Preparation method of NHC-boronized alkyne compound
By reacting ethynylbenzoxazolinone and nitrogen-containing carbene borane under blue LED irradiation, NHC-boryl alkynes are generated, solving the problems of harsh reaction conditions and high cost in existing technologies, and realizing a low-cost and environmentally friendly preparation method.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-04-10
AI Technical Summary
In the prior art, no method has been reported for generating NHC-boryl alkynes by reacting NHC-borane with ethynylbenzoxazolinone, and the existing methods have relatively harsh reaction conditions and high costs.
Using ethynylbenzoxazolinone compounds and nitrogen-containing heterocyclic carbene borane compounds as raw materials, 4-CzIPN as a photocatalyst, and Cs2CO3 as a base, the reaction is carried out in acetonitrile solvent under blue LED irradiation to generate NHC-boryl alkyne compounds.
A mild reaction condition and low-cost preparation of NHC-boryl alkynes were achieved, which is simple to operate, environmentally friendly, and yields high efficiency.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of synthesis of organic boron compounds, and particularly relates to a preparation method of NHC-borylated alkyne compounds. BACKGROUND
[0002] Organic boron compounds have important application value in medicinal chemistry and synthetic chemistry as well as material science, especially in the emerging boron neutron capture therapy (BNCT) in recent years, one of the key technologies of which is the research and development of boron-containing drugs. At present, the NHC-borane radical reaction mainly focuses on the borylation of electron-deficient olefins, the defluorination-borylation of fluorine-containing compounds, the dehalogenation of halogenated alkanes and the borylation-cyclization of unsaturated bonds. Among them, the borylation of electron-deficient olefins with NHC-borane has been studied more. However, there is no report on the reaction of NHC-borane and ethynyl benzoxazolinone to generate NHC-borylated alkyne compounds.
[0003] The literature (Wu, X., et al. Visible-Light-Mediated Radical trans-Hydroboration of Alkynes with NHCBorane. J. Org. Chem., 2025, 90, 658-662) first reported the realization of radical trans-hydroboration of alkyne with NHC-BH3 through photocatalysis, and finally generated products containing NHC-BH2-C=CAr structure, which was compatible with terminal alkyne / inner alkyne and could be used for biomolecule modification.
[0004] In view of the important role and outstanding development prospect of organic boron compounds in various fields, the development of new and efficient methods for synthesizing organic boron compounds is still the focus and frontier of boron chemistry research. SUMMARY
[0005] The technical problem solved by the application is to provide a preparation method of NHC-borylated alkyne compounds with mild reaction conditions and low cost.
[0006] To solve the above technical problems, the application adopts the following technical solution: a preparation method of NHC-borylated alkyne compounds, the specific preparation process of which is as follows: ethynyl benzoxazolinone compounds and NHC-borane compounds are used as reaction raw materials, 4-CzIPN is used as a photocatalyst, Cs2CO3 is used as a base, acetonitrile is used as a solvent, the reaction is carried out under blue light LED irradiation and nitrogen atmosphere, and finally the target product NHC-borylated alkyne compound is obtained. The synthesis route of the preparation process is as follows:
[0007]
[0008] wherein the substituent Ar is phenyl, substituted phenyl, naphthyl, thienyl or pyridyl, the substituted phenyl is fluoro, chloro, bromo, C 1-6 alkyl, acetonide, methoxy, acetonitrile or trifluoromethyl, the substituent R is C 1-6 alkyl or benzyl;
[0009] The structural formula of the photocatalyst 4-CzIPN is as follows:
[0010]
[0011] In the above preparation method, the substituent R is one or more of methyl, ethyl, propyl, isopropyl, n-butyl or benzyl.
[0012] In the above preparation method, the ethynyl benzoxazolinone compound and the azaheterocyclic carbene borane compound are magnetically stirred in acetonitrile solvent at 500 revolutions / min.
[0013] In the above preparation method, the molar ratio of the ethynyl benzoxazolinone compound to the azaheterocyclic carbene borane compound is 1:1-1:3. The optimal molar ratio is 1:1.5.
[0014] Compared with the prior art, the present application has the following advantages and beneficial effects: a series of NHC-boronized acetylene compounds are synthesized, and the synthesis process has the advantages of mild reaction conditions, low cost, simple operation and environmental friendliness. DETAILED DESCRIPTION
[0015] The above content of the present application is further described in detail through the following examples, but this should not be understood as limiting the scope of the above subject matter of the present application to only the following examples. Any technology realized based on the above content of the present application belongs to the scope of the present application.
[0016] Example 1
[0017] The following ingredients were weighed: (70mg, 0.2mmol), azaheterocyclic carbene borane (33mg, 0.3mmol), photocatalyst 4-CzIPN (3.2mg, 0.004mmol) and base Cs2CO3 (130mg, 0.4mmol) were added to the reaction bottle, replaced with nitrogen three times, and MeCN (2mL) was added with a syringe. The reaction bottle was placed under blue light LEDs and reacted at room temperature for 24h. After the reaction was completed, 10mL of water was added, extracted with DCM (3x 15mL), allowed to stand, the lower layer was poured out, the organic phase was combined, the organic phase was dried with anhydrous sodium sulfate, the organic phase was evaporated, and the dry sample was loaded and column chromatographed (petroleum ether: ethyl acetate = 10:1-1:1, v / v) to obtain the target product 36mg, yield 86%.
[0018] Example 2
[0019] Weighed (73 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photo- catalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), let stand, separated layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 38 mg, yield 83%.
[0020] Example 3
[0021] Weighed (73 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photo- catalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), let stand, separated layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 39 mg, yield 80%.
[0022] Example 4
[0023] Weighed (73 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photo- catalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), let stand, separated layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 42 mg. Yield: 73%.
[0024] Example 5
[0025] Weigh (72 mg, 0.2 mmol), azahexacyclic carbene borane (33 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol), and base Cs₂CO₃ (130 mg, 0.4 mmol) were added to the reaction flask, and nitrogen was purged three times. MeCN (2 mL) was added using a syringe. The reaction flask was placed under blue LEDs and reacted at room temperature for 24 h. After the reaction was complete, 10 mL of water was added, and the mixture was extracted with DCM (3 x 15 mL). The mixture was allowed to stand, and the layers were separated. The lower organic phase was poured off, and the two organic phases were combined. The organic phases were dried over anhydrous sodium sulfate, evaporated to dryness, and then loaded onto a dry column for column chromatography (petroleum ether: ethyl acetate = 10:1–1:1, v / v) to obtain the desired product. 34mg, yield 76%.
[0026] Example 6
[0027] Weigh (81 mg, 0.2 mmol), azahexacyclic carbene borane (33 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol), and base Cs₂CO₃ (130 mg, 0.4 mmol) were added to the reaction flask, and nitrogen was purged three times. MeCN (2 mL) was added using a syringe. The reaction flask was placed under blue LEDs and reacted at room temperature for 24 h. After the reaction was complete, 10 mL of water was added, and the mixture was extracted with DCM (3 x 15 mL). The mixture was allowed to stand, and the layers were separated. The lower organic phase was poured off, and the two organic phases were combined. The organic phases were dried over anhydrous sodium sulfate, evaporated to dryness, and then loaded onto a dry column for column chromatography (petroleum ether: ethyl acetate = 10:1–1:1, v / v) to obtain the desired product. 48mg, yield 90%.
[0028] Example 7
[0029] Weigh (78 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), allowed to stand, separated the layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 28 mg, yield 56%.
[0030] Example 8
[0031] weighed (78 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), allowed to stand, separated the layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 39 mg, yield 81%.
[0032] Example 9
[0033] weighed (78 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), allowed to stand, separated the layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 28 mg, yield 60%.
[0034] Example 10
[0035] Weighed (83mg, 0.2mmol), N-heterocyclic carbene borane (33mg, 0.3mmol), photocatalyst 4-CzIPN (3.2mg, 0.004mmol) and base Cs2CO3 (130mg, 0.4mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24h. After the reaction was completed, 10mL water was added, extracted with DCM (3x 15mL), let stand, separate layers, pour out the lower organic phase, combine the organic phase, dry the organic phase with anhydrous sodium sulfate, evaporate the organic phase, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 36mg, yield 65%.
[0036] Example 11
[0037] Weighed (72mg, 0.2mmol), N-heterocyclic carbene borane (33mg, 0.3mmol), photocatalyst 4-CzIPN (3.2mg, 0.004mmol) and base Cs2CO3 (130mg, 0.4mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24h. After the reaction was completed, 10mL water was added, extracted with DCM (3x 15mL), let stand, separate layers, pour out the lower organic phase, combine the organic phase, dry the organic phase with anhydrous sodium sulfate, evaporate the organic phase, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 27mg, yield 60%.
[0038] Example 12
[0039] Weighed (76mg, 0.2mmol), N-heterocyclic carbene borane (33mg, 0.3mmol), photocatalyst 4-CzIPN (3.2mg, 0.004mmol) and base Cs2CO3 (130mg, 0.4mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24h. After the reaction was completed, 10mL water was added, extracted with DCM (3x 15mL), let stand, separate layers, pour out the lower organic phase, combine the organic phase, dry the organic phase with anhydrous sodium sulfate, evaporate the organic phase, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 27mg, yield 55%.
[0040] Example 13
[0041] weighed (75mg, 0.2mmol), N-heterocyclic carbene borane (33mg, 0.3mmol), photocatalyst 4-CzIPN (3.2mg, 0.004mmol) and base Cs2CO3 (130mg, 0.4mmol) were added into the reaction vial, purged with nitrogen for three times, MeCN (2mL) was added by syringe. The reaction vial was placed under blue LEDs, reacted at room temperature for 24h. After the reaction was completed, 10mL water was added, extracted with DCM (3x 15mL), let stand, separate layers, pour out the lower organic phase, combine the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 38mg, yield 80%.
[0042] Example 14
[0043] weighed (75mg, 0.2mmol), N-heterocyclic carbene borane (33mg, 0.3mmol), photocatalyst 4-CzIPN (3.2mg, 0.004mmol) and base Cs2CO3 (130mg, 0.4mmol) were added into the reaction vial, purged with nitrogen for three times, MeCN (2mL) was added by syringe. The reaction vial was placed under blue LEDs, reacted at room temperature for 24h. After the reaction was completed, 10mL water was added, extracted with DCM (3x 15mL), let stand, separate layers, pour out the lower organic phase, combine the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 39mg, yield 70%.
[0044] Example 15
[0045] weighed (75mg, 0.2mmol), N-heterocyclic carbene borane (33mg, 0.3mmol), photocatalyst 4-CzIPN (3.2mg, 0.004mmol) and base Cs2CO3 (130mg, 0.4mmol) were added into the reaction vial, purged with nitrogen for three times, MeCN (2mL) was added by syringe. The reaction vial was placed under blue LEDs, reacted at room temperature for 24h. After the reaction was completed, 10mL water was added, extracted with DCM (3x 15mL), let stand, separate layers, pour out the lower organic phase, combine the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 45mg, yield 87%.
[0046] Example 16
[0047] Weighed (71 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photo- catalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL water was added, extracted with DCM (3 x 15 mL), let stand, separated layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 23 mg, yield 53%.
[0048] Example 17
[0049] Weighed (71 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photo- catalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL water was added, extracted with DCM (3 x 15 mL), let stand, separated layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 21 mg, yield 50%.
[0050] Example 18
[0051] Weighed (71 mg, 0.2 mmol), N-heterocyclic carbene borane (33 mg, 0.3 mmol), photo- catalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL water was added, extracted with DCM (3 x 15 mL), let stand, separated layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 34 mg, 76% yield.
[0052] Example 19
[0053] Weighed (70 mg, 0.2 mmol), N-heterocyclic carbene borane (42 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2C03(130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), let stand, separated layers, pour out the lower organic phase, combine the organic phase, dry the organic phase with anhydrous sodium sulfate, evaporate the organic phase, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 31 mg, 65% yield.
[0054] Example 20
[0055] Weighed (70 mg, 0.2 mmol), N-heterocyclic carbene borane (42 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2C03(130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), let stand, separated layers, pour out the lower organic phase, combine the organic phase, dry the organic phase with anhydrous sodium sulfate, evaporate the organic phase, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 31 mg, 65% yield.
[0056] Example 21
[0057] Weighed (70 mg, 0.2 mmol), N-heterocyclic carbene borane (46 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), allowed to stand, separated the layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 35 mg, yield 69%.
[0058] Example 22
[0059] weighed (70 mg, 0.2 mmol), N-heterocyclic carbene borane (56 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), allowed to stand, separated the layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 39 mg, yield 68%.
[0060] Example 23
[0061] weighed (70 mg, 0.2 mmol), N-heterocyclic carbene borane (50 mg, 0.3 mmol), photocatalyst 4-CzIPN (3.2 mg, 0.004 mmol) and base Cs2CO3 (130 mg, 0.4 mmol) were added to the reaction vial, purged with nitrogen three times, MeCN (2 mL) was added with a syringe. The reaction vial was placed under blue LEDs, and reacted at room temperature for 24 h. After the reaction was completed, 10 mL of water was added, extracted with DCM (3 x 15 mL), allowed to stand, separated the layers, poured out the lower organic phase, combined the organic phase, the organic phase was dried with anhydrous sodium sulfate, evaporated to dryness, dry loading, column chromatography (petroleum ether: ethyl acetate = 10: 1 ~ 1: 1, v / v) to obtain 30 mg, yield 56%.
[0062] The above examples describe the basic principles, main features and advantages of the present application, and those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made without departing from the principles of the present application, and such changes and improvements fall within the scope of the present application.
Claims
1. A method for preparing NHC-boryl alkyne compounds, characterized in that... The specific preparation process is as follows: using ethynylbenzoxazolinone compounds and nitrogen-containing heterocyclic carbene borane compounds as reactants, 4-CzIPN as a photocatalyst, Cs2CO3 as a base, and acetonitrile as a solvent, the reaction is carried out under blue LED irradiation and a nitrogen atmosphere to finally obtain the target product NHC-boryl alkyne compounds. The synthetic route for the preparation process is as follows: The substituent Ar is phenyl, substituted phenyl, naphthyl, thiophene, or pyridyl, and the substituted phenyl is fluorine, chlorine, bromine, or C. 1-6 Alkyl, acetone, methoxy, acetonitrile, or trifluoromethyl, with substituent R being C 1-6 Alkyl or benzyl; The structural formula of the photocatalyst 4-CzIPN is:
2. The method for preparing NHC-boryl alkyne compounds according to claim 1, characterized in that: The substituent R is one or more of methyl, ethyl, propyl, isopropyl, n-butyl, or benzyl.
3. The method for preparing NHC-boryl alkyne compounds according to claim 1, characterized in that: The acetylenylbenzoxazolinone and nitrogen-containing heterocyclic carbene borane compounds were magnetically stirred in acetonitrile solvent at a speed of 500 rpm.
4. The method for preparing NHC-boryl alkyne compounds according to claim 1, characterized in that: The molar ratio of the acetylenylbenzoxazolinone compound to the nitrogen-containing heterocyclic carbene borane compound is 1:1 to 1:
3.
5. The method for preparing NHC-boryl alkyne compounds according to claim 1, characterized in that: The molar ratio of the ethynylbenzoxazolinone compound to the nitrogen-containing heterocyclic carbene borane compound is 1:1.5.