Chiral bipyridine-bis-sulfonylated imidazoline ligand, preparation method thereof and application of chiral bipyridine-bis-sulfonylated imidazoline ligand in asymmetric catalytic reaction

Abstract

The invention discloses a chiral bipyridine-bis (sulfonylation) imidazoline'crab 'type ligand (Bpy-Bisulidine) and a preparation method of the chiral bipyridine-bis (sulfonylation) imidazoline'crab' type ligand (Bpy-Bisulidine). According to the invention, corresponding sulfonylation (R, R)-diphenylethylenediamine 1 and dipyridyl-dicarboxaldehyde 2 are subjected to a condensation reaction, and a final product, namely the chiral bipyridyl-bis-sulfonylation imidazoline'crab '-shaped ligand (Bpy-Bisulidine), is generated. The ligand contains a bipyridine group and an imidazoline group, and can form five-membered ring coordination with Lewis metal, so that a chiral ligand metal compound is generated, and the chiral ligand metal compound is applied as a chiral ligand in an asymmetric catalytic reaction. Therefore, the method has important application value in the field of asymmetric catalytic synthesis, and the synthesis method is very economical, simple and convenient. And the compound also has good air stability and wide applicability, and has good compatibility with various substituent groups.

Description

Technical Field

[0001] The present invention relates to the technical fields of chiral chemistry and asymmetric catalytic synthesis, and particularly to a chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine), a preparation method thereof, and an application thereof in a catalytic asymmetric Friedel-Crafts alkylation reaction involving indole. Background Art

[0002] Chiral pharmaceuticals are a frontier field in the pharmaceutical industry. The Nobel Prize in Chemistry in 2001 and 2021 was awarded to the main contributors to chiral catalysis. Currently, the total number of drugs used in the world is about 2,000, and chiral drugs account for more than 50%. Among the 250 commonly used clinical drugs, as many as 200 are chiral drugs.

[0003] The key preparation technology of chiral drugs was selected as one of the "Top Ten Chemical Technology Inventions that Changed the World" proposed by IUPAC. Asymmetric catalysis technology is the most efficient and greenest way to obtain chiral molecules. One of its core scientific issues is the creation of superior chiral ligands and catalysts. The design and synthesis of original superior chiral ligands play a key role in the development of asymmetric catalytic reactions and are the most attractive and challenging goals in asymmetric catalysis, which can provide the core technology for the efficient and green synthesis of chiral drugs and candidate drugs. In addition, an economically feasible synthesis route is also crucial for superior chiral ligands so that they can be widely used. In particular, the nitrogen atom of pyridine belongs to an electron-rich coordination site, and the unique property of the electron pair of bipyridine provides the opportunity to form complexes with various metals. Some studies have focused on the development of new chiral bipyridine ligands for metal-catalyzed reactions.

[0004] In this context, therefore, we designed and developed a new type of chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine) and tested their application in a catalytic asymmetric Friedel-Crafts alkylation reaction involving indole. Based on the design and synthesis of a metal complex of the new type of chiral bipyridine-bisulfonylated imidazoline ligand, our design idea refers to the bionic model diagram of the "crab" shape: the bisulfonylated imidazoline group is analogous to the pincers of two "crabs", and the bipyridine group is analogous to the main body of the "crab" (as Figure 1 shown). Summary of the Invention

[0005] The object of the present invention is to provide a chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine), its preparation method and application. It is an important class of chiral bipyridine ligands. This class of ligands contains bipyridine groups and imidazoline groups (the nitrogen groups of bipyridine and the tertiary amine nitrogen atoms of imidazoline belong to electron-rich coordination sites, and the N-H of imidazoline can participate in hydrogen bonding), and can form a five-membered ring coordination with Lewis metals, thereby generating a chiral ligand-metal complex, which is used as a chiral ligand in asymmetric catalytic reactions. Therefore, it has important application value in the field of asymmetric catalytic synthesis, and its synthesis method is very economical and simple. It also has good air stability, wide applicability, and good compatibility with various substituents.

[0006] The present invention is realized as follows: A chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine), this compound has the structure shown in general formula (Ⅰ);

[0007]

[0008] In the formula, Ar is a benzene ring or a p-methoxybenzene ring; R is a benzene ring substituted by hydrogen / methyl / fluorine / trifluoromethyl / isopropyl or trimethyl.

[0009] The preparation method of the chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine) is to carry out a condensation reaction between the corresponding sulfonylated (R,R)-diphenylethylenediamine 1 and bipyridine-dialdehyde 2 to generate the target product chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine);

[0010] An example of the synthetic route is as follows:

[0011]

[0012] The present invention also discovers the application of the chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine) in the asymmetric Friedel-Crafts alkylation reaction involving indole.

[0013] Our design idea is:

[0014]

[0015] The reaction mechanism of the chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine) catalyzing the asymmetric Friedel-Crafts alkylation reaction involving indole is exemplified as follows:

[0016]

[0017] By adopting the above technical solution, the corresponding sulfonylated (R,R)-diphenylethylenediamine 1 undergoes a condensation reaction with bipyridine-dialdehyde 2 to form the final product, the chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine). This type of ligand contains a bipyridine group and an imidazoline group (the nitrogen groups of bipyridine and the tertiary amine nitrogen atom of imidazoline belong to electron-rich coordination sites, and the N-H of imidazoline can participate in hydrogen bonding), and can form a five-membered ring coordination with a Lewis metal, thereby generating a chiral ligand-metal complex and being used as a chiral ligand in asymmetric catalytic reactions. Therefore, it has important application value in the field of asymmetric catalytic synthesis, and its synthesis method is very economical and simple. It also has good air stability, wide applicability, and good compatibility with various substituents. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The bionic model diagram of the "crab" form referred to in the present invention: the bisulfonylated imidazoline group is analogous to the pincers of two "crabs", and the bipyridine group is analogous to the main body of the "crab";

[0019] Figure 2 The design idea and creativity diagram of the chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine) synthesized in the present invention;

[0020] Figure 3 The single crystal diagrams of the chiral ligand Bpy-Bisulidine-2 and the metal complex synthesized in the present invention;

[0021] Figure 4 The single crystal diagram of the chiral ligand Bpy-Bisulidine-2 synthesized in the present invention;

[0022] Figure 5 and Figure 6 The spectral data of the chiral ligand Bpy-Bisulidine-1 in the examples of the present invention;

[0023] Figure 7 The chiral liquid phase spectral data of compound 5a in the examples of the present invention;

[0024] Figure 8 The chiral liquid phase spectral data of compound 7a in the examples of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0025] (I) Preparation of the chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine)

[0026]

[0027] Preparation of Chiral Bipyridine-bis(sulfonylated) Imidazoline Ligand (Bpy-Bisulidine-1): The raw material sulfonylated (R,R)-diphenylethylenediamine 1a (2.5 eq) and bipyridine-dicarboxaldehyde 2 (1 eq, 0.50 mmol) were dissolved in an appropriate amount of dichloromethane and reacted at 30 °C for about 12 h. After the reaction solution was post-treated, it was purified by column chromatography to obtain a pale yellow solid Bpy-Bisulidine-1; the yield was 60%, >20:1 dr; the results of nuclear magnetic resonance and high-resolution mass spectrometry tests are as follows: 1 H NMR(CDCl3,400MHz)δ:3.86(br s,1H),4.42(d,J=5.6Hz,2H),4.80(d,J=5.6Hz,2H),5.94(s,2H),7.03-7.06(m,4H),7.15-7.16(m,12H),7.25-7.29(m,8H),7.39-7.43(m,2H),7.58(d,J=7.6Hz,4H),7.80-7.86(m,4H),8.22-8.25(m,2H); 13 C NMR(CDCl3,100MHz)δ:69.0,70.5,77.3,119.9,123.4,125.8,126.2,126.6,126.7,126.8,127.3,127.6,127.8,131.9,136.6,136.9,138.1,138.9,154.1,156.6;HRMS(ESI-TOF)m / z:Calcd.For C 52 H 45 N6O4S2[M+H] + :881.2983;Found:881.2999.

[0028] The preparation methods of chiral ligands Bpy-Bisulidine-2 to Bpy-Bisulidine-9 prepared by the examples are the same as that of chiral ligand Bpy-Bisulidine-1, and the feeding ratios are the same as those of ligand Bpy-Bisulidine-1. Ligands Bpy-Bisulidine-2 to Bpy-Bisulidine-9 can be obtained. The reaction yields are shown in Table 1. However, it should be emphasized that the examples are intended to illustrate rather than limit the scope of the present invention. The compounds of the present invention are not limited to the content shown in Table 1.

[0029] Table 1 shows the chemical structures of chiral bipyridine-bis(sulfonylated) imidazoline ligands (Bpy-Bisulidine)

[0030]

[0031] Bpy - Bisulidine - 2: Pale yellow solid, yield 63%, >20:1 dr; The results of nuclear magnetic resonance and high - resolution mass spectrometry tests are as follows: 1 H NMR(CDCl3, 400 MHz) δ: 2.31(s, 6H), 4.42(d, J = 5.2 Hz, 2H), 4.78(d, J = 5.2 Hz, 2H), 5.89(s, 2H), 7.03 - 7.08(m, 8H), 7.14 - 7.19(m, 12H), 7.29 - 7.31(m, 4H), 7.50(d, J = 8.0 Hz, 4H), 7.79 - 7.86(m, 4H), 8.24(d, J = 7.2 Hz, 2H); 13 C NMR(CDCl3, 100 MHz) δ: 20.5, 68.9, 70.5, 77.4, 119.9, 123.4, 125.8, 126.2, 126.5, 126.8, 127.3, 127.4, 127.5, 128.5, 133.5, 136.8, 138.2, 139.1, 142.7, 154.1, 156.6; HRMS(ESI - TOF) m / z: Calcd.For C 54 H 49 N6O4S2[M + H] + : 909.3251; Found: 909.3234。

[0032] Bpy - Bisulidine - 3: Pale yellow solid, yield 57%, >20:1 dr; The results of nuclear magnetic resonance and high - resolution mass spectrometry tests are as follows: 1 H NMR(CDCl3, 400 MHz) δ: 2.01(s, 6H), 2.27(s, 12H), 4.69(d, J = 6.8 Hz, 2H), 4.83(d, J = 6.8 Hz, 2H), 6.28(s, 2H), 6.50(s, 4H), 6.87 - 6.91(m, 4H), 6.94 - 6.99(m, 2H), 7.02(d, J = 6.8 Hz, 4H), 7.23 - 7.33(m, 8H), 7.57(d, J = 7.6 Hz, 2H), 7.75 - 7.79(m, 2H), 8.37(d, J = 7.6 Hz, 2H); 1313C NMR (CDCl3, 100 MHz) δ: 19.7, 21.6, 69.8, 70.7, 76.7, 119.7, 122.9, 126.1, 126.8, 127.0, 127.7, 130.4, 130.5, 136.7, 137.7, 138.0, 139.4, 141.8, 154.6, 157.5; HRMS (ESI-TOF) m / z: Calcd. For C 58 H 57 N6O4S2 [M+H] + : 965.3877; Found: 965.3877.

[0033] Bpy - Bisulidine - 4: Pale yellow solid, yield 58%, >20:1 dr; The results of nuclear magnetic resonance and high - resolution mass spectrometry tests are as follows: 1 1H NMR (CDCl3, 400 MHz) δ: 0.89 - 0.93 (m, 12H), 1.08 - 1.10 (m, 12H), 2.68 - 2.73 (m, 2H), 3.83 - 3.90 (m, 4H), 4.98 - 5.03 (m, 4H), 6.24 (s, 2H), 6.86 (s, 4H), 6.92 - 6.95 (m, 4H), 6.98 - 7.04 (m, 6H), 7.16 - 7.18 (m, 2H), 7.25 - 7.32 (m, 6H), 7.37 (d, J = 6.8 Hz, 4H), 7.59 - 7.63 (m, 2H), 8.27 (d, J = 8.0 Hz, 2H); 13 13C NMR (CDCl3, 100 MHz) δ: 22.5, 23.8, 28.3, 33.1, 69.4, 71.1, 77.2, 119.5, 122.4, 122.5, 126.2, 126.6, 126.9, 127.1, 127.7, 130.2, 136.4, 137.8, 138.6, 150.4, 152.5, 154.6, 157.5; HRMS (ESI - TOF) m / z: Calcd. For C 70 H 81 N6O4S2 [M+H] + : 1133.5758; Found: 1133.5766.

[0034] Bpy - Bisulidine - 5: Pale yellow solid, yield 59%, >20:1 dr; The results of nuclear magnetic resonance and high - resolution mass spectrometry tests are as follows: 11H NMR (CDCl3, 400 MHz) δ: 3.98 (br s, 2H), 4.53 (d, J = 4.8 Hz, 2H), 4.88 (d, J = 4.8 Hz, 2H), 5.94 (s, 2H), 7.10 - 7.11 (m, 4H), 7.15 - 7.18 (m, 8H), 7.19 - 7.21 (m, 4H), 7.35 - 7.37 (m, 4H), 7.43 (d, J = 8.4 Hz, 4H), 7.60 (d, J = 8.0 Hz, 4H), 7.78 - 7.84 (m, 4H), 8.17 - 8.19 (m, 2H); 13 13C NMR (CDCl3, 100 MHz) δ: 68.8, 70.4, 77.8, 120.2, 123.6, 124.2 (q, J = 271.2 Hz), 124.8 (q, J = 4.2 Hz), 125.5, 126.3, 126.8, 126.9, 127.1, 127.5, 127.7, 133.2 (q, J = 33.1 Hz), 136.9, 137.9, 138.6, 140.4, 154.1, 155.9; HRMS (ESI-TOF) m / z: Calcd. For C 54 H 43 F6N6O4S2 [M + H] + : 1017.2690; Found: 1017.2701.

[0035] Bpy - Bisulidine - 6: Pale yellow solid, yield 60%, 19:1 dr; The results of nuclear magnetic resonance and high-resolution mass spectrometry tests are as follows: 1 1H NMR (CDCl3, 400 MHz) δ: 3.91 (br s, 2H), 4.68 (d, J = 4.8 Hz, 2H), 5.06 (d, J = 4.8 Hz, 2H), 6.08 (s, 2H), 7.15 - 7.26 (m, 16H), 7.33 (d, J = 6.8 Hz, 4H), 7.66 (d, J = 8.0 Hz, 6H), 7.74 (d, J = 7.6 Hz, 2H), 7.80 - 7.84 (m, 2H), 8.13 (d, J = 7.6 Hz, 2H); 1313C NMR(CDCl3, 100 MHz) δ: 69.2, 70.0, 77.8, 119.8, 120.3, 122.6, 123.9 (q, J=271.3 Hz), 124.8 (q, J=4.2 Hz), 125.5, 126.4, 127.1, 127.2, 127.6, 127.9, 131.0 (q, J=33.4 Hz), 137.0, 137.6, 137.7, 141.0, 154.3, 155.3; HRMS(ESI-TOF) m / z: Calcd. For C 56 H 41 F 12 N6O4S2[M + H] + : 1153.2434; Found: 1153.2419。

[0036] Bpy - Bisulidine - 7: Pale yellow solid, yield 50%, 18:1 dr; Results of nuclear magnetic resonance and high - resolution mass spectrometry tests are as follows: 1 1H NMR(CDCl3, 400 MHz) δ: 4.29(br s, 2H), 4.83(s, 2H), 5.18(s, 2H), 5.94(s, 2H), 7.15 - 7.19(m, 4H), 7.22 - 7.26(m, 4H), 7.28 - 7.32(m, 4H), 7.38(d, J=7.6 Hz, 4H), 7.58(d, J=6.8 Hz, 4H), 7.72 - 7.75(m, 2H), 7.77 - 7.82(m, 2H), 8.15(d, J=7.2 Hz, 2H); 13 13C NMR(CDCl3, 100 MHz) δ: 68.4, 69.7, 77.9, 120.8, 124.9, 125.1, 126.0, 126.7(d, J CF =43.2 Hz), 127.6, 127.7, 137.0, 138.4, 138.6, 143.4(d, J CF =253.4 Hz), 153.8; HRMS(ESI - TOF) m / z: Calcd. For C 52 H 34 F 10 N6NaO4S2[M + Na] + : 1083.1811; Found: 1083.1811。

[0037] Bpy - Bisulidine - 8: Pale yellow solid, yield 57%, >20:1 dr; Results of nuclear magnetic resonance and high - resolution mass spectrometry tests are as follows: 11H NMR (CDCl3, 400 MHz) δ: 2.58 (s, 6H), 4.56 (d, J = 5.6 Hz, 2H), 4.99 (d, J = 5.6 Hz, 2H), 6.00 (s, 2H), 7.20 - 7.21 (m, 6H), 7.25 - 7.39 (m, 14H), 7.74 (d, J = 7.6 Hz, 2H), 7.83 - 7.86 (m, 2H), 8.36 (d, J = 7.2 Hz, 2H); 13 13C NMR (CDCl3, 100 MHz) δ: 38.2, 69.2, 70.1, 76.9, 120.0, 123.1, 125.9, 126.3, 126.9, 127.2, 127.6, 127.8, 137.1, 137.8, 138.8, 154.3, 156.5; HRMS (ESI - TOF) m / z: Calcd. For C 42 H 41 N6O4S2 [M + H] + : 757.2621; Found: 757.2607.

[0038] Bpy - Bisulidine - 9: Pale yellow solid, yield 60%, >20:1 dr; The results of nuclear magnetic resonance and high - resolution mass spectrometry tests are as follows: 1 1H NMR (CDCl3, 400 MHz) δ: 2.33 (s, 6H), 3.69 (s, 6H), 3.70 (s, 6H), 4.31 (d, J = 6.0 Hz, 2H), 4.60 (d, J = 6.0 Hz, 2H), 5.88 (s, 2H), 6.65 - 6.70 (m, 8H), 6.91 (d, J = 8.4 Hz, 4H), 7.11 - 7.17 (m, 8H), 7.53 (d, J = 8.0 Hz, 4H), 7.78 - 7.86 (m, 4H), 8.22 (d, J = 7.2 Hz, 2H); 13 13C NMR (CDCl3, 100 MHz) δ: 20.5, 54.2, 54.3, 68.3, 70.3, 77.1, 112.7, 112.8, 119.7, 123.1, 126.9, 127.0, 127.5, 128.5, 130.0, 130.8, 133.5, 136.8, 142.7, 154.0, 157.1, 158.0, 158.1; HRMS (ESI - TOF) m / z: Calcd. For C 58 H 57 N6O8S2 [M + H] + : 1029.3675; Found: 1029.3682.

[0039] (2) Application of chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine) as a ligand in the asymmetric Friedel-Crafts alkylation reaction involving indole

[0040] The chiral bipyridine-bisulfonylated imidazoline ligand (Bpy-Bisulidine) of formula (1) in the present invention. This type of ligand contains a bipyridine group and an imidazoline group (the nitrogen groups of bipyridine and the tertiary amine nitrogen atom of imidazoline belong to electron-rich coordination sites, and the N-H of imidazoline can participate in hydrogen bonding), and can form a five-membered ring coordination with a Lewis metal, thereby generating a chiral ligand-metal complex for use in the asymmetric Friedel-Crafts alkylation reaction involving indole. It should be emphasized that the chiral ligand Bpy-Bisulidine of the present invention is not limited to being used as a chiral ligand only in the asymmetric Friedel-Crafts alkylation reaction involving indole.

[0041] Example 1: Application of chiral ligands Bpy-Bisulidine with various substituents in asymmetric catalytic reactions

[0042] To demonstrate the application value of the developed chiral ligand Bpy-Bisulidine in an asymmetric catalytic system, we selected the asymmetric Friedel-Crafts alkylation reaction involving indole 3a and α,β-unsaturated enone pyridine N-oxide 4a as the template reaction, and selected various substituted compounds Bpy-Bisulidine-1 to Bpy-Bisulidine-9 as chiral ligands to in-situ generate chiral complexes with the Lewis acid Ni(OTf)2 to verify the asymmetric catalytic effect of the chiral ligand Bpy-Bisulidine (Table 2).

[0043] Table 2 shows the application of chiral ligands Bpy-Bisulidine with various substituents in asymmetric catalytic reactions

[0044]

[0045] Experimental conclusion: The asymmetric Friedel-Crafts alkylation template reaction involving indole 3a and α,β-unsaturated enone pyridine N-oxide 4a was selected as the evaluation index. The experimental results showed that various substituted chiral ligands Bpy-Bisulidine-1 to Bpy-Bisulidine-9 of formula (1) showed excellent asymmetric catalytic effects in the asymmetric Friedel-Crafts alkylation reaction involving indole 3a and α,β-unsaturated enone pyridine N-oxide 4a, and could be developed into new dominant chiral bipyridine-bisulfonylated imidazoline ligands (Bpy-Bisulidine), which are worthy of further in-depth study.

[0046] Example 2: Application of Chiral Ligand Bpy - Bisulidine - 5 in Asymmetric Catalytic Reactions

[0047] To demonstrate the application value of the developed chiral ligand Bpy - Bisulidine - 5 in an asymmetric catalytic system, we selected the asymmetric Friedel - Crafts alkylation reaction involving indoles 3 with various substituents and α,β - unsaturated enone N - oxide pyridine 4 as the template reaction to verify the catalytic effect of the chiral ligand Bpy - Bisulidine - 5 (Table 3).

[0048] Table 3 shows the application of chiral ligand Bpy - Bisulidine - 5 in asymmetric catalytic reactions

[0049]

[0050] Experimental conclusion: The asymmetric Friedel - Crafts alkylation template reaction involving indoles 3 with various substituents and α,β - unsaturated enone N - oxide pyridine 4 was selected as the evaluation index. The experimental results showed that the chiral ligand Bpy - Bisulidine - 5 of formula (1) in - situ formed a chiral complex with Ni(OTf)2 and showed excellent asymmetric catalytic effects in the asymmetric Friedel - Crafts alkylation reactions involving indoles 3 with various substituents and α,β - unsaturated enone N - oxide pyridine 4, and it was capable of developing into a new dominant chiral ligand Bpy - Bisulidine, worthy of further in - depth research.

[0051] Example 3: Application of Chiral Ligand Bpy - Bisulidine - 2 in Asymmetric Catalytic Reactions

[0052] To demonstrate the application value of the developed chiral ligand Bpy - Bisulidine - 2 in an asymmetric catalytic system, we selected the asymmetric Friedel - Crafts alkylation reaction involving indoles 3 with various substituents and α,β - unsaturated enone imidazole 6 as the template reaction to verify the catalytic effect of the chiral ligand Bpy - Bisulidine - 2 (Table 4).

[0053] Table 4 shows the application of chiral ligand Bpy - Bisulidine - 2 in asymmetric catalytic reactions

[0054]

[0055] Experimental conclusion: The asymmetric Friedel-Crafts alkylation template reaction involving indole 3 with various substituents and α,β-unsaturated enone imidazole 6 was selected as the evaluation index. The experimental results showed that the chiral ligand Bpy-Bisulidine-2 shown in formula (1) in situ generated a chiral complex with Ni(OTf)2, which exhibited excellent asymmetric catalytic effects in the asymmetric Friedel-Crafts alkylation reactions involving indole 3 with various substituents and α,β-unsaturated enone imidazole 6, and it was worthy of further in-depth research to develop into a new dominant chiral ligand Bpy-Bisulidine.

Claims

1. A chiral bipyridine-bisulfonylated imidazoline ligand Bpy-Bisulidine, characterized in that: The compound has a structure shown in the general formula (I); In the formula, Ar is a benzene ring or a p-methoxybenzene ring; R is a benzene ring substituted by hydrogen / methyl / fluorine / trifluoromethyl / isopropyl or trimethyl. Among them, the chiral bipyridine-bisulfonylated imidazoline ligand Bpy-Bisulidine is specifically one of the following structural formulas:

2. A method for preparing the chiral bipyridine-bisulfonylated imidazoline ligand Bpy-Bisulidine as described in claim 1, characterized in that: The corresponding sulfonylated (R,R)-diphenylethylenediamine 1 reacts with bipyridine-dialdehyde 2 to form the target product chiral bipyridine-bisulfonylated imidazoline ligand Bpy-Bisulidine; The synthetic route is as follows:

3. Application of the chiral bipyridine-bisulfonylated imidazoline ligand Bpy-Bisulidine as claimed in claim 1 as a ligand in the asymmetric Friedel-Crafts alkylation reaction involving indole.

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