A bicyclic [2.1.1]hexene compound and its preparation and application

Abstract

This invention discloses a bicyclic [2.1.1]hexene compound and its preparation and application. The invention uses bicyclic [1.1.0]butanone and phosphate ester as starting materials, and potassium tert-butoxide tetrahydrofuran solution as base. The reaction is carried out under reflux at 80°C to obtain the bicyclic [2.1.1]hexene compound. The prepared compound has certain transpeptidase inhibitory activity and can effectively inhibit the infection and spread of Staphylococcus aureus.

Description

(I) Technical Field

[0001] This invention belongs to the field of biomedicine, and specifically relates to a novel bicyclic [2.1.1]hexene compound, its efficient synthetic route, and its antibacterial activity evaluation. (II) Background Technology

[0002] Bioisosteric substitution strategies play a crucial role in new drug development. Due to the widespread presence of phenyl groups in marketed drugs, research on bioisosteric substitution based on the benzene ring has received considerable attention. However, for rational isosteric substitution, isosteres must not only have the same total number of outer electrons, but also exhibit similarities in molecular size, shape (including bond angles and hybridization), conformation, electron distribution (polarization, inductive effect, conjugation effect, charge, dipole, etc.), lipid-water distribution coefficient, chemical reactivity, and hydrogen bond forming ability. Because bioisosteres lack universality, what works for one series of bioisosteres may not be suitable for another.

[0003] Bicyclic [2.1.1]hexene, as a potential phenyl bioisostere, presents significant challenges in synthesis due to its substantial intrinsic molecular strain. The synthesis and development of novel bicyclic [2.1.1]hexene compounds lays the foundation for the application of bicyclic skeletons in drug structure modification and is of great importance in the pharmaceutical field.

[0004] Sortase A plays a crucial role in the fixation of Staphylococcus aureus cell wall proteins and is considered a novel target for antimicrobial drugs. Inhibition of Sortase A can effectively suppress bacterial adhesion and colonization, thereby limiting the spread of infection. Developing novel bicyclic [2.1.1]hexene compounds with Sortase A inhibitory properties provides a potential new strategy for the development of novel antimicrobial agents. (III) Summary of the Invention

[0005] This invention provides a bicyclic [2.1.1]hexene compound and its preparation and application. The invention uses bicyclic [1.1.0]butanone and phosphate ester as starting materials, and potassium tert-butoxide in tetrahydrofuran solution as a base. The reaction is carried out under reflux at 80°C to obtain the bicyclic [2.1.1]hexene compound. The prepared compound has certain transpeptidase inhibitory activity and can effectively inhibit the infection and spread of Staphylococcus aureus.

[0006] The technical solution adopted in this invention is:

[0007] In a first aspect, the present invention provides a bicyclic [2.1.1]hexene compound containing multiple substitutions as shown in formula (Ⅰ):

[0008]

[0009] In equation (I), when R 1 =R 2 Time: R 1 R 2 Each of these can be independently classified as phenyl, 4-tert-butylphenyl, 4-phenylphenyl, 4-trifluoromethoxyphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, or 2-naphthyl;

[0010] In equation (I), when R 1 ≠R 2 Time: R 1 It is a phenyl group, R 2 It is one of 4-methylphenyl, 4-tert-butylphenyl, 4-phenylphenyl, 4-methoxyphenyl, 4-trifluoromethoxyphenyl, 4-methylthiophenyl, 4-trimethylsilylphenyl, 3,4-dimethylphenyl, 4-chlorophenyl, 4-bromophenyl, 4-trifluoromethylphenyl, 3-methylphenyl, 3-phenylphenyl, 3-methoxyphenyl, 3-chlorophenyl, 2-naphthyl, 2-pyridyl, 2-thienyl, 2-bromo-5-thienyl, 2-furanyl, 2-bromo-5-furanyl; R 2 It is a phenyl group, R 1 It is one of 4-methylphenyl, 4-phenylphenyl, 4-trifluoromethoxyphenyl, 4-trifluoromethylphenyl, and 3-phenylphenyl.

[0011] Furthermore, the bicyclic [2.1.1]hexene compound is one of the following:

[0012]

[0013]

[0014]

[0015] Secondly, the present invention provides a method for preparing a bicyclic [2.1.1]hexene compound as shown in formula (I), wherein the reaction formula of the method is as follows:

[0016]

[0017] In equation (II), when R 1 =R 2 Time: R 1 R 2 Each of these can be independently classified as phenyl, 4-tert-butylphenyl, 4-phenylphenyl, 4-trifluoromethoxyphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, or 2-naphthyl;

[0018] When R 1 ≠R 2 Time: R 1 It is a phenyl group, R 2It is one of 4-methylphenyl, 4-tert-butylphenyl, 4-phenylphenyl, 4-methoxyphenyl, 4-trifluoromethoxyphenyl, 4-methylthiophenyl, 4-trimethylsilylphenyl, 3,4-dimethylphenyl, 4-chlorophenyl, 4-bromophenyl, 4-trifluoromethylphenyl, 3-methylphenyl, 3-phenylphenyl, 3-methoxyphenyl, 3-chlorophenyl, 2-naphthyl, 2-pyridyl, 2-thienyl, 2-bromo-5-thienyl, 2-furanyl, 2-bromo-5-furanyl; R 2 It is a phenyl group, R 1 It is one of 4-methylphenyl, 4-phenylphenyl, 4-trifluoromethoxyphenyl, 4-trifluoromethylphenyl, and 3-phenylphenyl;

[0019] In formula (Ⅰ), R 1 In the same formula (II), R 1 In equation (Ⅰ), R 2 In the same formula (II), R 2 ;

[0020] The preparation method includes the following steps: at room temperature, compound (II) is placed in a dry reaction tube, tetrahydrofuran (THF) is added, and the mixture is stirred to dissolve; then compound (III) is added, followed by the dropwise addition of potassium tert-butoxide, and the mixture is refluxed with magnetic stirring at 80°C. The reaction progress is monitored by thin-layer chromatography (TLC) using a 10:1 volume ratio of petroleum ether and ethyl acetate as the developing solvent. After the reaction is complete, the magnetic stir bar is removed from the reaction solution, and a saturated ammonium chloride solution is added to quench the reaction solution. The reaction mixture is then extracted 1-3 times with ethyl acetate, and the resulting organic phases are combined and dried using anhydrous sodium sulfate. The dried organic phases are then further dried. Sodium sulfate was removed by phase filtration, and the solvent was removed by rotary evaporation under reduced pressure to obtain a crude product. The crude product was purified by silica gel chromatography using a 10:1 volume ratio of petroleum ether and ethyl acetate as eluents, with an elution volume of 5 to 10 column volumes (preferably 7 column volumes) and an elution rate of 5 to 15 mL / min (preferably 10 mL / min). During elution, a 10:1 volume ratio of petroleum ether and ethyl acetate mixture was used as the developing solvent for TLC monitoring. The elution fraction with an Rf value of 0.7 to 0.8 was collected, and the solvent was removed by rotary evaporation under reduced pressure to obtain the bicyclic [2.1.1]hexene compound represented by formula (Ⅰ).

[0021] Furthermore, the volumetric amount of tetrahydrofuran used, calculated as the amount of substance of compound (II), is 10 mL / mmol; the molar ratio of compound (II) to compound (III) and potassium tert-butoxide is 1:2:2.

[0022] The present invention also provides the application of the aforementioned bicyclic [2.1.1]hexene compounds in the preparation of transaminase activity inhibitors.

[0023] The present invention also provides the application of the aforementioned bicyclic [2.1.1]hexene compound in the preparation of Staphylococcus aureus antibacterial agents.

[0024] Compared with existing technologies, the beneficial effects of this invention are mainly reflected in the following aspects: This invention provides a novel bicyclic [2.1.1]hexene compound, which has a stable structure and is not easily degraded. Furthermore, the synthesis method used is green and simple, suitable for large-scale preparation, and has excellent application prospects. The bicyclic [2.1.1]hexene compound of this invention can effectively inhibit transaminase activity, and thus can be used to inhibit Staphylococcus aureus infection. (iv) Description of the attached drawings

[0025] Figure 1 Compound (Ⅰ-1) 1 H NMR spectrum (a) and 13 C NMR plot (b).

[0026] Figure 2 Compound (I-9) 1 H NMR spectrum (a) and 13 C NMR plot (b).

[0027] Figure 3 Compound (Ⅰ-11) 1 H NMR spectrum (a) and 13 C NMR plot (b).

[0028] Figure 4 Compound (Ⅰ-17) 1 H NMR spectrum (a) and 13 C NMR plot (b).

[0029] Figure 5 Compound (Ⅰ-30) 1 H NMR spectrum (a) and 13 C NMR plot (b). (V) Detailed Implementation

[0030] The present invention will be further explained and described below with reference to specific embodiments, but the specific embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents and methods involved in the embodiments are all commonly used reagents and methods in the art.

[0031] Compound (III) was obtained through commercial purchase, and the preparation of compound (II) was carried out in accordance with the literature J.Am.Chem.Soc.2023,145,21152–21158.

[0032] The room temperature described in this invention is 25-30℃.

[0033] Example 1: Preparation of ethyl 1,3-diphenylbicyclo[2.1.1]hex-2-en-2-carboxylate (Ⅰ-1):

[0034]

[0035] At room temperature, 3-phenylbicyclo[1.1.0]butylbenzophenone (II-1, 46.8 mg, 0.20 mmol) and tetrahydrofuran (2 mL) were added to a 5 mL dry reaction tube and stirred to dissolve. Then, ethyl 2-(diethoxyphosphono)ethyl acetate (III-1, 89.6 mg, 0.40 mmol) was added, followed by dropwise addition of potassium tert-butoxide (0.40 mL, 0.40 mmol). The mixture was refluxed at 80 °C with magnetic stirring for 6 hours. The reaction was monitored using a 10:1 volume ratio of petroleum ether to ethyl acetate as the developing solvent. After the reaction was complete, the magnetic stir bar was removed from the reaction solution, and a saturated ammonium chloride solution was added to quench the reaction. The reaction mixture was then extracted three times with ethyl acetate. The resulting organic phases were combined and dried using anhydrous sodium sulfate. The dried organic phase was filtered to remove sodium sulfate, and the solvent was removed by rotary evaporation under reduced pressure to obtain the crude product. The crude product was separated by silica gel column chromatography (silica gel particle size 200-300 mesh, column height 42 cm, diameter 15 mm), with V as the eluent. 石油醚 :V 乙酸乙酯 =10:1, elution volume 7 column volumes, elution rate 10 mL / min, TLC monitoring with petroleum ether and ethyl acetate in a volume ratio of 10:1, collecting the eluent with an Rf value of 0.7, rotary evaporating until no liquid eluent, yielding 54.0 mg of white solid, which is ethyl 1,3-diphenylbicyclo[2.1.1]hex-2-en-2-carboxylate (Ⅰ-1), with a yield of 89%. The compound (Ⅰ-1) has... 1 H NMR see Figure 1 a, 13 C NMR (see) Figure 1 b. 1 H NMR (500MHz, CDCl3) δ7.65-7.67(m,2H),7.36-7.40(m,2H),7.30-7.34(m,3H),7.21-7.25(m,3H),3.88(q ,J=7.0Hz,2H),3.17-3.19(m,3H),2.82(ddd,J1=4.0Hz,J2=2.5Hz,J3=1.5Hz,2H),0.81(t,J=7.0Hz,3H). 13C NMR (125MHz, CDCl3) δ165.4,163.8,141.6,140.0,134.1,128.6,128.1,127.9,127.8,126.3,126.2,66.7,60.2,59.7,43.9,13.4.HRMS (ESI-TOF): m / z calc'd for C 21 H 21 O2(M+H) + :305.1536,found 305.1534.

[0036] Using the same method, (II-1) and (III-1) in the preparation process of compound (Ⅰ-1) were replaced with the corresponding substituents in Table 1 to prepare compounds (Ⅰ-2) to (Ⅰ-33), respectively. The NMR data are shown in Table 1.

[0037] Table 1 Structural data of compound I-1-I-33

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048] Example 2: Evaluation of the compound's effect on Sortase A transpeptidase activity

[0049] 1. Study on the activity of compound I against sortase A in Staphylococcus aureus DSM 20231.

[0050] (1) Sample preparation:

[0051] 1) Preparation of substrate solution: Weigh 1.7 mg of substrate LPATG (purchased from Shanghai Jier Biochemical Co., Ltd.), dissolve it completely in 781.66 μL of DMSO, and then add 7.0349 mL of pure water to prepare a final concentration of 250 μM for the substrate solution. The final concentration of the substrate in each well (96-well plate) during the experiment was 25 μM.

[0052] 2) Preparation of compound solutions: Dissolve compounds I-1 to I-33 in DMSO to prepare 45 μM compound solutions.

[0053] 3) Buffer solution: pH 7.5, 50mM Tris-HCl buffer containing 150mM NaCl and 5mM CaCl2.

[0054] 4) Preparation of Buffer-E solution: Take 187.5 μL of Sortase A stored at -80℃ and add it to 11.8 mL of Buffer solution to prepare working buffer (Buffer-E solution).

[0055] (2) Sortase A activity assay:

[0056] The 96-well plate was divided into an experimental group, a control group A, and a control group B.

[0057] Experimental group: Add 80 μL of prepared Buffer-E solution and 10 μL of compound solution to each well.

[0058] Control group A (i.e., without transpeptidase): Add 80 μL of Buffer-E solution and 10 μL of Buffer solution to each well.

[0059] Control group B: Add 90 μL of buffer solution to each well.

[0060] After pre-incubating the 96-well plates at 37°C for 10 minutes, 10 μL of substrate solution was added to each well, resulting in a final concentration of 1.25 μM Sortase A and 4.5 μM of the compound per well. The initial fluorescence intensity (excitation wavelength λ1 = 305 nm, emission wavelength λ2 = 460 nm) was immediately measured and recorded as the fluorescence intensity at 0 minutes. The 96-well plates were then incubated at 37°C for another 60 minutes, and the fluorescence intensity was measured again. Changes in fluorescence intensity indicate the amount of product generated from substrate hydrolysis and are used to evaluate the inhibitory effect of the compound on Sortase A activity. Each experiment was repeated three times.

[0061] Formula for calculating the inhibition rate of Sortase A activity:

[0062] Sortase A activity inhibition rate = 100 - (F) 60 min -F0min +F 不加转肽酶 ) / F 加转肽酶 ×100

[0063] 2. Conclusion: The experimental results show that, under the condition of a final compound concentration of 4.5 μM, compounds I-15, I-18, and I-24 have good inhibitory activity against Sortase A of Staphylococcus aureus, among which compounds I-1, I-12, I-13, I-14, I-16, I-17, I-22, and I-23 have an inhibition rate of more than 22% against Sortase A of Staphylococcus aureus.

[0064] Table 2. Inhibition rate of bicyclic [2.1.1]hexene compounds on Sortase A (4.5 μM)

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bicyclic [2.1.1]hexene compound containing multiple substitutions as shown in formula (Ⅰ): In equation (Ⅰ), when R 1 =R 2 Time: R 1 R 2 It is phenyl; When R 1 ≠R 2 Time: R 2 It is a phenyl group, R 1 It is one of 4-trifluoromethoxyphenyl or 4-trifluoromethylphenyl.

2. A bicyclic [2.1.1]hexene compound, characterized in that, The bicyclic [2.1.1]hexene compound is one of the following:

3. A method for preparing the bicyclic [2.1.1]hexene compound according to claim 1, characterized in that, The method comprises the following steps: at room temperature, compound (II) is placed in a dry reaction tube, tetrahydrofuran is added, and the mixture is stirred to dissolve; then compound (III) is added, followed by the addition of potassium tert-butoxide, and the mixture is refluxed with magnetic stirring at 80°C. The reaction progress is monitored by thin-layer chromatography using a 10:1 volume ratio of petroleum ether and ethyl acetate as the developing solvent. After the reaction is complete, the magnetic stir bar is removed from the reaction solution, and a saturated ammonium chloride solution is added to quench the reaction solution. The reaction mixture is then extracted 1-3 times with ethyl acetate, and the resulting organic phases are combined and dried using anhydrous sodium sulfate. The dried organic phase is filtered to remove sodium sulfate, and the solvent is removed by rotary evaporation under reduced pressure to obtain the crude product. The crude product is purified by silica gel chromatography using a 10:1 volume ratio of petroleum ether and ethyl acetate as the eluent, with an elution volume of 5 to 10 column volumes and an elution rate of 5 to 15. mL / min; During the elution process, a mixture of petroleum ether and ethyl acetate with a volume ratio of 10:1 was used as the developing solvent for thin-layer chromatography monitoring. The elution fraction with an Rf value of 0.7 to 0.8 was collected, and the solvent was removed by rotary evaporation under reduced pressure to obtain the bicyclic [2.1.1]hexene compounds shown in formula (Ⅰ). In equation (II), when R 1 =R 2 Time: R 1 R 2 It is phenyl; When R 1 ≠R 2 Time: R 2 It is a phenyl group, R 1 It is one of 4-trifluoromethoxyphenyl or 4-trifluoromethylphenyl; In formula (Ⅰ), R 1 In the same formula (II), R 1 In equation (Ⅰ), R 2 In the same formula (II), R 2 .

4. The preparation method according to claim 3, characterized in that, The volumetric amount of tetrahydrofuran used, based on the amount of substance of compound (II), was 10 mL / mmol; the molar ratio of compound (II) to compound (III) and potassium tert-butoxide was 1:2:

2.

5. The use of the bicyclic [2.1.1]hexene compound of claim 1 in the preparation of transaminase activity inhibitors.

6. The use of the bicyclic [2.1.1]hexene compound of claim 1 in the preparation of a Staphylococcus aureus antibacterial agent.

Images