Method for catalyzing nitrile compound hydroboration reaction

Abstract

The invention provides a method for catalyzing the hydroboration reaction of nitrile compounds, which belongs to the technical field of nitrile reduction, the nitrile compounds are used as a substrate, molybdenum hexacarbonyl is used as a catalyst, pinacolborane is used as a hydrogen source, and the hydroboration reaction is carried out at 78-82 DEG C for 7.5-8.5 hours. Molybdenum hexacarbonyl is used as a catalyst in the reaction and is simple and easy to obtain, complex synthesis is not needed, and in addition, ligand participation is not needed in the reaction process; according to the method, pinacolborane is used as a hydrogen source, the reaction process does not need strict nitrogen protection experiment conditions, the nitrile hydroboration is realized, the substrate application range is wide, and the reaction is not only suitable for aromatic nitrile, but also suitable for fatty nitrile and even some dinitrile; in the reaction process, no solvent is needed, and the method is environment-friendly; after the reaction is finished, a corresponding hydroboration product can be obtained without further purification, and the reaction yield is high and is 84-100%.

Description

TECHNICAL FIELD

[0001] The application relates to a method for catalyzing the borohydration reaction of nitrile compounds and belongs to the technical field of nitrile reduction. BACKGROUND

[0002] The reduction of nitrile compounds into primary amines is an important method for synthesizing amines. Since nitrile compounds have a high carbon-nitrogen bond dissociation energy (750.0 kJ / mol), they are difficult to be reduced under conventional reaction conditions and often need the participation of catalysts. The hydrogenation reaction of nitriles can selectively generate primary amines, but the reaction requires high temperature and high pressure conditions, and imines, secondary amines, tertiary amines and other by-products may be generated in the reaction process. Therefore, it has always been a research difficulty to obtain primary amines by catalyzing the reduction of nitriles under mild reaction conditions. The silicon hydride and borohydration reactions of nitriles generate amine derivatives, and the reaction conditions are mild and the selectivity is high, so they are more and more favored by scientists. For nitrile compounds, the silicon hydride reaction can generate imine with single silane substitution and primary amine with double silane substitution. Compared with the silicon hydride reaction, the borohydration reaction has greater advantages in chemical selectivity, and therefore has been widely studied (J. Org. Chem., 2016, 81, 11153-11161.).

[0003] In the prior art, transition metal is used to catalyze the borohydration of nitrile compounds. For example, noble metal Ru and transition metals Fe, Co, Ni, Mo and Mn are successfully used for the borohydration reaction of nitrile compounds (Org. Biomol. Chem., 2022, 20, 3675-3702). However, these metal catalysts often need one-step or multi-step synthesis. Although the commercially available Ni(acac) can catalyze the borohydration of nitriles, a more active borane (catechol borane) is needed as the hydrogen source (Catal. Sci. Technol., 2017, 7, 3196-3199.).

[0004] There are few reports about the sixth group metal compound catalyzing the borohydration of nitriles. In 2012, Nikonov's group synthesized a tetravalent molybdenum compound Mo(PMe3)3NArHCl, which was used as a catalyst for the borohydration reaction of nitriles (Chem. Commun. 2012, 48(3), 455-457.). This is the first report about the borohydration of nitriles, which shows that molybdenum has high potential in the field of catalyzing the borohydration of nitriles. However, the catalytic system can only catalyze the reaction of acetonitrile or benzonitrile with catechol borane to generate boron amine compounds, and the substrate application range is limited; the synthesis of the catalyst is complex and needs more than three-step synthesis route; the catalyst contains multiple phosphorus ligands, which can easily cause environmental pollution; and the catalyst is sensitive to air and is not easy to store, and the reaction needs strict anhydrous and anaerobic conditions.

[0005] A W(CO)4(NCMe)2 / HBPin system based on tungsten chemistry was reported by Professor Song Heng's research group at Jiangsu University of Science and Technology (Chem. Commun., 2024, 60, 5026.). The catalytic system is sensitive to air, and the experimental operation generally requires nitrogen protection, and the catalyst also needs to be synthesized. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a method for catalyzing the borohydration reaction of nitrile compounds, using molybdenum hexacarbonyl as a catalyst, which is stable to air, pinacol borane as a hydrogen source, and the reaction process does not require strict anhydrous and oxygen-free experimental conditions, and does not require a solvent, to achieve the selective reduction of nitrile compounds to generate primary amine compounds substituted with diborane.

[0007] To solve the above technical problems, the present application adopts the following technical solutions: A method for catalyzing the borohydration reaction of nitrile compounds, using nitrile compounds as substrates, molybdenum hexacarbonyl as a catalyst, and pinacol borane as a hydrogen source, borohydration reaction at 78-82℃ for 7.5-8.5h.

[0008] The molar ratio of molybdenum hexacarbonyl to nitrile compounds is 1-2:20, and the molar ratio of nitrile compounds to pinacol borane is 1:3-6.

[0009] The nitrile compound is one of p-methylbenzonitrile, benzonitrile, m-methylbenzonitrile, o-methylbenzonitrile, p-fluorobenzonitrile, p-chlorobenzonitrile, p-bromobenzonitrile, p-iodobenzonitrile, p-trifluoromethylbenzonitrile, p-methoxybenzonitrile, p-tert-butylbenzonitrile, p-fluorophenylacetonitrile, p-phenyldinitrile, 2-cyano furan, 2-cyano thiophene, cyclohexyl cyanide, acetonitrile.

[0010] The borohydration product corresponding to the above nitrile compound is N, N-diborane p-methylphenethylamine, N, N-diborane phenethylamine, N, N-diborane m-methylphenethylamine, N, N-diborane o-methylphenethylamine, N, N-diborane p-fluorophenethylamine, N, N-diborane p-chlorophenethylamine, N, N-diborane p-bromophenethylamine, N, N-diborane p-iodophenethylamine, N, N-diborane p-trifluoromethylphenethylamine, N, N-diborane p-methoxyphenethylamine, N, N-diborane p-tert-butylphenethylamine, N, N-diborane p-fluorophenylpropylamine, N, N-diborane p-phenyldiethylamine, N, N-diborane-2-furanethylamine, N, N-diborane-2-thiopheneethylamine, N, N-diborane cyclohexyl ethylamine, N, N-diborane ethylamine.

[0011] Compared with the prior art, the present application has the following beneficial effects: The reaction of the application adopts molybdenum hexacarbonyl as a catalyst, is simple and easy to obtain, does not need to go through a complex synthesis, and in addition, a ligand is not needed in the reaction process.

[0012] The application uses pinacol borane as a hydrogen source, and the reaction process does not need strict anhydrous and oxygen-free experimental conditions, realizes the borohydration of nitrile, and the substrate has a wide application range, the reaction is not only suitable for aromatic nitrile, but also suitable for aliphatic nitrile and even some dinitrile, and has good functional group compatibility for different substituents such as halogen, methoxy, alkyl, trifluoromethyl and the like.

[0013] The reaction process of the application does not need a solvent, is environment-friendly, the corresponding borohydration product can be obtained without further purification after the reaction, the reaction yield is high, and the yield is 84-100%. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a nuclear magnetic hydrogen spectrum diagram of the borohydration product of example 3; Figure 2 It is a nuclear magnetic carbon spectrum diagram of the borohydration product of example 3; Figure 3 It is a nuclear magnetic hydrogen spectrum diagram of the borohydration product of example 11; Figure 4 It is a nuclear magnetic carbon spectrum diagram of the borohydration product of example 11; Figure 5 It is a nuclear magnetic hydrogen spectrum diagram of the borohydration product of example 12; Figure 6 It is a nuclear magnetic carbon spectrum diagram of the borohydration product of example 12; Figure 7 It is a nuclear magnetic hydrogen spectrum diagram of the borohydration product of example 13; Figure 8 It is a nuclear magnetic carbon spectrum diagram of the borohydration product of example 13; Figure 9 It is a nuclear magnetic hydrogen spectrum diagram of the borohydration product of example 14; Figure 10 It is a nuclear magnetic carbon spectrum diagram of the borohydration product of example 14; Figure 11 It is a nuclear magnetic hydrogen spectrum diagram of the borohydration product of example 15; Figure 12 It is a nuclear magnetic carbon spectrum diagram of the borohydration product of example 15; Figure 13 It is a nuclear magnetic hydrogen spectrum diagram of the borohydration product of example 16; Figure 14 It is a nuclear magnetic carbon spectrum diagram of the borohydration product of example 16; Figure 15 It is a nuclear magnetic hydrogen spectrum diagram of the borohydration product of example 17; Figure 16NMR carbon spectrum of the borohydride product of Example 17; Figure 17 NMR hydrogen spectrum of the borohydride product of Example 18; Figure 18 NMR carbon spectrum of the borohydride product of Example 18; Figure 19 NMR hydrogen spectrum of the borohydride product of Example 19; Figure 20 NMR carbon spectrum of the borohydride product of Example 19; Figure 21 NMR hydrogen spectrum of the borohydride product of Example 20; Figure 22 NMR carbon spectrum of the borohydride product of Example 20; Figure 23 NMR hydrogen spectrum of the borohydride product of Example 21; Figure 24 NMR carbon spectrum of the borohydride product of Example 21; Figure 25 NMR hydrogen spectrum of the borohydride product of Example 22; Figure 26 NMR carbon spectrum of the borohydride product of Example 22; Figure 27 NMR hydrogen spectrum of the borohydride product of Example 23; Figure 28 NMR carbon spectrum of the borohydride product of Example 23; Figure 29 NMR hydrogen spectrum of the borohydride product of Example 24; Figure 30 NMR carbon spectrum of the borohydride product of Example 24; Figure 31 NMR hydrogen spectrum of the borohydride product of Example 25; Figure 32 NMR carbon spectrum of the borohydride product of Example 25; Figure 33 NMR hydrogen spectrum of the borohydride product of Example 26; Figure 34 NMR carbon spectrum of the borohydride product of Example 26. DETAILED DESCRIPTION

[0015] Example 1 To a 5 mL reaction tube was added p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 30 °C for 8 hours. Reaction work-up: To the reaction was added tetraethylsilane (75 μL, 0.4 mmol) as an internal standard, followed by 0.6 mL of deuterated chloroform, the reaction was dissolved and mixed well, transferred to an NMR tube and analyzed by NMR. The NMR yield of the borohydration product was less than 5%.

[0016] Example 2 To a 5 mL reaction tube was added p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 50 °C for 8 hours. Reaction work-up: To the reaction was added tetraethylsilane (75 μL, 0.4 mmol) as an internal standard, followed by 0.6 mL of deuterated chloroform, the reaction was dissolved and mixed well, transferred to an NMR tube and analyzed by NMR. The NMR yield of the borohydration product was 78%.

[0017] Example 3 To a 5 mL reaction tube was added p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction was added tetraethylsilane (75 μL, 0.4 mmol) as an internal standard, followed by 0.6 mL of deuterated chloroform, the reaction was dissolved and mixed well, transferred to an NMR tube and analyzed by NMR. The NMR yield of the borohydration product was 99%.

[0018] Figure 1 The NMR hydrogen spectrum of the target product N,N-diborane-p-tolyl- ethylamine obtained in this Example 3 is shown below, Figure 2 The NMR carbon spectrum of the target product obtained in this Example 3 is shown below. Figure 1 and Figure 2 It can be seen that the structure of the product is correct.

[0019] 1 H NMR (400 MHz, CDCl3) δ 7.19 (d, J = 7.4 Hz, 2H), 7.03 (d, J = 7.5 Hz,2H), 4.18 (s, 2H), 2.28 (s, 3H), 1.19 (s, 24H). 13C NMR (101 MHz, CDCl3) δ 140.12 (s), 135.36 (s), 128.49 (s), 127.50 (s), 82.24 (s), 46.93 (s), 24.51(s), 21.04 (s). In combination with Examples 1-3, it is found that the borohydration reaction is almost impossible to occur at 30°C, and the yield of the reaction increases with the increase of temperature, and 80°C is the optimal reaction temperature.

[0020] Example 4 Into a 5 mL reaction tube, p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%) were added, 0.5 mL of tetrahydrofuran was used as solvent, and the mixture was heated at 80°C for 8 hours. After the reaction, the solvent was removed under reduced pressure, tetraethylsilane (75 μL, 0.4 mmol) was directly added into the reaction tube as an internal standard, then 0.6 mL of deuterated chloroform was added, the reaction was dissolved and mixed uniformly, and then transferred into a NMR tube for NMR analysis. Finally, it was found that the NMR yield of the reaction was 81%.

[0021] Example 5 Into a 5 mL reaction tube, p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%) were added, 0.5 mL of tetrahydrofuran was used as solvent, and the mixture was heated at 80°C for 8 hours. After the reaction, the solvent was removed under reduced pressure, tetraethylsilane (75 μL, 0.4 mmol) was directly added into the reaction tube as an internal standard, then 0.6 mL of deuterated chloroform was added, the reaction was dissolved and mixed uniformly, and then transferred into a NMR tube for NMR analysis. Finally, it was found that the NMR yield of the reaction was 81%.

[0022] In combination with Examples 3-5, it can be seen that the optimal condition of the reaction is without solvent, and although the yield is medium to high when tetrahydrofuran or dichloromethane is used as solvent, the solvent needs to be removed after the reaction.

[0023] Example 6 Into a 5 mL reaction tube, p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%) were added, 0.5 mL of tetrahydrofuran was used as solvent, and the mixture was heated at 80°C for 8 hours. After the reaction, the solvent was removed under reduced pressure, tetraethylsilane (75 μL, 0.4 mmol) was directly added into the reaction tube as an internal standard, then 0.6 mL of deuterated chloroform was added, the reaction was dissolved and mixed uniformly, and then transferred into a NMR tube for NMR analysis. Finally, it was found that the NMR yield of the reaction was 81%.

[0024] Example 7 Into a 5 mL reaction tube, p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Cr(CO)6(4.4 mg, 5 mol%) were added, heated at 80 °C for 8 hours. Reaction work-up: tetraethylsilane (75 μL, 0.4 mmol) was added directly into the reaction tube as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed uniformly, moved into a NMR tube, and analyzed by NMR. The NMR yield of the borohydration product of the reaction was 60%.

[0025] In combination with Examples 3, 6, and 7, the catalytic effect of hexacarbonylmolybdenum was significantly improved compared with the metal carbonyl compounds of the same group as molybdenum, tungsten hexacarbonyl or chromium hexacarbonyl.

[0026] Example 8 Into a 5 mL reaction tube, p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and molybdenum acetylacetonate (6.6 mg, 5 mol%) were added, heated at 80 °C for 8 hours. Reaction work-up: tetraethylsilane (75 μL, 0.4 mmol) was added directly into the reaction tube as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed uniformly, moved into a NMR tube, and analyzed by NMR. The NMR yield of the product was 21%.

[0027] Example 9 Into a 5 mL reaction tube, p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and molybdenum dioxide (2.5 mg, 5 mol%) were added, heated at 80 °C for 8 hours. Reaction work-up: tetraethylsilane (75 μL, 0.4 mmol) was added directly into the reaction tube as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed uniformly, moved into a NMR tube, and analyzed by NMR. The NMR yield of the product was 10%.

[0028] Example 10 Into a 5 mL reaction tube, p-tolunitrile (48 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and sodium molybdate (4.1 mg, 5 mol%) were added, heated at 80 °C for 8 hours. Reaction work-up: tetraethylsilane (75 μL, 0.4 mmol) was added directly into the reaction tube as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed uniformly, moved into a NMR tube, and analyzed by NMR. The NMR yield of the product was 19%.

[0029] In combination with Examples 3, 8, 9, 10, when different valence state molybdenum compounds (tetravalent molybdenum, hexavalent molybdenum) are used as catalysts, the reaction effect of hexacarbonylmolybdenum is the best, which indicates that the molybdenum compound with low valence state is more conducive to the oxidative addition of pinacol borane and metal center.

[0030] The product prepared in Example 1-10 is N, N-diborane p-methylphenethylamine.

[0031] In combination with Examples 1-10, the best reaction condition for catalyzing the nitrile borohydration reaction is: 5 mol% Mo(CO)6 as catalyst, 1.2 mmol HBpin is added, 80°C, solvent-free reaction for 8h.

[0032] Example 11 Into a 5 mL reaction tube, benzyl cyanide (41 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6 (5.3 mg, 5 mol%) are added, and heated at 80°C for 8 hours. After reaction, tetraethylsilane (75 μL, 0.4 mmol) is directly added to the reaction solution as an internal standard, then 0.6 mL of deuterated chloroform is added, the reaction is dissolved and mixed uniformly, and then transferred into a nuclear magnetic tube for nuclear magnetic analysis. Finally, the nuclear magnetic yield of the reaction is analyzed to be 96%.

[0033] Figure 3 The nuclear magnetic hydrogen spectrum of the target product N, N-diborane phenethylamine obtained in this Example 11 is shown as follows, Figure 4 The nuclear magnetic carbon spectrum of the target product obtained in this Example 11 is shown as follows. Figure 3 And Figure 4 It can be seen that the structure of the product is correct.

[0034] 1 H NMR (400 MHz, CDCl3) δ 7.29 (d, J = 7.3 Hz, 2H), 7.22 (t, J = 7.2 Hz,2H), 7.13 (t, J = 6.7 Hz, 1H), 4.23 (s, 2H), 1.20 (d, J = 11.6 Hz, 24H). 13 C NMR(101 MHz, CDCl3) δ 143.05 (s), 127.77 (s), 127.51 (s), 126.08 (s), 82.26 (s),47.26 (s), 24.50 (d, J = 5.1 Hz).

[0035] Example 12 Into a 5 mL reaction tube was added m-tolunitrile (46 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction mixture was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed well, moved into a NMR tube, and analyzed by NMR. The NMR yield of this reaction was 91% by analysis.

[0036] Figure 5 The NMR spectrum of the target product N, N-diborane-m-tolyl- ethylamine obtained in this example 12 is shown, Figure 6 The NMR spectrum of the target product obtained in this example 12 is shown. By Figure 5 and Figure 6 it can be known that the structure of the product is correct.

[0037] 1 H NMR (400 MHz, CDCl3) δ 7.17 – 7.03 (m, 3H), 6.95 (d, J = 6.4 Hz, 1H),4.20 (s, 2H), 2.29 (s, 3H), 1.19 (s, 23H). 13 C NMR (101 MHz, CDCl3) δ 142.96(s), 137.13 (s), 128.31 (s), 127.71 (s), 126.77 (s), 124.54 (s), 82.26 (s),47.14 (s), 24.49 (s), 21.37 (s).

[0038] Example 13 Into a 5 mL reaction tube was added o-tolunitrile (47 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction mixture was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed well, moved into a NMR tube, and analyzed by NMR. The NMR yield of this reaction was 90% by analysis.

[0039] Figure 7 The NMR spectrum of the target product N, N-diborane-o-tolyl- ethylamine obtained in this example 13 is shown, Figure 8 The NMR spectrum of the target product obtained in this example 13 is shown. By Figure 7 andFigure 8 The structure of the product was correct.

[0040] 1 H NMR (400 MHz, CDCl3) δ 7.02 (d, J = 7.3 Hz, 1H), 6.90 – 6.85 (m, 1H),6.84 (s, 2H), 4.01 (s, 2H), 2.08 (s, 3H),0.96 (s, 23H). 13 C NMR (101 MHz,CDCl3) δ 140.58 (s), 135.03 (s), 129.44 (s), 126.15 (s), 125.70 (s), 125.34(s), 82.19 (s), 44.73 (s), 24.83 (s), 24.43 (d, J = 12.2 Hz), 19.08 (s)。

[0041] Example 14 Into a 5 mL reaction tube was added p-fluorobenzonitrile (48 mg, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: directly added tetraethylsilane (75 μL, 0.4 mmol) as internal standard to the reaction, then added 0.6 mL deuterated chloroform, dissolved and mixed the reaction well, moved into a NMR tube, and analyzed by NMR. The final analysis showed that the NMR yield of this reaction was 100%.

[0042] Figure 9 The NMR hydrogen spectrum of the target product N, N-diborane p-fluorobenzene ethylamine obtained in this example 14 is shown, Figure 10 The NMR carbon spectrum of the target product obtained in this example 14 is shown. From Figure 9 and Figure 10 The structure of the product was correct.

[0043] 1 H NMR (400 MHz, CDCl3) δ 7.27 (t, J = 6.2 Hz, 2H), 6.91 (t, J = 8.1 Hz,2H), 4.17 (s, 2H), 1.22 (d, J = 19.0 Hz, 24H). 13C NMR (101 MHz, CDCl3) δ 162.74(s), 160.32 (s), 138.84 (d, J = 3.1 Hz), 129.18 (d, J = 7.9 Hz), 114.53 (s),114.32 (s), 82.31 (s), 46.56 (s), 24.45 (s)。

[0044] Example 15 Into a 5 mL reaction tube was added p-chlorobenzonitrile (55 mg, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction mixture was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed well, transferred into a NMR tube, and analyzed by NMR. The final analysis showed that the NMR yield of this reaction was 97%.

[0045] Figure 11 The NMR hydrogen spectrum of the target product N, N-diborane p-chloro-phenethylamine obtained in this Example 15 is shown below: Figure 12 The NMR carbon spectrum of the target product obtained in this Example 15 is shown below. From the above Figure 11 and Figure 12 it can be seen that the structure of the product is correct.

[0046] 1 H NMR (400 MHz, CDCl3) δ 7.22 (dd, J = 17.5, 7.7 Hz, 4H), 4.18 (s, 2H),1.21 (d, J = 19.7 Hz, 24H). 13 C NMR (101 MHz, CDCl3) δ 141.59 (s), 131.77 (s),128.95 (s), 127.88 (s), 82.36 (s), 46.63 (s), 24.46 (s).

[0047] Example 16 Into a 5 mL reaction tube was added p-bromobenzonitrile (73 mg, 0.4 mmol), HBpin (175 μL, 1.2 mmol), Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction mixture was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then 0.6 mL of deuterated chloroform was added, the reaction was dissolved and mixed well, and then transferred into an NMR tube for NMR analysis. The final NMR yield of this reaction was 99.5% by analysis.

[0048] Figure 13 The NMR hydrogen spectrum of the target product N, N-diborane p-bromobenzeneethylamine obtained in this example 16 is shown, Figure 14 The NMR carbon spectrum of the target product obtained in this example 16 is shown. From Figure 13 and Figure 14 it can be known that the product structure is correct.

[0049] 1 H NMR (400 MHz, CDCl3) δ 7.35 (d, J = 7.7 Hz, 2H), 7.18 (d, J = 7.7 Hz,2H), 4.16 (s, 2H), 1.25 (s, 24H). 13 C NMR (101 MHz, CDCl3) δ 142.07 (s), 130.80(s), 129.30 (s), 119.81 (s), 82.31 (s), 46.63 (s), 24.45(d, J = 3.6 Hz)。

[0050] Example 17 Into a 5 mL reaction tube was added p-iodobenzonitrile (92 mg, 0.4 mmol), HBpin (175 μL, 1.2 mmol), and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction mixture was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then 0.6 mL of deuterated chloroform was added, the reaction was dissolved and mixed well, and then transferred into an NMR tube for NMR analysis. The final NMR yield of this reaction was 92% by analysis.

[0051] Figure 15 The NMR hydrogen spectrum of the target product N, N-diborane p-iodobenzeneethylamine obtained in this example 17 is shown, Figure 16 The NMR carbon spectrum of the target product obtained in this example 17 is shown. From Figure 15 and Figure 16 it can be known that the product structure is correct.

[0052] 1 H NMR (400 MHz, CDCl3) δ 7.58 (dd, J = 21.0, 7.5 Hz, 2H), 7.07 (t, J =11.2 Hz, 2H), 4.18 (d, J = 22.9 Hz, 2H), 1.21 (d, J = 20.1 Hz, 24H). 13 C NMR (101MHz, CDCl3) δ 142.75 (s), 136.84 (s), 129.62 (s), 91.32 (s), 82.37 (s), 46.75(s), 24.51(d, J = 3.9 Hz)。

[0053] In combination with Examples 14-17, the reaction system has good functional group compatibility for halogen, and can obtain the corresponding borohydride product for F, Cl, Br and I with a yield of more than 90%.

[0054] Example 18 Into a 5 mL reaction tube, p-trifluoromethylbenzonitrile (53 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%) were added, and heated at 80°C for 8 hours. After reaction, tetraethylsilane (75 μL, 0.4 mmol) was directly added into the reaction solution as an internal standard, then 0.6 mL of deuterated chloroform was added, the reaction was dissolved and mixed uniformly, and then transferred into a nuclear magnetic tube for nuclear magnetic analysis. Finally, the nuclear magnetic yield of the reaction was analyzed to be 100%.

[0055] Figure 17 The nuclear magnetic hydrogen spectrum of the target product N, N-diborane p-trifluoromethyl benzene ethylamine obtained in this Example 18 is shown as follows: Figure 18 The nuclear magnetic carbon spectrum of the target product obtained in this Example 18 is shown as follows. It can be known from Figure 17 and Figure 18 that the product structure is correct.

[0056] 1 H NMR (400 MHz, CDCl3) δ 7.50 (d, J = 7.7 Hz, 2H), 7.41 (d, J = 7.8 Hz,2H), 4.28 (s, 2H), 1.19 (s, 25H). 13C NMR (101 MHz, CDCl3) δ 147.12 (s),127.63 (s), 124.74 (d, J = 3.8 Hz), 82.46 (s), 46.96 (s), 24.43 (d, J = 5.0 Hz)。

[0057] Example 19 Into a 5 mL reaction tube was added p-methoxybenzonitrile (54 mg, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: directly added tetraethylsilane (75 μL, 0.4 mmol) as internal standard to the reaction, then added 0.6 mL deuterated chloroform, dissolved and mixed the reaction well, moved into a NMR tube, and analyzed by NMR. The final analysis showed that the NMR yield of this reaction was 99.5%.

[0058] Figure 19 The NMR hydrogen spectrum of the target product N, N-diborane p-methoxyphenethylamine obtained in this example 19 is shown below, Figure 20 The NMR carbon spectrum of the target product obtained in this example 19 is shown below. From Figure 19 and Figure 20 it can be known that the product structure is correct.

[0059] 1 H NMR (400 MHz, CDCl3) δ 7.01 (d, J = 7.9 Hz, 2H), 6.53 (d, J = 7.9 Hz,2H), 3.92 (s, 2H), 3.50 (s, 3H), 0.98 (d, J = 10.6 Hz, 24H). 13 C NMR (101 MHz,CDCl3) δ 158.05 (s), 135.32 (s), 128.76 (s), 113.06 (s), 82.07 (s), 54.87(s), 46.50 (s), 24.42 (s).

[0060] Example 20 To a 5 mL reaction tube was added p-tert-butylbenzonitrile (64 mg, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed well, transferred to an NMR tube, and analyzed by NMR. The final analysis showed that the NMR yield of this reaction was 95%.

[0061] Figure 21 The NMR hydrogen spectrum of the target product N, N-diborane p-tert-butylphenethylamine obtained in this example 20 is shown, Figure 22 The NMR carbon spectrum of the target product obtained in this example 19 is shown. From Figure 21 and Figure 22 it can be seen that the structure of the product is correct.

[0062] 1 H NMR (400 MHz, CDCl3) δ 7.24 (s, 4H), 4.19 (s, 2H), 1.29 (s, 12H),1.20 (d, J = 10.5 Hz, 25H). 13 C NMR (101 MHz, CDCl3) δ 148.70 (s), 140.10 (s),127.38 (s), 124.58 (s), 83.05 (d, J = 17.4 Hz), 82.17 (s), 46.85 (s), 34.29(s), 31.42 (s), 24.86 (s), 24.51 (d, J = 2.3 Hz)。

[0063] Example 21 To a 5 mL reaction tube was added p-tert-butylbenzonitrile (64 mg, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed well, transferred to an NMR tube, and analyzed by NMR. The final analysis showed that the NMR yield of this reaction was 95%.

[0064] Figure 23 The NMR hydrogen spectrum of the target product N, N-diborane p-tert-butylphenethylamine obtained in this example 20 is shown, Figure 24The carbon NMR spectrum of the target product obtained in this example 21 is shown below. From Figure 23 and Figure 24 It can be seen that the structure of the product is correct.

[0065] 1 H NMR (400 MHz, CDCl3) δ 7.11 (s, 2H), 6.91 (t, J = 8.5 Hz, 2H), 3.27(t, J = 6.5 Hz, 2H), 2.67 (t, J = 6.4 Hz, 2H), 1.20 (d, J = 23.8 Hz, 23H). 13 C NMR(101 MHz, CDCl3) δ 162.57 (s), 160.15 (s), 130.58 (d, J = 7.7 Hz), 115.37 –114.73 (m), 114.55 (s), 82.95 (s), 82.00 (s), 45.09 (s), 38.43 (s), 24.42 (d, J = 9.2 Hz)。

[0066] Example 22 Into a 5 mL reaction tube, add terephthalonitrile (52 mg, 0.4 mmol), HBpin (350 μL, 2.4 mmol) and Mo(CO)6(10.6 mg, 10 mol%), heat at 80°C for 8 hours. After reaction, directly add tetraethylsilane (75 μL, 0.4 mmol) as internal standard into the reaction solution, then add 0.6 mL deuterated chloroform, dissolve and mix the reaction well, move into a NMR tube, and perform NMR analysis. Finally, the NMR yield of this reaction is 87.5% by analysis.

[0067] Figure 25 The hydrogen NMR spectrum of the target product N, N-diborane p-phenylenediamine obtained in this example 22 is shown below. Figure 26 The carbon NMR spectrum of the target product obtained in this example 22 is shown below. From Figure 25 and Figure 26 It can be seen that the structure of the product is correct.

[0068] 1 H NMR (400 MHz, CDCl3) δ 7.08 (s, 4H), 4.09 (s, 3H), 1.10 (s, 41H). 13C NMR (101 MHz, CDCl3) δ 140.66 (s), 126.84 (s), 82.88 (s), 82.81 - 81.66 (m), 46.84 (s), 24.44 (d, J = 6.3 Hz), 7.35 (s), 2.87 (s).

[0069] Example 23 Into a 5 mL reaction tube was added 2-cyanofuran (35 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction mixture was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then 0.6 mL deuterated chloroform was added, the reaction was dissolved and mixed well, transferred into a NMR tube, and analyzed by NMR. The final analysis showed that the NMR yield of this reaction was 88%.

[0070] Figure 27 The NMR hydrogen spectrum of the target product N, N-diborane-2-furan ethylamine obtained in this example 23 is shown below: Figure 28 The NMR carbon spectrum of the target product obtained in this example 23 is shown below: Figure 27 And Figure 28 It can be seen that the structure of the product is correct.

[0071] 1 H NMR (400 MHz, CDCl3) δ 7.24 (s, 1H), 6.22 (s, 1H), 6.04 (s, 1H),4.19 (s, 2H), 1.21 (s, 23H). 13 C NMR (101 MHz, CDCl3) δ 156.45 (s), 140.65 (s),109.84 (s), 105.04 (s), 82.28 (s), 40.57 (s), 24.78 (s), 24.41 (d, J = 7.7 Hz).

[0072] Example 24 Into a 5 mL reaction tube was added 2-cyanothiophene (37 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction mixture was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then deuterated chloroform was added, the reaction was dissolved and mixed well, transferred into an NMR tube, and analyzed by NMR. The final NMR yield of this reaction was 100%.

[0073] Figure 29 The NMR spectrum of the target product N, N-diborane-2-thiopheneethylamine obtained in this example 24 is shown below, Figure 30 The NMR spectrum of the target product obtained in this example 24 is shown below. From Figure 29 and Figure 30 it can be seen that the structure of the product is correct.

[0074] 1 H NMR (400 MHz, CDCl3) δ 7.12 – 7.03 (m, 1H), 6.90 (s, 1H), 6.85 (d, J = 1.4 Hz, 1H), 4.36 (s, 2H), 1.22 (s, 25H). 13 C NMR (101 MHz, CDCl3) δ 146.72(s), 126.13 (s), 124.53 (s), 123.54 (s), 82.42 (s), 42.09 (s), 24.50 (s).

[0075] In combination with examples 23 and 24, it is shown that the reaction system has good compatibility for aromatic heterocyclic compounds such as furan and thiophene.

[0076] Example 25 Into a 5 mL reaction tube was added 2-cyanothiophene (37 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%), heated at 80 °C for 8 hours. Reaction work-up: To the reaction mixture was added tetraethylsilane (75 μL, 0.4 mmol) directly as an internal standard, then deuterated chloroform was added, the reaction was dissolved and mixed well, transferred into an NMR tube, and analyzed by NMR. The final NMR yield of this reaction was 100%.

[0077] Figure 31 The NMR spectrum of the target product N, N-diborane-2-thiopheneethylamine obtained in this example 24 is shown below, Figure 32The carbon NMR spectrum of the target product obtained in this Example 25 is shown below. Figure 31 and Figure 32 It can be seen that the structure of the product is correct.

[0078] 1 H NMR (400 MHz, CDCl3) δ 2.87 (d, J = 6.5 Hz, 2H), 1.66 (t, J = 14.4 Hz,5H), 1.24 (d, J = 21.6 Hz, 31H). 13 C NMR (101 MHz, CDCl3) δ 81.80 (s), 49.57 (s),40.44 (s), 30.46 (s), 26.70 (s), 26.08 (s), 24.75 (s), 24.38 (d, J = 7.5 Hz)。

[0079] Example 26 Into a 5 mL reaction tube, acetonitrile (21 μL, 0.4 mmol), HBpin (175 μL, 1.2 mmol) and Mo(CO)6(5.3 mg, 5 mol%) were added, and heated at 80°C for 8 hours. After reaction, tetraethylsilane (75 μL, 0.4 mmol) was directly added to the reaction solution as an internal standard, then deuterated chloroform was added, the reaction was dissolved and mixed uniformly, and then transferred into a NMR tube for NMR analysis. Finally, the NMR yield of this reaction was analyzed to be 99.2%.

[0080] Figure 33 The hydrogen NMR spectrum of the target product N, N-diborane ethylamine obtained in this Example 26 is shown below. Figure 34 The carbon NMR spectrum of the target product obtained in this Example 26 is shown below. Figure 33 and Figure 34 It can be seen that the structure of the product is correct.

[0081] 1 H NMR (400 MHz, CDCl3) δ 3.06 (d, J = 6.6 Hz, 2H), 1.22 (s, 24H), 1.02(t, J = 6.4 Hz, 3H). 13 C NMR (101 MHz, CDCl3) δ 81.81 (s), 38.42 (s), 24.39 (d, J =4.5 Hz), 18.51 (s).

[0082] In connection with examples 21, 25, 26, it is shown that the reaction system is equally applicable for aliphatic nitriles.

Claims

1. A method for catalyzing the hydroboration reaction of nitrile compounds, characterized in that: Using nitrile compounds as substrates, molybdenum hexacarbonyl as catalyst, and pinacolborane as hydrogen source, the hydroboration reaction was carried out at 78-82℃ for 7.5-8.5 h.

2. The method for catalyzing the hydroboration reaction of nitrile compounds according to claim 1, characterized in that: The molar ratio of hexacarbonylmolybdenum to nitrile compounds is 1-2:20, and the molar ratio of nitrile compounds to pinacolborane is 1:3-6.

3. The method for catalyzing the hydroboration reaction of nitrile compounds according to claim 1, characterized in that: The nitrile compound is one of the following: p-methylbenzonitrile, benzonitrile, m-methylbenzonitrile, o-methylbenzonitrile, p-fluorobenzonitrile, p-chlorobenzonitrile, p-bromobenzonitrile, p-iodobenzonitrile, p-trifluoromethylbenzonitrile, p-methoxybenzonitrile, p-tert-butylbenzonitrile, p-fluorophenylacetonitrile, p-phthalonitrile, 2-cyanofuran, 2-cyanothiophene, cyclohexylbenzonitrile, and acetonitrile.

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