A method for modifying tryptophan and indole derivatives under electrooxidation conditions

Abstract

The present invention discloses a method for modifying tryptophan and indole derivatives under electrooxidation conditions. In a dry and clean reaction flask, indole shown in Formula III or a polypeptide containing tryptophan shown in Formula I is added, and an azide reagent, a metal catalyst, a ligand, an electrolyte, and a reaction solvent A are added. During the reaction, an electrode system is used to carry out an electrooxidation reaction at room temperature. After the reaction is completed, the reaction liquid system is quenched with water and extracted with dichloromethane, and the solvent is removed by concentration under reduced pressure. The crude product is separated and purified by silica gel column chromatography to obtain a pure product, an azide-substituted tetrazolo[1,5-a]indole shown in Formula IV or an azide-substituted tetrazolo[1,5-a]indole peptide shown in Formula II. The reaction formula is as follows: The method of the present invention avoids a large amount of metal or non-metal oxidants and additives, and can perform site-directed modification on small molecule indole and polypeptide compounds containing specific amino acids, with high reaction selectivity.

Description

Technical Field

[0001] The present invention belongs to the field of post-synthetic modification of polypeptides or small molecules, and specifically relates to a synthetic method for obtaining a series of azide-substituted tetrazolo[1,5-a]indoles, azide-substituted tetrazolo[1,5-a]indole peptides and derivatives by heterocyclization and azidation modification of the side chain of tryptophan or the N-1, C-2, and C-3 positions of indole using an electrocatalytic reaction in one-pot method. Background Art

[0002] Tryptophan is present in almost all proteins in nature, which means that most proteins of interest may have only one modification site. The indole moiety of tryptophan has become an attractive target for polypeptide modification due to its unique reactivity. Since tryptophan is low in abundance and important in function, targeting tryptophan is a promising strategy for modifying peptides or proteins (J. Am. Chem. Soc. 2018, 140, 6797-6800.). Existing studies have shown that tryptophan-containing polypeptides have been used in various drug studies such as antibacterial, anticancer, and analgesic.

[0003] In recent years, the fact that heterocyclic compounds have biological activities and pharmacological properties has become an important strategy in current research. Nitrogen-containing heterocyclic compounds are widely present in many natural products and have received extensive attention from the pharmaceutical community. Tetrazole is a bioisomer of carboxylic acid and is an important class of nitrogen-containing heterocyclic compounds with wide applications in medicinal chemistry. In medicinal chemistry, tetrazole derivatives are also key structural units of various drugs and bioactive substances, having a wide spectrum of biological and pharmacological properties, such as anti-allergic, anticancer, antifungal, anti-angiogenic, antiviral, antimalarial, antitubercular, and receptor modulators, etc. (Eur. J. Med. Chem. 2019, 184, 111744; Eur. J. Med. Chem. 2019, 170, 225-234). Substituted tetrazole compounds are valuable nitrogen-containing heterocyclic compounds in medicinal chemistry and usually play the role of key pharmacophores in many drugs, such as losartan and valsartan, angiotensin II receptor antagonists (Org. Lett. 2017, 19, 3211-3214.). Therefore, introducing tetrazole compounds into more complex skeletons is of great significance for discovering candidate drugs.

[0004] Traditional chemical reactions of C-H redox require expensive and large amounts of metal or non-metal oxidants, relatively high reaction temperatures, and long reaction times. In recent years, with the long-term development of metal-catalyzed C-H functionalization, electrocatalysis has been established as an increasingly powerful tool for molecular synthesis, and using the reaction mode of electrochemical oxidation to replace the traditional oxidant reaction mode has the advantages of environmental friendliness, energy saving and high efficiency.

[0005] Therefore, how to use electrocatalytic reactions to efficiently and highly selectively perform dearomatization modification on indole and polypeptides containing tryptophan side chains under mild conditions is a technical problem that needs to be solved at present. In summary, this has greatly encouraged us to introduce azidation reactions into the polypeptide backbone containing tryptophan and indole by one-pot electrocatalysis to construct a series of azide-substituted tetrazolo[1,5-a]indole peptides and azide-substituted tetrazolo[1,5-a]indoles. This avoids the use of a large amount of toxic and harmful metal or non-metal oxidants, shortens the reaction time, reduces the reaction temperature, improves the reaction efficiency, and constructs the dearomatization modification of tryptophan polypeptides and indole and a series of structurally novel derivatives. Summary of the Invention

[0006] The present invention designs indole or an active polypeptide containing tryptophan as a template substrate, and through a one-pot electrocatalytic reaction, a series of azide-substituted tetrazolo[1,5-a]indoles and tetrazolo[1,5-a]indole peptides are obtained. A method for constructing a series of derivatives by further using dipolar cycloaddition chemical reactions. The present invention avoids a large amount of metal or non-metal oxidants and additives, and can perform site-specific modification on small molecule indole and polypeptide compounds containing specific amino acids, with high reaction selectivity. The present invention also uses as an intermediate for the reaction to obtain a series of active indole-based small molecule compounds, polypeptides, and polypeptide drugs. The substrate of the present invention has wide applicability, broad application prospects, good yields, and simple operation. And the intermediate is developed in the laboratory and has originality.

[0007] The described method for modifying tryptophan and indole derivatives under electrooxidation conditions is characterized by including the following steps: Add indole shown in formula III or a polypeptide containing tryptophan shown in formula I to a dry and clean reaction flask, and add an azidation reagent, a metal catalyst, a ligand, an electrolyte, and reaction solvent A. During the reaction, an electrode system is used to perform electrooxidation reaction at room temperature; after the reaction is completed, the reaction liquid system is quenched with water and extracted with dichloromethane, and the solvent is removed by reduced pressure concentration. The crude product is separated and purified by silica gel column chromatography (the eluent uses petroleum ether / ethyl acetate volume ratio = 1:0.5 - 10) to obtain the pure product of azide-substituted tetrazolo[1,5-a]indole shown in formula IV or azide-substituted tetrazolo[1,5-a]indole peptide shown in formula II; The reaction formula is as follows:

[0008]

[0009] In formulas I and II, (AA) nrepresents an amino acid selected from a plurality of different amino acids, n represents the number of amino acids, and n is an integer ranging from 0 to 10; AA is glycine, alanine, serine, cysteine, threonine, valine, leucine, isoleucine, proline, methionine, phenylalanine, tyrosine, aspartic acid, asparagine, glutamic acid, glutamine, lysine, arginine or histidine; R 1 is selected from phthaloyl, tert-butoxycarbonyl, acetyl, benzyloxycarbonyl, 9-fluorenylmethoxycarbonyl or hydrogen; R 2 is selected from methoxy, ethoxy, benzyl, tert-butyl ester or hydrogen; wherein, R 1 and R 2 both represent no use of a protecting group when selecting H;

[0010] In formulas III and IV, R 3 is selected from C1-C15 alkyl, a substituted alkyl with 1-15 carbon atoms in which any -CH2- is substituted by -O-, -S-, -NH-, -CO-, -CO-O- or -O-CO-, alcohol hydroxyl group, ester group, amino group, aryl group or halogen.

[0011] In the present invention, the polypeptide containing tryptophan in the compound of formula I comprises an amino acid combination short peptide and an active peptide.

[0012] The specific amino acid combination short peptide is the following compound:

[0013]

[0014] The specific active peptide is the following compound

[0015]

[0016]

[0017] A method for modifying tryptophan and indole derivatives under electrooxidation conditions, characterized in that the reaction solvent A comprises a buffer-acid system and an organic solvent;

[0018] The buffer is phosphate buffer (PB) with pH = 6-8, phosphate buffer (PBS) with pH = 6-8, tris(hydroxymethyl)aminomethane (Tris) with pH = 6-8, tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) with pH = 6-8; the buffer-acid system is a mixed liquid system formed by adjusting the pH of the buffer to 2-4 with an acid, and the acid is selected from at least one of acetic acid and trifluoroacetic acid;

[0019] The organic solvent is selected from at least one of methanol, ethanol, isopropanol, hexafluoroisopropanol, propylene glycol, glycerol, tert-butanol, tert-pentanol, benzene, toluene, xylene, methyl acetate, ethyl acetate, dichloromethane, 1,2-dichloroethane, chloroform, tetrahydrofuran, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, and 1,4-dioxane;

[0020] The volume ratio of the buffer-acid system to the organic solvent is 0.8 to 1.5:1;

[0021] The concentration of the indole shown in formula III or the tryptophan-containing polypeptide shown in formula I in the reaction solvent is 0.003 to 0.1 mmol / mL.

[0022] The described method for modifying tryptophan and indole derivatives under electrooxidation conditions is characterized in that in the buffer-acid system, the buffer is a phosphate buffer with pH = 6 to 8 or a Tris buffer with pH = 6 to 8, the acid is acetic acid, and the organic solvent is acetonitrile, dichloromethane, or 1,2-dichloroethane; the concentration of the indole shown in formula III or the tryptophan-containing polypeptide shown in formula I in the reaction solvent is 0.04 to 0.08 mmol / mL.

[0023] The described method for modifying tryptophan and indole derivatives under electrooxidation conditions is characterized in that the metal catalyst is selected from one of the following: monovalent manganese catalyst, divalent manganese catalyst, or trivalent manganese catalyst; the molar amount of the metal catalyst is 10 to 30% of the molar amount of the indole shown in formula III or the tryptophan-containing polypeptide shown in formula I, preferably 20%.

[0024] The described method for modifying tryptophan and indole derivatives under electrooxidation conditions is characterized in that the electrode system used in the reaction is one of the following: GF-Ni, Carbon rod-Pt, Pt-Ni, GF-Pt, Carbon cloth-Pt, GC-Pt, Pt-Pt, GF-GF, Carbon cloth-Ni; the reaction is carried out at a temperature of 15 to 45 °C, the reaction temperature is preferably 25 - 30 °C, the reaction time is 2.0 to 24.0 hours, the reaction time is preferably 8 to 10 hours, and the current is 2 to 15 mA.

[0025] The described method for modifying tryptophan and indole derivatives under electrooxidation conditions is characterized in that the azide reagent is selected from one of the following: NaN3, TMSN3, TsN3, Togni-N3; the molar amount of the azide reagent is 2 to 60 times the molar amount of the indole shown in formula III or the tryptophan-containing polypeptide shown in formula I, preferably 3 to 10 times.

[0026] The described method for modifying tryptophan and indole derivatives under electrooxidation conditions is characterized in that the ligand is selected from one of the following: 3,3'-bipyridine, 4,4'-bipyridine, 2,2'-bipyridine, 2,4'-bipyridine, 4,4'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 6,6'-dimethyl-2,2'-bipyridine, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 1,10-phenanthroline-5,6-dione, 2,2-bis((S)-4-(tert-butyl)-4,5-dihydrooxazol-2-yl)acetonitrile, 2-((S)-4-phenyl-4,5-dihydrooxazol-2-yl)-2-((S)-4-phenyloxazolidin-2-ylidene)acetonitrile, 2,6-bis((S)-4-methyl-4,5-dihydrooxazol-2-yl)pyridine; the molar amount of the ligand is 10-30% of the molar amount of the indole shown in formula III or the polypeptide containing tryptophan shown in formula I, preferably 20%.

[0027] The described method for modifying tryptophan and indole derivatives under electrooxidation conditions is characterized in that the electrolyte is selected from one of the following: tetrabutylammonium bromide, tetrabutylammonium hexafluorophosphate, tetrabutylammonium perchlorate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium iodide, tetrabutylammonium acetate, lithium perchlorate, tetrabutylammonium hydrogen sulfate; the molar amount of the electrolyte is 100-300% of the molar amount of the indole shown in formula III or the polypeptide containing tryptophan shown in formula I, preferably 200%.

[0028] The described method for modifying tryptophan and indole derivatives under electrooxidation conditions further comprises the step of further synthesizing a derivatized product by a dipolar cycloaddition reaction, specifically:

[0029] Using the azide-substituted tetrazolo[1,5-a]indole shown in formula IV or the azide-substituted tetrazolo[1,5-a]indole peptide shown in formula II as raw materials, adding the alkynyl compound shown in formula V, adding copper sulfate and sodium ascorbate, adding reaction solvent B, and stirring and reacting overnight at room temperature; after the reaction is completed, the solvent is removed by reduced pressure concentration, and the crude product is separated and purified by silica gel column chromatography to obtain the derivatized product shown in formula VII or formula VI, and the reaction formula is as follows:

[0030]

[0031] The substituents R 1 、R 2 、(AA) n are the same as those in formula II, and the substituent R 3 in formula VII is the same as that in formula IV;

[0032] R 4 and R 5Each independently selected from a functional group substituted with triazole or tetrazole; R 6 Selected from C1-C10 alkyl, alcohol hydroxyl, ester group, amino group, aryl group or halogen.

[0033] Furthermore, for the azide-substituted tetrazolo[1,5-a]indole shown in Formula IV or the azide-substituted tetrazolo[1,5-a]indole peptide shown in Formula II as raw materials, the molar ratio of the alkyne compound shown in Formula V, copper sulfate and sodium ascorbate is 1:5-20:0.2-2:1-3, preferably 1:10:0.5:2; the reaction solvent B is dichloromethane, 1,2-dichloroethane or chloroform, preferably dichloromethane.

[0034] The modification method of tryptophan and indole derivatives under electrooxidation conditions, characterized in that it further includes the step of synthesizing a derivatized product by reductive amination reaction, specifically:

[0035] Using the azide-substituted tetrazolo[1,5-a]indole shown in Formula IV or the azide-substituted tetrazolo[1,5-a]indole peptide shown in Formula II as raw materials, adding metal catalyst A, adding reaction solvent C, and stirring and reacting at room temperature under a hydrogen atmosphere; after the reaction is completed, the solvent is removed by reduced pressure concentration, saturated sodium bicarbonate aqueous solution is added to the reaction system, and the crude product is obtained by extraction with ethyl acetate. The crude product is separated and purified by silica gel column chromatography to obtain the derivatized product shown in Formula IX or Formula VIII, and the reaction formula is as follows:

[0036]

[0037] The substituent R in Formula VIII 1 、R 2 、(AA) n is the same as that in Formula II, and the substituent R 3 in Formula IX is the same as that in Formula IV;

[0038] The concentration of the azide-substituted tetrazolo[1,5-a]indole shown in Formula IV or the azide-substituted tetrazolo[1,5-a]indole peptide shown in Formula II in the reaction solvent is 0.010-0.030 mmol / mL; the reaction is carried out at a temperature of 15-40 °C, the reaction temperature is preferably 25-35 °C, the reaction time is 2.0-24.0 hours, and the reaction time is preferably 2-4 hours.

[0039] The metal catalyst A is selected from one of the following: palladium hydroxide on carbon, palladium on carbon, triphenylphosphine. Preferably palladium hydroxide on carbon or palladium on carbon. The dosage of the metal catalyst A is 10-80% of the mass of the indole shown in Formula IV or the polypeptide containing tryptophan shown in Formula II; the reaction solvent C is selected from one of the following: acetic acid, tetrahydrofuran, ethyl acetate, methanol, water;

[0040] Preferred to acetic acid, water or methanol.

[0041] The present invention has the following advantages:

[0042] (1) Under relatively mild conditions, the azidation and heterocyclization of indole and tryptophan-containing polypeptides are achieved by means of an electro-oxidation reaction, avoiding the disadvantages of traditional reactions such as the need for expensive and large amounts of metal or non-metal oxidants, relatively high reaction temperatures and long reaction times, being green, environmentally friendly, energy-saving and highly efficient.

[0043] (2) The reaction has high selectivity and can site-specifically modify the N-1, C-2, and C-3 positions of indole on tryptophan in polypeptide compounds and small molecule indole, and can synthesize a variety of polypeptide sequences protected by protecting groups, providing a new idea and approach for the synthesis of polypeptide drugs containing these sequences or groups;

[0044] (3) The electro-oxidation reaction of the one-pot method synthesizes the modified tryptophan polypeptide, with high atom economy and step economy, and has broad application prospects;

[0045] (4) The substrate has a wide applicability range and has good applicability to substituted indole and various amino acid polypeptides containing tryptophan, and good yields are obtained, broadening the application range of the present invention in the fields of polypeptide and small molecule synthesis.

[0046] In summary, the present invention uses an electro-oxidation reaction method to replace the traditional reaction method, avoiding expensive and large amounts of metal or non-metal oxidants, relatively high reaction temperatures and long reaction times, and has the characteristics of being green, environmentally friendly, energy-saving and highly efficient; mild conditions; the one-pot method realizes azidation and heterocyclization, with high step economy; and high reaction selectivity; wide substrate applicability range, and is a polypeptide modification method with good promotion prospects.

[0047] The azido-substituted tetrazolo[1,5-a]indole and tetrazolo[1,5-a]indole peptide of the present invention can further synthesize a series of active indole, amino acid, polypeptide and pharmaceutical peptide through a dipolar cycloaddition reaction. The specific implementation steps are as follows: The structure is as shown in formula (II) or (IV), and is characterized in that the intermediate structure is: Wherein AA is different amino acids. Using the indole or polypeptide containing this structure as an intermediate, active indole-based small molecule compounds, active polypeptide compounds and polypeptide drugs are synthesized. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is the high-resolution mass spectrum of the product obtained in Example 23;

[0049] Figure 2High-resolution mass spectrum of the product obtained in Example 24. Detailed implementation manners

[0050] The technical solutions of the present invention will be described below by specific examples (Examples 1-28), but the protection scope of the present invention is not limited thereto.

[0051] Example 1: For the polypeptide raw material containing tryptophan of Compound I, the dipeptide substrate Ac-Trp-Val-OMe was used. In a clean and dry 10 mL reaction flask, Compound I (Ac-Trp-Val-OMe) (71.8 mg, 0.20 mmol), sodium azide (39 mg, 0.6 mmol), catalyst manganese fluoride (3.6 mg, 20 mmol%), ligand 1,10-Phen (7.2 mg, 20 mmol%), electrolyte lithium perchlorate (42.5 mg, 0.4 mmol), and buffer-acid system (add acetic acid (0.25 mL) to Tris (1.5 mL) at pH = 6-8 and mix well to form a buffer-acid system with pH = 2-4) and acetonitrile (1.5 mL) were added. An electrolysis system was installed in the reaction flask, with GF as the anode and Pt as the cathode. Under a nitrogen atmosphere at 25 °C, it was stirred and electrolyzed at a constant current of 5 mA for 10 hours. After completion, the reaction system was quenched with water and extracted with dichloromethane. The solvent was removed under reduced pressure and purified by silica gel column chromatography (volume ratio of petroleum ether / ethyl acetate = 1:1) to obtain 72.4 mg of Compound II product with azide substitution achieved on the Trp indole group of the dipeptide substrate Ac-Trp-Val-OMe. The yield was 82%.

[0052] Data characterization of Compound II in Example 1:

[0053] 1 H NMR (400 MHz, CDCl3): δ 7.86 (d, J = 8.0 Hz, 1H), 7.69–7.65 (m, 2H), 7.59–7.55 (m, 1H), 6.63 (d, J = 8.4 Hz, 1H), 6.14 (d, J = 8.4 Hz, 1H), 4.40 (dd, J = 8.8, 4.8 Hz, 1H), 4.35 (td, J = 8.8, 3.2 Hz, 1H), 3.73 (s, 3H), 3.00 (dd, J = 14.8, 9.2 Hz, 1H), 2.80 (dd, J = 14.8, 3.6 Hz, 1H), 2.16 –2.08 (m, 1H), 1.80 (s, 3H), 0.85 (dd, J = 10.4, 6.8 Hz, 6H).

[0054] 1313C NMR (100 MHz, CDCl3): δ 172.0, 170.4, 169.8, 161.8, 136.9, 134.1, 132.1, 129.8, 125.9, 114.3, 62.4, 57.6, 52.4, 49.6, 37.1, 31.2, 22.9, 19.0, 17.8.

[0055] MS (ESI) m / z: 464.18 [M+Na] + .HRMS (ESI) m / z calcd for C 19 H 23 N9NaO4 [M+Na] + : 464.1765; found: 464.1775.

[0056] Example 2: The steps and the added materials in Example 2 are exactly the same as those in Example 1, except that "Tris (1.5 mL) with pH = 6 - 8 in the buffer - acid system" is replaced by "phosphate buffer (1.5 mL) with pH = 6 - 8", and 70.4 mg of the product is obtained with a yield of 80%.

[0057] Example 3: The steps and the added materials in Example 3 are exactly the same as those in Example 1, except that "acetic acid (0.25 mL) in the buffer - acid system" is replaced by "trifluoroacetic acid (0.25 mL)", and 61.7 mg of the product is obtained with a yield of 70%.

[0058] Example 4: The steps and the added materials in Example 4 are exactly the same as those in Example 1, except that the anode and cathode of the electrolysis system are replaced, with a Carbon rod as the anode and Pt as the cathode, and 48.4 mg of the product is obtained with a yield of 55%.

[0059] Example 5: The steps and the added materials in Example 5 are exactly the same as those in Example 1, except that the reaction catalyst is adjusted to manganese bromide in an equal molar amount, and 65.1 mg of the product is obtained with a yield of 74%.

[0060] Example 6: The steps and the added materials in Example 6 are exactly the same as those in Example 1, except that the reaction catalyst is adjusted to manganese(III) acetate dihydrate in an equal molar amount, and 68.6 mg of the product is obtained with a yield of 78%.

[0061] Example 7: The steps and the added materials in Example 8 are exactly the same as those in Example 1, except that the azide reagent is adjusted to TMSN3 in an equal molar amount, and 44 mg of the product is obtained with a yield of 50%.

[0062] Example 8: The steps and the added materials in Example 9 and Example 1 are exactly the same, the only difference being that the reaction electrolyte is adjusted to tetrabutylammonium tetrafluoroborate of the same molar amount, obtaining 53.9 mg of the product with a yield of 61%.

[0063] Example 9: The steps and the added materials in Example 10 and Example 1 are exactly the same, the only difference being that the reaction electrolyte is adjusted to tetrabutylammonium hexafluorophosphate of the same molar amount, obtaining 42.2 mg of the product with a yield of 48%.

[0064] Example 10: The steps and the added materials in Example 11 and Example 1 are exactly the same, the only difference being that the reaction electrolyte is adjusted to tetrabutylammonium perchlorate of the same molar amount, obtaining 48.4 mg of the product with a yield of 55%.

[0065] Example 11: The steps and the added materials in Example 14 and Example 1 are exactly the same, the only difference being that the current is adjusted to 2 mA, obtaining 63.5 mg of the product with a yield of 72%.

[0066] Example 12: The steps and the added materials in Example 12 and Example 1 are exactly the same, the only difference being that the reaction current is adjusted to 4 mA, obtaining 66.0 mg of the product with a yield of 75%.

[0067] Example 13: The steps and the added materials in Example 17 and Example 1 are exactly the same, the only difference being that the reaction current is adjusted to 6 mA, obtaining 70.4 mg of the product with a yield of 80%.

[0068] Example 14: The steps and the added materials in Example 18 and Example 1 are exactly the same, the only difference being that the reaction time is adjusted to 6 hours, obtaining 70.0 mg of the product with a yield of 79%.

[0069] Example 15: The steps and the added materials in Example 19 and Example 1 are exactly the same, the only difference being that the reaction time is adjusted to 12 hours, obtaining 71.4 mg of the product with a yield of 81%.

[0070] Example 16: The steps and the added materials in Example 16 and Example 1 are exactly the same, the only difference being that the reaction temperature is adjusted to 15 °C, obtaining 68.8 mg of the product with a yield of 78%.

[0071] Example 18: The steps and the added materials in Example 17 and Example 1 are exactly the same, the only difference being that the reaction temperature is adjusted to 45 °C, obtaining 65.3 mg of the product with a yield of 74%.

[0072] Example 19: The polypeptide raw material containing tryptophan of Compound I uses the peptide substrate Ac-Trp-Val-CONH2. In a clean and dry 10 mL reaction flask, add Compound I (Ac-Trp-Val-CONH2) (68.8 mg, 0.20 mmol), sodium azide (39 mg, 0.6 mmol), manganese fluoride (3.6 mg, 20 mmol%), ligand 1,10-Phen (7.2 mg, 20 mmol%), lithium perchlorate (42.5 mg, 0.4 mmol), buffer-acid system (add acetic acid (0.25 mL) to Tris (1.25 mL) at pH = 6 - 8 and mix well to form a buffer-acid system with pH = 2 - 4), and acetonitrile (1.5 mL). Install an electrolysis system in the reaction flask, with GF as the anode and Pt as the cathode. Stir and electrolyze at a constant current of 5 mA for 10 hours under a nitrogen atmosphere at 25 °C. After completion, quench the reaction system with water and extract with dichloromethane. Remove the solvent under reduced pressure and purify by silica gel column chromatography (volume ratio of petroleum ether / ethyl acetate = 1:5) to obtain 62.1 mg of Compound II product with azide substitution on the Trp indole group of the peptide substrate Ac-Trp-Val-CONH2, with a yield of 74%.

[0073] Data characterization of Compound II in Example 19:

[0074] 1 H NMR (400 MHz, DMSO-d6): δ8.14 (d, J = 8.8 Hz, 1H), 7.97 (d, J = 8.0 Hz, 1H), 7.90 (d, J = 7.6 Hz, 1H), 7.74–7.70 (m, 1H), 7.63 (t, J = 7.6 Hz, 1H), 7.38 (s, 1H), 7.28 (d, J = 8.8 Hz, 1H), 7.04 (s, 1H), 4.04–3.98 (m, 2H), 3.01 (dd, J = 14.4, 3.2 Hz, 1H), 2.74 (dd, J = 14.4, 10.4 Hz, 1H), 1.94–1.84 (m, 1H), 1.52 (s, 3H), 0.77 (dd, J = 19.2, 6.8 Hz, 6H).

[0075] 13 C NMR (100 MHz, DMSO-d6): δ172.3, 169.5, 169.0, 161.4, 136.2, 133.8, 131.8, 129.4, 126.4, 113.9, 62.4, 57.4, 48.8, 36.7, 30.7, 22.1, 19.2, 17.7.

[0076] MS (ESI) m / z: 427.19 [M+H]+ .HRMS(ESI) m / z calcd for C 18 H 23 N 10 NaO3[M + H] + : 427.1949; found: 427.1960.

[0077] Example 20: In a clean and dry 10 mL reaction flask, add compound I (Ac-Phe-Trp-CONH2) (78.4 mg, 0.20 mmol), sodium azide (39 mg, 0.6 mmol), manganese fluoride (3.6 mg, 20 mmol%), ligand 1,10-Phen (7.2 mg, 20 mmol%), lithium perchlorate (42.5 mg, 0.4 mmol), buffer-acid system (mix acetic acid (0.25 mL) in Tris (1.25 mL) at pH = 6 - 8 to form a buffer-acid system with pH = 2 - 4), acetonitrile (1.5 mL). Install an electrolysis system in the reaction flask, with GF as the anode and Pt as the cathode. Stir and electrolyze at a constant current of 5 mA for 10 hours under a nitrogen atmosphere at 25 °C. After completion, quench the reaction system with water and extract with dichloromethane. Remove the solvent under reduced pressure and purify by silica gel column chromatography (volume ratio of petroleum ether / ethyl acetate = 1:5) to obtain 74.0 mg of compound II product with azide substitution on the Trp indole group of Ac-Phe-Trp-CONH2, with a yield of 78%.

[0078] Data characterization of compound II in Example 20:

[0079] 1 H NMR (600 MHz, DMSO-d6): δ8.14 (d, J = 8.4 Hz, 1H), 8.06 (d, J = 7.2 Hz, 1H), 7.99 (d, J = 7.8 Hz, 1H), 7.86 (d, J = 7.8 Hz, 1H), 7.75–7.72 (m, 1H), 7.64–7.62 (m, 1H), 7.27–7.23 (m, 2H), 7.21–7.16 (m, 4H), 6.81 (s, 1H), 4.10–4.07 (m, 1H), 3.95 (td, J = 9.0, 3.0 Hz, 1H), 3.06 (dd, J = 15.0, 3.6 Hz, 1H), 2.83–2.76 (m, 2H), 2.62 (dd, J = 14.4, 10.2 Hz, 1H), 1.79 (s, 3H).

[0080] 1313C NMR (150 MHz, DMSO-d6): δ 171.6, 171.1, 170.2, 161.3, 138.1, 136.4, 133.9, 131.8, 129.4, 129.0, 128.2, 126.4, 126.4, 114.0, 62.7, 54.8, 49.0, 36.7, 36.3, 22.6.

[0081] MS (ESI) m / z: 497.17 [M+Na] + .HRMS (ESI) m / z calcd for C 22 H 22 N 10 NaO3 [M+Na] + : 497.1769; found: 497.1785.

[0082] Example 21: In a clean and dry 10 mL reaction tube, add compound I (Ac-Trp-Ala-Ala-COOMe) (80.4 mg, 0.20 mmol), sodium azide (39 mg, 0.6 mmol), manganese fluoride (3.6 mg, 20% mmol), ligand 1,10-Phen (7.2 mg, 20% mmol), lithium perchlorate (42.5 mg, 0.4 mmol), buffer-acid system (mix acetic acid (0.25 mL) with Tris (1.25 mL) at pH = 6 - 8 to form a buffer-acid system with pH = 2 - 4), and acetonitrile (1.5 mL). Install an electrolysis system in the reaction flask, with GF as the anode and Pt as the cathode. Stir and electrolyze at a constant current of 5 mA for 10 hours under a nitrogen atmosphere at 25 °C. After completion, quench the reaction system with water and extract with dichloromethane. Remove the solvent under reduced pressure and purify by silica gel column chromatography (volume ratio of petroleum ether / ethyl acetate = 1:3) to obtain 76.4 mg of compound II product with azide substitution on the Trp indole group of Ac-Trp-Ala-Ala-COOMe, with a yield of 79%.

[0083] Data characterization of compound II in Example 21:

[0084] 11H NMR (400 MHz, DMSO-d6): δ 8.27 (d, J = 6.8 Hz, 1H), 7.97 (d, J = 8.0 Hz, 2H), 7.88 (d, J = 7.6 Hz, 1H), 7.76–7.71 (m, 2H), 7.63 (t, J = 7.6 Hz, 1H), 4.23–4.16 (m, 2H), 4.03–3.95 (m, 1H), 3.59 (s, 3H), 3.02 (dd, J = 14.4, 2.8 Hz, 1H), 2.68 (dd, J = 14.4, 10.8 Hz, 1H), 1.50 (s, 3H), 1.25 (d, J = 7.2 Hz, 3H), 1.16 (d, J = 7.2 Hz, 3H).

[0085] 13 13C NMR (100 MHz, DMSO-d6): δ 173.0, 171.8, 169.3, 168.9, 161.3, 136.2, 133.9, 131.8, 129.4, 126.4, 113.9, 62.4, 51.9, 48.4, 48.0, 47.6, 37.1, 22.2, 18.0, 16.8.

[0086] MS (ESI) m / z: 507.18 [M+Na] + .HRMS (ESI) m / z calcd for C 20 H 24 N 10 NaO5 [M+Na] + : 507.1823; found: 507.1843.

[0087] Example 22: In a clean and dry 10 mL reaction tube, add compound I (Ac-Trp-Ala-Val-Phe-OMe) (115.2 mg, 0.20 mmol), sodium azide (39 mg, 0.6 mmol), manganese fluoride (3.6 mg, 20% mmol), ligand 1,10-Phen (7.2 mg, 20% mmol), lithium perchlorate (42.5 mg, 0.4 mmol), buffer-acid system (mix acetic acid (0.25 mL) in Tris (1.25 mL) at pH = 6 - 8 to form a buffer-acid system with pH = 2 - 4), and acetonitrile (1.5 mL). Install an electrolysis system in the reaction flask, with GF as the anode and Pt as the cathode. Stir and electrolyze at a constant current of 5 mA for 10 hours under a nitrogen atmosphere at 25 °C. After completion, quench the reaction system with water and extract with dichloromethane. Remove the solvent under reduced pressure and purify by silica gel column chromatography (volume ratio of petroleum ether / ethyl acetate = 1:5) to obtain 99.4 mg of compound II product with azide substitution on the Trp indole group of Ac-Trp-Ala-Val-Phe-OMe, with a yield of 78%.

[0088] Data characterization of compound II in Example 22:

[0089] 1 H NMR (400 MHz, DMSO-d6): δ8.42 (d, J = 7.2 Hz, 1H), 8.02 (d, J = 9.2 Hz, 1H), 7.97 (d, J = 7.6 Hz, 1H), 7.90 (d, J = 2.8 Hz, 1H), 7.88 (d, J = 2.8 Hz, 1H), 7.73 (t, J = 7.6 Hz, 1H), 7.62 (d, J = 7.6 Hz, 1H), 7.59–7.56 (m, 1H), 7.24 (d, J = 6.4 Hz, 2H), 7.21–7.17 (m, 3H), 4.49–4.44 (m, 1H), 4.23–4.17 (m, 1H), 4.13 (dd, J = 9.0, 6.8 Hz, 1H), 4.00–3.97 (m, 1H), 3.55 (s, 3H), 3.04–2.89 (m, 3H), 2.70 (dd, J = 14.4, 10.8 Hz, 1H), 1.95–1.86 (m, 1H), 1.49 (s, 3H), 1.10 (d, J = 7.2 Hz, 3H), 0.77 (dd, J = 10.4, 6.8 Hz, 6H).

[0090] 1313C NMR(100MHz,DMSO-d6):δ171.8,171.5,171.0,169.4, 168.9,161.3,137.1,136.2,133.9,131.9,129.4,129.0,128.3,126.6,126.4,113.9,62.4,57.1,53.5,51.8,48.4,48.3,37.2,36.5,30.9,22.2, 19.1,17.8,17.8.

[0091] MS(ESI)m / z:660.30[M+H] + .HRMS(ESI)m / z calcd for C 31 H 38 N 11 O6[M+H] + :660.3001;found:660.3005.

[0092] Example 23: In a clean and dry 10 mL reaction tube, add compound I (octreotide) (20.4 mg, 0.020 mmol), sodium azide (39 mg, 0.6 mmol), manganese fluoride (3.6 mg), ligand 1,10-Phen (7.2 mg), lithium perchlorate (42.5 mg, 0.4 mmol), buffer-acid system (mix acetic acid (0.25 mL) in Tris (1.5 mL) at pH = 6 - 8 to form a buffer-acid system with pH = 2 - 4), and acetonitrile (1.5 mL). Install an electrolysis system in the reaction flask, with GF as the anode and Pt as the cathode. Stir and electrolyze at a constant current of 5 mA for 6 hours under a nitrogen atmosphere at 25 °C. After completion, quench the reaction system with water and extract with dichloromethane. Remove the solvent under reduced pressure, and separate by silica gel column chromatography (petroleum ether / ethyl acetate) and Prep-HPLC to obtain 78 mg of compound II product with azide substitution on the indole group of octreotide, with a yield of 35%.

[0093] Data characterization of product II:

[0094] HR-MS(ESI)m / z calcd for C 49 H 65 N 16 O 10 S2[M+Na]+:1101.4506;found:1101.4453.

[0095] Example 24: In a clean and dry 10 mL reaction tube, add compound Ⅰ H2N-LKKWWKKVKGLLGGLLGKVTSVIK-COOH (26.8 mg, 0.010 mmol), sodium azide (39 mg, 0.6 mmol), manganese fluoride (3.6 mg), ligand 1,10-Phen (7.2 mg), lithium perchlorate (42.5 mg, 0.4 mmol), buffer-acid system (mix acetic acid (0.25 mL) in Tris (1.5 mL) at pH = 6 - 8 to form a buffer-acid system with pH = 2 - 4), acetonitrile (1.5 mL). Install an electrolysis system in the reaction flask, with GF as the anode and Pt as the cathode. Stir and electrolyze at a constant current of 5 mA for 2 hours under a nitrogen atmosphere at 25 °C. After completion, quench the reaction system with water and extract with dichloromethane. Remove the solvent under reduced pressure, and separate by Prep-HPLC to obtain 6.5 mg of product Ⅱ corresponding to the following reaction formula, with a yield of 23%.

[0096]

[0097] Data characterization of product Ⅱ:

[0098] HRMS(ESI) m / z calcd for C 130 H 220 N 45 O 27 [M + H] + : 2843.7220; found [M + 4H] 4+ : 711.6870.

[0099] Example 25: In a clean and dry 10 mL reaction tube, add compound Ⅲ (3-indole ethanol) (32 mg, 0.20 mmol), sodium azide (39 mg, 0.6 mmol), manganese fluoride (3.6 mg, 20 mmol%), ligand 1,10-Phen (7.2 mg, 20 mmol%), lithium perchlorate (42.5 mg, 0.4 mmol), buffer-acid system (mix acetic acid (0.25 mL) in Tris (1.5 mL) at pH = 6 - 8 to form a buffer-acid system with pH = 2 - 4), acetonitrile (1.5 mL). Install an electrolysis system in the reaction flask, with GF as the anode and Pt as the cathode. Stir and electrolyze at a constant current of 5 mA for 8 hours under a nitrogen atmosphere at 25 °C. After completion, quench the reaction system with water and extract with dichloromethane. Remove the solvent under reduced pressure, and separate by silica gel column chromatography (petroleum ether / ethyl acetate = 3:1) and Prep-HPLC to obtain 78 mg of white solid product of compound IV with azide substitution on the indole group of 3-indole ethanol, with a yield of 72%.

[0100] Product data characterization of Compound Ⅳ in Example 25:

[0101] 1 H NMR (400 MHz, CDCl3): δ 7.88 (d, J = 7.6 Hz, 1H), 7.68–7.64 (m, 2H), 7.58–7.54 (m, 1H), 4.00–3.94 (m, 1H), 3.84–3.77 (m, 1H), 2.77–2.70 (m, 1H), 2.33–2.27 (m, 1H), 1.93 (s, 1H).

[0102] 13 C NMR (100 MHz, CDCl3): δ 162.3, 138.2, 134.0, 131.5, 129.4, 125.9, 114.1, 63.0, 58.3, 38.9.

[0103] MS (ESI) m / z: 244.1 [M+Na] + .HRMS (ESI) m / z calcd for C9H8N7NaO1 [M+Na] + : 244.0941; found: 244.0953.

[0104] In a clean and dry 10 mL reaction tube, weigh Compound Ⅱ (45.5 mg, 0.1 mmol), and successively add Compound Ⅴ (378 mg, 1.0 mmol), CuSO4·5H2O (13 mg, 0.05 mmol), and sodium ascorbate (40 mg, 0.2 mmol). Then add 3 mL of DCM and stir overnight at room temperature. After the reaction is completed, concentrate the solvent under reduced pressure, and purify the crude product by silica gel column chromatography (petroleum ether / ethyl acetate = 1:1) to obtain pure target product Ⅵ with a yield of 78%.

[0105] Among them, the specific structures of Compound Ⅱ, Compound Ⅴ, and target product Ⅵ are shown in the corresponding compound structures in the following reaction formula.

[0106]

[0107] Product data characterization of Compound Ⅵ in Example 26:

[0108] 11H NMR (400 MHz, CDCl3): δ 8.13 (d, J = 7.6 Hz, 1H), 7.93 (s, 1H), 7.88 (d, J = 8.0 Hz, 1H), 7.68 (t, J = 7.6 Hz, 1H), 7.59 (t, J = 7.2 Hz, 1H), 7.16 (d, J = 8.4 Hz, 2H), 7.04 (d, J = 8.4 Hz, 2H), 6.79 (d, J = 8.0 Hz, 1H), 6.13 (d, J = 9.2 Hz, 1H), 5.96 (s, 2H), 5.17 (s, 2H), 4.71–4.66 (m, 1H), 4.44–4.37 (m, 1H), 3.69 (s, 3H), 3.52 (dd, J = 15.2, 10.8 Hz, 1H), 3.24 (dd, J = 14.8, 2.0 Hz, 1H), 2.53 (s, 6H), 1.72 (s, 3H), 1.60–1.45 (m, 3H), 1.39 (s, 6H), 0.84 (t, J = 6.4 Hz, 6H).

[0109] 13 13C NMR (100 MHz, CDCl3): δ 172.9, 170.3, 169.6, 160.4, 158.7, 155.5, 143.6, 143.2, 141.5, 136.8, 133.5, 132.2, 131.8, 130.0, 129.4, 128.2, 128.0, 123.1, 121.3, 115.3, 114.1, 77.36, 63.3, 61.5, 52.5, 51.2, 49.3, 41.1, 39.6, 24.9, 22.8, 22.8, 21.9, 14.7.

[0110] 19 19F NMR (376 MHz, CDCl3): δ -146.23 (dd, J = 65.9, 32.4 Hz). MS (ESI) m / z: 856.36 [M+Na]+.

[0111] MS (ESI) m / z: 580.24 [M+Na] + . HRMS (ESI) m / z calcd for C 42 H 46 BF2N 11 NaO5 [M+Na] + : 856.3637; found: 856.3640.

[0112] Example 27 Weigh compound II (20 mg, 0.045 mmol) in a clean and dry 25 mL reaction tube. Sequentially add palladium on carbon with 75% palladium hydroxide content (15.0 mg), and then add acetic acid (0.5 mL), water (1.5 mL) and methanol (1.5 mL). Stir under a hydrogen atmosphere at room temperature for two hours. After the reaction is completed, filter by suction, concentrate under reduced pressure to remove the solvent, and add saturated sodium bicarbonate aqueous solution. Extract with ethyl acetate to obtain the crude product. The crude product is separated and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 1:4, volume ratio) to obtain the pure target product VIII with a yield of 70%.

[0113] Among them, the specific structures of compound II and the target product VIII are shown in the corresponding compound structures in the following reaction formula.

[0114]

[0115] Example 28 Weigh compound II (20 mg, 0.045 mmol) in a clean and dry 25 mL reaction tube. Sequentially add palladium on carbon with 20% palladium loading (4.0 mg), and then add methanol (4 mL). Stir under a hydrogen atmosphere at room temperature for two hours. After the reaction is completed, filter by suction, concentrate under reduced pressure to remove the solvent. The crude product is separated and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 1:4, volume ratio) to obtain the pure target product VIII with a yield of 63%.

[0116] Among them, the specific structures of compound II and the target product VIII are shown in the corresponding compound structures in the following reaction formula.

[0117]

[0118] Data characterization of compound VIII in Examples 27 and 28:

[0119] 1 H NMR (400 MHz, DMSO-d6) δ 7.85 (d, J = 8.4 Hz, 1H), 7.79 (d, J = 7.6 Hz, 1H), 7.71 (d, J = 7.4 Hz, 1H), 7.57–7.48 (m, 3H), 4.07 (t, J = 7.2 Hz, 1H), 3.90 (t, J = 9.8 Hz, 1H), 3.59 (s, 3H), 2.98 (br, 2H), 2.63 (d, J = 13.6 Hz, 1H), 2.53 (d, J = 13.6 Hz, 1H), 2.02–1.93 (m, 1H), 1.50 (s, 3H), 0.81 (d, J = 6.8 Hz, 6H).

[0120] 1313C NMR (100 MHz, DMSO-d6) δ 171.6, 171.0, 168.7, 165.9, 143.9, 133.5, 129.6, 128.5, 125.6, 112.8, 57.2, 57.1, 51.8, 49.6, 30.1, 22.2, 18.9, 18.1.

Claims

1. A method for modifying tryptophan and indole derivatives under electro-oxidation conditions, characterized in that It includes the following steps: An indole shown in Formula III or a tryptophan-containing polypeptide shown in Formula I is added into a dry and clean reaction flask, and an azidation reagent, a metal catalyst, a ligand, an electrolyte and a reaction solvent A are added. An electro-oxidation reaction is carried out at room temperature using an electrode system during the reaction; after the reaction is completed, the reaction liquid system is quenched with water and extracted with dichloromethane, the solvent is removed by reduced pressure concentration, and the crude product is separated and purified by silica gel column chromatography to obtain a pure product, an azide-substituted tetrazolo[1,5-a]indole shown in Formula IV or an azide-substituted tetrazolo[1,5-a]indole peptide shown in Formula II; The reaction formula is as follows: In Formulas I and II, (AA) n represents an amino acid selected from a plurality of different amino acids, n represents the number of amino acids, and n is an integer ranging from 0 to 10; AA is glycine, alanine, serine, cysteine, threonine, valine, leucine, isoleucine, proline, methionine, phenylalanine, tyrosine, aspartic acid, asparagine, glutamic acid, glutamine, lysine, arginine or histidine; R 1 is selected from phthaloyl, tert-butoxycarbonyl, acetyl, benzyloxycarbonyl, 9-fluorenylmethoxycarbonyl or hydrogen; R 2 is selected from methoxy, ethoxy, benzyl, tert-butyl ester or hydrogen; wherein, when R 1 , R 2 selects H, it means that no protecting group is used; In Formulas III and IV, R 3 is selected from C1-15 alkyl, C1-15 substituted alkyl, alcohol hydroxyl group, ester group, amino group, aryl group or halogen, wherein any -CH2- in the C1-15 substituted alkyl is substituted by -O-, -S-, -NH-, -CO-, -CO-O- or -O-CO-; The reaction solvent A includes a buffer-acid system and an organic solvent; The buffer is one of phosphate buffer (PB) with pH = 6 - 8, phosphate buffer solution (PBS) with pH = 6 - 8, tris(hydroxymethyl)aminomethane (Tris) with pH = 6 - 8, tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) with pH = 6 - 8; The buffer-acid system is a mixed liquid system formed by adjusting the pH of the buffer to 2 - 4 with an acid, and the acid is selected from at least one of acetic acid and trifluoroacetic acid; The organic solvent is selected from at least one of methanol, ethanol, isopropanol, hexafluoroisopropanol, propylene glycol, glycerol, tert-butanol, tert-amyl alcohol, benzene, toluene, xylene, methyl acetate, ethyl acetate, dichloromethane, 1,2-dichloroethane, chloroform, tetrahydrofuran, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, 1,4-dioxane; The volume ratio of the buffer-acid system to the organic solvent is 0.8 - 1.5:1; The metal catalyst is selected from one of the following: monovalent manganese catalyst, divalent manganese catalyst or trivalent manganese catalyst; The molar amount of the metal catalyst is 10 - 30% of the molar amount of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I; The azidation reagent is selected from one of the following: NaN3, TMSN3, TsN3, Togni-N3; The molar amount of the azidation reagent is 2 - 60 times the molar amount of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I; The ligand is selected from one of the following: 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline; The molar amount of the ligand is 10 - 30% of the molar amount of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I; The electrolyte is selected from one of the following: tetrabutylammonium bromide, tetrabutylammonium hexafluorophosphate, tetrabutylammonium perchlorate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium iodide, tetrabutylammonium acetate, lithium perchlorate, tetrabutylammonium hydrogen sulfate; The molar amount of the electrolyte is 100 - 300% of the molar amount of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I.

2. The modification method of tryptophan and indole derivatives under electrooxidation conditions according to claim 1, characterized in that The concentration of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I in the reaction solvent A is 0.003 - 0.1 mmol / mL.

3. The modification method of tryptophan and indole derivatives under electro-oxidation conditions according to claim 2, characterized in that In the buffer-acid system, the buffer is a phosphate buffer with a pH of 6-8 or a Tris buffer with a pH of 6-8, the acid is acetic acid, and the organic solvent is acetonitrile, dichloromethane or 1,2-dichloroethane; the concentration of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I in the reaction solvent is 0.04-0.08 mmol / mL; The molar amount of the metal catalyst is 20% of the molar amount of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I.

4. The modification method of tryptophan and indole derivatives under electro-oxidation conditions according to claim 1, characterized in that The electrode system used in the reaction is one of the following: GF-Ni, Carbon rod-Pt, Pt-Ni, GF-Pt, Carboncloth-Pt, GC-Pt, Pt-Pt, GF-GF, Carbon cloth-Ni.

5. The modification method of tryptophan and indole derivatives under electro-oxidation conditions according to claim 1, characterized in that The reaction is carried out under a temperature condition of 15-45 °C, and the reaction time is 2.0-24.0 hours.

6. The modification method of tryptophan and indole derivatives under electro-oxidation conditions according to claim 5, characterized in that The reaction temperature is 25-30 °C, and the reaction time is 8-10 hours.

7. A method for modifying tryptophan and indole derivatives under electrooxidation conditions according to claim 1, characterized in that The current is 2-15 mA.

8. The modification method of tryptophan and indole derivatives under electrooxidation conditions as claimed in claim 1, characterized in that The molar amount of the azide reagent is 3-10 times the molar amount of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I.

9. The modification method of tryptophan and indole derivatives under electro-oxidation conditions according to claim 1, characterized in that The molar amount of the ligand is 20% of the molar amount of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I; The molar amount of the electrolyte is 200% of the molar amount of the indole shown in Formula III or the tryptophan-containing polypeptide shown in Formula I.

10. The modification method of tryptophan and indole derivatives under electro-oxidation conditions according to claim 1, characterized in that It further includes the step of further synthesizing a derivatized product by a dipolar cycloaddition reaction, specifically: Using the azide-substituted tetrazolo[1,5-a]indole shown in Formula IV or the azide-substituted tetrazolo[1,5-a]indole peptide shown in Formula II as a raw material, adding the alkynyl compound shown in Formula V, and adding copper sulfate and sodium ascorbate, adding reaction solvent B, and stirring and reacting overnight at room temperature; after the reaction is completed, the solvent is removed by concentration under reduced pressure, and the crude product is separated and purified by silica gel column chromatography to obtain the derivatized product shown in Formula VII or Formula VI. The reaction formula is as follows: The substituent R in formula VI 1 、R 2 、(AA) n is the same as that in formula II, and the substituent R in formula VII 3 is the same as that in formula IV; R 4 and R 5 each independently selected from a triazole- or tetrazole-substituted functional group; R 6 is selected from C1-C10 alkyl, alcohol hydroxyl, ester group, amino group, aryl or halogen; The molar ratio of the azide-substituted tetrazolo[1,5-a]indole shown in Formula IV or the azide-substituted tetrazolo[1,5-a]indole peptide shown in Formula II as a raw material to the alkynyl compound, copper sulfate and sodium ascorbate shown in Formula V is 1:5-20:0.2-2:1-3; the reaction solvent B is dichloromethane, 1,2-dichloroethane or chloroform.

11. A method for modifying tryptophan and indole derivatives under electrooxidation conditions as described in claim 10, characterized in that The molar ratio of the azide-substituted tetrazolo[1,5-a]indole shown in Formula IV or the azide-substituted tetrazolo[1,5-a]indole peptide shown in Formula II as a raw material to the alkynyl compound, copper sulfate and sodium ascorbate shown in Formula V is 1:10:0.5:2; the reaction solvent B is dichloromethane.

12. The modification method of tryptophan and indole derivatives under electro-oxidation conditions according to claim 1, characterized in that It further includes the step of further synthesizing a derivatized product by a reductive amination reaction, specifically: Using the azido-substituted tetrazolo[1,5-a]indole shown in Formula IV or the azido-substituted tetrazolo[1,5-a]indole peptide shown in Formula II as the raw material, adding metal catalyst A, adding reaction solvent C, and stirring and reacting at room temperature under a hydrogen atmosphere; after the reaction is completed, the solvent is removed by concentration under reduced pressure, saturated sodium bicarbonate aqueous solution is added to the reaction system, and the crude product is obtained by extraction with ethyl acetate; the crude product is separated and purified by silica gel column chromatography to obtain the derivatized product shown in Formula IX or Formula VIII, and the reaction formula is as follows: The substituent R in formula VIII 1 、R 2 、(AA) n are the same as those in formula II, and the substituent R in formula IX 3 is the same as that in formula IV; The concentration of the azido-substituted tetrazolo[1,5-a]indole shown in Formula IV or the azido-substituted tetrazolo[1,5-a]indole peptide shown in Formula II in the reaction solvent C is 0.010 - 0.030 mmol / mL; The reaction solvent C is selected from one or a combination of several of the following: acetic acid, tetrahydrofuran, ethyl acetate, methanol, and water; The metal catalyst A is selected from one of the following: palladium hydroxide on carbon, palladium on carbon, triphenylphosphine; the mass of the metal catalyst is 10 - 80% of the dosage of the indole shown in Formula IV or the tryptophan-containing polypeptide shown in Formula II; The reaction is carried out at a temperature of 15 - 40 °C, and the reaction time is 1.0 - 24.0 hours.

13. A method for modifying tryptophan and indole derivatives under electrooxidation conditions according to claim 12, characterized in that In the step of further synthesizing the derivatized product by reductive amination reaction, The reaction solvent C is acetic acid, water, or methanol; The metal catalyst A is palladium hydroxide on carbon or palladium on carbon; The reaction temperature is 25 - 35 °C, and the reaction time is 2 - 4 hours.

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