A β-alkynyl tetrahydropyridine compound and a synthesis method thereof

Abstract

The invention belongs to the technical field of organic chemistry, and discloses a β-alkynyl tetrahydropyridine compound and a synthesis method thereof, for solving the technical problem of high cost of the process for synthesizing β-alkynyl tetrahydropyridine structure from allene. By dissolving alkenyl allene compound 1 and phenylimine compound 2 in a solvent, adding copper trifluoromethanesulfonate, and heating the reaction to obtain β-alkynyl tetrahydropyridine compound. The present invention uses copper trifluoromethanesulfonate as a catalyst, and obtains β-alkynyl tetrahydropyridine compound by a one-step reaction, which has the advantages of simple operation, mild conditions, wide substrate range, etc., and has excellent application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis, and in particular relates to a β-alkynyltetrahydropyridine compound and a synthesis method thereof. Background Art

[0002] β-Alkynyltetrahydropyridines are important intermediates for the preparation of natural products and pharmaceutical molecules, making the development of facile synthetic methods for these structures highly desirable. Allenes, a class of 1,2-propene-type compounds with cumulative double bonds, consist of two adjacent carbon-carbon double bonds and are an important class of synthons. Compared to alkenes, allenes exhibit higher reactivity due to their higher strain. In recent years, allenes have attracted extensive research attention due to their unique reactivity, selectivity, availability, and stability. Allenes can undergo a variety of addition reactions under the action of transition metals, efficiently constructing a range of carbon-hydrogen, carbon-carbon, and carbon-hetero bonds. Subsequent cycloaddition reactions can then yield synthetically useful heterocyclic compounds. Compared to traditional catalytic systems, transition metal catalysis offers higher efficiency, improved thermal and chemical stability, and longer catalytic cycle life. In particular, when metal-activated allenes are captured by nucleophiles under transition metal catalysis, a very important class of reaction intermediates—metal carbenes—can be formed. The previous synthesis method for preparing metal carbenes is mainly produced by metal decomposition of explosive diazo compounds. Due to the high risk, the further application of the method is limited, especially in large-scale practical production. The strategy of using allenes as precursors to construct metal carbenes replaces the method of producing such carbene intermediates from explosive diazo compounds in the previous synthetic route, which makes the production of metal carbene intermediates safer and more efficient. However, this method is still mainly limited to precious metal catalysis (C.-N.Chen, R.-S.Liu, Angew.Chem.Int.Ed.2019,58,9831.). If it can be extended to cheap metal catalysis, it will be of great significance for the development of allene chemistry. Summary of the Invention

[0003] To address the technical problem of existing allene-based synthesis of six-membered ring pyridine compounds requiring the use of highly toxic, unstable, and expensive precious metal catalysts, the present invention proposes a method for synthesizing β-alkynyltetrahydropyridine compounds from allenes using copper catalysts, which are less toxic, more stable, and more inexpensive. This method synthesizes β-alkynyltetrahydropyridine compounds through a tandem reaction of an alkenyl allene compound with a phenylimine compound, including cyclization and migration reactions. It offers advantages such as simple operation, mild conditions, and a wide substrate range, and has excellent application prospects.

[0004] To achieve the above object, the technical solution of the present invention is implemented as follows:

[0005] A method for synthesizing a β-alkynyltetrahydropyridine compound comprises the following steps: dissolving an alkenyl alkene compound 1 and a phenylimine compound 2 in a solvent, adding copper trifluoromethanesulfonate, and reacting to obtain a β-alkynyltetrahydropyridine compound 3;

[0006] Among them, the structural formula of alkenyl-linked olefin compound 1 is There are electron-withdrawing and electron-donating groups on R; the structural formula of phenylimine compound 2 is

[0007] Furthermore, the above R is a phenyl group or a substituted phenyl group, and the substituent on the phenyl ring of the substituted phenyl group is fluorine, chlorine, trifluoromethyl or methyl.

[0008] Furthermore, the above substituents are at the para or meta position of the benzene ring.

[0009] The reaction equation for the above synthesis is as follows:

[0010]

[0011] The above solvent plays the role of dissolving the raw materials, and can be selected from 1,2-dichloroethane, dichloromethane, toluene, chlorobenzene or trifluorotoluene.

[0012] The molar ratio of the alkenyl allene compound 1, the phenylimine compound 2 and the copper trifluoromethanesulfonate is 1:(1-3):(0.05-0.15).

[0013] The reaction temperature is 25-60°C and the reaction time is 5-10 hours; the reaction is carried out in air.

[0014] Copper is located in the 29th position of the periodic table, in the fourth period IB group, with an outer electron of 3d 10 4s 1 , large in size, low in positive charge, and highly polarizable, it has a loose grip on outer electrons and is a soft acid. The carbon in the allene has high polarizability, low electronegativity, and is easily oxidized, making it a soft base. According to the theory of hard and soft acids and bases, soft acids are more likely to combine with soft bases, so when copper activates the allene, the electrons on the allene will flow to the empty orbital of copper, making it easier for the two to combine. In addition, the trifluoromethanesulfonate ion, as a coordinated anion, can form a coordination bond with the copper complex through the oxygen on the trifluoromethanesulfonate ion, increasing stability and thus being more conducive to the reaction.

[0015] The β-alkynyl tetrahydropyridine compound is synthesized by using the above-mentioned synthesis method of β-alkynyl tetrahydropyridine compounds.

[0016] Furthermore, the structural formula of the above-mentioned β-alkynyl tetrahydropyridine compound is as follows:

[0017]

[0018]

[0019] The above-mentioned β-alkynyltetrahydropyridine compounds are used as intermediates in the field of chemistry.

[0020] The beneficial effects produced by the present invention are:

[0021] (1) The synthesis process is simple and efficient. Through the tandem reaction of alkenyl allene compounds and phenylimine compounds, β-alkynyl tetrahydropyridine compounds are directly obtained in a one-step reaction; (2) the raw materials are cheap and readily available; (3) the reaction conditions are mild and the operation is simple; (4) the substrate has good universality and a wide range of applications. Therefore, the present invention provides a new, economical, practical, and environmentally friendly method for the synthesis of β-alkynyl tetrahydropyridine compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of compound 3a prepared in Example 1 of the present invention.

[0024] Figure 2 This is the carbon NMR spectrum of compound 3a prepared in Example 1 of the present invention.

[0025] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of compound 3b prepared in Example 2 of the present invention.

[0026] Figure 4 This is the carbon NMR spectrum of compound 3b prepared in Example 2 of the present invention.

[0027] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of compound 3c prepared in Example 3 of the present invention.

[0028] Figure 6 This is the carbon NMR spectrum of compound 3c prepared in Example 3 of the present invention.

[0029] Figure 7 This is the hydrogen nuclear magnetic resonance spectrum of compound 3d prepared in Example 4 of the present invention.

[0030] Figure 8 This is the carbon NMR spectrum of compound 3d prepared in Example 4 of the present invention.

[0031] Figure 9 This is the hydrogen nuclear magnetic resonance spectrum of compound 3e prepared in Example 5 of the present invention.

[0032] Figure 10 This is the carbon NMR spectrum of compound 3e prepared in Example 5 of the present invention.

[0033] Figure 11 This is the hydrogen nuclear magnetic resonance spectrum of compound 3f prepared in Example 6 of the present invention.

[0034] Figure 12 This is the carbon NMR spectrum of compound 3f prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] The synthesis method of a β-alkynyl tetrahydropyridine compound of this embodiment, the synthesis equation and synthesis steps are as follows:

[0038]

[0039] To a 10 mL Shrek tube, alkenyl allene 1a (0.2 mmol, 39.2 mg), phenylimine 2 (0.4 mmol, 103.6 mg), 1,2-dichloroethane (4.0 mL), and copper trifluoromethanesulfonate (0.02 mmol, 7.3 mg) were added sequentially. The reaction system was then heated to 40°C and stirred for 8 hours. The reaction was monitored by TLC. After the reaction was completed, the reaction system was cooled to room temperature. The product was then filtered and concentrated. Column chromatography (petroleum ether / ethyl acetate = 10 / 1) afforded the oily product 3a (74.7 mg, 82%). Characterization data for this compound are as follows: 1 H NMR (400MHz, CDCl3) δ7.73(d,J=6.9Hz,2H),7.51(d,J=7.7Hz,2H),7.37-7.30(m,4H),7.28-7.24(m,6H),5.82( d,J=5.4Hz,1H),2.86-2.77(m,1H),2.71(d,J=17.5Hz,1H),2.40(s,3H),2.15(s,3H),1.59(s,3H),1.26(s,3H); 13C NMR (100MHz, CDCl3) δ142.41,142.12,140.90,137.09,131.10,129.44,128.27,128 .21,128.08,128.01,127.18,126.47,124.18,123.38,94.09,86.65,77.32,77.00,7 6.68,60.97,54.66,33.70,28.73,27.75,22.97,21.42;IR(neat):2922,1728,1648, 1527,1436,1418,1376,1325,1264,1171,1129,1088,948,658; HRMS(ESI)m / z:[M+H] + calcd for C 29 H 30 NO2S 456.1992, found 456.1994. H NMR spectrum and C NMR spectrum are as follows Figure 1 and Figure 2 shown.

[0040] Example 2

[0041] The synthesis method of a β-alkynyl tetrahydropyridine compound of this embodiment, the synthesis equation and synthesis steps are as follows:

[0042]

[0043] To a 10 mL Shrek tube, alkenyl allene 1b (0.2 mmol, 42.8 mg), phenylimine 2 (0.4 mmol, 103.6 mg), 1,2-dichloroethane (4.0 mL), and copper trifluoromethanesulfonate (0.02 mmol, 7.3 mg) were added sequentially. The reaction system was then heated to 40°C and stirred for 8 hours. The reaction was monitored by TLC. After the reaction was completed, the reaction system was cooled to room temperature. The product was then filtered and concentrated. Column chromatography (petroleum ether / ethyl acetate = 10 / 1) afforded the oily product 3b (71.9 mg, 76%). Characterization data for this compound are as follows: 1 H NMR (400MHz, CDCl3) δ7.72(d,J=8.3Hz,2H),7.50(d,J=7.7Hz,2H),7.35-7.29(m,4H),7.26-7.22(m,3H),6.96(t,J=8.7H z,2H),5.81(d,J=4.9Hz,1H),2.84-2.76(m,1H),2.74-2.67(m,1H),2.39(s,3H),2.13(s,3H),1.57(s,3H),1.25(s,3H);13 CNMR (100MHz, CDCl3) δ163.51,161.03,142.43,142.06,140.83,137.24,132.97,132.88,129 .44,128.20,128.04,127.17,126.44,124.00,119.45,119.42,115.65,115.43,92.96,86.29 ,77.32,77.00,76.68,60.88,54.62,33.65,28.71,27.74,22.95,21.40; IR(neat):2924,172 1,1683,1546,1489,1425,1373,1315,1248,1189,1143,1046,957,662; HRMS(ESI)m / z:[M+H] + calcd for C 29 H 29 FNO2S 474.1898, found 474.1896. H NMR spectrum and C NMR spectrum are as follows Figure 3 and Figure 4 shown.

[0044] Example 3

[0045] The synthesis method of a β-alkynyl tetrahydropyridine compound of this embodiment, the synthesis equation and synthesis steps are as follows:

[0046]

[0047] To a 10 mL Shrek tube, alkenyl allene 1c (0.2 mmol, 46.0 mg), phenylimine 2 (0.4 mmol, 103.6 mg), 1,2-dichloroethane (4.0 mL), and copper trifluoromethanesulfonate (0.02 mmol, 7.3 mg) were added sequentially. The reaction system was then heated to 40°C and stirred for 8 hours. The reaction was monitored by TLC. After completion of the reaction, the reaction system was cooled to room temperature. The product was then filtered and concentrated. Column chromatography (petroleum ether / ethyl acetate = 10 / 1) afforded the oily product 3c (78.5 mg, 80%). Characterization data for this compound are as follows: 1H NMR (400MHz, CDCl3) δ7.73(d,J=6.8Hz,2H),7.51(d,J=7.5Hz,2H),7.38-7.30(m,4H),7.27-7.23(m,5H),5.82( d,J=5.3Hz,1H),2.86-2.77(m,1H),2.71(d,J=17.5Hz,1H),2.40(s,3H),2.15(s,3H),1.59(s,3H),1.26(s,3H); 13 C NMR (100MHz, CDCl3) δ142.41,142.12,140.90,137.08,131.10,129.44,128.27,128 .20,128.07,128.00,127.17,126.47,124.18,123.38,94.09,86.65,77.32,77.00,7 6.68,60.96,54.66,33.71,28.73,27.75,22.97,21.40;IR(neat):2924,1726,1618, 1564,1483,1427,1373,1346,1276,1148,1102,1057,967,669; HRMS(ESI)m / z:[M+H] + calcd for C 29 H 29 ClNO2S 490.1602, found 490.1603. H NMR spectrum and C NMR spectrum are as follows Figure 5 and Figure 6 shown.

[0048] Example 4

[0049] The synthesis method of a β-alkynyl tetrahydropyridine compound of this embodiment, the synthesis equation and synthesis steps are as follows:

[0050]

[0051] To a 10 mL Shrek tube, alkenyl allene 1d (0.2 mmol, 52.8 mg), phenylimine 2 (0.4 mmol, 103.6 mg), 1,2-dichloroethane (4.0 mL), and copper trifluoromethanesulfonate (0.02 mmol, 7.3 mg) were added sequentially. The reaction system was then heated to 40°C and stirred for 8 hours. The reaction was monitored by TLC. After completion of the reaction, the reaction system was cooled to room temperature. The product was then filtered and concentrated. Column chromatography (petroleum ether / ethyl acetate = 10 / 1) afforded the oily product 3d (77.6 mg, 74%). Characterization data for this compound are as follows: 1H NMR (400MHz, CDCl3) δ7.73(d,J=8.3Hz,2H),7.55-7.48(m,4H),7.44(d,J=8.2Hz,2H),7.32(t,J=7.5Hz,2H),7.27-7.24( m,3H),5.83(d,J=4.3Hz,1H),2.85-2.78(m,1H),2.76-2.68(m,1H),2.40(s,3H),2.16(s,3H),1.58(s,3H),1.26(s,3H); 13 CNMR (100MHz, CDCl3) δ142.51,142.02,140.73,138.76,131.29,129.48,128.25,128. 03,127.26,126.46,125.26,125.22,125.19,125.15,123.84,92.77,89.11,77.32,77. 00,76.68,60.81,54.62,33.78,28.76,27.77,23.05,21.42;IR(neat):2922,1773,164 8,1573,1494,1452,1343,1361,1260,1152,1108,1047,965,672; HRMS(ESI)m / z:[M+H] + calcd for C 30 H 29 F3NO2S 524.1866, found524.1864. H NMR spectrum and C NMR spectrum are as follows Figure 7 and Figure 8 shown.

[0052] Example 5

[0053] The synthesis method of a β-alkynyl tetrahydropyridine compound of this embodiment, the synthesis equation and synthesis steps are as follows:

[0054]

[0055] To a 10 mL Shrek tube, alkenyl allene 1e (0.2 mmol, 42.8 mg), phenylimine 2 (0.4 mmol, 103.6 mg), 1,2-dichloroethane (4.0 mL), and copper trifluoromethanesulfonate (0.02 mmol, 7.3 mg) were added sequentially. The reaction system was then heated to 40°C and stirred for 8 hours. The reaction was monitored by TLC. After the reaction was completed, the reaction system was cooled to room temperature. The product was then filtered and concentrated. Column chromatography (petroleum ether / ethyl acetate = 10 / 1) afforded the oily product 3e (74.1 mg, 78%). Characterization data for this compound are as follows: 1 H NMR (400MHz, CDCl3) δ7.72(d,J=8.3Hz,2H),7.50(d,J=7.6Hz,2H),7.32(t,J=7.5Hz,2H),7.26-7.20(m,4H),7.12(d,J=7.7Hz,1H),7.06-7.0 2(m,1H),7.00-6.95(m,1H),5.82(d,J=4.5Hz,1H),2.85-2.77(m,1H), 2.75-2.68(m,1H),2.40(s,3H),2.14(s,3H),1.57(s,3H),1.25(s,3H); 13 C NMR (100MHz, CDCl3) δ163.54,161.09,142.47,142.05,140.78,138.09,129.88,129.80,129.46, 128.23,128.04,127.22,126.99,126.96,126.45,123.90,117.96,117.74,115.42,115.21,92.8 8,87.57,77.32,77.00,76.68,60.85,54.62,33.73,28.73,27.75,23.00,21.42; IR(neat):2925 ,1743,1672,1518,1476,1432,1375,1346,1288,1164,1131,1047,967,629; HRMS(ESI)m / z:[M+H] + calcd for C 29 H 29 FNO2S 474.1898, found474.1897. H NMR spectrum and C NMR spectrum are as follows Figure 9 and Figure 10 shown.

[0056] Example 6

[0057] The synthesis method of a β-alkynyl tetrahydropyridine compound of this embodiment, the synthesis equation and synthesis steps are as follows:

[0058]

[0059] To a 10 mL Shrek tube, alkenyl allene 1f (0.2 mmol, 42.0 mg), phenylimine 2 (0.4 mmol, 103.6 mg), 1,2-dichloroethane (4.0 mL), and copper trifluoromethanesulfonate (0.02 mmol, 7.3 mg) were added sequentially. The reaction system was then heated to 40°C and stirred for 8 hours. The reaction was monitored by TLC. After completion of the reaction, the reaction system was cooled to room temperature. The product was then filtered and concentrated. Column chromatography (petroleum ether / ethyl acetate = 10 / 1) afforded the oily product 3f (76.1 mg, 81%). Characterization data for this compound are as follows: 1 H NMR (400MHz, CDCl3) δ7.72(d,J=8.1Hz,2H),7.50(d,J=7.7Hz,2H),7.31(t,J=7.6Hz,2H),7.26-7.23(m,4H),7.18-7.14(m,3H),7.10-7.06 (m,1H),5.81(d,J=5.1Hz,1H),2.84-2.76(m,1H),2.70(d,J=17.3Hz,1H),2.40(s,3H),2.29(s,3H),2.14(s,3H),1.58(s,3H),1.26(s,3H); 13 C NMR (100MHz, CDCl3) δ142.40,142.13,140.92,137.97,136.89,131.65,129.43,128.91, 128.20,128.18,128.08,127.17,126.47,124.24,123.18,94.27,86.29,77.32,77.00,7 6.68,60.99,54.67,33.71,28.74,27.76,22.97,21.41,21.15;IR(neat):2924,1753,16 73,1547,1486,1434,1358,1312,1273,1186,1135,1076,928,637; HRMS(ESI)m / z:[M+H] + calcd for C 30 H 32 NO2S 470.2148, found 470.2146. H NMR spectrum and C NMR spectrum are as follows Figure 11 and Figure 12 shown.

[0060] Example 7

[0061] The synthesis method of a β-alkynyl tetrahydropyridine compound of this embodiment, the synthesis equation and synthesis steps are as follows:

[0062]

[0063] To a 10 mL Shrek tube, alkenyl allene 1a (0.2 mmol, 39.2 mg), phenylimine 2 (0.2 mmol, 51.8 mg), 1,2-dichloroethane (4.0 mL), and copper trifluoromethanesulfonate (0.03 mmol, 10.85 mg) were added sequentially. The reaction system was then stirred at 25°C for 10 hours and monitored by TLC. After the reaction was complete, the reaction system was cooled to room temperature. The product was then filtered and concentrated. Column chromatography (petroleum ether / ethyl acetate = 10 / 1) afforded the oily product 3a (51.2 mg, 56%). Characterization data for this compound are as follows: 1 H NMR (400MHz, CDCl3) δ7.73(d,J=6.9Hz,2H),7.51(d,J=7.7Hz,2H),7.37-7.30(m,4H),7.28-7.24(m,6H),5.82( d,J=5.4Hz,1H),2.86-2.77(m,1H),2.71(d,J=17.5Hz,1H),2.40(s,3H),2.15(s,3H),1.59(s,3H),1.26(s,3H); 13 C NMR (100MHz, CDCl3) δ142.41,142.12,140.90,137.09,131.10,129.44,128.27,128 .21,128.08,128.01,127.18,126.47,124.18,123.38,94.09,86.65,77.32,77.00,7 6.68,60.97,54.66,33.70,28.73,27.75,22.97,21.42;IR(neat):2922,1728,1648, 1527,1436,1418,1376,1325,1264,1171,1129,1088,948,658; HRMS(ESI)m / z:[M+H] + calcd for C 29 H 30 NO2S 456.1992, found 456.1994.

[0064] Example 8

[0065] The synthesis method of a β-alkynyl tetrahydropyridine compound of this embodiment, the synthesis equation and synthesis steps are as follows:

[0066]

[0067] To a 10 mL Shrek tube, alkenyl allene 1f (0.2 mmol, 42.0 mg), phenylimine 2 (0.6 mmol, 155.4 mg), 1,2-dichloroethane (4.0 mL), and copper trifluoromethanesulfonate (0.01 mmol, 3.6 mg) were added sequentially. The reaction system was then heated to 60°C and stirred for 5 hours. The reaction was monitored by TLC. After completion of the reaction, the reaction system was cooled to room temperature. The product was then filtered and concentrated. Column chromatography (petroleum ether / ethyl acetate = 10 / 1) afforded the oily product 3f (57.5 mg, 61%). Characterization data for this compound are as follows: 1 H NMR (400MHz, CDCl3) δ7.72(d,J=8.1Hz,2H),7.50(d,J=7.7Hz,2H),7.31(t,J=7.6Hz,2H),7.26-7.23(m,4H),7.18-7.14(m,3H),7.10-7.06 (m,1H),5.81(d,J=5.1Hz,1H),2.84-2.76(m,1H),2.70(d,J=17.3Hz,1H),2.40(s,3H),2.29(s,3H),2.14(s,3H),1.58(s,3H),1.26(s,3H); 13 C NMR (100MHz, CDCl3) δ142.40,142.13,140.92,137.97,136.89,131.65,129.43,128.91, 128.20,128.18,128.08,127.17,126.47,124.24,123.18,94.27,86.29,77.32,77.00,7 6.68,60.99,54.67,33.71,28.74,27.76,22.97,21.41,21.15;IR(neat):2924,1753,16 73,1547,1486,1434,1358,1312,1273,1186,1135,1076,928,637; HRMS(ESI)m / z:[M+H] + calcd for C 30 H 32 NO2S 470.2148, found 470.2146.

[0068] 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, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for synthesizing β-alkynyl tetrahydropyridine compounds, characterized in that: The steps are as follows: dissolving an alkenyl allene compound 1 and a phenylimine compound 2 in a solvent, adding copper trifluoromethanesulfonate, and reacting to obtain a β-alkynyl tetrahydropyridine compound; wherein the structural formula of the alkenyl allene compound 1 is , the structural formula of phenylimine compound 2 is ; R is phenyl or substituted phenyl, and the substituent on the phenyl ring of the substituted phenyl is fluorine, chlorine, trifluoromethyl or methyl; The reaction equation is as follows: 。 2. The method for synthesizing β-alkynyltetrahydropyridine compounds according to claim 1, wherein The substituent is at the para position or meta position of the benzene ring.

3. The method for synthesizing the β-alkynyltetrahydropyridine compound according to claim 1 or 2, wherein: The solvent is 1,2-dichloroethane, dichloromethane, toluene, chlorobenzene or trifluorotoluene.

4. The method for synthesizing β-alkynyltetrahydropyridine compounds according to claim 3, wherein The molar ratio of the alkenyl allene compound 1, the phenylimine compound 2 and the copper trifluoromethanesulfonate is 1:(1-3):(0.05-0.15).

5. The method for synthesizing β-alkynyltetrahydropyridine compounds according to claim 4, characterized in that: The reaction temperature is 25-60° C. and the reaction time is 5-10 h.

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