A method for the decarbonylation and cyclization of ortho-halobenzoic esters to synthesize 1-substituted phenanthrene compounds catalyzed by palladium.

Abstract

This invention provides a palladium-catalyzed method for the decarbonylation and cyclization of o-halobenzoic esters to synthesize 1-substituted phenanthrene compounds. The method involves the decarbonylation and cyclization of o-substituted iodobenzene, norbornadiene, and o-halobenzoic esters in an aprotic solvent under palladium catalysis to yield 1-substituted phenanthrene compounds. This method uses o-halobenzoic esters as cyclizing agents, which not only expands the applicability of cyclizing agents but also offers advantages such as milder reaction conditions, no need for inert gas protection (e.g., nitrogen), and no use of organophosphorus ligands. It is an economical and convenient method for preparing 1-substituted phenanthrene compounds.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology and relates to a method for the decarbonylation and cyclization of ortho-halobenzoic esters to synthesize 1-substituted phenanthrene compounds by palladium catalysis. Background Technology

[0002] Phenanthrene is a polycyclic aromatic hydrocarbon compound with three fused benzene rings, found in some medicinal plants such as Dendrobium, Dendrobium nobile, Juncus effusus, and Euphorbia lathyris. Furthermore, the polycyclic conjugated structure of phenanthrene compounds has wide applications in pharmaceuticals and organic light-emitting materials. Given the importance of phenanthrene compounds, many synthetic methods have been developed. Recently, Kwong et al. from Hong Kong Polytechnic University developed a method for synthesizing phenanthrene using a palladium-catalyzed coupling reaction between iodoaryl hydrocarbons, o-bromobenzoic acid, and norbornene (Angew. Chem. Int. Ed. 2017, 56 (25), 7166-7170). This method uses o-haloarylcarboxylic acid as the cyclizing agent, with harsh reaction conditions and a narrow substrate range. Since esters, especially methyl esters, are widely available, stable, and easy to store and transfer, and some esters are even more readily available than their corresponding acids, their participation in C / C bond formation reactions has attracted widespread interest from scientists in recent years.

[0003] This invention provides a method for synthesizing 1-substituted phenanthrene compounds via a palladium-catalyzed cyclization reaction between o-haloaryl carboxylate esters and o-substituted iodoaryl hydrocarbons. The reaction temperature is mild (reduced from 130°C to 100°C compared to the previous method using 2-haloaryl carboxylic acids). The method's broad substrate applicability expands the substrate range for the synthesis of 1-substituted phenanthrene compounds. Furthermore, this method does not use organophosphorus ligands and does not require inert gas protection such as nitrogen, making the operation simpler and possessing significant application value in the synthesis of 1-substituted phenanthrene compounds. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the decarbonylation and cyclization of ortho-halobenzoic esters to synthesize 1-substituted phenanthrene compounds catalyzed by palladium.

[0005] A palladium-catalyzed method for the decarbonylation and cyclization of ortho-halobenzoic acid esters to synthesize 1-substituted phenanthrene compounds involves mixing ortho-substituted aryl iodide compounds with ortho-haloaryl carbamates, adding palladium catalyst, norbornene, and a base, and heating the mixture in an aprotic solvent to 80-100°C for 2-10 hours. After the reaction is complete, the mixture is extracted with saturated brine and ethyl acetate, dried over anhydrous Na2SO4, and purified by column chromatography to obtain the target product, the 1-substituted phenanthrene compound.

[0006] The synthesis route is as follows:

[0007]

[0008] In the above structural formula, R 1 It is any one of alkyl, aryl, alkoxy, halogen, or alkoxycarbonyl; R 2 R 3 They are one or more of the following: hydrogen, alkyl, alkoxy, aryl, benzyl, nitro, halogen, carbonyl, and alkoxycarbonyl; R 2 R is a single substituent at any position of 2, 3, or 4 of phenanthrene, or multiple substituents at positions 2, 3, and 4 of phenanthrene; 3 Ar is a single substituent at either position 6 or 7 of phenanthrene, or multiple substituents at positions 6 or 7 of phenanthrene; Ar and Ar' are benzene rings, naphthyl rings, pyridine, or thiophene; R 4 It can be methyl, ethyl, isopropyl, tert-butyl, or aryl.

[0009] The base is one of sodium carbonate, potassium carbonate, cesium carbonate, potassium tert-butoxide, sodium tert-butoxide, or triphenylmethyl sodium. The palladium catalyst is palladium chloride, tetraphenylphosphine palladium, diphenylphosphine dichloride palladium, or palladium acetate. The aprotic solvent is one of toluene, tetrahydrofuran, 1,4-dioxane, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide. The molar ratio of the ortho-substituted aryl iodide compound to the ortho-haloaryl carboxylate is 1:1 to 1:3. The molar ratio of the ortho-substituted aryl iodide compound to the palladium catalyst is 100:1 to 10:1. The molar ratio of the ortho-substituted aryl iodide compound to norbornadiene is 1:1 to 1:4. The molar ratio of the ortho-substituted aryl iodide compound to the base is 1:1 to 1:5.

[0010] The structure of the product prepared by this invention was characterized by mass spectrometry, nuclear magnetic resonance and other analytical methods, confirming that the synthesized compound was the target compound.

[0011] The beneficial effects of this invention are as follows: The method provided by this invention uses o-halobenzoic acid esters, which are widely available, stable, and easy to store, as cyclizing reagents. Under palladium catalysis, they can undergo cyclization reactions with iodoaromatics and norbornene under milder conditions (this method: 100℃; using 2-halobenzoic acid: 130℃), exhibiting good reaction performance. Furthermore, this method uses o-halobenzoic acid esters as cyclizing reagents, which not only expands the applicable range of cyclizing reagents but also eliminates the need for inert gas protection such as nitrogen and the use of organophosphine ligands, making it an economical and convenient method for preparing 1-substituted phenanthrene compounds. Detailed Implementation

[0012] The synthesis of the compounds of the present invention will be further described below through specific embodiments.

[0013] Example 1: Synthesis of 1-Methylphenanthrene

[0014]

[0015] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-iodotoluene (65.4 mg, 0.3 mmol), methyl o-bromobenzoate (129 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 56.1 mg (yield: 97%).

[0016] 1 (CDCl3, 600MHz) δ (ppm): 8.66 (d, J = 8.1 Hz, 1H), 8.54 (d, J = 8.4 Hz, 1H), 7.91 (d, J = 9.1 Hz, 1H), 7.86 (d, J = 7.7 Hz, 1H), 7.74 (d, J = 9.1 Hz, 1H), 7.61 (td, J = 7.0, 1.3 Hz, 1H), 7.56 (t, J = 7.4 Hz, 1H), 7.51 (t, J = 7.0 Hz, 1H), 7.41 (d, J = 7.1 Hz, 1H), 2.72 (s, 3H).

[0017] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 134.8, 131.6, 130.8, 130.6,130.3,128.4, 127.7, 126.6, 126.5, 126.4, 126.1, 122.9, 122.8, 120.8, 20.8.

[0018] Example 2: Synthesis of 1-Ethylphenanthrene

[0019]

[0020] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-iodoethylbenzene (69.6 mg, 0.3 mmol), methyl o-bromobenzoate (129 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 58.8 mg (yield: 95%).

[0021] 1 (CDCl3, 400 MHz) δ (ppm): 8.67 (d, J = 8.2 Hz, 1H), 8.56 (d, J = 8.3 Hz, 1H), 7.98 (d, J = 9.2 Hz, 1H), 7.86 (d, J = 7.6 Hz, 1H), 7.74 (d, J = 9.2 Hz, 1H), 7.59 (td, J = 7.2, 1.0 Hz, 1H), 7.55 (t, J = 7.9 Hz, 2H), 7.44 (d, J = 7.1 Hz, 1H), 3.14 (d, J = 7.5 Hz, 2H), 1.39 (t, J = 7.6 Hz, 3H).

[0022] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 141.0, 131.6, 130.8, 130.6, 130.0,128.4, 126.7, 126.5, 126.4, 126.3, 126.2, 123.0, 122.5, 120.9, 26.5, 15.5.

[0023] Example 3: Synthesis of 1-Phenylenol

[0024]

[0025] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-iodobiphenyl (84.0 mg, 0.3 mmol), methyl o-bromobenzoate (129 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 70.2 mg (yield: 92%).

[0026] 1 (CDCl3,600 MHz) δ (ppm): 8.76 (t, J = 7.1 Hz, 2H), 7.89 (d , J = 7.8 Hz, 1H), 7.83 (d, J = 9.2 Hz, 1H), 7.74–7.65 (m, 3H), 7.62 (td, J = 7.4, 0.9 Hz, 1H), 7.56 (dd, J = 7.1, 0.9 Hz, 1H), 7.54–7.50 (m, 4H), 7.49–7.43 (m, 1H).

[0027] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 141.1, 141.0, 131.7, 130.6,130.4,130.2, 129.9, 128.4, 128.2, 127.9, 127.2, 126.8, 126.7, 126.6, 125.9, 124.6,122.9, 122.1.

[0028] Example 4: Synthesis of 1-trifluoromethoxyphenanthrene

[0029]

[0030] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-trifluoromethoxyiodobenzene (85.4 mg, 0.3 mmol), methyl o-bromobenzoate (129 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 70.0 mg (yield: 89%).

[0031] 1 (CDCl3, 400 MHz) δ (ppm): 8.67 (d, J = 8.1 Hz, 1H), 8.63 (d, J = 8.4 Hz, 1H), 8.08 (d, J = 9.2 Hz, 1H), 7.92 (dd, J = 7.5, 1.2 Hz, 1H), 7.85 (d, J = 9.2 Hz, 1H), 7.70 (dd, J = 7.1, 1.4 Hz, 1H), 7.71–7.64 (m, 2H), 7.52 (d, J = 7.9 Hz, 1H).

[0032] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 145.7, 132.1, 131.9, 129.6,128.8,128.2, 127.3, 127.2, 126.0, 125.4, 122.9, 121.4, 120.9 (q, J = 257.9 Hz), 119.3, 117.6.

[0033] Example 5: Synthesis of 2-fluoro-1-methylphenanthrene

[0034]

[0035] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 3-fluoro-2-methyliodobenzene (70.8 mg, 0.3 mmol), methyl o-bromobenzoate (129 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 54.2 mg (yield: 86%).

[0036] 1 (CDCl3, 400 MHz) δ (ppm): 8.62 (d, J = 8.2 Hz, 1H), 8.53 (dd, J = 8.9,5.4 Hz, 1H), 7.96–7.86 (m, 2H), 7.81 (d, J = 9.2 Hz, 1H), 7.66 (t, J = 7.1 Hz, 1H), 7.60 (t, J = 7.4 Hz, 1H), 7.38 (t, J = 9.1 Hz, 1H), 2.65 (s, 3H).

[0037] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 164.23 (d, J = 243.1 Hz), 132.4 (d, J =5.5 Hz), 131.0, 130.5, 128.6, 127.8, 126.9, 126.8 (d, J = 1.9 Hz), 126.3,122.6, 122.2 (d, J = 4.9 Hz), 122.2, 122.1, 119.2 (d, J = 15.1 Hz), 10.3 (d, J =5.7 Hz).

[0038] Example 6: Synthesis of 1-methyl-3-methoxycarbonylphenanthrene

[0039]

[0040] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-trifluoromethoxyiodobenzene (82.8 mg, 0.3 mmol), methyl o-bromobenzoate (129 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 58.5 mg (yield: 78%).

[0041] 1 (CDCl3, 400 MHz) δ (ppm): 9.32 (s, 1H), 8.80 (d, J = 8.3 Hz, 1H), 8.06(s, 1H), 7.95 (d, J = 9.2 Hz, 1H), 7.92 (d, J = 7.8 Hz, 1H), 7.88 (d, J = 9.2 Hz, 1H), 7.71 (td, J = 7.0, 1.1 Hz, 1H), 7.64 (t, J = 7.4 Hz, 1H), 4.02 (s, 3H), 2.79 (s, 3H).

[0042] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 167.5, 135.2, 133.7, 131.7,131.0,129.8, 129.2, 128.6, 127.4, 127.2, 127.2, 126.9, 123.4, 123.1, 122.4, 52.2,19.9.

[0043] Example 7: 4-Methoxybenzo[ f Synthesis of isoquinoline

[0044]

[0045] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-methoxy-3-iodopyridine (70.5 mg, 0.3 mmol), methyl o-bromobenzoate (129 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 37.0 mg (yield: 59%).

[0046] 1 (CDCl3, 600 MHz) δ (ppm): 8.62–8.56 (m, 1H), 8.25 (d, J = 5.9 Hz, 1H), 8.16 (d, J = 8.9 Hz, 1H), 7.99 (d, J = 5.9 Hz, 1H), 7.96–7.88 (m, 1H), 7.81 (d, J =9.0 Hz, 1H), 7.70–7.64 (m, 2H), 4.17 (s, 3H)..

[0047] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 161.3, 141.6, 136.7, 133.6,128.6,128.5, 128.2, 127.3, 126.8, 123.6, 121.0, 117.0, 110.3, 53.8.

[0048] Example 8: Synthesis of 6-methoxy-1-methylphenanthrene

[0049]

[0050] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-iodotoluene (65.4 mg, 0.3 mmol), methyl 4-methoxy-2-bromobenzoate (147.0 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 54.7 mg (yield: 82%).

[0051] 1 (CDCl3, 400 MHz) δ (ppm): 8.60 (d, J = 8.7 Hz, 1H), 8.49 (d, J = 8.4 Hz, 1H), 7.95 (d, J = 9.1 Hz, 1H), 7.72 (d, J = 9.1 Hz, 1H), 7.52 (t, J = 7.4 Hz, 1H), 7.39 (d, J = 7.1 Hz, 1H), 7.31–7.26 (m, 2H), 3.97 (s, 3H), 2.75 (s, 3H).

[0052] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 158.1, 134.8, 133.0, 130.4,129.8,126.8, 126.2 (2C), 125.0, 124.6, 123.4, 120.3, 117.2, 108.3, 55.4, 19.9.

[0053] Example 9: Synthesis of 6-chloro-1-methylphenanthrene

[0054]

[0055] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-iodotoluene (65.4 mg, 0.3 mmol), methyl 2,4-dichlorobenzoate (123.0 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 57.1 mg (yield: 84%).

[0056] 1 (CDCl3, 400 MHz) δ (ppm): 8.66 (d, J = 1.5 Hz, 1H), 8.48 (d, J = 8.3 Hz, 1H), 7.95 (d, J = 9.1 Hz, 1H), 7.82 (d, J = 8.5 Hz, 1H), 7.74 (d, J = 9.1 Hz, 1H),7.60–7.50 (m, 2H), 7.48 (d, J = 7.1 Hz, 1H), 2.76 (s, 3H).

[0057] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 134.9, 132.5, 131.7, 131.0,129.9,129.8, 129.3, 128.3, 126.9, 126.4, 125.9, 123.2, 122.6, 120.9, 19.9.

[0058] Example 10: Synthesis of 7-methylbenzo[h]isoquinoline

[0059]

[0060] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-iodotoluene (65.4 mg, 0.3 mmol), methyl 3-chloroisonicotinamide (102.9 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 35.9 mg (yield: 62%).

[0061] 1 (CDCl3, 400 MHz) δ (ppm): 10.05 (s, 1H), 8.70 (d, J = 5.5 Hz, 1H), 8.67(d, J = 8.5 Hz), 8.14 (d, J = 9.1 Hz, 1H), 7.71 (d, J = 4.3 Hz), 7.69 (s, 1H), 7.62(t, J = 7.8 Hz, 1H), 7.50 (d, J = 7.1 Hz, 1H), 2.75 (s, 3H).

[0062] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 147.1, 144.8, 135.3 (2C), 130.9, 129.4, 128.6, 127.6, 127.5, 125.4, 124.5, 121.0, 120.7, 19.8.

[0063] Example 11: 6-Methylnaphtho[2,1- b Synthesis of thiophene

[0064]

[0065] Palladium acetate (3.4 mg, 5 mol%), potassium tert-butoxide (168 mg, 1.5 mmol), 2-iodotoluene (65.4 mg, 0.3 mmol), methyl 3-bromothiophenecarboxylate (132.6 mg, 0.6 mmol), norbornadiene (82.8 mg, 0.9 mmol), and N,N-dimethylacetamide (2 mL) were added sequentially to a 25 mL single-necked reaction tube. The reaction was carried out at 100 °C for 6 hours. The reaction progress was monitored by TLC. After the substrate was consumed, the reaction system was extracted multiple times with saturated brine (15 mL) and ethyl acetate (15 mL). The organic phase was separated by standing, dried over anhydrous Na₂SO₄, and concentrated to obtain a mixture. The target product was purified by column chromatography to obtain 35.1 mg (yield: 59%).

[0066] 1 (CDCl3, 400 MHz) δ (ppm): 8.24 (d, J = 8.2 Hz, 1H), 8.01 (d, J = 5.4 Hz,1H), 7.95 (s, 2H), 7.59 (d, J = 5.4 Hz, 1H), 7.53 (t, J = 7.6 Hz, 1H), 7.40 (d, J =7.0 Hz, 1H), 2.79 (s, 3H).

[0067] 13 C NMR (CDCl3, 151 MHz) δ (ppm): 137.1, 136.4, 135.0, 129.9,129.4,126.3, 126.1, 125.7, 122.3, 121.9, 121.1, 120.4, 20.1.

Claims

1. A palladium-catalyzed method for decarbonylation and cyclization of ortho-halobenzoic acid esters to synthesize 1-substituted phenanthrene compounds, comprising mixing ortho-substituted aryl iodide compounds with ortho-haloaryl carbamates, adding palladium catalyst, norbornene, and base, heating to 80-100°C in an aprotic solvent, reacting for 2-10 hours, and after the reaction is completed, extracting with saturated brine and ethyl acetate, drying with anhydrous Na2SO4, and separating and purifying by column chromatography to obtain the target product 1-substituted phenanthrene compounds; The structural formula of the ortho-substituted aryl iodine compound is: ； The structural formula of o-halogenated aryl carbamate is: ； The structure of 1-substituted phenanthrene compounds is as follows: ； In the above structural formula, R 1 It is any one of alkyl, aryl, alkoxy, halogen, or alkoxycarbonyl; R 2 R 3 They are one or more of hydrogen, alkyl, alkoxy, aryl, benzyl, nitro, and halogen; R 2 R is a single substituent at any position of 2, 3, or 4 of phenanthrene, or multiple substituents at positions 2, 3, and 4 of phenanthrene; 3 Ar is a single substituent at either position 6 or 7 of phenanthrene, or multiple substituents at positions 6 or 7 of phenanthrene; Ar and Ar' are benzene rings; R 4 It is methyl, ethyl, isopropyl, or tert-butyl; The base is either potassium tert-butoxide or sodium tert-butoxide; the palladium catalyst is palladium acetate; and the aprotic solvent is either N,N-dimethylformamide or N,N-dimethylacetamide.

2. The method for synthesizing 1-substituted phenanthrene compounds by palladium-catalyzed decarbonylation and cyclization of ortho-halobenzoic esters as described in claim 1, characterized in that: The molar ratio of ortho-substituted aryl iodine compounds to ortho-haloaryl carboxylate esters is 1:1 to 1:

3.

3. The method for synthesizing 1-substituted phenanthrene compounds by palladium-catalyzed decarbonylation and cyclization of ortho-halobenzoic esters as described in claim 1, characterized in that: The molar ratio of the ortho-substituted aryl iodine compound to the palladium catalyst is 100:1 to 10:

1.

4. The method for synthesizing 1-substituted phenanthrene compounds by palladium-catalyzed decarbonylation and cyclization of o-halobenzoic esters as described in claim 1, characterized in that: The molar ratio of ortho-substituted aryl iodine compounds to norbornadiene is 1:1 to 1:

4.

5. The method for synthesizing 1-substituted phenanthrene compounds by palladium-catalyzed decarbonylation and cyclization of o-halobenzoic esters as described in claim 1, characterized in that: The molar ratio of ortho-substituted aryl iodine compounds to bases is 1:1 to 1:5.

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