A 2-vinyl chroman compound and preparation method thereof

Abstract

The present invention relates to a kind of 2-vinyl chroman compound and preparation method thereof, the method comprises the following steps: 2-(3-hydroxypentyl-4-ene-1-yl)phenol compound, solvent and catalyst are stirred and mixed, reacted; after monitoring by thin layer chromatography until the raw material completely disappears, quench the reaction, extract, and obtain a crude product; after the crude product is purified, 2-vinyl chroman compound is obtained. Compared with the prior art, the present invention uses simple and easy-to-obtain 2-(3-hydroxypentyl-4-ene-1-yl)phenol compound as reaction raw material, cheap and easy-to-obtain bistrifluoromethanesulfonyl imide or trimethylsilyl trifluoromethanesulfonate as catalyst, in dichloromethane or 1,2-dichloroethane solvent, by intramolecular allyl substitution reaction, a series of 2-vinyl chroman compounds are successfully synthesized; the present invention avoids the use of expensive and usually toxic transition metal catalysts, simplifies the reaction system, and can react at room temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis and relates to a 2-vinyl chroman compound and a preparation method thereof. Background Art

[0002] Chroman compounds have become one of the hot areas in organic synthesis and drug development due to their unique structure and wide range of biological activities, and are widely used in organic synthesis and biomedicine. For example: the drug nebivolol, which is synthesized with chroman as the core skeleton, is often used to treat patients with mild to moderate hypertension, and can also be used to treat angina pectoris and congestive heart failure (see reference: Chen XZ. et al. J. Chem. Res., 2006, 12, 807); the natural product catechin has multiple pharmacological effects such as anti-tumor, antioxidant, antibacterial and protection of heart and brain organs, which also contains the chroman core skeleton (see reference: Yanase, E. et al. Tetrahedron Lett., 2020, 61, 151601); Vitamin E, a fat-soluble vitamin essential to the human body, is an excellent antioxidant and nutrient and is widely used in clinical, pharmaceutical, food, feed, health products and cosmetics industries (see reference: Tsubogo, T. et al. Chem. Pharm. Bull., 2018, 66, 843). However, in the existing literature, the synthesis methods of chroman compounds and their derivatives are mainly carried out using expensive and usually toxic transition metal catalysts, while there are relatively few reports on cheaper and more environmentally friendly Brønsted acid catalysis.

[0003] Therefore, it is of great research significance to develop a method for efficiently synthesizing 2-vinyl chroman compounds using Bronsted acid catalysis. The following are the main synthetic methods reported in the literature:

[0004] (i) In 1986, Hosokawa et al. converted (E)-2-(pent-3-en-1-yl)phenol into 2-vinylchroman under the synergistic catalysis of palladium acetate and copper acetate in an oxygen atmosphere (see reference: Hosokawa, T. et al. Bull. Chem. Soc. Jpn., 1986, 59, 2191).

[0005]

[0006] (ii) In 1993, Larock et al. used 2-iodophenol and penta-1,4-diene as raw materials, and obtained 2-vinyl chroman in N,N-dimethylformamide solvent under the catalysis of palladium acetate. The reaction also required the addition of a base to promote the reaction (see reference: Larock, RC et al. J. Org. Chem., 1993, 58, 4509).

[0007]

[0008] (III) In 2005, Helmechen's research group used (E)-5-(2-hydroxyphenyl)pent-2-en-1-yl carbonate as the starting material, and carried out an intramolecular allylic substitution reaction under the synergistic catalysis of metal iridium catalyst, chiral ligand and 1,5,7-triazidobicyclo(4.4.0)dec-5-ene (TBD), and synthesized 2-vinyl chroman with a yield of 60% and an ee value of 95% (see reference: Helmchen, G. et al. Org. Lett., 2005, 7, 1239).

[0009]

[0010] (IV) In 2015, White et al. started from 2-(pent-4-en-1-yl)phenol compounds and synthesized a series of chroman compounds with a yield of 57-84% by intramolecular allylic substitution reaction under the synergistic catalysis of a complex formed by palladium acetate and sulfur ligands, chromium salts and benzoquinone (see reference: White, MC et al. J. Am. Chem. Soc., 2014, 136, 10834).

[0011]

[0012] (V) In 2017, Carreira et al. synthesized 2-vinyl chroman with a yield of 66% by intramolecular allyl substitution reaction of 2-(3-hydroxypentyl-4-en-1-yl)phenol under the synergistic catalysis of iridium catalyst Zn(OTf)2 (see reference: Carreira, EM et al. Org. Lett., 2017, 19, 3235).

[0013]

[0014] In summary, there are only a few methods for synthesizing 2-vinyl chroman compounds in one step. However, in these reactions, expensive palladium or iridium catalysts are required, the source of reaction raw materials is not easy, the preparation process is relatively complicated, and additional bases or oxidants need to be added to promote the reaction. The reaction system is complex and has other disadvantages.

[0015] Patent CN107540649A discloses a method for preparing 3-substituted isochroman compounds. The method uses o-iodobenzyl alcohol and phenyl benzyl ether compounds as raw materials, toluene as solvent, and metal palladium catalysis in a nitrogen protection system to synthesize the target compound. The specific steps are as follows: o-iodobenzyl alcohol (1 mmol), n-Bu4NCl (1 mmol), NaHCO3 (2 mmol), and Pd(dppe)Cl2 (0.05 mmol) are added to a reaction tube in sequence, and phenyl benzyl ether compounds (1.2 mmol) are dissolved in toluene. Benzene, under nitrogen protection, add the phenyl benzyl ether compound dissolved in toluene to the reaction tube, then place it in a 100°C oil bath, react for 24 hours, and after the reaction, transfer the reaction solution to a 250mL separatory funnel, first add 25mL of ethyl acetate and saturated brine, extract the aqueous phase with ethyl acetate twice after separation, combine the organic phases, wash the organic phase with saturated brine once, and then dry the organic phase with anhydrous Na2SO4, filter, concentrate, and finally separate the column with a mobile phase of petroleum ether: ethyl acetate = 10:1 column chromatography to obtain a white solid. However, this patent requires the use of expensive palladium catalysts, high-temperature heating, and the addition of alkali to promote the reaction. Summary of the invention

[0016] The purpose of the present invention is to provide a 2-vinyl chroman compound and a preparation method thereof in order to overcome at least one defect of the above-mentioned prior art. The present invention successfully synthesizes a series of 2-vinyl chroman compounds through intramolecular allyl substitution reaction, avoids the use of expensive and usually toxic transition metal catalysts, simplifies the reaction system, and can be carried out at room temperature with a high yield.

[0017] The purpose of the present invention can be achieved by the following technical solutions:

[0018] One of the technical solutions of the present invention is to provide a method for preparing a 2-vinyl chroman compound, the method comprising the following steps:

[0019] (1) stirring and mixing a 2-(3-hydroxypentyl-4-en-1-yl)phenol compound, a solvent and a catalyst to react;

[0020] (2) After monitoring by thin layer chromatography (TLC) until the starting material completely disappears, the reaction is quenched and extracted to obtain a crude product;

[0021] (3) The crude product is purified to obtain 2-vinyl chromane compounds.

[0022] Furthermore, the structural formula of the 2-(3-hydroxypentyl-4-ene-1-yl)phenol compound in step (1) is:

[0023]

[0024] Here, R is a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, a tert-butyl group or a phenyl group.

[0025] Furthermore, in step (1), the catalyst is bistrifluoromethanesulfonyl imide (Tf2NH) or trimethylsilyl trifluoromethanesulfonate (TMSOTf), and the solvent is dichloromethane (DCM) or 1,2-dichloroethane (DCE).

[0026] Furthermore, in step (1), the molar ratio of the 2-(3-hydroxypentyl-4-en-1-yl)phenol compound to the catalyst is 1:(0.1-0.2), and the amount ratio of the 2-(3-hydroxypentyl-4-en-1-yl)phenol compound to the solvent is 1 mmol:(5-10 mL).

[0027] As a preferred technical solution, the reactor in step (1) is a Shrek tube. Under nitrogen protection, the Shrek tube is dried and nitrogen is replaced by a hot drying gun under reduced pressure; after returning to room temperature, a 2-(3-hydroxypentyl-4-en-1-yl)phenol compound is added and nitrogen is replaced.

[0028] As a preferred technical solution, the reduced pressure is 0.2-0.3 kPa.

[0029] Furthermore, in step (1), the stirring speed is 300-400 rpm, the reaction temperature is 20-25° C., and the reaction time is 5-8 h.

[0030] Furthermore, in step (2), the quenching agent is water or saturated saline, and the extracting agent is dichloromethane or ethyl acetate.

[0031] Furthermore, in step (2), the ratio of the amount of 2-(3-hydroxypentyl-4-en-1-yl)phenol compound to the quenching agent is 1 mmol:(10-20 mL), the number of extractions is three to four times, and the ratio of the amount of 2-(3-hydroxypentyl-4-en-1-yl)phenol compound to the extraction agent each time is 3 mmol:(30-50 mL).

[0032] Furthermore, the purification in step (3) is performed by silica gel column chromatography.

[0033] Furthermore, the silica gel column chromatography developing solvent is a mixed solvent of petroleum ether and ethyl acetate, or n-hexane and ethyl acetate, in a volume ratio of (20-30):1.

[0034] One of the technical solutions of the present invention is to provide a 2-vinyl chroman compound prepared by the method described, the structural formula of the compound is:

[0035]

[0036] Here, R is a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, a tert-butyl group or a phenyl group.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] (1) The present invention uses a simple and easily available 2-(3-hydroxypentyl-4-en-1-yl)phenol compound as a reaction raw material, and a cheap and easily available bistrifluoromethanesulfonyl imide or trimethylsilyl trifluoromethanesulfonate as a catalyst, and in a dichloromethane or 1,2-dichloroethane solvent, through an intramolecular allyl substitution reaction, to efficiently construct a 2-vinyl chroman compound in one step;

[0039] (2) The present invention avoids the use of expensive and usually toxic transition metal catalysts by using cheap and environmentally friendly Bronsted acid as the catalyst, simplifies the reaction system, and can be carried out at room temperature with a high yield;

[0040] (3) The 2-vinyl chroman compounds synthesized by the method of the present invention have good development potential and application prospects in the field of biomedicine. DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0042] Unless otherwise specified, the equipment used in the following examples are all conventional equipment in the art; the reagents used are all commercially available products or prepared by conventional methods in the art unless otherwise specified. Anything not described in detail in the following examples can be achieved by conventional experimental means in the art.

[0043] A 2-vinyl chroman compound, the compound structure is:

[0044]

[0045] Here, R is a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, a tert-butyl group or a phenyl group.

[0046] A method for preparing a 2-vinyl chroman compound, comprising the following steps:

[0047] (1) 2-(3-hydroxypentyl-4-en-1-yl)phenol compound and bistrifluoromethanesulfonyl imide (Tf2NH) catalyst were mixed in a molar ratio of 0.3 mmol:0.03 mmol with 3 mL of dichloromethane (DCM) solvent, stirred at 25 °C and 400 rpm, and reacted for 5 h;

[0048] (2) After monitoring by thin layer chromatography (TLC) until the starting material completely disappears, the reaction is quenched with water and extracted with dichloromethane to obtain a crude product;

[0049] (3) The crude product is purified by silica gel column chromatography to obtain a 2-vinyl chromane compound.

[0050] The reaction formula used in this embodiment is:

[0051]

[0052] Here, R is a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, a tert-butyl group or a phenyl group.

[0053] Embodiment 1:

[0054] A 2-vinyl chroman compound and a preparation method thereof, the specific steps are as follows:

[0055] (1) Under nitrogen protection, a 10 mL Shrek tube was dried and replaced with nitrogen three times with a hot drying gun under 0.2 kPa reduced pressure; after returning to room temperature, 2-(3-hydroxypentyl-4-en-1-yl)phenol (53.5 mg, 0.3 mmol) was added and replaced with nitrogen three times; then anhydrous dichloromethane (3 mL) and bistrifluoromethanesulfonimide (8.4 mg, 0.03 mmol) were added, and the reaction was stirred at 25 °C and 400 rpm for 5 h;

[0056] (2) Monitor by TLC until the reaction starting material disappears to obtain a product mixed solution; add water (3 mL) to quench the reaction, and extract three times with anhydrous dichloromethane (5 mL);

[0057] (3) The crude product was purified by silica gel column chromatography using a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 20:1 as the developing solvent to obtain a light yellow oily liquid (38.9 mg, yield 81%), i.e., a 2-vinyl chroman compound with the structural formula:

[0058]

[0059] The basic parameters of this compound are as follows:

[0060] 1H NMR (400MHz, CDCl3): δ7.09(t,J=7.5Hz,1H),7.04(d,J=7.5Hz,1H),6.82-6.86(m,2H),5.99(ddd,J=17.5,10.5,5.6Hz,1H),5.38(d,J=17.0Hz,1 H),5.23(d,J=10.5Hz,1H),4.56(m,1H),2.86(ddd,J=16.5,10.5,5.9Hz, 1H),2.77(dt,J=16.5,5.0Hz,1H),2.05-2.10(m,1H),1.81-1.89(m,1H);

[0061] 13 C NMR (101MHz, CDCl3): δ154.6,137.7,129.6,127.4,121.9,120.3,116.9,116.3,76.2,27.6,24.3.

[0062] Embodiment 2:

[0063] A 8-fluoro-2-vinyl chroman compound and a preparation method thereof are basically the same as those in Example 1, except that the raw material is 2-fluoro-6-(3-hydroxypentyl-4-en-1-yl)phenol (58.9 mg, 0.3 mmol), and a light yellow oily liquid (30.4 mg, yield 57%) is obtained, namely, a 8-fluoro-2-vinyl chroman compound, the structural formula of which is:

[0064]

[0065] The basic parameters of the compound are as follows:

[0066] IR(KBr,cm -1 ):2927,2851,1506,1420,1301,1251,1121,1044,926,853,797;

[0067] 1 H NMR (400MHz, CDCl3): δ6.95-6.87(m,1H),6.86-6.78(m,1H),6.76-6.72(m,1H),6.00(ddd,J=17.5,10.6,5.5Hz,1H),5.4 0(d,J=17.3Hz,1H),5.26(d,J=10.6Hz,1H),4.66-4.62(m,1H),2.88-2.73(m,2H),2.13-2.07(m,1H),1.92-1.80(m,1H);

[0068] 13 C NMR (101MHz, CDCl3): δ151.7 (d, J = 244.6Hz), 142.8 (d, J = 10.8Hz), 136.9, 124.5, 124 .4,119.5(d,J=7.3Hz),116.8,113.82(d,J=18.1Hz),76.4,27.1,23.8(d,J=2.6Hz);

[0069] 19 F NMR (376MHz, CDCl3): δ-137.1 (m, Ar-F);

[0070] HRMS(EI)m / z:calcd for C 11 H 11 FO[M] + :178.0794, found 178.0786.

[0071] Embodiment 3:

[0072] A 7-methyl 2-vinyl chroman compound and a preparation method thereof are basically the same as those in Example 1, except that the raw material is 2-(3-hydroxypentyl-4-en-1-yl)-5-methylphenol (57.7 mg, 0.3 mmol), and a light yellow oily liquid (39.2 mg, yield 75%) is obtained, namely, a 7-methyl 2-vinyl chroman compound, the structural formula of which is:

[0073]

[0074] The basic parameters of the compound are as follows:

[0075] IR(KBr,cm -1 ):2927,2851,1572,1506,1420,1301,1251,1121,1044,997,926,799;

[0076] 1 H NMR (400MHz, CDCl3): δ7.00-6.91(m,1H),6.77-6.62(m,2H),6.00(ddd,J=17.3,10.6,5.6Hz,1H),5.40(d,J=17.3Hz, 1H),5.25(d,J=10.6Hz,1H),4.58-4.52(m,1H),2.92-2.68(m,2H),2.30(s,3H),2.10-2.04(m,1H),1.90-1.79(m,1H);

[0077] 13 C NMR (101MHz, CDCl3): δ154.4,137.8,137.3,129.4,121.2,118.8,117.3,116.2,76.2,27.7,23.9,21.2;

[0078] HRMS(ESI)m / z:calcd for C 12 H 15 O[M+H] + :175.1118, found 175.1120.

[0079] Embodiment 4:

[0080] A 6-tert-butyl 2-vinyl chroman compound and a preparation method thereof are basically the same as those in Example 1, except that the raw material is 4-(tert-butyl)-2-(3-hydroxypentyl-4-en-1-yl)phenol (70.3 mg, 0.3 mmol), and a light yellow oily liquid (51.3 mg, yield 79%) is obtained, i.e., a 6-tert-butyl 2-vinyl chroman compound, the structural formula of which is:

[0081]

[0082] The basic parameters of the compound are as follows:

[0083] IR(KBr,cm -1 ):2956,2863,1498,1297,1238,1129,991,923,819;

[0084] 1 H NMR (400MHz, CDCl3): δ7.17-7.13(m,1H),7.07-7.05(m,1H),6.82(d,J=8.5Hz,1H),6.01(ddd,J=17.3,10.6,5.7Hz,1H),5.40(d, J=17.2Hz,1H),5.25(d,J=10.5Hz,1H),4.57-4.51(m,1H),2.92-2.66(m,2H),2.11-2.04(m,1H),1.91-1.81(m,1H),1.31(s,9H);

[0085] 13 C NMR (101MHz, CDCl3): δ152.3,142.9,137.9,126.3,124.5,120.9,116.4,116.3,76.3,34.1,31.7,27.8,24.6;

[0086] HRMS(ESI)m / z:calcd for C 15 H 21 O[M+H] + :217.1587,found 217.1582.

[0087] Embodiment 5:

[0088] A 6-methoxy-2-vinyl chroman compound and a preparation method thereof are basically the same as those in Example 1, except that the raw material is 2-(3-hydroxypentyl-4-en-1-yl)-4-methoxyphenol (62.5 mg, 0.3 mmol), and a light yellow oily liquid (35.7 mg, yield 63%) is obtained, i.e., a 6-methoxy-2-vinyl chroman compound, the structural formula of which is:

[0089]

[0090] The basic parameters of this compound are as follows:

[0091] 1 H NMR (600MHz, CDCl3): δ6.79 (d, J=8.9Hz, 1H), 6.69 (dd, J=8.9, 3.0Hz, 1H), 6.60 (d,J=3.0Hz,1H),5.99(ddd,J=17.5,10.6,5.6Hz,1H),5.38(d,J=17.2Hz,1H),5 .23(d,J=10.6Hz,1H),4.52-4.48(m,1H),3.75(s,3H),2.85(ddd,J=16.4,10.4, 6.1Hz,1H),2.75(dt,J=16.5,5.0Hz,1H),2.10-2.01(m,1H),1.87-1.80(m,1H);

[0092] 13 C NMR (151MHz, CDCl3): δ153.3,148.6,137.8,122.4,117.5,116.3,114.1,113.4,76.1,55.8,27.6,24.6.

[0093] Embodiment 6:

[0094] A 6-chloro-2-vinyl chroman compound and a preparation method thereof are substantially the same as those in Example 1, except that the raw material is 4-chloro-2-(3-hydroxypentyl-4-en-1-yl)phenol (63.8 mg, 0.3 mmol), and a light yellow oily liquid (49.7 mg, 85% yield) is obtained, namely, a 6-chloro-2-vinyl chroman compound, having the structural formula:

[0095]

[0096] The basic parameters of this compound are as follows:

[0097] 1 H NMR (400MHz, CDCl3): δ7.10-6.97(m,2H),6.78(d,J=8.5Hz,1H),5.96(ddd,J=17.2,10.6,5.6Hz,1H),5.37(d,J= 17.2Hz,1H),5.25(d,J=10.6Hz,1H),4.57-4.51(m,1H),2.92-2.67(m,2H),2.09-2.02(m,1H),1.87-1.76(m,1H);

[0098] 13 C NMR (101MHz, CDCl3): δ153.2,137.2,129.1,127.4,124.9,123.4,118.2,116.6,76.3,27.1,24.1.

[0099] Embodiment 7:

[0100] A 6-bromo-2-vinyl chroman compound and a preparation method thereof are substantially the same as those in Example 1, except that the raw material is 4-bromo-2-(3-hydroxypentyl-4-en-1-yl)phenol (77.1 mg, 0.3 mmol), and a yellow solid (61.0 mg, 84% yield) is obtained, i.e., a 6-bromo-2-vinyl chroman compound having the structural formula:

[0101]

[0102] The melting point is 33-35℃.

[0103] The basic parameters of this compound are as follows:

[0104] 1 H NMR (400MHz, CDCl3): δ7.20-7.15(m,2H),6.73(d,J=8.2,1H),5.96(ddd,J=17.3,10.6,5.6Hz,1H),5.37(d,J=1 7.3Hz,1H),5.25(d,J=10.5Hz,1H),4.56-4.51(m,1H),2.90-2.67(m,2H),2.09-2.02(m,1H),1.87-1.77(m,1H);

[0105] 13C NMR (101MHz, CDCl3): δ153.7,137.2,132.1,130.2,124.1,118.7,116.6,112.2,76.3,27.1,24.0.

[0106] Embodiment 8:

[0107] A 2-vinyl-3,4-dihydro-2H-benzo[g]chromene compound and a preparation method thereof are substantially the same as those in Example 1, except that the raw material is 3-(3-hydroxypentyl-4-en-1-yl)naphthalene-2-ol (68.5 mg, 0.3 mmol), and a white solid (47.9 mg, 76% yield) is obtained, namely, a 2-vinyl-3,4-dihydro-2H-benzo[g]chromene compound having the structural formula:

[0108]

[0109] The melting point is 55-57℃.

[0110] The basic parameters of the compound are as follows:

[0111] IR(KBr,cm -1 ):2928,2850,1504,1456,1431,1251,1160,1113,985,914,870,746;

[0112] 1 H NMR (400MHz, CDCl3): δ7.71-7.64(m,2H),7.54(s,1H),7.38-7.32(m,1H),7.30-7.23(m,2H),6.03(ddd,J=17.3,10.6,5.5Hz,1 H),5.43(d,J=17.3Hz,1H),5.27(d,J=10.5Hz,1H),4.71-4.63(m,1H),3.13-2.96(m,2H),2.22-2.11(m,1H),1.99-1.87(m,1H);

[0113] 13 C NMR (101MHz, CDCl3): δ153.2,137.7,133.7,128.8,128.0,127.1,126.5,125.7,124.1,123.5,116.5,111.4,76.6,27.7,24.9;

[0114] HRMS(ESI)m / z:calcd for C 15 H 15 O[M+H]+ :211.1118, found 211.1116.

[0115] In this example, a simple and readily available 2-(3-hydroxypentyl-4-en-1-yl)phenol compound is used as a reaction raw material, and a cheap and readily available bistrifluoromethanesulfonyl imide is used as a catalyst. In a dichloromethane solvent, an intramolecular allyl substitution reaction is performed to efficiently construct a 2-vinyl chroman compound in one step, which has good development potential and application prospects in the field of biomedicine.

[0116] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a 2-vinyl chroman compound, characterized in that: The method comprises the following steps: (1) Under nitrogen protection, a 2-(3-hydroxypentyl-4-en-1-yl)phenol compound, a solvent and a catalyst are stirred and mixed to react; (2) After monitoring by thin layer chromatography until the raw material completely disappears, the reaction is quenched and extracted to obtain a crude product; (3) Purifying the crude product to obtain a 2-vinyl chroman compound; The structural formula of the 2-(3-hydroxypentyl-4-ene-1-yl)phenol compound in step (1) is: wherein R is a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, a tert-butyl group or a phenyl group; In step (1), the catalyst is bistrifluoromethanesulfonimide and the solvent is dichloromethane or 1,2-dichloroethane; The 2-vinyl chroman compounds prepared by the method described above have the structural formula: Here, R is a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, a tert-butyl group or a phenyl group.

2. The method for preparing a 2-vinyl chroman compound according to claim 1, wherein In step (1), the molar ratio of the 2-(3-hydroxypentyl-4-ene-1-yl)phenol compound to the catalyst is 1:(0.1-0.2), and the amount ratio of the 2-(3-hydroxypentyl-4-ene-1-yl)phenol compound to the solvent is 1 mmol:(5-10 mL).

3. The method for preparing a 2-vinyl chroman compound according to claim 1, characterized in that: In step (1), the stirring speed is 300-400 rpm, the reaction temperature is 20-25° C., and the reaction time is 5-8 h.

4. The method for preparing a 2-vinyl chroman compound according to claim 1, characterized in that: In step (2), the quenching agent is water or saturated saline, and the extracting agent is dichloromethane or ethyl acetate.

5. The method for preparing a 2-vinyl chroman compound according to claim 1, characterized in that: In step (2), the ratio of 2-(3-hydroxypentyl-4-ene-1-yl)phenol compound to quencher is 1 mmol:(10-20 mL), the number of extractions is three to four times, and the ratio of 2-(3-hydroxypentyl-4-ene-1-yl)phenol compound to extractant each time is 3 mmol:(30-50 mL).

6. The method for preparing a 2-vinyl chroman compound according to claim 1, characterized in that: In step (3), purification is performed by silica gel column chromatography.

7. The method for preparing a 2-vinyl chroman compound according to claim 6, characterized in that: The silica gel column chromatography developing agent is a mixed solvent of petroleum ether and ethyl acetate, or n-hexane and ethyl acetate, in a volume ratio of (20-30):1.

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