstrated according to the embodiments described in this disclosure.

[0130] Bacterial culture preparation and in vitro inactivation test method of Mycobacterium strains

[0131] Bacterial culture preparation

[0132] i. Inoculate monoclonal Mycobacterium smegmatis (M.smeg) or Mycobacterium bovis (BCG) in 7H9 Middlebrook medium containing Tween 80

[0133] ii. Cultivate the bacteria at 37°C for 36 to 48 hours

[0134] iii. Take 1 mL of grown Mycobacterium smegmatis or Mycobacterium bovis (BCG) at room temperature (RT) and centrifuge at 5000 rpm for 5 minutes.

[0135] iv. Remove the supernatant and dissolve the pellet in 1 ml of autoclaved 1X PBS.

[0136] v. Similarly, the culture was centrifuged at 5000 rpm for 5 minutes at room temperature

[0137] vi. Dissolve the precipitate formed at this time in 1X PBS for the next test

[0138] Mycobacterium inactivation test in vitro

[0139] a. Measure the OD of Mycobacterium smegmatis or Mycobacterium bovis 600 , and set to 0.1

[0140] b. Prepare mixtures of bacteria and different drug concentrations (5-azaindole or furano[b]pyridine or furano[b]pyridine-isatin hybrid) separately in microcentrifuge tubes (the mixture volume for all concentrations was kept at 200 μL)

[0141] c. The test tubes containing the bacteria and drug mixture were incubated at 37°C for 0, 6, 12, and 24 hours

[0142] d. After each individual time point, prepare up to 10 -5 1:10 serial dilutions (using 1× PBST)

[0143] e. 10 -3 , 10 -4 , 10 -5 Place the plate containing 7H9 / LB (5 μL spot)

[0144] Agar culture medium in a petri dish

[0145] f. Incubate the plate at 37°C for 36 hours or longer to allow visible colonies to form.

[0146] g. Count colonies using a colony counter

[0147] Fig. 20 The in vitro anti-tuberculosis activity of furano[b]pyridine-isatin hybrid derivative 26 according to the examples described in the present disclosure is shown against Mycobacterium smegmatis (50 to 100 μM), SD (n=3); multidrug-resistant / opportunistic Mycobacterium bovis (70 to 100 μM) SD (n=3).

[0148] Example

[0149] Example 1: General method for the synthesis of fused pyridine heterocycles (3aa-fa, 18aa-fa, 20aa-ba and 28aa-ac). A mixture of aldehyde (1a-i, 17a-h, 19a-b or 27, 2.00 mmol), glycine alkyl ester hydrochloride (2a-c, 1.00 mmol) and N,N-diisopropylethylamine (DIPEA, 3.50 mmol) was heated at 120 to 150 °C in a sealed tube (25 mL, borosilicate) for 3 to 12 hours with continuous stirring (monitored by TLC). The reaction mixture was cooled to room temperature and washed with CH 2 Cl 2 (1×10 mL) and washed with brine (1×10 mL). The reaction mixture was washed with CH 2 Cl 2 (3 × 10 ml) for further extraction. The combined organic layers were added to anhydrous Na 2 SO 4 The resulting mixture was dried over high temperature, filtered, concentrated, and purified by column chromatography over neutral alumina (175 mesh) using a hexane-EtOAc mixture as the eluent.

[0150] Example 2: 1-Benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3aa). According to the general method above, 1a (100 mg, 0.54 mmol), 2a (34 mg, 0.27 mmol) and DIPEA (0.165 mL, 0.95 mmol) were heated at 150 °C in a sealed tube for 6 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using n-hexane-EtOAc (94:6) as eluent; yield 58% (66 mg); yellow crystalline solid; mp = 134 to 136 °C; Rf 0.65 (2:1 hexane-EtOAc); IR (KBr) 3028 (=CH), 2922-2850 (CH), 1722 (C=O), 1712-1554 (C=C), 1357 (CH bending), 779 (=CH bending) cm-1; 1H NMR (500 MHz, CDCl 3 )δ8.01 (s, 1H), 7.35-7.27 (m, 3H), 7.24 (d, J=3.2Hz, 1H), 7.18-7.13 (m, 2H), 7.12-7.08 (m, 3H), 7.07-7.02 (m, 2H), 6.91 (d, J=3 .2Hz, 1H), 6.90-6.87 (m, 1H), 6.82 (dd, J=3.7, 1.7Hz, 1H), 6.29 (dd, J=2.9, 2.3Hz, 1H), 5.88 (s, 2H), 5.34 (s, 2H), 3.95 (s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ167.4, 145.8, 140.5, 139.6, 138.7, 136.2, 131.2, 130.4, 129.0, 128.2, 128.2, 127.1, 127.0, 126.8, 125.7, 125.0, 113.2, 108.2, 105.7, 103.7, 52.5, 51.7, 50.2; HRMS (ESI) [C 27 H 23 N 3 O 2 H + ]Calculated value 422.1863, measured value 422.1859.

[0151] Example 3: 1-(4-methoxybenzyl)-4-(1-(4-methoxybenzyl)-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3ba). According to the general method above, 1b (100 mg, 0.46 mmol), 2a (29 mg, 0.23 mmol) and DIPEA (0.140 ml, 0.81 mmol) were heated in a sealed tube at 150 °C for 6 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (88:12) as eluent; yield 61% (68 mg); yellow liquid; Rf 0.60 (1:1 hexane-EtOAc); IR (KBr) 3073 (=CH), 2958-2851 (CH), 1743 (C=O), 1109-1029 (CO) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.04 (s, 1H), 7.22 (d, J = 3.2Hz, 1H), 7.08 (d, J = 8.5Hz, 2H), 7.02 (d, J = 8.5Hz, 2H), 6.90-6.81 (m, 4H), 6.78 (dd, J = 3.5, 1.5H z, 1H), 6.69 (d, J=8.8Hz, 2H), 6.25 (dd, J=3.3, 2.6Hz, 1H), 5.77 (s, 2H), 5.28 (s, 2H), 3.97 (s, 3H), 3.78 (s, 3H), 3.69 (s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.7,158.8,157.8,145.1,139.6,137.9,130.9,130.3,129.6,127.9,127.8,127.4,124.7,124.4,113.7,112.9,112.5,107.3,105.0,102.8,54.6,54.4,51.7,50.4,49.0; calculate [C 29 H 27 N 4 O 3 +H + ]HRMS(ESI) of 482.2074, equal to 482.2074.

[0152] Example 4: 1-methyl-4-(1-methyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3ca). According to the general method above, 1c (100 mg, 0.92 mmol), 2a (29 mg, 0.46 mmol) and DIPEA (0.281 mL, 1.61 mmol) were heated in a sealed tube at 150 °C for 6 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (92:8) as eluent; yield 48% (59 mg); yellow-brown liquid; Rf 0.60 (1:1 hexane-EtOAc); IR (KBr) 3126-3084 (=CH), 2926-2852 (CH), 1732 (C=O), 1714-1556 (C=C), 1350 (CH bend), 721 (=CH bend) cm-1; 1 H NMR (400MHz, CDCl3) δ8.04 (s, 1H), 7.24-7.17 (m, 1H), 6.89-6.81 (m, 1H), 6.80-6.74 (m , 1H), 6.73-6.68(m, 1H), 6.25-6.13(m, 1H), 4.03(s, 3H), 3.97(s, 3H), 3.85(s, 3H); 13C NMR (100MHz, CDCl 3 )δ167.5, 145.7, 140.7, 138.5, 132.0, 130.7, 126.2, 124.9, 112.6, 107.5, 105.5, 103.1, 52.5, 36.4, 33.1; HRMS (ESI) [C 15 H 15 N 3 O 2 +H + ]Calculated value 270.1237, measured value 270.1233.

[0153] Example 5: tert-Butyl 1-benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylate (3ac) According to the general method above, 1a (100 mg, 0.54 mmol), 2c (45 mg, 0.27 mmol) and DIPEA (0.165 ml, 1.61 mmol) were heated in a sealed tube at 150 °C for 8 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (95:5) as eluent; yield 40% (50 mg); yellow liquid; Rf 0.50 (4:1 hexane-EtOAc); IR (KBr) 3063 (=CH), 2976-2849 (CH), 1732 (C=O), 1701-1564 (C=C), 1363 (CH bending), 723 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ7.93 (s, 1H), 7.37-7.26 (m, 3H), 7.22 (d, J = 3.2Hz, 1H), 7.19-7.04 (m, 7H), 6.91 (d, J = 3.2Hz , 1H), 6.89-6.82 (m, 2H), 6.26 (dd, J=3.2, 3.0Hz, 1H), 6.03 (s, 2H), 5.33 (s, 2H), 1.59 (s, 9H); 13 C NMR (100MHz, CDCl3) δ166.0, 145.4, 140.7, 140.2, 139.8, 136.3, 130.9, 130.5, 129.0, 128.3, 128.1, 127.2, 127.0, 126.8, 125.8, 124.3, 113.3, 108.1, 105.0, 103.5, 81.1, 51.8, 50.1, 28.3; HRMS (ESI) [C 30 H 29 N 3 O 2 +H + ]Calculated value 464.2333, measured value 464.2334.

[0154] Example 6: 1-methyl-4-(1-methyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid ethyl ester (3cb). According to the general method above, 1c (100 mg, 0.92 mmol), 2b (64 mg, 0.46 mmol) and DIPEA (0.281 mL, 1.61 mmol) were heated in a sealed tube at 150 °C for 7 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (92:8) as eluent; yield 46% (60 mg); pale yellow liquid; Rf 0.50 (2:1 hexane-EtOAc); IR (KBr) 3077 (=CH), 2957-2850 (CH), 1731 (C=O), 1714-1558 (C=C), 1374 (CH bending), 725 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.04(s, 1H), 7.24-7.19(m, 1H), 6.92-6.85(m, 1H), 6.83-6.78(m, 1H), 6.78-6.72(m, 1H) , 6.27-6.19 (m, 1H), 4.46 (q, J=6.8Hz, 2H), 4.10 (s, 3H), 3.88 (s, 3H), 1.45 (t, J=6.8Hz, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.9, 145.5, 140.7, 138.7, 131.9, 130.7, 126.3, 124.6, 112.7, 107.5, 105.2, 103.0, 61.3, 36.6, 33.1, 14.4; HRMS (ESI) [C 16 H 17 N 3 O 2 +H + ]Calculated value 284.1394, measured value 284.1389.

[0155] Example 7: 1-Benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid ethyl ester (3ab). According to the general method above, 1a (100 mg, 0.54 mmol), 2b (38 mg, 0.27 mmol) and DIPEA (0.165 ml, 0.95 mmol) were heated in a sealed tube at 150 °C for 6 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using n-hexane-EtOAc (94:6) as eluent; yield 55% (65 mg); yellow liquid; Rf 0.60 (4:1 hexane-EtOAc); IR (KBr) 3056 (=CH), 2977-2851 (CH), 1729 (C=O), 1712-1554 (C=C), 1367 (CH bending), 726 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ7.99 (s, 1H), 7.38-7.26 (m, 3H), 7.26-7.21 (m, 1H), 7.19-7.13 (m, 2H), 7.13-7.02 (m, 5H), 6.95-6.90 (m, 1H), 6.90-6. 86 (m, 1H), 6.85-6.80 (m, 1H), 6.33-6.24 (m, 1H), 5.94 (s, 2H), 5.35 (s, 2H), 4.41 (q, J=6.8Hz, 2H), 1.38 (t, J=6.8Hz, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.9, 145.7, 140.6, 139.7, 139.0, 136.3, 131.1, 130.4, 129.0, 128.3, 128.2, 127.2, 12 7.0, 126.8, 125.8, 124.8, 113.3, 108.2, 105.5, 103.6, 61.3, 51.7, 50.2, 14.4; HRMS (ESI) [C 28 H 25 N 3 O 2 +H+] calculated value 436.2020, found value 436.2024.

[0156] Example 8: 1-(4-methoxybenzyl)-4-(1-(4-methoxybenzyl)-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid ethyl ester (3bb). According to the general method above, 1b (100 mg, 0.46 mmol), 2a (32 mg, 0.23 mmol) and DIPEA (0.140 ml, 0.81 mmol) were heated in a sealed tube at 150 °C for 8 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (90:10) as eluent; yield 60% (68 mg); yellow liquid; Rf 0.55 (2:1 hexane-EtOAc); IR (KBr) 3067 (=CH), 2955-2852 (CH), 1738 (C=O), 1713-1515 (C=C), 1369 (CH bending), 1106-1028 (CO), 727 (=CH bending) cm-1; 1H NMR (400MHz, CDCl3) δ8.03 (s, 1H), 7.21 (d, J=3Hz, 1H), 7.08 (d, J=8.5Hz, 2H), 7. 05 (d, J=8.8Hz, 2H), 6.88 (d, J=3.0Hz, 1H), 6.87-6.82 (m, 3H), 6.80 (dd, J=3.3, 1 .2Hz, 1H), 6.69 (d, J=8.8Hz, 2H), 6.26 (dd, J=3.0, 2.5Hz, 1H), 5.83 (s, 2H), 5.28 (s, 2H), 4.43 (q, J=7.0Hz, 2H), 3.78 (s, 3H), 3.70 (s, 3H), 1.40 (t, J=7.0Hz, 3H); 13 C NMR (100 MHz, CDCl 3 )δ167.0, 159.5, 158.5, 145.7, 140.4, 138.9, 131.7, 130.9, 130.3, 128.6, 128.6, 128.2, 125.4, 1 24.8, 114.4, 113.7, 113.2, 108.0, 105.5, 103.5, 61.3, 55.3, 55.2, 51.1, 49.7, 14.4; HRMS (ESI) [C 30 H 29 N 3 O 4 +H + ]Calculated value 496.2231, measured value 496.2230.

[0157] Example 9: tert-Butyl 1-(4-methoxybenzyl)-4-(1-(4-methoxybenzyl)-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylate (3bc). According to the general method above, 1b (100 mg, 0.46 mmol), 2c (39 mg, 0.23 mmol) and DIPEA (0.140 mL, 0.81 mmol) were heated in a sealed tube at 150 °C for 7 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (9:1) as eluent; yield 42% (50 mg); yellow-orange oily liquid; Rf 0.55 (2:1 hexane-EtOAc); IR (KBr) 3066 (=CH), 2995-2833 (CH), 1730 (C=O), 1715-1554 (C=C), 1366 (CH bending), 1113-1033 (CO), 727 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ7.96 (s, 1H), 7.19 (d, J = 3.3Hz, 1H), 7.08 (d, J = 8.6Hz, 2H), 7.04 (d, J = 8.5Hz, 2H), 6.88 (d, J = 3.3Hz, 1H), 6.87-6.79 (m, 4H), 6.69 (d, J=8.5Hz, 2H), 6.25 (dd, J=3.5, 2.4Hz, 1H), 5.93 (s, 2H), 5.26 (s, 2H), 3.78 (s, 3H), 3.69 (s, 3H), 1.61 (s, 9H); 13 C NMR (100MHz, CDCl3) δ166.1, 159.5, 158.5, 145.4, 140.6, 140.1, 131.8, 130.7, 130.4, 128.7, 128.6, 128.3 , 125.5, 124.3, 114.4, 113.7, 113.3, 108.0, 105.0, 103.4, 81.1, 55.3, 55.2, 51.3, 49.7, 28.3; HRMS (ESI) [C 32 H 33 N 3 O 4 +H + ]Calculated value 524.2544, measured value 524.2551.

[0158] Example 10: 1-p-Toluenesulfonyl-4-(1-p-Toluenesulfonyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3da). According to the general method above, 1d (100 mg, 0.40 mmol), 2a (25 mg, 0.20 mmol) and DIPEA (0.122 mL, 0.70 mmol) were heated at 150 °C in a sealed tube for 12 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (85:15) as eluent; yield 47% (52 mg); off-white solid; mp = 120 to 122 °C; Rf 0.50 (1:1 hexane-EtOAc); IR (KBr) 3132-3064 (=CH), 2955-2850 (CH), 1728 (C=O), 1710-1512 (C=C), 1371 (CH bending), 1309 (NS=O), 1145 (S=O), 725 (=CH bending) cm-1; 1 H NMR (400MHz, CDCl3) δ8.72 (s, 1H), 7.93 (d, J = 8.0Hz, 2H), 7.86 (d, J = 8.3Hz, 2H), 7.70 (d, J = 3.8Hz, 1H), 7.41-7.36 (m, 1H), 7.32 (d, J = 8.0 Hz, 2H), 7.29-7.25 (m, 2H), 6.66 (d, J=3.8Hz, 1H), 6.41-6.36 (m, 1H), 6.33 (dd, J=3.3, 2.6Hz, 1H), 4.03 (s, 3H), 2.40 (s, 3H), 2.38 (s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.1, 146.2, 145.5, 145.0, 142.0, 139.3, 136.0, 134.8, 131.0, 130.5, 130.2, 129.8, 129.3, 128.3, 127.2, 124.3, 117.3, 112.2, 110.2, 108.1, 53.0, 29.8, 21.7; HRMS (ESI) [C 27 H 23 N 3 O 6 S 2 +H + ]Calculated value 550.1101, measured value 550.1096.

[0159] Example 11: 1-(phenylsulfonyl)-4-(1-(phenylsulfonyl)-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3ea). According to the general method above, 1e (100 mg, 0.43 mmol), 2a (27 mg, 0.21 mmol) and DIPEA (0.128 mL, 0.74 mmol) were heated at 150 °C in a sealed tube for 12 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (85:15) as eluent; yield 45% (49 mg); yellow solid; mp = 104 to 106 °C; Rf 0.50 (1:1 hexane-EtOAc); IR (KBr) 3132-3064 (=CH), 3005-2850 (CH), 1728 (C=O), 1710-1512 (C=C), 1371 (CH bending), 1309 (NS=O), 1145 (S=O), 725 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.74 (s, 1H), 8.06 (d, J=7.5Hz, 2H), 7.99 (d, J=7.5Hz, 2H), 7.71 (d, J=3.8Hz, 1H), 7.67-7.43 (m, 6H), 7.40 (dd, J=3.0, 1.5Hz, 1H), 6.67 (d, J=3.8Hz, 1H), 6.42 (dd, J=3.0, 1.5Hz, 1H), 6.35 (dd, J=3.3, 2.5Hz, 1H), 4.01 (s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.0, 145.3, 142.1, 139.3, 139.0, 137.7, 134.8, 133.8, 131.0, 129.8, 129.6, 129.3, 129.1, 128.1, 127.1, 124.4, 117.5, 112.3, 110.1, 108.2, 52.9; HRMS(ESI)C 25 H 19 N 3 O 6 S 2 +Na+] calculated value 544.0607, found value 544.0603.

[0160] Example 12: 1-Benzyl-4-(1-benzyl-5-methyl-1H-pyrrol-2-yl)-2-methyl-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3fa). According to the general method above, 1f (100 mg, 0.50 mmol), 2a (32 mg, 0.25 mmol) and DIPEA (0.150 mL, 0.88 mmol) were heated in a sealed tube at 150 °C for 6 hours. After work-up, the crude residue was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (90:10) as eluent; yield 64% (72 mg); yellow liquid; Rf 0.55 (2:1 hexane-EtOAc); IR (KBr) 3027 (=CH), 2949-2852 (CH), 1727 (C=O), 1712-1539 (C=C), 1355 (CH bending), 782 (=CH bending) cm-1; 1 H NMR (400MHz, CDCl3) δ7.88 (s, 1H), 7.43-7.26 (m, 3H), 7.19-7.01 (m, 3H), 6.99-6.90 (m, 2H), 6.89-6.82 (m, 2 H), 6.80-6.66(m, 2H), 6.12-6.02(m, 1H), 5.92(s, 2H), 5.33(s, 2H), 3.87(s, 3H), 2.38(s, 3H), 2.22(s, 3H); 13 CNMR (100MHz, CDCl3)δ 13 C NMR (100MHz, CDCl3) δ167.5, 144.7, 141.4, 140.5, 139.9, 138.0, 136.5, 133.2, 130.4, 129.5, 129.0, 12 8.2, 127.7, 126.3, 126.1, 126.0, 112.3, 107.5, 105.1, 102.5, 52.3, 47.8, 46.8, 12.9, 12.7; HRMS(ESI)C 29 H 27 N 3 O 2 +H + ]Calculated value 450.2176, measured value 450.2173.

[0161] Example 13: 1-Benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxamide (11). In a round-bottom flask (100 mL), 1-benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3aa, 100 mg, 0.24 mmol) and KOH (14 mg, 0.24 mmol) were dissolved in methanol (5 mL) and stirred continuously at room temperature. Aqueous ammonia (25%, 0.350 mL, 9.40 mmol) was added dropwise to the mixture using a glass syringe for 10 minutes. The reaction mixture was stirred for 24 hours at room temperature. After the reaction was completed, MeOH was evaporated under reduced pressure. MilliQ water (5 mL) and EtOAc (5 mL) were added to the residue and the organic layer was separated. The aqueous phase was further extracted with EtOAc (5×3 mL). The combined organic layers were stirred in anhydrous Na 2 SO 4 The mixture was dried on ice, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography on neutral alumina (175 mesh) with EtOAc as eluent; yield 78% (150 mg), yellow colloid; Rf 0.50 (EtOAc); IR (KBr) 3431 (NH), 3033 (=CH), 2960-2852 (CH), 1677 (C=O), 1562 (CN bend), 1376-1360 (CH bend), 1296-1029 (CO), 726 (=CH bend) cm-1; 1 H NMR (400MHz, CDCl3) δ8.07 (s, 1H), 7.38-7.19 (m, 7H), 7.16-7.06 (m, 3H), 6.95 (d, J=3.0Hz, 1H), 6.92- 6.85 (m, 2H), 6.85-6.78 (m, 1H), 6.40 (dd, J=3.0, 2.6Hz, 1H), 5.59 (s, 2H), 5.38 (s, 2H), 4.89 (brs, 2H); 13 C NMR (100MHz, CDCl3) δ168.1, 144.1, 141.1, 140.0, 136.3, 131.0, 129.0, 129.0, 128.7, 128.1, 127.0, 127.0, 126.9, 126.1, 125.3, 124.9, 112.6, 108.8, 103.5, 103.0, 51.3, 50.2; MS (ESI) [C 26 H 22 N 4O +H + ]Calculated value 407.1866, measured value 407.2023.*

[0162] * Compound 11 was unstable in polar solvents and no good HRMS could be recorded.

[0163] Example 14: 1-Benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carbonitrile (12). 1-Benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxamide (11, 40 mg, 0.098 mmol) was charged into an oven-dried single-necked round-bottom flask (25 mL) and POCl was added dropwise at room temperature using a glass syringe. 3 (5 mL). A reflux condenser was fixed on the round-bottom flask, and the reaction mixture was heated and stirred at 60 ° C overnight. After the reaction was completed (monitored by TLC), the reaction mixture was diluted with toluene (5 mL) and the solvent was evaporated under reduced pressure. Saturated NaHCO 3 (10 mL) was slowly added to the reaction mixture to neutralize the excess phosphorus oxychloride. The aqueous phase was extracted with EtOAc (5×3 mL). The combined organic layers were stirred in anhydrous Na 2 SO 4 The residue was dried on ice, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography on neutral alumina (175 mesh) with hexane-EtOAc (90:10) as eluent to obtain 12; yield 66% (25 mg), colorless liquid; Rf 0.20 (2:1 hexane-EtOAc); IR (KBr) 3431 (NH), 3031 (=CH), 2960-2852 (CH), 2223 (-C≡N extension), 1588-1530 (C=C), 1376-1360 (CH bending), 725 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ7.43 (s, 1H), 7.39-7.31 (m, 3H), 7.30 (d, J = 3.0Hz, 1H), 7.22-7.02 (m, 7H), 6.94 (d, J = 3.0Hz, 1H), 6 .93-6.89 (m, 1H), 6.85 (dd, J=3.5, 1.2Hz, 1H), 6.31 (dd, J=3.0, 2.4Hz, 1H), 5.75 (s, 2H), 5.31 (s, 2H); 13C NMR (100MHz, CDCl3) δ147.3, 139.2, 135.5, 131.7, 129.5, 129.2, 128.5, 128.5, 128.4, 127.2, 1 27.0, 126.9, 126.6, 124.6, 123.1, 119.2, 114.1, 109.1, 108.4, 104.1, 52.1, 50.6; HRMS (ESI) [C 26 H 20 N 4 +H + ]Calculated value 389.1761, measured value 389.1777.

[0164] Example 15: 1-Benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridin-6-yl)methanol (13). In a two-necked round-bottom flask (50 mL), 1-benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid methyl ester (3aa, 250 mg, 0.59 mmol) was dissolved in dry THF (5 mL) under an inert atmosphere. The reaction mixture was cooled to 0 °C before solid LiAlH4 (68 mg, 1.78 mmol) was added in a single portion. The reaction mixture was warmed to room temperature and stirred for a further 20 minutes. After consumption of the ester 3aa, as confirmed by TLC, the mixture was heated to 40 °C with saturated NH 4 The reaction mixture was quenched with Cl (10 mL) solution and further diluted with EtOAc (10 mL). The aqueous layer was extracted with EtOAc (10 × 3 mL). The combined organic extracts were washed with water and stirred in anhydrous Na 2 SO 4 The mixture was dried on ice, filtered, evaporated under reduced pressure and the crude residue was purified by column chromatography on neutral alumina (175 mesh) using hexane-EtOAC (75:25) as eluent; yield 94% (220 mg); colorless liquid; Rf 0.35 (2:1 hexane-EtOAC); IR (KBr) 3414 (OH), 3028 (=CH), 2958-2850 (CH), 1695-1559 (C=C), 1357 (CH bending), 1100-1023 (CO stretching) cm-1; 1H NMR (400MHz, CDCl3) δ7.36-7.17 (m, 6H), 7.13 (d, J=3.3Hz, 1H), 7.07 (dd, J=7.5, 8.0Hz, 4H), 6.90 (s, 1H) , 6.89-6.80 (m, 3H), 6.36 (dd, J=3.0, 2.6Hz, 1H), 5.65 (s, 2H), 5.28 (s, 2H), 4.63 (s, 2H), 3.24 (brs, 1H); 13 C NMR (100MHz, CDCl3) δ149.6, 144.7, 141.6, 139.7, 136.6, 131.1, 129.2, 129.0, 128.5, 128.0, 127.0, 126.8, 126.3, 125.2, 122.7, 112.6, 108.5, 103.0, 99.0, 64.7, 51.7, 50.1; HRMS (ESI) [C 26 H 23 N 3 O+H + ]Calculated value 394.1914, measured value 394.1913.

[0165] Example 16: 1-Benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-acetaldehyde (14). In a round-bottom flask (100 mL), a solution of (1-benzyl-4-(1-benzyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridin-6-yl)methanol (13, 100 mg, 0.25 mmol) in dichloromethane (5 mL) was prepared and solid MnO was added in a single portion. 2 (326 mg, 3.75 mmol). A double-layer reflux condenser was fixed on the round-bottom flask, and the reaction mixture was refluxed overnight. After the reaction was completed, the solvent was evaporated under reduced pressure. The residue was purified by neutral alumina (175 mesh) column chromatography with hexane-EtOAc (95:5) as eluent; yield 70% (70 mg); off-white liquid; Rf 0.55 (2:1 hexane-EtOAc); IR (KBr) 3030 (=CH), 2960-2852 (CH), 1696 (C=O), 1606-1556 (C=C), 1358-1331 (CH bending), 1287-1079 (CO), 725 (=CH bending) cm-1; 1H NMR (400MHz, CDCl3) δ10.02 (s, 1H), 7.83 (s, 1H), 7.42-7.27 (m, 4H), *7.23-7.02 (m, 7H), 6.98-6 .93(m, 1H), 6.92-6.88(m, 1H), 6.88-6.82(m, 1H), 6.42-6.28(m, 1H), 5.81(s, 2H), 5.36(s, 2H); 13 C NMR (100MHz, CDCl3) δ194.3, 146.3, 145.1, 140.4, 139.5, 136.0, 132.3, 130.3, 129.1, 128.4 , 128.3, 127.0*, 126.8, 126.2, 125.9, 113.3, 108.5, 103.7, 102.2, 51.9, 50.4; HRMS (ESI) [C 26 H 21 N 3 O+H + ]Calculated value 392.1757, measured value 392.1756. * High Strength Carbon

[0166] Example 17: 1-Methyl-4-(1-methyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylic acid (15). A solution of methyl 1-methyl-4-(1-methyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridine-6-carboxylate (3ca, 200 mg, 0.74 mmol) in THF (3 mL) was prepared in a round-bottom flask (50 mL). 1 M aqueous LiOH solution (2.5 mL) was added at room temperature, and the reaction mixture was stirred at the same temperature for 3 h (monitored by TLC). After consumption of 3ca, ether (10 mL) and saturated NaHCO were added to the reaction mixture. 3 (10 mL). The aqueous layer was separated and acidified to pH 4 (6N HCl was added dropwise). The aqueous phase was extracted with EtOAc (5×10 mL). 2 SO 4 The combined organic layers were dried on 4% paraffin, filtered, and evaporated under reduced pressure to give the crude product 15, which was used in the next step without further purification; crude yield 90% (172 mg), yellow oily liquid; Rf 0.10 (EtOAc); 1H NMR (400MHz, CDCl3) δ8.14 (s, 1H), 7.32 (d, J=3.0Hz, 1H), 6.90 (d, J=3.0Hz, 1H), 6.86 (m, 1H), 6.77 (dd, J=3.5, 1.3Hz, 1H), 6.29 (dd, J=2.8, 2.4Hz, 1H), 3.94 (s, 3H), 3.91 (s, 3H); 13 C NMR (100MHz, CDCl3) δ164.8, 142.8, 140.3, 135.8, 132.0, 128.2, 125.8, 124.5, 112.6, 107.3, 102.9, 102.7, 35.3, 32.3; HRMS (ESI) [C 14 H 13 N 3 O 2 +H + ]Calculated value 256.1081, measured value 256.1066.

[0167] Example 18: (1-methyl-4-(1-methyl-1H-pyrrol-2-yl)-1H-pyrrolo[3,2-c]pyridin-6-yl)(morpholino)methanone (16). Unpurified 15 (100 mg, 0.39 mmol) dissolved in dry DMF (4 mL) was charged into a two-necked round-bottom flask (50 mL) under an inert atmosphere. The reaction mixture was briefly cooled to 0 °C, and then morpholine (0.13 mL, 1.57 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (300 mg, 1.57 mmol), hydroxybenzotriazole (212 mg, 1.57 mmol) and DIPEA (0.54 mL, 3.13 mmol) were added sequentially under continuous stirring. The reaction mixture was heated to room temperature and stirred again for 16 hours. After consumption of 15 (confirmed by TLC), cold brine (10 mL) was added to the reaction mixture. The reaction mixture was extracted with EtOAc (10×3 mL), and the combined organic layers were washed with anhydrous Na 2 SO 4 The product was dried on a flask, filtered, concentrated, and purified by column chromatography on neutral alumina (175 mesh) using hexane-EtOAc (50:50) as the eluent; yield 49% (60 mg); white crystalline solid; mp = 95 to 96°C; Rf 0.40 (1:1 hexane-EtOAc); IR (KBr) 3065 (=CH), 2957-2850 (CH), 1682 (C=O), 1641-1513 (C=C), 1371 (CH bending), 723 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3)δ7.65 (s, 1H), 7.17 (d, J=3.0Hz, 1H), 6.82 (d, J=3.0Hz, 1H), 6.80-6.77 (m, 1H), 6.76-6.7 1 (m, 1H), 6.25 (dd, J=2.8, 2.4Hz, 1H), 3.97 (s, 3H), 3.92-3.76 (m, 9H), 3.72-3.60 (m, 2H); 13 C NMR (100MHz, CDCl3) δ169.2, 144.2, 144.1, 141.1, 131.1, 130.9, 125.9, 123.4 ,112.6,107.6,104.3,102.8,67.3,67.0,48.1,43.1,36.6,32.9; HRMS(ESI)C 18 H 20 N 4 O 2 +H+] calculated value 325.1659, found value 325.1655.

[0168] Example 19: 5-Methyl-1-(1-methyl-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylic acid methyl ester (18aa). According to the general method above, 17a (100 mg, 0.62 mmol), 2a (39 mg, 0.31 mmol) and DIPEA (0.190 mL, 1.09 mmol) were heated at 120 °C in a sealed tube for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (80:20) as eluent; yield 70% (80 mg); yellow solid; mp = 210 to 212 °C; Rf 0.35 (2:1 hexane-EtOAc); IR (KBr) 3055 (=CH), 2956-2854 (CH), 1734 (C=O), 1687-1534 (C=C), 1407-1376 (CH bending), 782 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3)δ8.31 (s, 1H), 7.82 (d, J = 8.0Hz, 1H), 7.74 (d, J = 8.0Hz, 1H), 7.56 (dd, J = 8.0, 7.3Hz, 1H), 7.51 (d, J = 8.3Hz, 1H), 7.45 (d, J = 8.3Hz, 1H), 7 .33 (dd, J=8.0, 7.8Hz, 1H), 7.19 (dd, J=7.5, 7.5Hz, 1H), 7.15 (dd, J=7.5, 7.6Hz, 1H), 6.99 (s, 1H), 4.05 (s, 3H), 4.00 (s, 3H), 3.75 (s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.9, 146.3, 145.8, 142.9, 142.2, 138.3, 137.6, 128.1, 127.9, 123.1, 122.4, 121.3 ,121.2,121.1,120.8,119.8,109.8,109.1,105.7,104.3,53.0,31.0,29.6; HRMS(ESI)C 23 H 19 N 3 O 2 +H+] calculated value 370.1550, found value 370.1515.

[0169] Example 20: 5-Methyl-1-(1-methyl-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylic acid methyl ester (18ab). According to the general method above, 17a (100 mg, 0.62 mmol), 2b (43 mg, 0.31 mmol) and DIPEA (0.190 mL, 1.09 mmol) were heated at 120 °C in a sealed tube for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (85:15) as eluent; yield 66% (78 mg); yellow solid; mp = 175 to 177 ° C; Rf 0.40 (2: 1 hexane-EtOAc); IR (KBr) 3058 (=CH), 2988-2851 (CH), 1735 (C=O), 1704-1536 (C=C), 1409-1375 (CH bending), 780 (=CH bending) cm-1; 1H NMR (400MHz, CDCl3) δ8.27 (s, 1H), 7.89 (d, J=8.0Hz, 1H), 7.73 (d, J=7.8Hz, 1H), 7.56 (dd, J=7.8, 7.3Hz, 1H), 7.50 (d, J=8.0Hz, 1H), 7.46 (d, J=8.0Hz, 1H), 7.33 (dd, J=7.8, 7.8Hz, 1H), 7.19 (m, 2H), 7.01 (s, 1H), 4.53 (q, J=7.0Hz, 2H), 3.99 (s, 3H), 3.79 (s, 3H), 1.48 (t, J=7.0Hz, 3H); 13 CNMR (100MHz, CDCl 3 )δ166.3, 146.3, 145.9, 143.2, 142.2, 138.3, 137.6, 128.0, 127.8, 123.1, 122.4, 121.2, 12 1.1, 120.9, 120.8, 119.8, 109.8, 109.1, 105.5, 104.4, 61.9, 31.1, 29.5, 14.5; HRMS (ESI) [C 24 H 21 N 3 O 2 +H + ]Calculated value 384.1707, measured value 384.1672.

[0170] Example 21: tert-Butyl 5-methyl-1-(1-methyl-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylate (18ac) According to the general method above, 17a (100 mg, 0.62 mmol), 2c (52 mg, 0.31 mmol) and DIPEA (0.190 mL, 1.09 mmol) were heated at 120 °C in a sealed tube for 8 hours. After work-up, the crude reaction mixture was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (90:10) as eluent; yield 67% (85 mg); yellow solid; mp = 200 to 202°C; Rf 0.60 (1:1 hexane-EtOAc); IR (KBr) 3053 (=CH), 2972-2852 (CH), 1729 (C=O), 1686-1532 (C=C), 3.921412 (CH bending), 781 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3)δ8.14 (s, 1H), 8.08 (d, J=3.0Hz, 1H), 7.73 (d, J=3.0Hz, 1H), 7.61-7.41 (m, 1H), 7.37-7 .28(m, 1H), 1.697.23(dd, J=7.06, 2.4Hz, 1H), 3.97(s, 3H), 3.89(m, 3H), -3.60(m, 9H); 13 C NMR (100MHz, CDCl3) δ165.2, 146.2, 146.1, 144.3, 142.2, 138.4, 137.7, 127.8, 120.9 *,127.7, 123.1, 122.4, 121.2, 120.9, 119.7, 109.8, 109.0, 104.7, 29.5; HRMS (ESI) [C 26 H 25 N 3 O 2 +H+] calculated value 325.1659, found value 412.2012. * High Strength Carbon

[0171] Example 22: 5-Benzyl-1-(1-benzyl-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylic acid methyl ester (18ba). According to the general method above, 17b (0.100 g, 0.42 mmol), 2a (26 mg, 0.21 mmol) and DIPEA (0.095 mL, 0.74 mmol) were heated at 120 °C in a sealed tube for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (85:15) as eluent; yield 58% (63 mg); yellow solid; mp = 168 to 170°C; Rf 0.60 (2:1 hexane-EtOAc); IR (ATR) 3062 (=CH), 2920-2850 (CH), 1710 (C=O), 1667-1528 (C=C), 1467-1315 (CH bending), 787-694 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3)δ8.20 (s, 1H), 8.13 (d, J = 8.0Hz, 1H), 7.75 (d, J = 7.5Hz, 1H), 7.48 (dd, J = 7.5, 7.3Hz, 1H), 7.41 (m, 2H), 7.35-7.23 (m, 4H), 7.20 (d, J=7.5Hz, 1H), 7.16 (d, J=8.0Hz, 1H), 7.14-7.08 (m, 3H), 6.99-6.89 (m, 5H), 5.67 (s, 2H), 5.60 (s, 2H), 3.98 (s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.8, 146.5, 145.8, 142.9, 141.7, 138.3, 138.1, 136.9, 135.6, 129.0, 128.1*, 128.0, 127.9, 126.7, 126.6, 126 .3, 123.3, 122.7, 121.3, 121.13, 121.06, 121.0, 120.0, 110.6, 109.6, 105.7, 105.5, 52.9, 47.7, 46.8; HRMS(ESI)C 35 H 27 N 3 O 2 +H + ]Calculated value 522.2176, measured value 522.2160. * High Strength Carbon

[0172] Example 23: 5-Benzyl-1-(1-benzyl-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylic acid ethyl ester (18bb). According to the general method above, 17b (0.100 g, 0.62 mmol), 2b (43 mg, 0.31 mmol) and DIPEA (0.190 ml, 1.09 mmol) were heated in a sealed tube at 120 °C for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (80:20) as eluent; yield 66% (78 mg); reddish yellow liquid; Rf 0.40 (2:1 hexane-EtOAc); IR (KBr) 3059 (=CH), 2965-2860 (CH), 1722 (C=O), 1609-1574 (C=C), 1423-1383 (CH bending), 799 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3)δ8.21-8.14 (m, 2H), 7.75 (d, J=7.5Hz, 1H), 7.47 (dd, J=7.8, 7.3Hz, 1H), 7.40 (m, 2H), 7.35-7.23 (m, 4H), 7.20 (d, J=7.3Hz, 1H), 7. 16 (d, J=7.3Hz, 1H), 7.14-7.08 (m, 3H), 7.02-6.89 (m, 5H), 5.72 (s, 2H), 5.59 (s, 2H), 4.45 (q, J=7.1Hz, 2H), 1.40 (t, J=7.1Hz, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.2, 146.5, 145.9, 143.2, 141.7, 138.4, 138.1, 136.9, 135.7, 129.0, 128.2, 128.1, 128.0, 127.8, 126.7, 126.6, 126 .4, 123.3, 122.7, 121.2, 121.1, 121.0, 120.9, 120.0, 110.6, 109.6, 105.52, 105.48, 61.8, 47.7, 46.8, 14.4; HRMS (ESI) [C 36 H 29 N 3 O 2 +H + ]Calculated value 536.2333, measured value 536.2349.

[0173] Example 24: tert-Butyl 5-benzyl-1-(1-benzyl-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylate (18bc) According to the general method above, 17b (0.100 g, 0.62 mmol), 2c (52 mg, 0.31 mmol) and DIPEA (0.190 mL, 1.09 mmol) were heated in a sealed tube at 120 °C for 8 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (85:15) as eluent; yield 66% (84 mg); yellow solid; mp = 148 to 150°C; Rf 0.60 (2:1 hexane-EtOAc); IR (ATR) 3062 (=CH), 2926-2848 (CH), 1706 (C=O), 1665-1531 (C=C), 1495-1323 (CH bending), 782-694 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3)δ8.28 (d, J=8.0Hz, 1H), 8.06 (s, 1H), 7.75 (d, J=7.8Hz, 1H), 7.47 (dd, J=7.5, 7.3Hz, 1H), 7.43-7.36 (m, 2H), 7.3 4-7.22(m, 4H), 7.21-7.15(m, 2H), 7.15-7.10(m, 3H), 7.02-6.93(m, 5H), 5.86(s, 2H), 5.58(s, 2H), 1.63(s, 9H); 13 C NMR (100 MHz, CDCl 3 )δ165.2, 146.4, 146.1, 144.5, 141.7, 138.6, 138.1, 137.0, 135.8, 129.0, 128.2, 128.0, 127.84, 127.75, 126.7, 126.5, 1 26.4, 123.3, 122.7, 121.2, 121.1, 120.9, 120.4, 120.0, 110.6, 109.6, 105.7, 104.9, 81.8, 47.5, 46.8, 28.2; HRMS (ESI) [C 38 H 33 N 3 O 2 +H + ]Calculated value 564.2646, measured value 564.2644.

[0174] Example 25: 8-methoxy-1-(5-methoxy-1-methyl-1H-indol-2-yl)-5-methyl-5H-pyrido[4,3-b]indole-3-carboxylic acid methyl ester (18ca) According to the general method above, 17c (70 mg, 0.37 mmol), 2a (23 mg, 0.18 mmol) and DIPEA (0.110 mL, 0.63 mmol) were heated at 120 °C in a sealed tube for 3 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (85:15) as eluent; yield 66% (84 mg); yellow solid; mp = 160 to 162 °C; Rf 0.60 (2:1 hexane-EtOAc); IR (ATR) 3070 (=CH), 2957-2850 (CH), 1701 (C=O), 1660-1528 (C=C), 1485-1329 (CH bending), 1105-991 (CO), 810-688 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3)δ8.26 (s, 1H), 7.40 (d, J=9.8Hz, 1H), 7.32 (d, J=8.8Hz, 1H), 7.21-7.16 (m, 2H), 7.15 (d, J=2.0Hz, 1H), 6.9 7 (dd, J=9.0Hz, 2.3Hz, 1H), 6.91 (s, 1H), 4.05 (s, 3H), 3.96 (s, 3H), 3.89 (s, 3H), 3.71 (s, 3H), 3.55 (s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ167.0, 154.8, 154.3, 146.3, 145.8, 142.6, 137.9, 137.2, 133.8, 128.1, 121.2, 120.8, 117.7 , 112.8, 110.4, 109.9, 105.8, 105.0, 103.8, 102.5, 55.8, 55.7, 53.0, 31.1, 29.6; HRMS (ESI) [C 25 H 23 N 3 O 4 +H + ]Calculated value 430.1761, measured value 430.1764.

[0175] Example 26: 5-(4-methoxybenzyl)-1-(1-(4-methoxybenzyl)-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylic acid methyl ester (18da). According to the general method above, 17d (0.100 g, 0.38 mmol), 2a (24 mg, 0.19 mmol) and DIPEA (0.120 mL, 0.66 mmol) were heated at 120 °C in a sealed tube for 3 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (85:15) as eluent; yield 66% (84 mg); yellow solid; mp = 106 to 108 ° C; Rf 0.60 (2:1 hexane-EtOAc); IR (ATR) 3056 (=CH), 2952-2835 (CH), 1737 (C=O), 1664-1512 (C=C), 1457-1348 (CH bending), 1106-989 (CO), 819-695 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3)δ8.22 (s, 1H), 8.04 (d, J=8.0Hz, 1H), 7.73 (d, J=7.8Hz, 1H), 7.51-7.39 (m, 3H), 7. 27 (d, J=7.3Hz, 1H), 7.18 (dd, J=7.5, 7.0Hz, 1H), 7.12 (dd, J=7.3, 7.3Hz, 1H), 7.07 (d, J=8.5Hz, 2H), 7.06 (s, 1H), 6.85 (d, J=8.8Hz, 2H), 6.83 (d, J=8.8Hz, 2H), 6.45 ( d, J=8.5Hz, 2H), 5.55(s, 2H), 5.54(s, 2H), 3.99(s, 3H), 3.76(s, 3H), 3.52(s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.9, 159.4, 158.4, 146.6, 145.7, 142.9, 141.7, 138.0, 137.0, 130.4, 128.1, 127.95, 127.92, 127.75, 127.68, 123.3, 122. 6, 121.2, 121.1, 121.04, 121.01, 119.9, 114.5, 113.5, 110.6, 109.6, 105.7, 105.3, 55.3, 55.1, 52.9, 47.2, 46.4; HRMS (ESI) [C 37 H 31 N 3 O 4 +H + ]Calculated value 582.2387, measured value 582.2373.

[0176] Example 27: 5-Butyl-1-(1-butyl-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylic acid methyl ester (18ea). According to the general method above, 17e (0.100 g, 0.49 mmol), 2a (31 mg, 0.25 mmol) and DIPEA (0.114 ml, 0.88 mmol) were heated in a sealed tube at 120 °C for 3 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (85:15) as eluent; yield 66% (84 mg); yellow liquid; Rf 0.60 (2:1 hexane-EtOAc); IR (KBr) 3064 (=CH), 2972-2854 (CH), 1726 (C=O), 1621-1570 (C=C), 1462-1317 (CH bending), 796 (=CH bending) cm-1; 1H NMR (400 MHz, CDCl 3 )δ8.27 (s, 1H), 8.00 (d, J=8.0Hz, 1H), 7.72 (d, J=7.5Hz, 1H), 7.59-7.45 (m, 3H), 7.30 (dd, J=7.6, 7.5Hz, 1H), 7.18 (dd, J=8.2, 7.2Hz, 1H), 7.13 (dd, J=8.2, 7.3Hz, 1H), 6.97 (s, 1H), 4.43(t, J=6.8Hz, 2H), 4.34(t, J=7.0Hz, 2H), 4.05(s, 3H), 2.00-1.87(m, 2H), 1.71-1.60( m, 2H), 1.52-1.39 (m, 2H), 1.16-1.04 (m, 2H), 0.99 (t, J=7.0Hz, 3H), 0.62 (t, J=7.3Hz, 3H); 13 C NMR (100 MHz, CDCl 3 )δ167.1, 146.8, 145.4, 142.7, 141.6, 137.7, 136.9, 127.92, 127.87, 123.3, 122.2, 121.3, 120.9, 120.8 *, 119.6, 110.2, 109.3, 105.6, 104.7, 52.9, 43.9, 43.4, 32.2, 31.1, 20.6, 20.0, 13.9, 13.5; HRMS (ESI) [C 29 H 31 N 3 O 2 +H + ]Calculated value 454.2489, measured value 454.2559. * Combined Carbon.

[0177] Example 28: 5-Butyl-1-(1-butyl-1H-indol-2-yl)-5H-pyrido[4,3-b]indole-3-carboxylic acid methyl ester (18fa) According to the general method above, 17f (0.100 g, 0.33 mmol), 2a (21 mg, 0.17 mmol) and DIPEA (0.101 mL, 0.58 mmol) were heated at 120 °C in a sealed tube for 8 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (90:10) as eluent; yield 63% (70 mg); yellow solid; mp = 205 to 207 °C; Rf 0.60 (2:1 hexane-EtOAc); IR (ATR) 3413 (NH), 3062 (=CH), 2956-2850 (CH), 1706 (C=O), 1633-1489 (C=C), 1448-1350 (CH bend), 1307 (NS=O), 1145 (S=O), 812-687 (=CH bend) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.16 (dd, J=8.0, 8.0Hz, 2H), 7.73 (d, J=8.5Hz, 2H), 7.70 (d, J=8.5Hz, 2H ), 7.32-7.26 (m, 3H), 7.24-7.19 (m, 3H), 7.18-7.14 (m, 2H), 7.09 (d, J=2.0 Hz, 1H), 6.98 (dd, J=7.5, 7.3Hz, 1H), 6.59 (d, J=2.0Hz, 1H), 6.38 (d, J=7.8 Hz, 1H), 5.90 (s, 1H), 5.64 (s, 1H), 3.83 (s, 3H), 2.41 (s, 3H), 2.37 (s, 3H); 13 C NMR (100MHz, CDCl3) δ163.9, 145.4, 145.0, 139.4, 137.7, 137.4, 136.3, 135.2, 135.0, 132.6, 130.1, 129.9, 128.8, 127.7, 126 .8, 126.3, 125.2, 124.4, 124.0, 123.8, 121.2, 117.5, 114.9, 114.8, 113.1, 110.6, 94.4, 52.6, 47.9, 21.7, 21.6; HRMS*(ESI)[C 35 H 27 N 3 O 6 S 2 +H + ]Calculated value 650.1414, measured value 650.1386.* The HRMS peaks corresponded to the dehydrogenated or aromatized forms of compound 18fa.

[0178] Example 29: Methyl 4-(Furan-2-yl)furo[3,2-c]pyridine-6-carboxylate (20aa) According to the general method above, 19a (200 mg, 2.08 mmol), 2a (130 mg, 1.04 mmol) and DIPEA (0.670 mL, 3.72 mmol) were heated in a sealed tube at 120 °C for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (98:2) as eluent; yield 50% (126 mg); off-white solid; mp = 95 to 97 °C; Rf 0.65 (4:1 hexane-EtOAc); IR (KBr) 3032 (=CH), 2957-2856 (CH), 1731 (C=O), 1713-1560 (C=C), 1359 (CH bending), 1112-993 (CO), 722 (=CH bending) cm-1; 1H NMR (400 MHz, CDCl 3 )δ8.19 (s, 1H), 7.85 (d, J=3.0Hz, 1H), 7.65 (dd, J=1.9, 0.92Hz, 1H), 7.45-7. 40 (m, 1H), 7.36 (d, J=3.0Hz, 1H), 6.61 (dd, J=3.5Hz, 1.9Hz, 1H), 4.03 (s, 3H); 13 C NMR (100 MHz, CDCl 3 )δ166.0, 160.6, 153.2, 148.1, 144.2, 143.5, 143.2, 122.7, 112.2, 111.4, 107.9, 106.9, 53.0; HRMS (ESI) [C 13 H 9 NO 4 +Na + ]Calculated value 266.0424, measured value 266.0417

[0179] Example 30: Ethyl 4-(furan-2-yl)furo[3,2-c]pyridine-6-carboxylate (20ab). According to the general method above, furan-2-carbaldehyde (19a, 200 mg, 2.08 mmol), glycine ethyl ester (2b, 145 mg, 1.04 mmol) and DIPEA (0.670 mL, 3.72 mmol) were heated in a sealed tube at 120 °C for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (99:1) as eluent; yield 48% (128 mg); yellow liquid; Rf 0.70 (4:1 hexane-EtOAc); IR (KBr) 3032 (=CH), 2976-2855 (CH), 1742 (C=O), 1730-1524 (C=C), 1371 (CH bending), 1165-1005 (CO), 741 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.17 (s, 1H), 7.83 (d, J=2.0Hz, 1H), 7.64 (m, 1H), 7.42 (dd, J=2.0Hz, 0.8Hz, 1H), 7.37 (d, J=3.2Hz, 1H), 6.60 (dd, J=3.3Hz, 1.8Hz, 1H), 4.49 (q, J=7.3Hz, 2H), 1.47 (t, J=7.3Hz, 3H); 13 C NMR (400MHz, CDCl3) δ165.4, 160.7, 153.4, 148.1, 144.1, 143.6, 143.5, 122.5, 112.3, 111.4, 107.8, 106.9, 62.0, 14.4; HRMS (ESI) [C 14 H 11 NO 4 +Na + ]Calculated value 280.0580, measured value 280.0571.

[0180] Example 31: tert-Butyl 4-(furan-2-yl)furo[3,2-c]pyridine-6-carboxylate (20ac) According to the general method above, 19a (200 mg, 2.08 mmol), 2c (175 mg, 1.04 mmol) and DIPEA (0.670 mL, 3.72 mmol) were heated in a sealed tube at 120 °C for 7 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (99:1) as eluent; yield 46% (136 mg); off-white solid; mp = 78 to 80°C; Rf 0.70 (4:1 hexane-EtOAc); IR (KBr) 3032 (=CH), 2976-2855 (CH), 1742 (C=O), 1730-1524 (C=C), 1371 (CH bending), 1165-1005 (CO), 741 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.08 (s, 1H), 7.82 (d, J=3.0Hz, 1H), 7.63 (dd, J=1.5, 0.5Hz, 1H), 7.43 (dd, J=2.0 Hz, 0.8Hz, 1H), 7.39 (d, J=3.0Hz, 1H), 6.60 (dd, J=3.5Hz, 1.8Hz, 1H), 1.66 (s, 9H); 13 C NMR (400MHz, CDCl3) δ164.0, 160.7, 153.7, 147.9, 144.6, 143.9, 143.4, 122.2, 112.2, 111.2, 107.4, 106.9, 82.0, 28.2; HRMS (ESI) [C 16 H 15 NO 4 +Na + ]Calculated value 308.0893, measured value 308.0890.

[0181] Example 32: 2-methyl-4-(5-methylfuran-2-yl)furo[3,2-c]pyridine-6-carboxylic acid methyl ester (20ba). According to the general method above, 5-methylfuran-2-acetaldehyde (19b, 200 mg, 1.82 mmol), glycine methyl ester hydrochloride (2a, 114 mg, 0.91 mmol) and DIPEA (0.555 mL, 3.18 mmol) were heated at 120 °C in a sealed tube for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (99:1) as eluent; yield 54% (133 mg); off-white solid; mp = 78 to 80°C; Rf 0.70 (4:1 hexane-EtOAc); IR (KBr) 3032 (=CH), 2976-2855 (CH), 1742 (C=O), 1730-1524 (C=C), 1371 (CH bending), 1165-1005 (CO), 741 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.04 (s, 1H), 7.17 (d, J=3.0Hz, 1H), 6.96 (s, 1H), 6.18 (d, J=3.0Hz, 1H), 4.00 (s, 3H), 2.55 (s, 3H), 2.45 (s, 3H); 13C NMR (400MHz, CDCl 3 )δ166.2, 160.3, 159.4, 154.2, 151.5, 142.3, 142.2, 124.0, 112.3, 108.5, 106.8, 102.9, 52.8, 14.2, 14.0.

[0182] Example 33: (2-methyl-4-(5-methylfuran-2-yl)furo[3,2-c]pyridin-6-yl)methanol (21). In a two-necked round-bottom flask (50 mL), methyl 2-methyl-4-(5-methylfuran-2-yl)furo[3,2-c]pyridine-6-carboxylate (20ba, 0250gms, 0,92mmol) was dissolved in dry THF (5mL) under inert atmosphere. The reaction mixture was cooled to 0°C and a single portion of solid LiAlH4 (0.104gms, 2.76mmol) was carefully added thereto. The reaction mixture was heated to room temperature and stirred for 20 minutes. The reaction progress was monitored by TLC. The reaction mixture was cooled to 0°C again and saturated NH 4 Cl (10 mL) solution to quench the excess LiAlH 4 The aqueous layer was extracted with EtOAc (10 × 3 ml) and then washed with anhydrous Na 2 SO 4The combined organic extracts were dried on 4% paraffin. The crude product was filtered and the solvent was evaporated under reduced pressure. The residue was purified by column chromatography on neutral alumina (175 mesh) using hexane-EtOAc (80:20) as eluent; yield 66% (148 mg); yellow liquid; Rf 0.45 (1:1 hexane-EtOAc); 1 H NMR (400MHz, CDCl3) δ7.15-7.05 (m, 2H), 6.90 (s, 1H), 6.17 (d, J=1.7Hz, 1H), 4.80 (s, 2H), 2.50 (s, 3H), 2.45 (s, 3H); 13 C NMR (400 MHz, CDCl 3 ) δ161.2, 156.7, 153.8, 153.2, 152.3, 140.9, 120.4, 111.1, 108.3, 102.3, 100.9, 64.3, 14.04, 14.01.

[0183] Example 34: 2-methyl-4-(5-methylfuran-2-yl)-6-((propyn-2-yn-1-oxy)methyl)furo[3,2-c]pyridine (22). In a two-necked round-bottom flask (50 mL), (2-methyl-4-(5-methylfuran-2-yl)furo[3,2-c]pyridin-6-yl)methanol (21,70 mg, 0,29 mmol) was dissolved in dry DMF (2 mL) under an inert atmosphere. The reaction mixture was cooled to 0 °C and a single portion of sodium hydride (55-60% suspended in mineral oil, 14 mg, 0.35 mmol) was added thereto. The reaction mixture was stirred at the same temperature for 20 minutes. Propynyl bromide (80% dissolved in toluene, 33 μL, 0.35 mmol) was added dropwise by a micropipette. The reaction mixture was heated to room temperature and further stirred for 3 hours. The progress of the reaction was monitored by TLC. The reaction mixture was cooled briefly and then quenched by adding brine (5 mL). The aqueous layer was extracted with EtOAc (10×3 ml) and the combined organic extracts were washed with water in anhydrous Na 2 SO 4 The crude product was filtered and the solvent was evaporated under reduced pressure. The residue was purified by column chromatography on neutral alumina (175 mesh) using hexane-EtOAc (97:3) as eluent; yield 70% (57 mg); yellow oily liquid; Rf 0.70 (7:3 hexane-EtOAc).

[0184] Example 35: 1-(2-(4-((2-methyl-4-(5-methylfuran-2-yl)furo[3,2-c]pyridin-6-yl)methoxy)methyl)-1H-1,2,3-triazol-1-yl)ethyl)indole-2,3-dione (26). In a round bottom flask (25 mL), 2-methyl-4-(5-methylfuran-2-yl)-6-((propyn-2-yn-1-oxy)methyl)furo[3,2-c]pyridine (22, 30 mg, 0.11 mmol) and 1-(2-azidoethyl)indole-2,3-dione (25, 24 mg, 0.11 mmol) were dissolved in DMF (2 mL). Copper(II) acetate (monohydrate, 12 mg, 0.06 mmol) was added to the above solution in one portion under inert atmosphere at room temperature. The reaction mixture was stirred at room temperature for another 24 hours. The reaction progress was monitored by TLC. Brine (5 mL) was added to quench the reaction, and the aqueous layer was extracted with EtOAc (5×3 mL). The combined organic extracts were added to anhydrous Na 2 SO 4 The crude product was filtered and the excess solvent was evaporated under reduced pressure. 2 Cl 2 -MeOH (95:5) solvent mixture was used as eluent to purify the residue by neutral alumina (175 mesh) column chromatography; yield 82% (45 mg), yellow-orange liquid; Rf 0.25 (1:3 n-hexane-EtOAc); 1 H NMR (400 MHz, CDCl 3 )δ7.62 (s, 1H), 7.51 (d, J=7.5Hz, 1H), 7.45 (dd, J=7.8, 7.5Hz, 1H), 7.25 (s, 1H), 7.05-6.95 (m, 2H), 6.87 (s, 1H), 6.52 (d, J=8. 0Hz, 1H), 6.17 (d, J=2.8Hz, 1H), 4.75-4.68 (m, 4H), 4.67 (s, 2H), 4.25 (t, J=5.8Hz, 2H), 2.52 (s, 3H), 2.45 (s, 3H); HRMS (ESI) [C 27 H 23 N 5 O 5 +Na+] calculated value 520.1591, found value 520.1595.

[0185] Example 36: Methyl 1-(Benzofuran-2-yl)benzofurano[3,2-c]pyridine-3-carboxylate (28aa) According to the general method above, 27 (100 mg, 0.68 mmol), 2a (43 mg, 0.34 mmol) and DIPEA (0.240 mL, 1.36 mmol) were heated in a sealed tube at 120 °C for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (98:2) as eluent; yield 60% (70 mg); yellow-orange solid; mp = 163 to 165 ° C; Rf 0.40 (8:2 hexane-EtOAc); IR (KBr) 3065 (=CH), 2948-2850 (CH), 1720 (C=O), 1612-1539 (C=C), 1350-1338 (CH bending), 1256-1094 (CO), 735 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.85 (d, J=7.8Hz, 1H), 8.30 (s, 1H), 7.81 (s, 1H), 7.78-7.71 (m, 2H), 7.69 (d, J=8.0Hz, 1H), 7.63 (dd, J=8.0, 7.3Hz, 1H), 7.51 (dd, J=7.6, 7.5Hz, 1H), 7.44 (dd, J=7.8, 7.5Hz, 1H), 7.34 (dd, J=7.6, 7.5Hz, 1H), 4.08 (s, 3H); 13 C NMR (400 MHz, CDCl 3 )δ165.5, 162.7, 157.4, 155.4, 154.5, 145.4, 144.3, 129.6, 128.4, 125.7, 125.6, 1 24.3, 123.7, 122.1, 120.9, 120.8, 111.9, 111.5, 108.7, 108.4, 53.1; HRMS (ESI) [C 21 H 13 NO 4 +Na + ]Calculated value 366.0737, measured value 366.0693.

[0186] Example 37: Ethyl 1-(Benzofuran-2-yl)benzofurano[3,2-c]pyridine-3-carboxylate (28ab) According to the general method above, 27 (100 mg, 0.68 mmol), 2b (48 mg, 0.34 mmol) and DIPEA (0.240 mL, 1.36 mmol) were heated in a sealed tube at 120 °C for 6 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (98:2) as eluent; yield 55% (67 mg); yellow solid; mp = 141 to 143 °C; Rf 0.40 (8:2 hexane-EtOAc); IR (KBr) 3065 (=CH), 2987-2850 (CH), 1714 (C=O), 1625-1540 (C=C), 1367-1340 (CH bending), 1266-1097 (CO), 750 (=CH bending) cm-1; 1 H NMR (400MHz, CDCl3) δ8.85 (d, J=8.0Hz, 1H), 8.26 (s, 1H), 7.81 (s, 1H), 7.75 (d, J=8.0Hz, 1H), 7.72 (d, J=7.8Hz, 1H), 7.67 (d, J=8.3Hz, 1H), 7.61 (dd, J =8.0, 7.5Hz, 1H), 7.49 (dd, J = 8.0, 8.3Hz, 1H), 7.43 (dd, J = 7.8, 7.5Hz, 1H) , 7.34 (dd, J=8.0, 8.3Hz, 1H), 4.54 (q, J=7.1Hz, 2H), 1.51 (t, J=7.1Hz, 3H); 13 C NMR (100MHz, CDCl3) δ164.9, 162.8, 157.4, 155.5, 154.7, 145.8, 144.3, 129.6, 128.5, 125.74, 1 25.73, 124.3, 123.7, 122.2, 121.0, 120.7, 111.9, 111.6, 108.7, 108.3, 62.2, 14.4; HRMS (ESI) [C 22 H 15 NO 4 +Na+] calculated value 380.0893, found value 380.0844.

[0187] Example 38: tert-Butyl 1-(Benzofuran-2-yl)benzofuran[3,2-c]pyridine-3-carboxylate (28ac) According to the general method above, 27 (100 mg, 0.68 mmol), 2c (57 mg, 0.34 mmol) and DIPEA (0.240 mL, 1.36 mmol) were heated at 120 °C in a sealed tube for 7 hours. After work-up, the crude product was purified by alumina (neutral, 175 mesh) column chromatography using hexane-EtOAc (98:2) as eluent; yield 45% (64 mg); yellow solid; mp = 100 to 102°C; Rf 0.40 (8:2 hexane-EtOAc); IR (KBr) 3060 (=CH), 2977-2851 (CH), 1715 (C=O), 1626-1540 (C=C), 1365-1340 (CH bending), 1273-1074 (CO), 738 (=CH bending) cm-1; 1 H NMR (400 MHz, CDCl 3 )δ8.88 (d, J=8.0Hz, 1H), 8.18 (s, 1H), 7.83 (s, 1H), 7.747.71 (m, 1H), 7.65 (d, J=8.0Hz, 1H), 7.59 (dd, J=8.0, 7 .3Hz, 1H), 7.48 (dd, J=7.6, 7.5Hz, 1H), 7.42 (dd, J=8.3, 7.5Hz, 1H), 7.33 (dd, J=7.6, 7.5Hz, 1H), 1.71 (s, 9H); 13 C NMR (400 MHz, CDCl 3 )δ163.6, 163.6, 162.8, 157.4, 155.4, 154.9, 146.8, 144.1, 129.3, 128.5, 125.7, 125. 6, 124.2, 123.6, 122.1, 121.0, 120.2, 111.8, 111.5, 108.6, 107.9, 82.4; HRMS (ESI) [C 24 H 13 NO 4 +Na + ]Calculated value 366.0737, measured value 408.1153.

[0188] The above description of specific embodiments will fully reveal the general nature of the embodiments herein, so that others can easily modify and / or adapt the various applications of these specific embodiments by applying existing knowledge without departing from the general concept, and therefore, such adaptations and modifications should and are intended to be understood within the equivalent meaning and scope of the disclosed embodiments. It should be understood that the words or terms used herein are for descriptive rather than limiting purposes. Therefore, although the embodiments herein have been described according to preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced by modifications within the spirit and scope of the embodiments as herein.

Claims

1. A compound of formula II, wherein, the compound of formula II has the following structure:

2. A method for preparing the compound of formula II according to claim 1, wherein, it comprises the following steps: a) Synthesizing an alkyne derivative in the following manner: b) Synthesizing an azidoindigo in the following manner: c) Reacting the alkyne derivative in step a) with the azidoindigo in step b) to synthesize the compound of formula II in the following manner:

3. The method for the compound of formula II according to claim 2, wherein, In step a), the is synthesized as follows: wherein said R 1 =CH 3 , R 2 =COOMe.

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