A method for preparing a seven-membered fused-ring compound

Abstract

This invention discloses a method for preparing a seven-membered fused-ring compound, comprising the following steps: 1) Compound 1 reacts with trifluoromethanesulfonic anhydride in the presence of a base to obtain Compound 2; 2) Compound 2 and Compound 6 undergo a catalytic coupling reaction to obtain Compound 3; 3) Compound 3 undergoes a ring-closure reaction to obtain Compound 4; 4) Compound 4 undergoes a reductive ring-closure reaction to obtain Compound 5; The reaction route is shown below. This method has a short route, inexpensive starting materials, small catalyst dosage, low cost, does not involve explosive or hazardous reactions, is safe and environmentally friendly, has a high yield, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescence, and specifically relates to a method for preparing a seven-membered fused ring compound. Background Technology

[0002] Organic light-emitting displays (OLEDs) are thin-film light-emitting devices primarily made of organic materials, including hole injection materials, hole transport materials, hole auxiliary materials, light-emitting auxiliary materials, electron blocking materials, light-emitting materials, electron buffer materials, hole blocking materials, electron transport materials, and electron injection materials. When a voltage is applied, the light-emitting materials convert electrical energy into light energy. Compared to traditional displays, OLEDs do not require backlights, have wider viewing angles, are more environmentally friendly and energy-efficient, and are composed of organic coatings and glass substrates of tens of nanometers, resulting in thinner and lighter screens.

[0003] Currently, OLEDs have received widespread attention in the industry, with more and more research institutions and companies investing in their development, and they are expected to become the next generation of flat panel displays. OLEDs can be divided into two different technology types based on the organic materials used in their components. One is small-molecule OLEDs using organic dyes and pigments as light-emitting materials, and the other is polymer-based OLEDs using conjugated polymers as light-emitting materials, abbreviated as PLED. The principle of organic small-molecule electroluminescence is as follows: electrons are injected from the cathode and holes are injected from the anode. The injected electrons and holes are transported within the organic layer. The first layer's function is to transport holes and block electrons, preventing electrons that have not recombinated with holes from entering the positive electrode. The second layer is the electroluminescent layer. The injected electrons and holes are transported within the organic layer and recombine within the light-emitting layer, thereby exciting the molecules in the light-emitting layer to generate singlet excitons. These singlet excitons then emit light through radiative transitions. However, issues such as the dissolution of the organic thin film during light emission and heating, chemical aging, uneven light emission due to excessive display size, and the color purity of the light-emitting materials all hinder the widespread adoption of OLEDs. Considering current market demands, there is an urgent need to develop highly superior light-emitting materials.

[0004] Seven-membered fused-ring compounds have a high degree of conjugation, which improves the stability of the material structure. Their relatively large molecular weight increases the glass transition temperature of the material, ensuring that the material will not decompose during long-term vapor deposition. They have many advantages and are intermediates for many luminescent materials.

[0005] Several methods exist for preparing this seven-membered fused ring. Patent CN113173879 uses 1,8-dibromonaphthalene as a starting material, involving a three-step reaction including a one-pot process to obtain the final product. However, each step requires column chromatography, and the starting material is expensive. Patent CN112759543 uses 2-nitro-1-naphthol as a starting material, which is cheaper, but requires five steps and multiple column chromatography steps, resulting in a low overall yield. Furthermore, it uses a diazotization reaction, posing a significant risk to industrial production. CN110922422 uses 1-bromo-2-naphthylamine as a starting material, involving four steps, but the ring-closing yield is low due to the use of aluminum trichloride. CN112521411, CN11320612, and CN110698387 all use 1-bromo-8-iodonaphthalene as a starting material, which is expensive, leading to high industrial production costs. Among these, patent CN110698387 achieves a higher ring-closing yield, but requires a higher amount of palladium catalyst. Therefore, it is necessary to develop a low-cost, high-yield, and simple method for preparing seven-membered fused rings. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing seven-membered fused ring compounds. This method has a short route, requires a small amount of catalyst, has simple post-processing, is safe and environmentally friendly, has low cost, and has a high overall yield.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing the seven-membered fused-ring compound shown in formula (5),

[0009]

[0010] The method includes the following steps:

[0011] 1) Compound 1 reacts with trifluoromethanesulfonic anhydride (Tf2O) in the presence of a base to give compound 2;

[0012] 2) Compound 2 and compound 6 undergo a catalytic coupling reaction to give compound 3;

[0013] 3) Compound 3 undergoes a cyclization reaction to give compound 4;

[0014] 4) Compound 4 undergoes a reductive cyclization reaction to give compound 5;

[0015] The reaction route is as follows:

[0016]

[0017] The method may include one or more of the following features regarding steps 1)-4):

[0018] In one embodiment, in step 1), compound 1 is reacted with trifluoromethanesulfonic anhydride (Tf2O) in the presence of a base to obtain compound 2; the base is selected from at least one of triethylamine, pyridine, and 4-dimethylaminopyridine (DMAP), preferably, the base is pyridine;

[0019] In one embodiment, in step 1), the molar ratio of compound 1 to trifluoromethanesulfonic anhydride is 1:(1.2-1.25); the molar ratio of compound 1 to the base is 1:(1.5-2.4).

[0020] In one embodiment, in step 1), the reaction solvent is dichloromethane;

[0021] In one embodiment, in step 1), after the reaction is completed, the reaction solution is quenched, washed with water, concentrated, and slurried with petroleum ether to obtain compound 2.

[0022] In one embodiment, in step 2), compound 2 and compound 6 undergo a catalytic coupling reaction in the presence of a catalyst and a base to obtain compound 3; the catalyst is tetrakis(triphenylphosphine)palladium (Pd(PPh3)4), and the base is selected from at least one of potassium carbonate, cesium carbonate, sodium carbonate, and lithium carbonate;

[0023] In one embodiment, in step 2), the reaction is carried out in a mixed solvent; the mixed solvent is selected from methanol, toluene and water; ethanol, toluene and water; isopropanol, toluene and water; at least one of toluene and water; preferably, the mixed solvent is a mixture of toluene and water;

[0024] In one embodiment, in step 2), the molar ratio of compound 2 to tetrakis(triphenylphosphine)palladium is 1:(0.005-0.01);

[0025] In one embodiment, in step 2), the molar ratio of compound 2 to the base is 1:(2-3);

[0026] In one embodiment, in step 2), the reaction temperature is 80°C-120°C;

[0027] In one embodiment, in step 2), after the reaction is completed, the reaction solution is quenched, extracted, concentrated, and slurried with petroleum ether to obtain compound 3;

[0028] In one embodiment, in step 3), compound 3 undergoes a cyclization reaction in the presence of a catalyst, an acid, and a base to obtain compound 4; the catalyst is selected from bis(tricyclohexylphosphine)palladium dichloride (Pd(PCy3)2Cl2); the base is selected from at least one of potassium carbonate, cesium carbonate, sodium carbonate, and lithium carbonate; and the acid is selected from t-BuCOOH.

[0029] In a further embodiment, in step 3), compound 3 undergoes a cyclization reaction in the presence of a catalyst, acid, base, and phosphorus ligand to obtain compound 4; preferably, the phosphorus ligand is tricyclohexylphosphine (Pcy3); the addition of phosphorus ligand can further improve the yield;

[0030] In one embodiment, in step 3), the molar ratio of compound 3 to acid is 1:(0.05-2);

[0031] In one embodiment, in step 3), the molar ratio of compound 3 to catalyst is 1:(0.015-0.05), preferably 1:0.02;

[0032] In one embodiment, in step 3), the molar ratio of compound 3 to the phosphine ligand is 1:(0.1-1);

[0033] In one embodiment, in step 3), the reaction solvent is a polar aprotic solvent, such as N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), or N,N-dimethylformamide (DMF); the preferred solvent is N,N-dimethylacetamide (DMAc).

[0034] In one embodiment, in step 3), the reaction temperature is 150°C-180°C, preferably 180°C;

[0035] In one embodiment, in step 3), after the reaction is complete, the reaction solution is diluted with ethyl acetate, washed with water, and concentrated to obtain compound 4;

[0036] In one embodiment, in step 4), compound 4 undergoes a reductive cyclization reaction in the presence of a phosphine reagent to obtain compound 5; the phosphine reagent is selected from at least one of triphenylphosphine (PPh3) and triethyl phosphite (P(OEt)3); the preferred phosphine reagent is triphenylphosphine;

[0037] In one embodiment, in step 4), the reaction solvent is selected from at least one of 1,2-dichlorobenzene (o-DCB) and N,N-dimethylacetamide (DMAc);

[0038] In one embodiment, in step 4), after the reaction is completed, the reaction solution is subjected to column chromatography, and after being slurried with toluene, compound 5 is obtained; the purity can reach more than 99%.

[0039] In one embodiment, steps 3) and 4) can be completed in one pot. That is, after the reaction in step 3) is completed, the reaction solution is not treated and a phosphine reagent is directly added to carry out a reduction and cyclization reaction to obtain compound 5.

[0040] Beneficial effects:

[0041] 1) The route of this invention is short, in which compounds 3 to 5 can be completed in one pot, reducing post-processing operations;

[0042] 2) The starting materials of this invention are inexpensive, the amount of catalyst used is low, and the production cost is reduced;

[0043] 3) This invention does not involve any explosive or dangerous reactions, and the post-processing only requires one column chromatography step, making it safe, environmentally friendly, and suitable for large-scale industrial production;

[0044] 4) The present invention has a high overall yield and high purity of the final product. Attached Figure Description

[0045] Figure 1 It is a seven-membered fused-ring compound 5. 1 H NMR spectrum. Detailed Implementation

[0046] The technical solution of the present invention will be further illustrated below through examples. Those skilled in the art should understand that the examples are merely illustrative of the invention and should not be considered as specific limitations thereof. Unless otherwise specified, compounds synthesized using methods not mentioned in this invention are commercially available raw material products. Compound 6 is commercially available and can also be prepared according to the method of this invention.

[0047] The meanings of the English abbreviations appearing in the examples are as follows:

[0048] Pd(PPh3)4: Tetra(triphenylphosphine)palladium

[0049] Pd(PCy3)2Cl2: bis(tricyclohexylphosphine)palladium dichloride

[0050] t-BuCOOH: Pteropenic acid

[0051] PCy3: Tricyclohexylphosphine

[0052] Na2CO3: Sodium carbonate

[0053] K2CO3: Potassium carbonate

[0054] Cs2CO3: Cesium carbonate

[0055] DMAc: N,N-dimethylacetamide

[0056] PPh3: Triphenylphosphine

[0057] P(OEt)3: Triethylphosphite

[0058] o-DCB: 1,2-Dichlorobenzene

[0059] Example 1: Preparation of Compound 2

[0060]

[0061] Method 1-1: Compound 1 (2-nitro-1-naphthol, 40 g, 1 eq) was dissolved in dichloromethane (280 ml, 7V). Pyridine (25 ml, 1.5 eq) was added at room temperature, and trifluoromethanesulfonic anhydride (40 ml, 1.2 eq) was added dropwise under ice bath. The reaction was allowed to proceed overnight at room temperature. The reaction was diluted with dichloromethane, and the reaction was quenched by adding saturated sodium bicarbonate solution under ice bath. The mixture was washed three times with saturated sodium bicarbonate, three times with water, and once with saturated brine. After drying with magnesium sulfate, the mixture was concentrated to obtain a brown solid. This solid was then slurried with petroleum ether (160 ml, 4V) to obtain a brown powdery solid compound 2 (68 g, yield approximately 100%).

[0062] Methods 1-2: Compound 1 (10 g, 1 eq) was dissolved in dichloromethane (17.5 ml, 1.75 V), and triethylamine (17.6 ml, 2.4 eq) was added at room temperature. Trifluoromethanesulfonic anhydride (11 ml, 1.25 eq) was added dropwise under ice bath conditions, and the reaction was allowed to proceed overnight at room temperature. The reaction was diluted with dichloromethane, and the reaction was quenched by adding saturated sodium bicarbonate solution under ice bath conditions. The mixture was washed three times with saturated sodium bicarbonate, three times with water, and once with saturated brine. After drying with magnesium sulfate, the mixture was concentrated to obtain a brown solid. This solid was then slurried with petroleum ether to obtain a brown powdery solid compound 2 (14.6 g, 86%).

[0063] Compound 2: 1 H NMR (400MHz, CDCl3) δ: 8.29 (m, 1H), 8.09 (d, J = 9.0Hz, 1H), 8.04–

[0064] 7.97 (m, 2H), 7.84–7.76 (m, 2H).

[0065] Example 2 Preparation of Compound 3

[0066]

[0067] Method 2-1: Weigh compound 2 (500 mg, 1.0 eq) into a reaction flask, then weigh compound 6 (362 mg, 1.0 eq), Pd(PPh3)4 (9 mg, 0.005 eq), and Na2CO3 (368 mg, 2.0 eq) in sequence. Add toluene (4 ml) and water (1 ml), heat to 120 °C and react for 12 h. Quench the reaction solution with saturated ammonium chloride, extract with ethyl acetate, dry and concentrate, and then beat with petroleum ether to obtain brown powder solid compound 3 (475 mg, 95%).

[0068] Method 2-2: Weigh compound 2 (500 mg, 1.0 eq) into a reaction flask, then weigh compound 6 (362 mg, 1.0 eq), Pd(PPh3)4 (9 mg, 0.005 eq), and K2CO3 (646.6 mg, 3.0 eq) in sequence. Add isopropanol (1 ml), toluene (4 ml), and water (1 ml). Heat to 80 °C and react for 10 h. Quench the reaction solution with saturated ammonium chloride, extract with ethyl acetate, dry and concentrate, and then beat with petroleum ether to obtain brown powdery solid compound 3 (112 mg, 20%).

[0069] Method 2-3: Weigh compound 2 (500 mg, 1.0 eq) into a reaction flask, then weigh compound 6 (362 mg, 1.0 eq), Pd(PPh3)4 (18 mg, 0.01 eq), and K2CO3 (413 mg, 2.5 eq) in sequence. Add ethanol (1 ml), toluene (4 ml), and water (1 ml), heat to 110 °C and react for 5 h. Quench the reaction solution with saturated ammonium chloride, extract with ethyl acetate, dry and concentrate, and then beat with petroleum ether to obtain brown powder solid compound 3 (375.2 mg, 67%).

[0070] Compound 3: 1 H NMR (600MHz, Acetone) δ8.02(t,J=14.5Hz,1H),8.00–7.87(m,1H),7.83–7.37(m,6H),7.38–7.09(m,2H),6.99(d,J=44.1Hz,2H).

[0071] Example 3 Preparation of Compound 4

[0072]

[0073] Method 3-1: Compound 3 (1 g, 1.0 eq) was weighed into a reaction flask, followed by Pd(PCy3)2Cl2 (41 mg, 0.02 eq), t-BuCOOH (14.2 mg, 0.05 eq), PCy3 (77.9 mg, 0.1 eq), and K2CO3 (766.6 mg, 2.0 eq). DMAc (5 ml) was added, and the mixture was heated to 180 °C and reacted for 24 h. The reaction solution was diluted with ethyl acetate, washed with water, dried, concentrated, and subjected to column chromatography (petroleum ether: ethyl acetate = 20:1) to obtain a brown powdery solid compound 4 (593 mg, 66%) and a seven-membered fused-ring compound 5 (89 mg, 10%). The combined total yield was 76%.

[0074] Method 3-2: Weigh compound 3 (1g, 1.0eq) into a reaction flask, and weigh Pd(PCy3)2Cl2 (31mg, 0.015eq), t-BuCOOH (11mg, 0.03eq), PCy3 (78mg, 0.1eq), and K2CO3 (766mg, 2.0eq) in sequence. Add DMAc (5ml) and heat to 180℃ for 24h. Dilute the reaction solution with ethyl acetate, wash with water, dry and concentrate, and then beat with toluene to obtain brown powder solid compound 4 (480mg, 47%).

[0075] Method 3-3: Weigh compound 3 (100 mg, 1.0 eq) into a reaction flask, and weigh Pd(PCy3)2Cl2 (10.25 mg, 0.05 eq), t-BuCOOH (56.77 mg, 2.0 eq), and Cs2CO3 (181 mg, 2.0 eq) in sequence. Add DMAc (3 ml) and heat to 170 °C for 24 h. Dilute the reaction solution with ethyl acetate, wash with water, dry and concentrate, and then beat with toluene to obtain brown powder solid compound 4 (51 mg, 50%).

[0076] Methods 3-4: Weigh compound 3 (500 mg, 1.0 eq) into a reaction flask, then weigh Pd(PCy3)2Cl2 (51.25 mg, 0.05 eq), t-BuCOOH (141.8 mg, 1.0 eq), and K2CO3 (384.1 mg, 2.0 eq) in sequence. Add DMAc (5 ml) and heat to 170 °C for 24 h. Dilute the reaction solution with ethyl acetate, wash with water, dry and concentrate, and then beat with toluene to obtain brown powder solid compound 4 (280 mg, 53%).

[0077] Compound 4: 1 H NMR (600MHz, Acetone-d6) δ8.07(q,J=8.7Hz,2H),8.01(t,J=7.4Hz,2H),7.88(d,J=7.8Hz,1H),7.79(t,J=8.5Hz,2H),7 .58(t,J=7.5Hz,1H),7.51(dt,J=14.9,7.5Hz,2H),7.36(t,J=7.6Hz,1H),7.19(d,J=7.9Hz,1H),6.88(d,J=7.9Hz,1H).

[0078] Example 4 Preparation of Compound 5

[0079]

[0080] Method 4-1: Weigh compound 4 (500 mg, 1 eq) into a reaction flask, add o-DCB (2.5 ml, 5 V) to dissolve it, add PPh3 (1 g, 2.5 eq), heat to 180 °C and react for 12 h. Column chromatography (petroleum ether: ethyl acetate = 10:1) yields compound 5 (329 mg, 73%), which is then recrystallized from methanol (5 ml) to obtain compound 5 (300 mg, 67%) with a purity greater than 99%.

[0081] Method 4-2: Weigh compound 4 (500 mg, 1 eq) into a reaction flask, add DMAc (2.5 ml, 5 V) to dissolve it, add P(OEt)3 (642.3 mg, 2.5 eq), heat to 180 °C and react for 12 h, column chromatography (petroleum ether: ethyl acetate = 10:1) to obtain compound 5 (225 mg, 50%), with a purity of about 98%.

[0082] Method 4-3: Weigh compound 4 (500 mg, 1 eq) into a reaction flask, add DMAc (2.5 ml, 5 V) to dissolve it, add PPh3 (1 g, 2.5 eq), heat to 180 °C and react for 12 h, column chromatography (petroleum ether: ethyl acetate = 10:1) to obtain compound 5 (319 mg, 71%), with a purity of about 98%.

[0083] Example 5: Preparation of Compound 5

[0084]

[0085] Compound 3 (3 g, 1.0 eq) was weighed into a reaction flask, followed by Pd(PCy3)2Cl2 (123 mg, 0.02 eq), t-BuCOOH (68 mg, 0.08 eq), PCy3 (234 mg, 0.1 eq), and K2CO3 (2.3 g, 2.0 eq). DMAc (15 ml, 5 V) was added, and the mixture was heated to 180 °C and reacted for 24 h. After complete conversion of compound 3 by TLC, PPh3 (1 g, 2.5 eq) was added, and the mixture was heated to 180 °C and reacted for 12 h. Column chromatography (petroleum ether: ethyl acetate = 10:1) yielded compound 5 (1.36 g, 56%) with a purity of approximately 98%.

[0086] Compound 5: 1H NMR (600MHz, Acetone-d6) δ10.79–10.36(m,1H),7.95–7.90(m,1H),7.81(d,J=8.0Hz,1H),7.75(dd,J=5.2,3.7H z,2H),7.68–7.64(m,2H),7.62(dt,J=7.3,3.6Hz,1H),7.44–7.35(m,4H),7.32(t,J=7.8Hz,1H).HRMS(ESI)calcd for C 11 H6N4NaO[M] + :291.1043,found 291.1066.

[0087] Example 6 Preparation of Compound 6 (2-chloro-2-boronic acid biphenyl)

[0088]

[0089] Compound 7 (10 g) was weighed into a reaction flask and dissolved in tetrahydrofuran (100 ml, 10 V). The reaction solution was cooled to -60 °C, and n-butyllithium (10 ml, 0.5 eq, 2.5 M THF solution) was added dropwise at this temperature. The mixture was then moved to room temperature and reacted for 2 hours. The reaction solution was then moved to -60 °C, and n-butyllithium (10 ml, 0.5 eq, 2.5 M THF solution) was added dropwise at this temperature. The mixture was then reacted for 1 hour. Trimethyl borate (3.4 ml, 0.6 eq) was then added dropwise, and the mixture was moved to room temperature and reacted overnight. 6 N HCl was added and stirred for 4 hours. The mixture was extracted with ethyl acetate, concentrated, and then slurried with petroleum ether to obtain a white powdery solid compound 6 (4.8 g, 80%).

[0090] The above embodiments are for illustrative purposes only. The preparation method of the present invention is also applicable to the preparation of compounds with substituents on a seven-membered fused ring. Any improvements and modifications made by those skilled in the art based on the content of the present invention, as long as they do not depart from the spirit of the present invention, shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a seven-membered fused-ring compound, characterized in that, The seven-membered fused ring compound is shown in formula (5): The method includes the following steps: 1) Compound 1 reacts with trifluoromethanesulfonic anhydride in the presence of a base to give compound 2; wherein the base is selected from at least one of pyridine and 4-dimethylaminopyridine; 2) Compound 2 and Compound 6 undergo a catalytic coupling reaction in the presence of a catalyst and a base to yield Compound 3; the catalyst is tetrakis(triphenylphosphine)palladium, and the base is selected from at least one of potassium carbonate, cesium carbonate, sodium carbonate, and lithium carbonate; the reaction is carried out in a mixed solvent selected from a mixture of toluene and water; 3) Compound 3 undergoes a cyclization reaction in the presence of a catalyst, an acid, a base, and a phosphine ligand to yield compound 4; the catalyst is selected from bis(tricyclohexylphosphine)palladium dichloride, the base is selected from at least one of potassium carbonate, cesium carbonate, sodium carbonate, and lithium carbonate, and the acid is selected from tervastatinic acid; the phosphine ligand is tricyclohexylphosphine; the molar ratio of compound 3 to acid is 1:(0.05-2); the molar ratio of compound 3 to catalyst is 1:(0.02-0.05). 4) Compound 4 undergoes a reductive cyclization reaction in the presence of a phosphine reagent to give compound 5; The reaction route is as follows: Steps 3) and 4) are completed in a one-pot process. After the reaction in step 3) is completed, the reaction solution is not treated and phosphine reagent is directly added to carry out a reduction and cyclization reaction to obtain compound 5.

2. The preparation method according to claim 1, characterized in that, In step 1), the base is pyridine.

3. The preparation method according to claim 1, characterized in that, In step 1), the molar ratio of compound 1 to trifluoromethanesulfonic anhydride is 1:(1.2-1.25); the molar ratio of compound 1 to the base is 1:(1.5-2.4).

4. The preparation method according to claim 1, characterized in that, In step 2), the molar ratio of compound 2 to tetra(triphenylphosphine)palladium is 1:(0.005-0.01); the molar ratio of compound 2 to the base is 1:(2-3).

5. The preparation method according to claim 1, characterized in that, In step 3), the molar ratio of compound 3 to catalyst is 1:0.

02.

6. The preparation method according to claim 1, characterized in that, In step 3), the molar ratio of compound 3 to the phosphine ligand is 1:(0.1-1).

7. The preparation method according to claim 1, characterized in that, In step 4), the phosphine reagent is selected from at least one of triphenylphosphine and triethylphosphite.

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