A hexahydrocyclobutanone derivative, its preparation method and application

Abstract

This invention discloses a hexahydrocyclobutanone derivative, its preparation method, and its application. The preparation method includes the following steps (a) and (c) or (b) and (c): (a) mixing Bronsted acid, cyclobutanone, aniline, and a solvent, heating to 70-80°C, reacting for 4-6 hours, and then purifying to obtain the hexahydrocyclobutanone product; (b) mixing Bronsted acid, cyclobutanone, aniline, and a solvent, adding a dehydrating agent, reacting for 4-6 hours, and then purifying to obtain the hexahydrocyclobutanone product; (c) dissolving the hexahydrocyclobutanone product in dichloromethane, adding a base, adding acetyl chloride or acid anhydride at 0-10°C, reacting for 0.5-1 hours, and then purifying to obtain the hexahydrocyclobutanone derivative. The preparation method of this invention has simple reaction operation, uses inexpensive and readily available catalysts, is metal-free, and has a rapid reaction with excellent yield, reaching over 80%. The compounds prepared by the method of this invention and their pharmaceutically acceptable salts have good promoting activity on cell differentiation, bone formation, bone repair and bone mass increase during osteogenic processes.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical chemistry, specifically relating to a hexahydrocyclobutanone derivative, its preparation method, and its application. Background Technology

[0002] Tetrahydroquinoline derivatives play a crucial role in organic synthesis and have significant applications in drug manufacturing. Tetrahydroquinoline (THQ) is considered a promising motif for new drug development. Using THQ as a parent component to link high-strain rings such as cyclobutane can increase the rigidity of heterocyclic motifs and alter the physicochemical and pharmacokinetic properties of compounds. Tetrahydroquinoline structures containing cyclobutane are pharmaceutically interesting motifs and have been used as candidate motifs for treating lipoxygenase-based diseases and Alzheimer's disease (US Patent 2006 / 0128790 A1, 2006). The inhibition of G protein-coupled receptor 2 (CRTH2) by tetrahydroquinoline derivatives can be used to treat inflammation, such as allergic asthma and allergic rhinitis (WO2004035543A1, 2004).

[0003] There are many synthetic methods for constructing the parent tetrahydroquinoline (THQ): (1) Akiyama reported the cyclization of an aldehyde imine with a vinyl ether (J. Am. Chem. Soc. 2006, 128, 13070–13071); (2) Gong achieved the cyclization of 2-(3-phenyl-2-propynyl)aniline with Hantzsch ester by combining gold with Brønsted acid catalysis (J. Am. Chem. Soc. 2009, 131, 9182–9183); (3) Huang and colleagues disclosed that chiral phosphoric acid promotes the reaction of aniline with 2-oxopropionate to generate cis-2,4-diquaternized THQ (J. Am. Chem. Soc. 2013, 135, 8193–8196); (4) Zhou's team has demonstrated a strategy for forming THQ by cyclization of aminophenyl diazobutyrate and hydroxyaniline (Adv.). Synth. Catal. 2016, 358, 2366–2370). Developing novel tetrahydroquinoline compounds with cyclobutane structures plays an extremely important role in organic synthesis and pharmaceutical development. Although progress has been made in developing methods to substituted THQ, few synthetic methods that can efficiently obtain hexahydrocyclobutanequinoline derivatives have been studied. Currently, there are only two examples: (1) Guan's team disclosed a pioneering example of cyclizing formamide aniline with iridium / Brønsted acid to form isoindolone-containing compounds via iridium / Brønsted acid co-catalysis (CCS Chem. 2021, 3, 1775–1786); (2) Zeng's team reported the diastereoselective domino cyclization of aniline with cyclobutanone and homologues via chromium catalysis (Org. Lett. 2023, 25, 23, 4241–4246). This method inevitably uses transition metals as catalysts, which may lead to metal residues in the product and result in a long overall reaction time and low yield. Summary of the Invention

[0004] To address the issues of metal residues, long reaction times, and low yields in the aforementioned synthetic methods, this invention provides a hexahydrocyclobutanone derivative, its preparation method, and its applications. This method features a wide range of applicable substrates, mild conditions, short reaction time, and simple operation.

[0005] To achieve the above objectives, the present invention provides a method for preparing a hexahydrocyclobutanone derivative, comprising the following steps (a) and (c) or (b) and (c):

[0006] (a) Brønsted acid, cyclobutanone, aniline and solvent are mixed, heated to 70-80℃, reacted for 4-6 hours and then purified to obtain hexahydrocyclobutanone product;

[0007] (b) Mix Brønsted acid, cyclobutanone, aniline and solvent, add dehydrating agent, react at room temperature for 4-6 h and then purify to obtain hexahydrocyclobutanone product;

[0008] (c) Dissolve the hexahydrocyclobutanone product in dichloromethane, add alkali, add acetyl chloride or acid anhydride at 0~10℃, react for 0.5~1h and then purify to obtain the hexahydrocyclobutanone derivative.

[0009] Normally, the four-membered ring structure of cyclobutanone is unstable under acidic conditions, and the four-membered ring usually breaks, preventing the reaction from occurring. In the above technical solution, Brønsted acid is used as a catalyst. Under the catalysis of Brønsted acid, cyclobutanone can quickly condense with aniline to form a Schiff base. The two molecules of the generated Schiff base immediately undergo a condensation reaction under the action of acid to form the product. The specific reaction formula is as follows:

[0010]

[0011] The reaction conditions are mild, the reaction time is short, the operation is simple, and the yield can reach over 80%.

[0012] Preferably, in steps (a) and (b), the Brønsted acid is selected from one or more of formic acid, acetic acid, propionic acid, octanoic acid, boric acid, phenylboronic acid, benzoic acid, p-toluenesulfonic acid, phosphoric acid, methanesulfonic acid, thioacetic acid, oxalic acid, 2-chloropropionic acid, methacrylic acid, 2-naphthalenesulfonic acid, lauric acid, phenylglycine, trifluoromethanesulfonic acid, glyoxylic acid, lactic acid, 2-pyridinecarboxylic acid, chlorophenylboronic acid, leucine, trimethylacetic acid, nicotinic acid, valine, 6-bromohexanoic acid, citric acid, and methionine.

[0013] Preferably, in steps (a) and (b), the aniline is selected from one of aniline, halogenated aniline, C1-4 alkylaniline, methoxyaniline, and (methylthio)aniline.

[0014] Halogenated anilines include 3-fluoroaniline, 4-fluoroaniline, 3-chloroaniline, 4-chloroaniline, 3-bromoaniline, 4-bromoaniline, 3-iodoaniline, 4-iodoaniline, etc.

[0015] C1-4 alkylanilines such as 3-methylaniline, 4-methylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 3,4,5-trimethylaniline, 3-ethylaniline, 4-ethylaniline, 3,4-diethylaniline, 3-tert-butylaniline, 4-tert-butylaniline, 3-propylaniline, 4-propylaniline, 3-isopropylaniline, 4-isopropylaniline, 4-isobutylaniline, etc.

[0016] Methoxyanilines, such as 3-methoxyaniline and 4-methoxyaniline, etc.

[0017] (Methylthio)aniline, such as 3-(methylthio)aniline, 4-(methylthio)aniline, etc.

[0018] The aniline is preferably aniline, 3-chloroaniline, 4-chloroaniline, 3-bromoaniline, 4-bromoaniline, 3-methylaniline, 4-methylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 3-ethylaniline, 4-ethylaniline, 3-methoxyaniline, 4-methoxyaniline, 3-tert-butylaniline, 3-propylaniline, 4-tert-butylaniline, 4-propylaniline, 3-isopropylaniline, or 4-isopropylaniline. Using these anilines, the yield of the product can reach over 90%, and can be as high as 98%.

[0019] These anilines can be rapidly condensed with cyclobutanone under the catalysis of Brønsted acid to form Schiff base.

[0020] Preferably, in steps (a) and (b), the solvent is selected from one or more of benzene, toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, nitrobenzene, dichloromethane, dichloroethane, chloroform, diethyl ether, tert-butyl methyl ether, ethylene glycol dimethyl ether, n-hexane, n-pentane, anhydrous methanol, anhydrous ethanol, cyclohexane, tetrahydrofuran, and dimethyl sulfoxide.

[0021] Specifically, in steps (a) and (b), the molar ratio of aniline, cyclobutanone and Brønsted acid is (2~2.2):1:(0.1~0.2), and in step (c), the molar ratio of the hexahydrocyclobutanone product to the base and acetyl chloride is 1:(2~3):(10~15), or the molar ratio of the hexahydrocyclobutanone product to the base and acid anhydride is 1:(2~3):(10~15).

[0022] The purification operations in steps (a), (b), and (c) are as follows: a certain amount of saturated sodium bicarbonate solution is added to the reaction system, followed by extraction with dichloromethane several times. The resulting organic phases are combined, dried with anhydrous sodium sulfate, filtered, and the solvent is removed under reduced pressure to obtain the crude product. The purified product is then obtained by silica gel column chromatography.

[0023] Preferably, in step (b), the dehydrating agent is a molecular sieve, which serves to accelerate the formation of Siefer base, and more preferably, it is a 4A molecular sieve.

[0024] A second aspect of the present invention provides a hexahydrocyclobutanone derivative prepared by the above-described preparation method, which has the following structure:

[0025] ,

[0026] In the formula, R1 is a fatty acyl group, C 6-8 Aryl, heteroaryl, or aliphatic; R2 and R3 are hydrogen, fatty acyl, or C 6-8Aryl, heteroaryl, or aliphatic; R4, R5, R6, and R7 are hydrogen, halides, or C. 6-8 Aryl, heteroaryl, or aliphatic; X is C, O, or S.

[0027] A third aspect of the present invention provides a pharmaceutical composition comprising the above-mentioned hexahydrocyclobutanone derivative, or a salt thereof formed with a pharmaceutically acceptable acid, preferably, the acid comprising inorganic acid salts and organic acid salts. The inorganic acid salts include: hydrochloric acid, sulfuric acid, phosphoric acid, carbonic acid, bicarbonate, nitric acid, monohydrogen phosphate, dihydrogen phosphate, hydrobromic acid, or hydroiodic acid; the organic acids include: maleic acid, tartaric acid, citric acid, methanesulfonic acid, succinic acid, acetic acid, p-toluenesulfonic acid, mandelic acid, isobutyric acid, malonic acid, etc.

[0028] A fourth aspect of the present invention provides the use of the above-described pharmaceutical composition in the preparation of a drug for treating bone defects and osteoporosis.

[0029] The compounds prepared by the method of the present invention, or their pharmaceutically acceptable salt forms, can effectively promote the differentiation and proliferation activity of bone marrow mesenchymal stem cells (BMSCs), induce them to differentiate into bone lineage cells, and promote bone formation.

[0030] The compounds prepared by the method of this invention, or their pharmaceutically acceptable salt forms, are small molecules capable of effectively promoting the functional activity of bone biomarkers such as alkaline phosphatase. Alkaline phosphatase is a characteristic of cell differentiation during osteogenic processes. Generally, its related activity increases with osteogenic processes; therefore, the compounds prepared by this invention, or their pharmaceutically acceptable salt forms, can promote bone formation and / or bone repair.

[0031] The compounds prepared by the method of the present invention, or their pharmaceutically acceptable salt forms, can effectively promote bone synthesis and increase bone mass, thereby improving osteoporosis.

[0032] Through the above technical solution, the present invention achieves the following beneficial effects:

[0033] 1. The preparation method of the present invention has simple reaction operation, the reaction catalyst is inexpensive and readily available, there is no metal catalysis, the reaction is fast and the yield is excellent, reaching more than 80%.

[0034] 2. The compounds prepared by the method of this invention and their pharmaceutically acceptable salts exhibit good promoting activity on cell differentiation, bone formation, bone repair, and bone mass increase during osteogenic processes. Bioactivity evaluation showed that the prepared compounds significantly promoted the proliferation and differentiation activity of bone marrow mesenchymal stem cells (BMSCs) (greater than 2.5-fold) and significantly induced the content of alkaline phosphatase after BMSCs cell culture and differentiation (greater than 2-fold). Evaluation of cortical and cancellous bone mass showed a significant promoting effect on increasing femoral bone mass in mice (greater than 2-fold). Attached Figure Description

[0035] Figure 1 The results show the effects of some compounds of this invention on the proliferation activity of mouse BMSCs cells;

[0036] Figure 2 The results show the effects of some compounds of this invention on the alkaline phosphatase (ALP) content in mouse BMSCs cells.

[0037] Figure 3 The results show the effects of some compounds of this invention on alkaline phosphatase (ALP) in mouse BMSCs cells.

[0038] Figure 4 These are the in vivo experimental results of the effects of some compounds of this invention on osteoporosis in mice;

[0039] Figure 5 Micro-CT images of mouse femurs showing administration of some compounds of this invention into the medullary cavity;

[0040] Figure 6 The results of systemic administration experiments on mice of some compounds of this invention are shown.

[0041] Figure 7 This is a statistical graph showing the average number of femoral trabeculae in mice during systemic administration experiments of some of the compounds of this invention.

[0042] Figure 8 Micro-CT images of the femur of mice used in a systemic drug administration experiment of some of the compounds of this invention.

[0043] Figure 9 These are the results of an in situ administration experiment on the effects of some compounds of this invention on femoral defects in mice;

[0044] Figure 10 This is a photograph of an in situ administration experiment demonstrating the effects of some compounds of this invention on femoral defects in mice. Detailed Implementation

[0045] The specific embodiments of the present invention will be described in detail below with reference to examples. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0046] The raw materials and equipment used in the following examples are all known products, obtained by purchasing commercially available products. This invention can be prepared into salt form using methods commonly used in the art, such as: dissolving a hexahydrocyclobutanone derivative in hydrochloric acid ethanol at room temperature to generate hydrochloride; or adding benzenesulfonate to generate benzenesulfonate.

[0047] Example 1

[0048] Add 6.9 mg of p-toluenesulfonic acid, 28 μL of cyclobutanone, and 19 μL of aniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 29 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product (product structure shown in Table 1). The overall yield is 92%.

[0049] Example 2

[0050] Add 6.9 mg of p-toluenesulfonic acid, 28 μL of cyclobutanone, and 19 μL of aniline to a reaction flask, then add 2 mL of dichloromethane solution, followed by 4A molecular sieve. Stir at room temperature for 6 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 29 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 95%.

[0051] Example 3

[0052] Add 1.8 mg formic acid, 28 μL cyclobutanone, and 19 μL 3-fluoroaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 70 °C and react for 6 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 33 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 1 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 80%.

[0053] Example 4

[0054] Add 2.4 mg acetic acid, 28 μL cyclobutanone, and 23 μL 4-fluoroaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 33 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 85%.

[0055] Example 5

[0056] Add 3 mg propionic acid, 28 μL cyclobutanone, and 21 μL 3-chloroaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 36 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetic anhydride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 92%.

[0057] Example 6

[0058] Add 5.8 mg of octanoic acid, 28 μL of cyclobutanone, and 18 μL of 4-chloroaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 36 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 95%.

[0059] Example 7

[0060] Add 2.5 mg boric acid, 28 μL cyclobutanone, and 22 μL 3-bromoaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 75 °C and react for 5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 45 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 93%.

[0061] Example 8

[0062] Add 4.9 mg benzoic acid, 28 μL cyclobutanone, and 24 μL 4-bromoaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 6 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 45 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 95%.

[0063] Example 9

[0064] Add 3.9 mg of phosphoric acid, 28 μL of cyclobutanone, and 23 μL of 3-iodoaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 6 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 54 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 83%.

[0065] Example 10

[0066] Add 3.8 mg of methanesulfonic acid, 28 μL of cyclobutanone, and 24 μL of 4-iodoaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 54 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 88%.

[0067] Example 11

[0068] Add 3 mg of thioacetic acid, 28 μL of cyclobutanone, and 21 μL of 3-methylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 32 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 95%.

[0069] Example 12

[0070] Add 3.6 mg of oxalic acid, 28 μL of cyclobutanone, and 20 μL of 4-methylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 32 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 98%.

[0071] Example 13

[0072] 4.3 mg of 2-chloropropionic acid, 28 μL of cyclobutanone, and 23 μL of 3,4-dimethylaniline were added to a reaction flask, followed by 2 mL of dichloromethane solution. The mixture was heated to 80 °C and reacted for 4 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. 35 mg of the product was dissolved in 1 mL of dichloromethane, 35 μL of triethylamine was added, and 1 mL of acetyl chloride was added at 0 °C. The mixture was stirred at room temperature for 0.5 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. The overall yield was 92%.

[0073] Example 14

[0074] 3.4 mg of methacrylic acid, 28 μL of cyclobutanone, and 25 μL of 3,5-dimethylaniline were added to a reaction flask, followed by 2 mL of dichloromethane solution. The mixture was heated to 80 °C and reacted for 4 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. 35 mg of the product was dissolved in 1 mL of dichloromethane, 35 μL of triethylamine was added, and 1 mL of acetyl chloride was added at 0 °C. The mixture was stirred at room temperature for 0.5 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. The overall yield was 90%.

[0075] Example 15

[0076] 8.3 mg of 2-naphthalenesulfonic acid, 28 μL of cyclobutanone, and 27 μL of 3,4,5-trimethylaniline were added to a reaction flask, followed by 2 mL of dichloromethane solution. The mixture was heated to 80 °C and reacted for 4 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. 37 mg of the product was dissolved in 1 mL of dichloromethane, 35 μL of triethylamine was added, and 1 mL of acetyl chloride was added at 0 °C. The mixture was stirred at room temperature for 0.5 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. The overall yield was 86%.

[0077] Example 16

[0078] 7.5 mg of lauric acid, 28 μL of cyclobutanone, and 25 μL of 3-ethylaniline were added to a reaction flask, followed by 2 mL of dichloromethane solution. The mixture was heated to 80 °C and reacted for 4 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. 35 mg of the product was dissolved in 1 mL of dichloromethane, 35 μL of triethylamine was added, and 1 mL of acetyl chloride was added at 0 °C. The mixture was stirred at room temperature for 0.5 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. The overall yield was 93%.

[0079] Example 17

[0080] Add 6 mg of phenylglycine, 28 μL of cyclobutanone, and 24 μL of 4-ethylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 35 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 95%.

[0081] Example 18

[0082] Add 6 mg of trifluoromethanesulfonic acid, 28 μL of cyclobutanone, and 32 μL of 3,4-diethylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 40 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 84%.

[0083] Example 19

[0084] Add 3 mg of glyoxylic acid, 28 μL of cyclobutanone, and 22 μL of 3-methoxyaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 35 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 90%.

[0085] Example 20

[0086] 3.6 mg of lactic acid, 28 μL of cyclobutanone, and 23 μL of 4-methoxyaniline were added to a reaction flask, followed by 2 mL of dichloromethane solution. The mixture was heated to 80 °C and reacted for 4 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. 35 mg of the product was dissolved in 1 mL of dichloromethane, 35 μL of triethylamine was added, and 1 mL of acetyl chloride was added at 0 °C. The mixture was stirred at room temperature for 0.5 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. The overall yield was 92%.

[0087] Example 21

[0088] Add 4.9 mg of 2-pyridinecarboxylic acid, 28 μL of cyclobutanone, and 32 μL of 3-tert-butylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 40 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 90%.

[0089] Example 22

[0090] 6.3 mg of chlorophenylboronic acid, 28 μL of cyclobutanone, and 27 mg of 3-propylaniline were added to a reaction flask, followed by 2 mL of dichloromethane solution. The mixture was heated to 80 °C and reacted for 4 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. 37 mg of the product was dissolved in 1 mL of dichloromethane, 35 μL of triethylamine was added, and 1 mL of acetyl chloride was added at 0 °C. The mixture was stirred at room temperature for 0.5 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. The overall yield was 90%.

[0091] Example 23

[0092] Add 5.3 mg leucine, 28 μL cyclobutanone, and 30 mg 4-tert-butylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 40 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 92%.

[0093] Example 24

[0094] Add 4.1 mg of trimethylacetic acid, 28 μL of cyclobutanone, and 27 mg of 4-propylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 37 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 92%.

[0095] Example 25

[0096] Add 4.9 mg of nicotinic acid, 28 μL of cyclobutanone, and 27 mg of 3-isopropylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 37 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 90%.

[0097] Example 26

[0098] Add 4.7 mg valine, 28 μL cyclobutanone, and 27 mg 4-isopropylaniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 37 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 92%.

[0099] Example 27

[0100] 7.8 mg of 6-bromohexanoic acid, 28 μL of cyclobutanone, and 30 mg of 4-isobutylaniline were added to a reaction flask, followed by 2 mL of dichloromethane solution. The mixture was heated to 80 °C and reacted for 4 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. 40 mg of the product was dissolved in 1 mL of dichloromethane, 35 μL of triethylamine was added, and 1 mL of acetyl chloride was added at 0 °C. The mixture was stirred at room temperature for 0.5 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography. The overall yield was 80%.

[0101] Example 28

[0102] Add 7.7 mg citric acid, 28 μL cyclobutanone, and 28 mg 3-(methylthio)aniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 38 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 80%.

[0103] Example 29

[0104] Add 6 mg of methionine, 28 μL of cyclobutanone, and 28 mg of 4-(methylthio)aniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 38 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 82%.

[0105] Example 30

[0106] Add 5.6 mg of 2,4-difluorophenylboronic acid, 28 μL of cyclobutanone, and 19 μL of aniline to a reaction flask, then add 2 mL of anhydrous methanol solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 23 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 86%.

[0107] Example 31

[0108] Add 6.9 mg of p-toluenesulfonic acid, 24 μL of oxetane, and 19 μL of aniline to a reaction flask, then add 2 mL of dichloromethane solution. Heat to 80 °C and react for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 29 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 80%.

[0109] Example 32

[0110] Add 6.9 mg of p-toluenesulfonic acid, 24 μL of oxetine, and 19 μL of aniline to a reaction flask, then add 2 mL of dichloromethane solution, followed by 4A molecular sieve. Stir at room temperature for 4 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. Dissolve 29 mg of the product in 1 mL of dichloromethane, add 35 μL of triethylamine, and add 1 mL of acetyl chloride at 0 °C. Stir at room temperature for 0.5 h, then stop stirring. Add a certain amount of saturated sodium bicarbonate solution to the reaction system, then extract three times with dichloromethane. Combine the obtained organic phases, dry with anhydrous sodium sulfate, filter, and remove the solvent under reduced pressure to obtain the crude product. Then, perform silica gel column chromatography to obtain the pure product. The overall yield is 85%.

[0111] Comparative Example 1

[0112] 15 mg of trihydrofuran(chromium chloride), 28 μL of cyclobutanone, and 76 μL of aniline were added to a reaction flask, followed by 1 mL of tetrahydrofuran solution. The mixture was stirred at room temperature for 12 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography in 72% yield.

[0113] Comparative Example 2

[0114] 11.6 mg of copper trifluoroacetate, 28 μL of cyclobutanone, and 19 μL of aniline were added to a reaction flask, followed by 1 mL of n-hexane solution. The mixture was stirred at 80 °C for 12 h, after which stirring was stopped. A certain amount of saturated sodium bicarbonate solution was added to the reaction system, followed by extraction three times with dichloromethane. The resulting organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography in 75% yield.

[0115] Table 1. Comparison Table of Compounds in Examples

[0116]

[0117] The following is an evaluation of the bioactivity of some compounds in this invention.

[0118] I. Effects of the compound in Example 1 on the proliferation activity of mouse BMSCs cells:

[0119] The experimental method is as follows: First, BMSCs were prepared to a concentration of 5 × 10⁻⁶. 7Cell suspension was seeded at 100 μL per well in 96-well plates, followed by α-MEM medium containing 10% fetal bovine serum and 1% penicillin-streptomycin antibiotics. The plates were incubated at 37°C with 5% CO2 for 24 h. The original culture medium and non-adherent cells were discarded. Cells were then cultured according to experimental groups (3 replicates per group): normal group, 5 μM, 500 nM, and 50 nM drug groups. Each well in the drug treatment groups received 100 μL of the corresponding compound. The normal group received α-MEM medium containing 10% fetal bovine serum and 1% penicillin-streptomycin antibiotics. After 1, 3, and 5 days of culture, 10 μL of MTT was added to each well, and the plates were incubated at 37°C for 4 h. The medium was then aspirated, and 150 μL of LDMSO was added to each well, followed by gentle shaking for 10 min. 100 μL of each well was taken and the absorbance was measured at 490 nm using a microplate reader. Results are shown below. Figure 1 As shown in the figure, there is a significant difference in absorbance values ​​between the high-dose group and the normal group. After 5 days of cell culture, the absorbance value measured by enzymatic method is 2.5 times greater than that of the normal group, indicating that the compound has significant inducing activity on the differentiation and proliferation of BMSCs.

[0120] II. Determination of the effect of the compounds in Example 7 on the alkaline phosphatase (ALP) content in mouse BMSCs cells:

[0121] The experimental methods are as follows: Cells were cultured and induced to differentiate according to experimental groups. Cell groups included a normal group, 5 μM and 500 nM drug groups, and a positive control group. Cells were washed twice with PBS buffer, digested with 0.04 g / L trypsin, and then reacted with 0.09 mol / L p-nitrophenol phosphate in a reaction solution at pH 10.3 at 37°C for 30 min. Finally, the reaction was terminated by adding 0.1 mol / L NaOH. Results are expressed as absorbance (OD) values ​​measured at 405 nm using a microplate reader. Each group was performed in triplicate. Results are as follows: Figure 2 and Figure 3 As shown in the figure, there were significant differences in absorbance values ​​between the high-dose group, the normal group, and the positive group. The absorbance values ​​measured by enzymatic methods after cell culture were more than twice that of the normal group, indicating that the compound significantly increased the ALP level (ALP is a marker of osteoblasts) after BMSC differentiation, demonstrating significant inducing activity. Compared with the normal group, this compound, at a concentration of 5 μM, significantly promoted ALP expression in BMSCs, thereby promoting osteoblast growth.

[0122] III. In vivo intramedullary administration experiment of the compound in Example 13 on osteoporosis in mice:

[0123] The experimental method is as follows: Several 6-week-old female C57 mice were randomly divided into 6 groups: normal group, model group, 1.25 mg / kg compound group, 2.5 mg / kg compound group, 5 mg / kg compound group, and 10 mg / kg compound group. After 3 days of acclimatization, the mice were anesthetized by intraperitoneal injection of 4% chloral hydrate and underwent ovariectomy. The normal group underwent sham surgery. Subsequently, the femoral medullary cavity was injected with 0.1 mL of the compound. After the surgery, the mice were kept warm and allowed free access to food. After 4 weeks of feeding, the mice were euthanized by cervical dislocation, and the femurs were harvested, fixed with paraformaldehyde, and examined by micro-CT. The results are as follows. Figure 4 and Figure 5 As shown in the figure, a single intramedullary administration of the compounds at doses of 1.25 mg / kg and 2.5 mg / kg significantly increased femoral bone mass, showing a significant difference (greater than 2 times) compared to the model group, indicating that the compounds prepared in this invention have a significant effect in inducing and improving osteoporosis.

[0124] IV. Systemic administration experiment of compound 19 on osteoporosis in mice:

[0125] The experimental method is as follows: Several 6-week-old female C57 mice were randomly divided into 6 groups: normal group (sham castration), model group, 300 mg / kg gavage group (ig), 150 mg / kg gavage group (ig), 300 mg / kg intraperitoneal injection group (ip), and 150 mg / kg intraperitoneal injection group (ip). After 3 days of acclimatization, the mice were anesthetized by intraperitoneal injection of 4% chloral hydrate and ovariectomy was performed, while the normal group underwent sham castration. After the surgery, the mice were kept warm and allowed free access to food. After 4 weeks of feeding, the osteoporosis model was established, and the mice were given drugs in the appropriate groups: the model group and the normal group were given the same dose of physiological saline by gavage; the drug-treated groups were given drugs daily. The drug treatment lasted for 4 weeks. During the 4 weeks, the mice had free access to food and water. After 4 weeks, the mice were sacrificed by cervical dislocation, and the femurs were collected, fixed with paraformaldehyde, and examined by micro-CT. The results are as follows. Figures 6-8 As shown in the figure, compared with the model group, the 150 mg / kg ig and 150 mg / kg ip groups significantly improved the bone content and mean number of trabeculae in the femur of mice.

[0126] V. In situ administration experiment of compound 28 on the effect of compound on femoral defects in mice:

[0127] The experimental method was as follows: Several 12-week-old female ICR mice were randomly divided into 5 groups, with 3 mice in each group: model day 0 group (0 d M), model day 5 group (5 d M), drug administration day 5 group (5 d), model day 20 group (20 d M), and drug administration day 20 group (20 d). After 3 days of acclimatization, the mice were anesthetized by intraperitoneal injection of 4% chloral hydrate. The left hind limb of the mice was shaved, disinfected, and the skin and muscles were cut open to expose the femur. A 2 mm hole was drilled at the upper end of the femoral shaft, and the hole was rinsed with physiological saline to remove bone fragments. Except for the model group, which did not receive the drug, each mouse was given 2 mg of the compound in situ at the medullary cavity of the femoral defect. The wound was closed, the muscles and skin were sutured, and the area was disinfected. The mice were kept warm and allowed free access to food and water after recovery from anesthesia. The mice were sacrificed on days 5 and 20, the femur was removed, the size of the defect was measured, and the results were compared. Figure 9 and Figure 10 As shown in the figure, compared with the bone defect model group at the same time, the bone defect area of ​​mice in the 20-day treatment group was significantly reduced, indicating that the compound can significantly promote new bone formation at the bone defect site.

[0128] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0129] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0130] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A hexahydrocyclobutanone derivative, characterized in that, It has any of the following structures: ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， ， 。 2. The method for preparing the hexahydrocyclobutanone derivative according to claim 1, characterized in that, Includes steps (a) and (c) or (b) and (c): (a) Brønsted acid, cyclobutanone, aniline and solvent are mixed, heated to 70-80℃, reacted for 4-6 hours and then purified to obtain hexahydrocyclobutanone product; (b) Mix Brønsted acid, cyclobutanone, aniline and solvent, add dehydrating agent, react at room temperature for 4-6 h and then purify to obtain hexahydrocyclobutanone product; (c) Dissolve the hexahydrocyclobutanone product in dichloromethane, add alkali and acetyl chloride or acid anhydride at 0-10°C, react for 0.5-1 h and then purify to obtain the hexahydrocyclobutanone derivative. The aniline is aniline, 3-fluoroaniline, 4-fluoroaniline, 3-chloroaniline, 4-chloroaniline, 3-bromoaniline, 4-bromoaniline, 3-iodoaniline, 4-iodoaniline, 3-methylaniline, 4-methylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 3,4,5-trimethylaniline, 3-ethylaniline, 4-ethylaniline, 3,4-diethylaniline, 3-methoxyaniline, 4-methoxyaniline, 3-tert-butylaniline, 3-propylaniline, 4-tert-butylaniline, 4-propylaniline, 3-isopropylaniline, 4-isopropylaniline, 4-isobutylaniline, 3-(methylthio)aniline, or 4-(methylthio)aniline.

3. The preparation method according to claim 2, characterized in that, In steps (a) and (b), the Brønsted acid is selected from one or more of formic acid, acetic acid, propionic acid, octanoic acid, boric acid, phenylboronic acid, benzoic acid, p-toluenesulfonic acid, phosphoric acid, methanesulfonic acid, thioacetic acid, oxalic acid, 2-chloropropionic acid, methacrylic acid, 2-naphthalenesulfonic acid, lauric acid, phenylglycine, trifluoromethanesulfonic acid, glyoxylic acid, lactic acid, 2-pyridinecarboxylic acid, chlorophenylboronic acid, leucine, trimethylacetic acid, nicotinic acid, valine, 6-bromohexanoic acid, citric acid, and methionine.

4. The preparation method according to claim 2, characterized in that, In steps (a) and (b), the solvent is selected from one or more of benzene, toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, nitrobenzene, dichloromethane, dichloroethane, chloroform, diethyl ether, tert-butyl methyl ether, ethylene glycol dimethyl ether, n-hexane, n-pentane, anhydrous methanol, anhydrous ethanol, cyclohexane, tetrahydrofuran, and dimethyl sulfoxide.

5. The preparation method according to any one of claims 2 to 4, characterized in that, In step (b), the dehydrating agent is a molecular sieve.

6. A pharmaceutical composition, characterized in that, This includes the hexahydrocyclobutanol derivative of claim 1, or its salts formed with a pharmaceutically acceptable acid.

7. The pharmaceutical composition according to claim 6, characterized in that, The acid includes one or more of the following: hydrochloric acid, sulfuric acid, phosphoric acid, carbonic acid, bicarbonate, nitric acid, monohydrogen phosphate, dihydrogen phosphate, hydrobromic acid, hydroiodic acid, maleic acid, tartaric acid, citric acid, methanesulfonic acid, succinic acid, acetic acid, p-toluenesulfonic acid, mandelic acid, isobutyric acid, and malonic acid.

8. The use of the pharmaceutical composition according to claim 6 or 7 in the preparation of a drug for treating bone defects and osteoporosis.

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