Method for synthesizing benzofluorene compound by substituting unsaturated aldehyde ketone with alkenyl benzene

Abstract

The invention provides a synthesis method of a benzo [a] fluorene compound. According to the method, o-aryl vinyl substituted cinnamyl aldehyde or o-aryl vinyl substituted chalcone derivatives are used as raw materials, protonic acids or lewis acids such as trifluoromethanesulfonic acid and iron trifluoromethanesulfonate are used as catalysts, reaction is performed for 2-12 hours at the temperature of 50-100 DEG C, reaction liquid is separated and purified, and the benzo [a] fluorene compound shown in the formula (I) is obtained. The synthesis method disclosed by the invention has the characteristics of simplicity and convenience in operation, high atom economy, simplicity in substrate preparation, wide application range and the like, and is suitable for actual organic synthesis.

Description

Technical Field

[0001] This invention relates to a method for synthesizing benzo[a]fluorene compounds. Background Technology

[0002] Benzo[a]fluorene compounds are a very important class of polycyclic aromatic hydrocarbons. Due to their unique conjugated structure and photoelectric properties, they are used to design novel organic light-emitting materials, semiconductor materials, fluorescent probes, and optoelectronic devices such as solar cells. Some benzo[a]fluorene derivatives exhibit biological activities, such as antitumor and antibacterial properties. Their molecular skeletons can serve as the core structure for drug design, allowing for the development of novel small molecule drugs or bioactive molecules by introducing functional groups. As structural units of polymer materials, benzo[a]fluorene compounds can be used to synthesize high-performance polymers, improving the thermal stability, optical transparency, and mechanical strength of materials. Therefore, benzo[a]fluorene compounds have broad application prospects in the fields of optoelectronic materials, medicinal chemistry, and materials science.

[0003] The reported synthetic methods for benzo[a]fluorene compounds mainly include: (1) radical cascade reaction to construct benzo[a]fluorene (see J. Am. Chem. Soc. 2015, 137, 1165-1180); (2) rhodium-catalyzed three-component reaction to synthesize benzo[a]fluorene (see J. Org. Chem. 2020, 85, 8489-8500); (3) o-alkynylbenzaldehyde (3) Benzo[a]fluorene was constructed by [2+2] cycloaddition / alkyne-acetal coupling reaction with aryl alkynes (see Chem. Commun. 2014, 50, 9925-9928); (4) Benzo[a]fluorene and its ketone derivatives were prepared by trifluoromethanesulfonic acid-promoted cationic cycloisomerization of enynyl ketones (see Adv. Synth. Catal. 2018, 360, 1453-1465); (5) aryl fusion of 1,6-diyne-3 (5) Cycloisomerization of ketones to synthesize benzo[a]fluorene compounds (see J. Org. Chem. 2021, 86, 333-351); (6) Gold-catalyzed 1,7-carbene transfer reaction to construct benzo[a]fluorene systems (see Chem. Commun. 2016, 52, 11000-11003); (7) Gold-catalyzed tandem cyclization of alkylenecyclopropanes and alkynes to construct benzo[a]fluorene compounds (see Chem. Commun. 2021, 86, 333-351); (88) Gold-catalyzed alkylenecyclopropane-alkyne tandem cyclization reaction to construct benzo[a]fluorene compounds (see Chem. Commun. 2021, 86, 333-351); (89) Gold-catalyzed alkylenecyclopropane-alkyne tandem cyclization reaction to construct benzo[a]fluorene compounds (see Chem. Commun. 2021, 86, 333-351); (80) Gold-catalyzed 1,7-carbene transfer reaction to construct benzo[a]fluorene systems ... (17,53,11666-11669); (8) Synthesis of benzo[a]fluorene derivatives by aromatic CH bond functionalization of electron-rich aromatic hydrocarbons with conjugated 1,5-enyne (see GreenChem. 2021, 23, 4144-4149); (9) Synthesis of benzo[a]fluorene by palladium-catalyzed cyclization of 5-(2-bromophenyl)pent-3-en-1-yne (see J. Org. Chem. 2024, 89, 12341-12348). The previously reported methods have drawbacks such as requiring noble metal catalysts or having complex raw material preparation. Therefore, it is necessary to develop simpler and more efficient routes to synthesize benzo[a]fluorene compounds. Summary of the Invention

[0004] To address the shortcomings of existing synthetic techniques, this invention provides a simple and efficient method for synthesizing benzo[a]fluorene compounds. This method can simultaneously construct two ring systems through a [3+3]-cyclic aromatization reaction, offering advantages such as simple substrate preparation, convenient operation, mild reaction conditions, and high atom economy. This method has promising application prospects.

[0005] The technical solution of this invention is:

[0006] A method for synthesizing benzo[a]fluorene compounds of formula (I), wherein the method comprises: using 2-arylvinyl-substituted cinnamaldehyde derivatives of formula (II) or 2-arylvinyl-substituted chalcone derivatives of formula (III) as raw materials, reacting at 50-100°C for 2-12 hours under the action of protic acid, Lewis acid, and solvent, and the reaction solution is separated and purified to obtain benzo[a]fluorene compounds of formula (I).

[0007] In equations (I), (II), and (III), R 1 or R 2 It can be hydrogen, alkyl, alkoxy, halogen, nitro, aryl, etc.

[0008] In equation (I) or equation (II), R 3 It can be hydrogen, alkyl, benzyl, etc.

[0009] In equation (I) or equation (III), R 3 It can be hydrogen, alkyl, benzyl, cycloalkyl, benzocycloalkyl, etc.; R 4 It can be alkyl, phenyl, substituted phenyl, cycloalkyl, benzocycloalkyl, etc.

[0010] The equations for preparing compound (I) using formula (II) or formula (III) are as follows:

[0011] The catalyst described in this invention is one or more of ferric chloride, ferric chloride hexahydrate, trifluoromethanesulfonic acid, and ferric trifluoromethanesulfonate.

[0012] Furthermore, the amount of the trifluoromethanesulfonic acid catalyst of the present invention is 10% to 30% of the amount of the reactant of formula (II) or formula (III), most preferably 10%.

[0013] Furthermore, the amount of the ferric trifluoromethanesulfonate, ferric chloride, and ferric chloride hexahydrate catalyst described in this invention is 10% to 30% of the amount of the reactants of formula (II) or formula (III), with the most preferred amount being 10%.

[0014] The solvent described in this invention is one or more of benzene, toluene, 1,2-dichloroethane, and chloroform, preferably 1,2-dichloroethane.

[0015] The reaction temperature described in this invention is 50–100°C, preferably 80°C.

[0016] The reaction time described in this invention is 2 to 12 hours.

[0017] The preferred molar ratio of the reactant of formula (II) or formula (III) of the present invention to the catalyst trifluoromethanesulfonic acid and the catalyst iron trifluoromethanesulfonate is 1:0.1:0.1.

[0018] The post-processing method described in this invention is as follows: After the reaction is complete, the reaction is quenched with water, then extracted three times with an appropriate amount of ethyl acetate, and the ethyl acetate extract is washed twice with saturated sodium chloride aqueous solution. The ethyl acetate extract is dried with anhydrous magnesium sulfate or sodium sulfate, filtered through a sintered glass funnel, and the solvent is evaporated from the filtrate to obtain the crude product. The crude product is then separated by silica gel column chromatography to obtain the target product shown in formula (I).

[0019] Preferably, the compound of formula (I) of the present invention is one of the following compounds:

[0020]

[0021] The beneficial effects of this invention are:

[0022] (1) Two ring systems, a five-membered ring and a benzene ring, can be constructed simultaneously in one step, resulting in high synthetic efficiency;

[0023] (2) The substrate preparation is simple and has a wide range of applications. The target product can be obtained for cinnamaldehyde and chalcone derivatives containing multiple substituents.

[0024] (3) The reaction conditions are mild and the operation is simple;

[0025] (4) The reaction loses only one molecule of water, which has high atom economy;

[0026] (5) The reaction can be used to construct benzo[a]fluorene derivatives containing cyclopentane, cyclohexane, cycloheptane, cyclooctane and tetrahydronaphthalene ring structures. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments. The examples given are only for explaining the present invention, but the scope of protection of the present invention is not limited thereto:

[0028] Example 1

[0029]

[0030] In a pressure-resistant reaction tube, 3 mL of 1,2-dichloroethane, (E)-2-methyl-3-(2-styrylphenyl)propenal (0.3 mol), trifluoromethanesulfonic acid (10 mol%), and ferric trifluoromethanesulfonate (10 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. Then, it was extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, the solvent was evaporated using a rotary evaporator, and the crude product was concentrated. The crude product was purified by silica gel column chromatography to obtain the target product G1 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 95%.

[0031] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.98 (dd, J=13.3, 7.8Hz, 2H), 7.81 (d, J=7.4Hz, 1H), 7.66- 7.58(m,2H),7.50-7.37(m,3H),7.32(t,J=7.4Hz,1H),4.16(s,2H),2.87(s,3H); 13 C NMR (125MHz, CDCl3): δ143.8,143.5,140.4,138.3,132.6,131.8,129.1,1 28.0,127.9,126.7,125.7,125.5,125.5,124.8,123.8,122.7,35.7,21.6.

[0032] Example 2

[0033]

[0034] In a pressure-resistant reaction tube, 3 mL of 1,2-dichloroethane, (E)-3-(2-styrylphenyl)propenal (0.3 mol), trifluoromethanesulfonic acid (10 mol%), and ferric trifluoromethanesulfonate (10 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. Then, it was extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, the solvent was evaporated using a rotary evaporator, and the crude product was concentrated. The crude product was purified by silica gel column chromatography to obtain the target product G2 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 53%.

[0035] Characterization data: 1H NMR (500MHz, CDCl3): δ8.02(d,J=8.3Hz,1H),7.92(t,J=6.8Hz,2H),7.88(d,J=8.4Hz,1H),7.84(d,J=7.6Hz,1H),7.64( d,J=7.4Hz,1H),7.55(t,J=7.6Hz,1H),7.47(t,J=7.5Hz,1H),7.41(t,J=7.5Hz,1H),7.33(t,J=7.4Hz,1H),4.20(s,2H); 13 C NMR (150MHz, CDCl3): δ143.3,142.6,139.8,138.9,132.8,130.7,128.9,127.7,126.7,126.4,126.3,125.3,124.9,124.0,119.6,118.7,35.6.

[0036] Example 3

[0037]

[0038] In a pressure-resistant reaction tube, 3 mL of 1,2-dichloroethane, (E)-3-(4-methyl-2-((E)-4-nitrostyryl)phenyl)propenal (0.3 mol), trifluoromethanesulfonic acid (10 mol%), and ferric trifluoromethanesulfonate (10 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. Then, it was extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, the solvent was evaporated using a rotary evaporator, and the crude product was concentrated. The crude product was purified by silica gel column chromatography to obtain the target product G3 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 34%.

[0039] Characterization data: 1 H NMR (500MHz, CDCl3) δ8.78(d,J=2.3Hz,1H),8.23(dd,J=9.1,2.3Hz,1H),8.06(d,J=9.1Hz,1H),7. 94(d,J=7.9Hz,1H),7.79(s,1H),7.51(s,1H),7.28(s,1H),4.20(s,2H),2.92(s,3H),2.49(s,3H); 13C NMR (125MHz, CDCl3) δ144.9,144.4,142.5,139.8,139.7,137.2,134.0,131. 6,130.7,130.0,127.9,125.8,125.2,124.8,123.2,119.0,35.6,22.6,21.6.

[0040] Example 4

[0041]

[0042] In a pressure-resistant reaction tube, 3 mL of 1,2-dichloroethane, (E)-1-phenyl-3-(2-styrylphenyl)-2-propen-1-one (0.3 mol), trifluoromethanesulfonic acid (10 mol%), and ferric trifluoromethanesulfonate (10 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. Then, it was extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, the solvent was evaporated using a rotary evaporator, and the crude product was concentrated. The crude product was purified by silica gel column chromatography to obtain the target product G17 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 78%.

[0043] Characterization data: 1 H NMR (600MHz, CDCl3): δ8.08(d,J=8.3Hz,1H),7.93(d,J=8.6Hz,1H),7.87(s,1H),7.81(d,J=7.6Hz,1H),7.65(d ,J=7.4Hz,1H),7.58-7.51(m,5H),7.47(t,J=7.3Hz,1H),7.43-7.39(m,2H),7.34(t,J=6.8Hz,1H),4.24(s,2H); 13 C NMR (150MHz, CDCl3): δ142.5,141.2,140.2,139.27,138.4,131.1,130.9,130.2,1 28.2,127.3,127.2,126.8,126.4,126.3,125.3,124.9,124.3,119.8,119.6,35.7.

[0044] Example 5

[0045]

[0046] In a pressure-resistant reaction tube, 3 mL of 1,2-dichloroethane, (E)-2-(2-styrylbenzyl)cyclopentanone (0.3 mol), trifluoromethanesulfonic acid (10 mol%), and ferric trifluoromethanesulfonate (10 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. Then, it was extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, the solvent was evaporated using a rotary evaporator, and the crude product was concentrated. The crude product was purified by silica gel column chromatography to obtain the target product G26 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 52%.

[0047] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.95(d,J=9.5Hz,1H),7.79(d,J=7.5Hz,2H),7.56(d,J=6.8Hz,1H),7.41(td,J=7.4,6.8,3.7Hz,2H) ,7.33(t,J=7.0Hz,1H),7.24(t,J=7.4Hz,1H),4.11(s,2H),3.43(t,J=7.5Hz,2H),3.30-3.21(m,2H),2.32(p,J=7.5Hz,2H); 13 C NMR (125MHz, CDCl3): δ142.8,142.2,138.8,137.6,135.1,134.6,128.5,128.4, 125.6,124.8,124.3,124.2,124.1,123.7,123.5,120.6,34.8,31.8,29.7,23.5.

[0048] Example 6

[0049]

[0050] In a pressure-resistant reaction tube, 3 mL of 1,2-dichloroethane, (E)-2-(2-styrylbenzyl)-3,4-dihydronaphth-1(2H)-one, trifluoromethanesulfonic acid (10 mol%), and ferric trifluoromethanesulfonate (10 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. Then, it was extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, the solvent was evaporated using a rotary evaporator, and the crude product was concentrated. The crude product was purified by silica gel column chromatography to obtain the target product G31 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 75%.

[0051] Characterization data: 1 H NMR (500MHz, CDCl3): δ8.46(d,J=7.9Hz,1H),7.91(d,J=7.9Hz,1H),7.87(d,J=7.7Hz,1H),7.74(d,J=6.5Hz,1H),7.51(d,J=7.3Hz,1 H),7.42–7.32(m,2H),7.27(dt,J=15.5,7.5Hz,3H),7.21(t,J=7.8Hz,2H),4.07(s,2H),3.26(t,J=7.0Hz,2H),2.78(t,J=6.9Hz,2H); 13 C NMR (125MHz, CDCl3): δ142.9,142.0,138.9,137.7,135.7,133.3,132.3,131.1,129.1,128.12, 128.0,126.4,125.7,125.6,124.9,124.8,124.4,124.3,123.8,123.5,121.9,34.9,28.2,25.9.

[0052] Example 7

[0053]

[0054] The preparation method of G4 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G4 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 51%.

[0055] Characterization data: 1H NMR (500MHz, CDCl3): δ7.98(d,J=7.7Hz,1H),7.89(d,J=8.7Hz,1H),7.78(d,J=2.1Hz,1H),7.63( d,J=7.4Hz,1H),7.49(s,1H),7.44-7.38(m,2H),7.33(t,J=7.4Hz,1H),4.13(s,2H),2.86(s,3H); 13 C NMR (125MHz, CDCl3): δ143.5,143.1,140.3,138.6,133.2,133.0,131.1,1 27.3,127.1,126.8,126.6,126.3,126.0,125.5,124.8,122.8,35.7,21.6.

[0056] Example 8

[0057]

[0058] The preparation method of G5 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G5 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 81%.

[0059] Characterization data: 1 H NMR (600MHz, CDCl3): δ7.99(d,J=7.7Hz,1H),7.89(d,J=8.4Hz,1H),7.63(d,J=7.4Hz,1H),7.59(s, 1H),7.52(s,1H),7.40(t,J=7.5Hz,1H),7.34-7.29(m,2H),4.17(s,2H),2.87(s,3H),2.52(s,3H); 13 C NMR (125MHz, CDCl3): δ142.6,139.3,136.4,134.1,131.8,130.7,126.7,1 26.3,126.2,125.8,125.6,124.5,123.7,122.7,121.5,34.7,20.7,20.6.

[0060] Example 9

[0061]

[0062] The preparation method of G6 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G6 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 92%.

[0063] Characterization data: 1 H NMR (600MHz, CDCl3): δ7.97(d,J=7.7Hz,1H),7.89(d,J=8.6Hz,1H),7.62(d,J=7.4Hz,1H),7.51(s,1H),7 .40(t,J=7.6Hz,1H),7.30(t,J=7.4Hz,1H),7.15(d,J=8.6Hz,2H),4.15(s,2H),3.94(s,3H),2.87(s,3H); 13 C NMR (125MHz, CDCl3): δ156.4,142.6,142.3,139.5,135.2,132.7,131.3,125. 9,125.6,124.4,124.3,123.7,123.4,121.2,117.1,104.9,54.2,34.6,20.6.

[0064] Example 10

[0065]

[0066] The preparation method of G7 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G7 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 58%.

[0067] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.96(d,J=8.1Hz,1H),7.83(d,J=7.9Hz,1H),7.69-7.64(m,1H),7.61(s,1 H),7.54(dd,J=8.2,5.4Hz,1H),7.51-7.43(m,2H),7.04-6.97(m,1H),4.13(s,2H),2.85(s,3H); 13 C NMR (125MHz, CDCl3): δ163.4(d,J C-F =238.7Hz), 145.2(d,J C-F =8.7Hz),141.8,139.0,138.9,137.6,137.5,132.8,131.6,129.0,128.2(d,J C-F=30.0Hz), 125.9(d,J) C-F =18.7Hz), 125.4(d,J) C-F =10.0Hz), 123.9, 112.4 (d, J) C-F =23.7Hz), 109.9(d,J) C-F =23.7Hz), 35.1, 21.4.

[0068] Example 11

[0069]

[0070] The preparation method of G8 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G8 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 52%.

[0071] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.99-7.93(m,2H),7.83(d,J=7.7Hz,1H),7.61(s,1H),7.54(d,J =7.9Hz,1H),7.51-7.44(m,2H),7.29(dd,J=7.9,1.9Hz,1H),4.14(s,2H),2.86(s,3H); 13 C NMR (125MHz, CDCl3): δ145.1,141.9,141.2,137.3,132.8,132.6,131.6,128.9,128.2,127.9,125.9,125.7,125.6,123.8,122.8,35.3,21.5.

[0072] Example 12

[0073]

[0074] The preparation method of G9 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G9 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 65%.

[0075] Characterization data: 1H NMR (600MHz, CDCl3): δ7.97(d,J=8.1Hz,1H),7.82(d,J=8.0Hz,1H),7.59(d,J=15.6Hz,2H),7.53( d,J=7.4Hz,1H),7.50-7.42(m,2H),6.89(d,J=8.2Hz,1H),4.13(s,2H),3.92(s,3H),2.88(s,3H); 13 C NMR (125MHz, CDCl3): δ157.8,143.7,140.6,137.0,134.8,131.5,130.6,128. 0,126.9,126.8,124.5,124.5,124.0,122.8,109.7,108.2,54.5,33.9,20.5.

[0076] Example 13

[0077]

[0078] The preparation method of G10 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G10 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 60%.

[0079] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.96(d,J=8.1Hz,1H),7.87(d,J=7.9Hz,1H),7.81(d,J=8.0Hz,1H),7.59(s,1H),7 .46(d,J=5.6Hz,2H),7.42(t,J=7.4Hz,1H),7.22(d,J=7.9Hz,1H),4.14(s,2H),2.87(s,3H),2.46(s,3H); 13 C NMR (125MHz, CDCl3): δ144.1,140.8,139.9,138.4,135.6,132.4,131.6,129. 1,127.9,127.9,127.4,125.7,125.4,125.2,123.7,122.4,35.5,21.6,21.49.

[0080] Example 14

[0081]

[0082] The preparation method of G11 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G11 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 68%.

[0083] Characterization data: 1 H NMR (400MHz, CDCl3): δ7.90 (dd, J=8.1, 6.2Hz, 2H), 7.66-7.59 (m, 2H), 7.52 (s, 1H), 7.41 (t, J=7.6Hz, 1H), 7.31 (td, J=8.2, 7.5, 1.5Hz, 2H), 4 .17(s,2H),3.24-3.15(m,2H),2.52(s,3H),1.82(p,J=7.5Hz,2H),1.54(d,J=7.1Hz,2H),1.41(dd,J=14.2,7.4Hz,2H),0.93(t,J=7.2Hz,3H); 13 C NMR (150MHz, CDCl3): δ143.7,143.1,140.7,136.8,136.7,135.1,132.8,127.7,127.3,12 7.0,126.7,126.6,125.4,124.7,123.7,122.5,35.7,34.6,31.8,29.75,22.6,21.7,14.1.

[0084] Example 15

[0085]

[0086] The preparation method of G12 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G12 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 57%.

[0087] Characterization data: 1H NMR (600MHz, CDCl3): δ7.93-7.85(m,2H),7.66-7.60(m,1H),7.51(s,1H),7.40(t,J=7.6Hz,1H),7.29(t,J=7.4Hz,1H),7.15(d,J=8.1Hz,2H),4.15( s,2H),3.95(d,J=10.2Hz,3H),3.18(t,J=7.9Hz,2H),1.85-1.79(m,2H),1 .52(dd,J=13.4,5.9Hz,2H), 1.42(q,J=7.4Hz,2H), 0.94(t,J=6.6Hz,3H); 13 C NMR (125MHz, CDCl3): δ156.5,142.5,142.10,140.0,136.2,134.6,132.7,125.7,125.1,1 24.5,124.2,123.7,123.5,121.3,117.2,105.0,54.2,34.7,33.6,30.8,28.7,21.6,13.1.

[0088] Example 16

[0089]

[0090] The preparation method of G13 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G13 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 65%.

[0091] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.93(d,J=8.4Hz,1H),7.80(dd,J=7.2,1.7Hz,1H),7.64-7.59(m,1H),7.57(s,1H),7.42( s,1H),7.35(dd,J=8.4,1.8Hz,1H),7.31-7.26(m,4H),7.24-7.20(m,3H),4.63(s,2H),4.21(s,2H),2.51(s,3H); 13 C NMR (125MHz, CDCl3): δ157.6,143.4,142.9,141.20,139.7,136.1,134.5,133.7,129.0,128 .6,127.6,126.7,126.1,125.5,125.4,124.7,124.7,122.6,118.7,106.2,55.3,40.1,35.8.

[0092] Example 17

[0093]

[0094] The preparation method of G14 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G14 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 62%.

[0095] Characterization data: 1 H NMR (500MHz, CDCl3): δ8.03(d,J=8.2Hz,1H),7.84-7.78(m,2H),7.66-7.61(m,1H),7.55-7.48(m ,2H),7.45(t,J=7.5Hz,1H),7.30(t,J=6.6Hz,4H),7.25-7.21(m,3H),4.66(s,2H),4.24(s,2H); 13 C NMR (150MHz, CDCl3): δ143.7,142.7,140.9,139.6,138.2,133.8,132.5,129.3,128.8,1 28.7,128.5,128.2,126.7,126.1,125.9,125.8,125.6,124.7,123.8,122.9,40.1,35.8.

[0096] Example 18

[0097]

[0098] The preparation method of G15 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G15 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 87%.

[0099] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.77(dd,J=17.9,8.4Hz,2H),7.41(s,1H),7.35(s,1H),7.12(d,J =8.0Hz,1H),7.06(t,J=4.6Hz,2H),4.02(s,2H),3.85(s,3H),2.76(s,3H),2.37(s,3H); 13C NMR (125MHz, CDCl3): δ157.3,143.7,141.0,140.1,136.4,135.1,133.6,132.2, 127.4,126.8,125.6,125.4,124.6,122.0,118.1,106.0,55.3,35.5,21.6,21.4.

[0100] Example 19

[0101]

[0102] The preparation method of G16 is basically the same as in Example 1, except that the starting materials and reaction time are different. The target product G16 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 77%.

[0103] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.84(d,J=8.1Hz,2H),7.57(s,1H),7.48(s,1H),7.42(s,1H),7.29( d,J=8.4Hz,1H),7.19(d,J=7.8Hz,1H),4.09(s,2H),2.83(s,3H),2.50(s,3H),2.44(s,3H); 13 C NMR (125MHz, CDCl3): δ144.0,141.0,139.8,137.6,135.3,134.8,132.7,131.6,1 27.7,127.4,127.37,127.2,126.9,125.6,123.6,122.2,35.5,21.7,21.6,21.4.

[0104] Example 20

[0105]

[0106] The preparation method of G18 is basically the same as in Example 1, except that the starting materials and reaction time are different. The target product G18 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 71%.

[0107] Characterization data: 1H NMR (500MHz, CDCl3): δ7.91(d,J=8.2Hz,1H),7.84(d,J=8.5Hz,1H),7.73(s,1H),7.67(d,J=7.4Hz,1H),7.49(d,J=7.4Hz,1 H),7.40(t,J=6.9Hz,1H),7.33(d,J=8.0Hz,2H),7.30-7.25(m,2H),7.20(dd,J=12.2,8.2Hz,3H),4.06(s,2H),2.36(s,3H); 13 CNMR (125MHz, CDCl3): δ142.3,141.5,139.1,138.0,137.3,137.2,135.8,130.1,129.8,1 29.0,127.9,126.2,125.7,125.3,125.2,124.2,123.8,123.2,118.7,118.5,34.6,20.2.

[0108] Example 21

[0109]

[0110] The preparation method of G19 is basically the same as in Example 1, except that the starting materials and reaction time are different. The target product G19 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 88%.

[0111] Characterization data: 1 H NMR (500MHz, CDCl3): δ8.00(d,J=8.1Hz,1H),7.88(d,J=8.5Hz,1H),7.77(s,1H),7.73(d,J=7.6Hz,1H),7.57(d,J=7.5Hz,1H),7. 47(t,J=6.9Hz,1H),7.41(d,J=8.7Hz,2H),7.37-7.29(m,2H),7.28-7.23(m,1H),6.99(d,J=8.6Hz,2H),4.16(s,2H),3.84(s,3H); 13 C NMR (125MHz, CDCl3): δ157.9,142.4,141.5,138.9,137.9,137.4,132.5,130.3,130.2,1 29.9,126.3,125.8,125.3,125.2,124.3,123.8,123.3,118.8,118.6,112.7,54.3,34.7.

[0112] Example 22

[0113]

[0114] The preparation method of G20 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G20 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 72%.

[0115] Characterization data: 1 H NMR (600MHz, CDCl3): δ7.98(d,J=8.3Hz,1H),7.82(s,1H),7.79(d,J=7.5Hz,1H),7.69(s,1H),7.63(d,J=7.4Hz,1 H),7.58-7.51(m,4H),7.47(t,J=7.1Hz,1H),7.41-7.37(m,2H),7.32(t,J=7.4Hz,1H),4.22(s,2H),2.45(s,3H); 13 C NMR (150MHz, CDCl3): δ143.2,142.7,141.4,139.2,135.1,131.3,130.2,129.1,1 28.5,128.2,127.1,126.8,126.2,126.1,124.8,124.2,119.9,119.5,35.7,21.9.

[0116] Example 23

[0117]

[0118] The preparation method of G21 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G21 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 67%.

[0119] Characterization data: 1 H NMR (600MHz, CDCl3): δ7.99(d,J=9.0Hz,1H),7.83(s,1H),7.77(d,J=7.5Hz,1H),7.62(d,J=7.5Hz,1H),7.58(d,J=6.9Hz,2H),7.53 (t,J=7.4Hz,2H),7.46(t,J=7.3Hz,1H),7.39(t,J=6.9Hz,1H),7.33-7.27(m,2H),7.24(d,J=9.0Hz,1H),4.20(s,2H),3.78(s,3H);13 C NMR (125MHz, CDCl3): δ156.3,142.0,141.6,140.4,138.4,137.9,135.5,131.2,129.0,1 27.3,126.1,125.7,125.3,124.9,124.8,123.7,119.3,118.2,117.5,105.0,54.1,34.7.

[0120] Example 24

[0121]

[0122] The preparation method of G22 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G22 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 53%.

[0123] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.98-7.91(m,2H),7.56(d,J=7.4Hz,1H),7.43(t,J=7.3Hz,2H),7.37(t,J=7.2 Hz,2H),7.30(d,J=9.2Hz,2H),7.25(d,J=6.4Hz,1H),7.22(d,J=6.7Hz,3H),4.14(s,2H),2.51(s,3H); 13 C NMR (125MHz, CDCl3): δ144.0,143.8,140.2,139.8,138.6,138.2,132.12,130.7,129.7,1 28.8,128.4,127.5,127.0,126.7,125.8,125.4,125.3,124.8,123.9,123.2,35.9,19.0.

[0124] Example 25

[0125]

[0126] The preparation method of G23 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G23 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 70%.

[0127] Characterization data: 1H NMR (600MHz, CDCl3): δ8.06(d,J=7.6Hz,1H),8.02(d,J=9.1Hz,1H),7.81(d,J=7.5Hz,1H),7.77(s,1H),7.62(d,J=7.4 Hz,1H),7.58-7.53(m,1H),7.51(t,J=6.8Hz,1H),7.41(t,J=7.5Hz,1H),7.34-7.29(m,1H),4.15(s,2H),2.80(s,3H); 13 CNMR (125MHz, CDCl3): δ143.5,142.7,138.5,138.0,134.0,132.0,130.8,1 26.7,126.2,126.1,125.2,125.1,124.8,124.6,119.5,119.5,35.6,19.9.

[0128] Example 26

[0129]

[0130] The preparation method of G24 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G24 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 80%.

[0131] Characterization data: 1 H NMR (600MHz, CDCl3): δ7.92(d,J=8.3Hz,1H),7.82(s,1H),7.78(d,J=7.6Hz,1H),7.73(s,1H),7.60 (d,J=7.4Hz,1H),7.41–7.36(m,2H),7.29(t,J=6.8Hz,1H),4.13(s,2H),2.77(s,3H),2.57(s,3H); 13 C NMR (150MHz, CDCl3): δ143.3,142.9,138.0,137.7,134.7,133.2,132.2,128 .9,128.2,126.6,125.9,124.7,124.5,124.4,119.,119.3,35.5,22.0,19.9.

[0132] Example 27

[0133]

[0134] The preparation method of G25 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G25 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 57%.

[0135] Characterization data: 1 H NMR (400MHz, CDCl3): δ7.93(d,J=8.9Hz,1H),7.80-7.71(m,2H),7.58(d,J=7.4Hz,1H),7.38(t,J=6.9Hz,1H),7.30 (d,J=2.7Hz,1H),7.26(dd,J=7.5,1.2Hz,1H),7.22(dd,J=9.0,2.5Hz,1H),4.11(s,2H),3.96(s,3H),2.74(s,3H); 13 C NMR (125MHz, CDCl3): δ156.2,142.0,141.8,137.2,135.5,132.1,131.5,125. 6,125.1,125.0,124.7,123.7,118.9,118.1,117.1,103.2,54.2,34.5,19.0.

[0136] Example 28

[0137]

[0138] The preparation method of G27 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G27 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 54%.

[0139] Characterization data: 1 H NMR (500MHz, CDCl3): δ8.09-7.98(m,3H),7.64(d,J=7.4Hz,1H),7.54-7.47(m,2H),7.39(t,J=7.6Hz,1H) ,7.31(t,J=7.4Hz,1H),4.19(s,2H),3.39(d,J=6.0Hz,2H),3.22(t,J=5.2Hz,2H),2.02(p,J=3.4Hz,4H); 13C NMR (125MHz, CDCl3): δ143.9,138.1,137.1,135.0,131.7,131.4,130.6,127.2,12 7.0,126.5,125.2,124.6,124.4,123.2,122.9,35.7,29.1,26.6,23.0,22.7,22.2.

[0140] Example 29

[0141]

[0142] The preparation method of G28 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G28 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 59%.

[0143] Characterization data: 1 H NMR (500MHz, CDCl3): δ8.02(d,J=7.8Hz,1H),7.92(d,J=8.3Hz,1H),7.82(s,1H),7.62(d,J=7.3Hz,1H),7.41-7.32(m,2H ),7.29(t,J=7.4Hz,1H),4.16(s,2H),3.36(d,J=5.2Hz,2H),3.26-3.09(m,2H),2.56(s,3H),2.01(q,J=4.5,3.9Hz,4H); 13 C NMR (125MHz, CDCl3): δ143.9,138.1,137.1,135.0,131.7,131.4,130.6,127.2,12 7.0,126.5,125.2,124.6,124.4,123.2,122.9,35.7,29.1,26.6,23.0,22.7,22.2.

[0144] Example 30

[0145]

[0146] The preparation method of G29 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G29 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 51%.

[0147] Characterization data: 1H NMR (500MHz, CDCl3): δ8.18-8.13(m,1H),8.08(d,J=7.9Hz,1H),8.04-7.99(m,1H),7.63(d,J=7.4Hz,1H),7.50-7.44(m,2H),7.42-7.35(m,1H) ,7.30(t,J=6.8Hz,1H),4.18(s,2H),3.60-3.50(m,2H),3.43-3.33(m,2 H),1.95(p,J=5.8Hz,2H),1.85(p,J=5.8Hz,2H),1.77(p,J=5.8Hz,2H); 13 C NMR (125MHz, CDCl3): δ144.2,143.6,139.1,138.5,137.1,130.5,126.6,125.6 ,125.4,124.9,124.9,124.7,124.3,122.8,35.8,31.5,29.9,27.4,27.0,25.9.

[0148] Example 31

[0149]

[0150] The preparation method of G30 is basically the same as that in Example 1, except that the starting materials and reaction time are different. The target product G30 was obtained by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 51%.

[0151] Characterization data: 1 H NMR (500MHz, CDCl3): δ8.07-8.03(m,1H),7.97-7.93(m,2H),7.57(d,J=7.4Hz,1H),7.43-7.38(m,2H),7.33(t,J=7.5 Hz,1H),7.24(t,J=7.3Hz,1H),4.11(s,2H),3.37(d,J=39.1Hz,4H),1.83(dt,J=59.1,6.0Hz,4H),1.45-1.28(m,4H); 13 C NMR (125MHz, CDCl3): δ143.1,142.3,137.9,136.1,134.5,133.8,129.6,128.5,125.7 ,124.5,124.4,123.9,123.8,123.7,121.9,34.8,29.6,29.0,27.5,25.9,25.2,25.0.

[0152] Example 32

[0153]

[0154] In a pressure-resistant reaction tube, 3 mL of 1,2-dichloroethane, (E)-2-methyl-3-(2-styrylphenyl)propenal (0.3 mol), and ferric trifluoromethanesulfonate (10 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. The mixture was then extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, and the solvent was evaporated using a rotary evaporator. The solution was concentrated to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain the target product G1 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 57%.

[0155] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.98 (dd, J=13.3, 7.8Hz, 2H), 7.81 (d, J=7.4Hz, 1H), 7.66- 7.58(m,2H),7.50-7.37(m,3H),7.32(t,J=7.4Hz,1H),4.16(s,2H),2.87(s,3H); 13 C NMR (125MHz, CDCl3): δ143.8,143.5,140.4,138.3,132.6,131.8,129.1,1 28.0,127.9,126.7,125.7,125.5,125.5,124.8,123.8,122.7,35.7,21.6.

[0156] Example 33

[0157]

[0158] In a pressure-resistant reaction tube, 3 mL of 1,2-dichloroethane, (E)-2-methyl-3-(2-styrylphenyl)propenal (0.3 mol), and trifluoromethanesulfonic acid (20 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. Then, it was extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, the solvent was evaporated using a rotary evaporator, and the crude product was concentrated. The crude product was purified by silica gel column chromatography to obtain the target product G1 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 80%.

[0159] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.98 (dd, J=13.3, 7.8Hz, 2H), 7.81 (d, J=7.4Hz, 1H), 7.66- 7.58(m,2H),7.50-7.37(m,3H),7.32(t,J=7.4Hz,1H),4.16(s,2H),2.87(s,3H); 13 C NMR (125MHz, CDCl3): δ143.8,143.5,140.4,138.3,132.6,131.8,129.1,1 28.0,127.9,126.7,125.7,125.5,125.5,124.8,123.8,122.7,35.7,21.6.

[0160] Example 34

[0161]

[0162] In a pressure-resistant reaction tube, 3 mL of toluene, (E)-2-methyl-3-(2-styrylphenyl)propenal (0.3 mol), and trifluoromethanesulfonic acid (20 mol%) were added sequentially. The mixture was heated to 80 °C under magnetic stirring, and the reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature and quenched with water. Then, it was extracted three times with an appropriate amount of ethyl acetate. The ethyl acetate extract was washed twice with a small amount of saturated sodium chloride aqueous solution and dried with anhydrous magnesium sulfate or anhydrous sodium sulfate. After drying, the desiccant was filtered off using a sintered glass funnel, the solvent was evaporated using a rotary evaporator, and the crude product was concentrated. The crude product was purified by silica gel column chromatography to obtain the target product G1 (eluent: petroleum ether / ethyl acetate = 200 / 1), with a yield of 75%.

[0163] Characterization data: 1 H NMR (500MHz, CDCl3): δ7.98 (dd, J=13.3, 7.8Hz, 2H), 7.81 (d, J=7.4Hz, 1H), 7.66- 7.58(m,2H),7.50-7.37(m,3H),7.32(t,J=7.4Hz,1H),4.16(s,2H),2.87(s,3H); 13 C NMR (125MHz, CDCl3): δ143.8,143.5,140.4,138.3,132.6,131.8,129.1,1 28.0,127.9,126.7,125.7,125.5,125.5,124.8,123.8,122.7,35.7,21.6.

[0164] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes 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. Attached Figure Description Figure 1 This is the general molecular structural formula of the benzo[a]fluorene compounds synthesized in this invention.

Claims

1. A method for synthesizing benzo[a]fluorene compounds of formula (I), characterized in that... The method is as follows: using 2-arylvinyl-substituted cinnamaldehyde derivatives of formula (II) or 2-arylvinyl-substituted chalcone derivatives of formula (III) as raw materials, the reaction is carried out at 50-100℃ for 2-12 hours under the action of protic acid, Lewis acid and solvent. The reaction solution is separated and purified to obtain benzo[a]fluorene compounds of formula (I). In equations (I), (II), and (III), R 1 or R 2 It can be hydrogen, alkyl, alkoxy, halogen, nitro, aryl, etc.; R 3 For example, hydrogen, alkyl, benzyl, cycloalkyl, etc.; R 4 It can be alkyl, phenyl, substituted phenyl, cycloalkyl, etc.

2. The method according to claim 1, characterized in that: The catalyst is one or more of ferric chloride, ferric chloride hexahydrate, trifluoromethanesulfonic acid, and ferric trifluoromethanesulfonate.

3. The method according to claim 1, characterized in that: The solvent is one or more of 1,2-dichloroethane, toluene, benzene, and chloroform.

4. The method according to claim 1, characterized in that: The amount of the one or more catalyst substances is 10% to 30% of the amount of the starting material.

5. The method according to claim 1, characterized in that: The reaction temperature is 50–100°C.

6. The method according to claim 1, characterized in that... The separation and purification method is as follows: after the reaction is complete, the reaction is quenched with water, then extracted three times with an appropriate amount of ethyl acetate, the ethyl acetate extract is washed twice with saturated sodium chloride aqueous solution, the ethyl acetate extract is dried with anhydrous magnesium sulfate or sodium sulfate, filtered through a sintered glass funnel, and the solvent is evaporated from the filtrate to obtain the crude product. The crude product is then separated by silica gel column chromatography to obtain the target product shown in formula (I).

7. The reaction method according to any one of claims 1-6, characterized in that... The chemical structural formula of the compound of formula (I) is as follows:

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