A method for synthesizing allene carboxylic acid based on CO2

Abstract

The present invention discloses a method for synthesizing allene carboxylic acid based on CO2, which belongs to the field of organic synthesis technology. The method comprises the following steps: dissolving a 1,3-enyne substrate, an iodide, a formate, a hydrogen transfer catalyst, a photocatalyst and an alkali in a solvent, introducing CO2 under normal pressure and room temperature, reacting by blue light irradiation, and separating and purifying after acidification to obtain an allene carboxylic acid compound. The present invention is based on the photocatalytic CO2 participation in the 1,4-carbon carboxylation reaction of 1,3-enyne, thereby realizing the synthesis of allene carboxylic acid. The method has mild reaction conditions, good regioselectivity, good functional group tolerance, and makes up for many deficiencies of the prior art. The method provides an efficient and green innovative path for drug molecule modification, functional material development and CO2 resource utilization, and at the same time expands new ideas for green chemical synthesis and carbon cycle technology.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for synthesizing allene carboxylic acid based on CO2. Background Art

[0002] In recent years, with the excessive release of carbon dioxide from industrial activities, the cumulative concentration of CO2 in the atmosphere has continued to rise, and the resulting intensified greenhouse effect has become a global environmental problem. Against this backdrop, exploring carbon dioxide resource conversion technologies has become a research hotspot in the international academic community, with research on the use of CO2 as a C1 synthon to construct high-value-added organic molecular systems attracting considerable attention. In the field of organic synthesis, integrating CO2 into the skeleton of carboxylic acid compounds through catalytic conversion strategies, especially the development of novel allene carboxylic acid synthesis methodologies, can not only effectively circumvent the technical bottlenecks of traditional processes such as high energy consumption and poor substrate applicability, but also provide innovative solutions for achieving carbon recycling. This research direction has dual scientific value in promoting the development of green chemistry and addressing the challenges of climate change. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for synthesizing allene carboxylic acid based on CO2, so as to solve the technical problems of limited reaction sites, weak chemical selectivity and strict reaction conditions required for allene carboxylic acid synthesis.

[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide a synthesis method of allene carboxylic acid based on CO2, comprising the following steps: the technical solution of the present invention is: 1,3-enyne, iodide, photocatalyst, hydrogen transfer catalyst, base, formate and solvent are added to a reaction vessel, and then carbon dioxide gas is introduced under normal pressure, reacted at room temperature under blue light and visible light, and after acidification, separated and purified to obtain an allene carboxylic acid compound. The reaction formula is as follows ( Figure 1 ):

[0005]

[0006] where R 1 is phenyl, R 2 is tert-butyl, R 3 It is phenyl, 4-methylphenyl, 3-methylphenyl, 2-methylphenyl, 4-methoxyphenyl, 4-isopropylphenyl, 4-phenylphenyl, 4-trifluoromethylphenyl, 4-chlorophenyl, 4-cyanophenyl, or 1-naphthyl.

[0007] On the basis of the above technical solution, the present invention can also be improved as follows:

[0008] (1) Furthermore, the photocatalyst is Ir[(ppy)2(dtbbpy)]PF6, 4CzIPN, 4DPAIPN, 3DPF2FBN or fac-Ir(ppy)3.

[0009] (2) Furthermore, the hydrogen transfer catalyst is DABCO, methyl thiosalicylate, cyclohexylmercaptan, thiophenol or amines.

[0010] (3) Furthermore, the base is a carbonate, a bicarbonate, a phosphate, a fluoride, an alkoxy base or a carboxylate.

[0011] (4) Furthermore, the formate used is potassium formate, sodium formate, or cesium formate.

[0012] (5) Furthermore, the solvent used is DMSO, toluene, tetrahydrofuran, DMF, DMA or acetonitrile.

[0013] (6) Furthermore, the CO2 pressure in the reaction container is normal pressure; the distance between the light source and the reaction container is 0.1-10 cm, the wavelength of the light is 435-450 nm, and the power of the light source is 1-100 W.

[0014] The present invention has the following beneficial effects:

[0015] 1. The method of the present invention has the advantages of high efficiency, mild reaction conditions, low reagent toxicity, absence of transition metals, good substrate universality, and low cost. It can effectively solve the problems of existing technologies such as multi-step functional group pre-modification, dependence on transition metal catalysts, and insufficient reaction economy.

[0016] 2. The present invention utilizes visible light to promote CO2 to participate in the 1,4-carbon carboxylation of 1,3-enynes to synthesize allene carboxylic acid compounds, develops a new modular synthesis strategy, and establishes a preparation system with high atom economy and strong substrate universality. It can not only break through the construction limitations of the existing allene carboxylic acid library, but also provide an innovative toolkit for the modification of drug lead compounds and the development of bioactive molecules, which has important scientific value for promoting the development of precision medicine. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 1. Figure 1 It is the general formula for the synthesis of allene carboxylic acid;

[0018] 2. Figure 2 is the reaction formula for the preparation of allene carboxylic acid 3a;

[0019] 3. Figure 3 is the reaction formula for the preparation of allene carboxylic acid 3b;

[0020] 4. Figure 4 is the reaction formula for the preparation of allene carboxylic acid 3c;

[0021] 5. Figure 5 is the reaction formula for the preparation of allene carboxylic acid 3d;

[0022] 6. Figure 6 is the reaction formula for the preparation of allene carboxylic acid 3e;

[0023] 7. Figure 7 is the reaction formula for the preparation of allene carboxylic acid 3f;

[0024] 8. Figure 8 This is the reaction formula for preparing 3g of allene carboxylic acid;

[0025] 9. Figure 9 This is the reaction formula for preparing allene carboxylic acid 3h;

[0026] 10. Figure 10 is the reaction formula for the preparation of allene carboxylic acid 3i;

[0027] 11. Figure 11 This is the reaction formula for preparing 3g of allene carboxylic acid;

[0028] 12. Figure 12 This is the reaction formula for the preparation of allene carboxylic acid 3k. DETAILED DESCRIPTION

[0029] The present invention is further described below through specific examples, but this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0030] Implementation Case 1

[0031] Using 1,3-enyne compound 1a and iodobenzene 2a as raw materials ( Figure 2 )

[0032]

[0033] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), iodobenzene 2a (2 equiv., 45 μL), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), cesium carbonate (3.0 equiv., 195 mg), and 2 mL of ultra-dry DMSO. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3a.

[0034] The product detection data are as follows: white solid, yield 82%, melting point: 149.0~151.0℃.

[0035] 1 H NMR (400MHz, CDCl3) δ7.20–6.99 (m, 10H), 3.40 (q, J = 15.6Hz), 1.12 (s, 9H).

[0036] 13 C NMR (101MHz, CDCl3) δ211.58,172.85,138.56,133.24,129.13,128.25,128.13,127.89,127.18,126.35,119.64,104.38,35.26,34.68,29.15.

[0037] Implementation Case 2

[0038] Using 1,3-enyne compound 1a and aryl iodide 2b as raw materials ( Figure 3 )

[0039]

[0040] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2b (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), cesium carbonate (3.0 equiv., 195 mg), and 2 mL of ultra-dry DMSO. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3b.

[0041] The product detection data are as follows: white solid, yield 73%, melting point: 123.6~125.8℃.

[0042] 1 H NMR (400MHz, CDCl3) δ11.64 (s, 1H), 7.69–6.74 (m, 9H), 3.51 (q, J = 15.6Hz, 2H), 2.33 (s, 3H), 1.25 (s, 9H).

[0043] 13 C NMR (101MHz, CDCl3) δ211.54,172.23,135.82,135.50,133.35,128.98,128.85,128.29,127.91,127.19,119.86,35.32,34.29,29.19,21.04.

[0044] Implementation Case 3

[0045] Using 1,3-enyne compound 1a and aryl iodide 2c as raw materials ( Figure 4 )

[0046]

[0047] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2c (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), and cesium carbonate (3.0 equiv., 195 mg). 2 mL of ultra-dry DMSO was then added. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3c.

[0048] The product detection data are as follows: white solid, yield 72%, melting point: 111.9~113.8℃.

[0049] 1 H NMR (400MHz, CDCl3) δ11.94 (s, 1H), 7.31–6.92 (m, 9H), 3.45 (q, J = 15.6Hz, 2H), 2.20 (s, 3H), 1.20 (s, 9H).

[0050] 13 C NMR (101MHz, CDCl3) δ211.64,172.91,138.47,137.64,133.29,129.98,128.27,128.00 ,127.90,127.17,127.06,126.08,119.76,104.32,53.39,35.24,34.58,29.16,21.14.

[0051] Implementation Case 4

[0052] Using 1,3-enyne compound 1a and aryl iodide 2d as raw materials ( Figure 5 )

[0053]

[0054] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2d (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), cesium carbonate (3.0 equiv., 195 mg), and 2 mL of ultra-dry DMSO. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3d.

[0055] The product detection data are as follows: white solid, yield 78%, melting point: 157.2~159.2℃.

[0056] 1 H NMR (400MHz, CDCl3) δ12.18 (s, 1H), 7.54–6.91 (m, 9H), 3.62 (q, J = 15.8Hz, 2H), 2.36 (s, 3H), 1.42 (s, 9H).

[0057] 13 C NMR (101MHz, CDCl3) δ210.96,172.80,136.76,136.39,133.25,130.07,130.05,128 .29,127.74,127.11,126.67,125.71,119.39,104.62,35.19,32.05,29.04,19.00.

[0058] Implementation Case 5

[0059] Using 1,3-enyne compound 1a and aryl iodide 2e as raw materials ( Figure 6 )

[0060]

[0061] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2e (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), cesium carbonate (3.0 equiv., 195 mg), and 2 mL of ultra-dry DMSO. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3e.

[0062] The product detection data are as follows: white solid, yield 66%, melting point: 102.0~103.0℃.

[0063] 1 H NMR (400MHz, CDCl3) δ11.72(s,1H),7.57–7.07(m,7H),6.82(d,J=8.6Hz,1H),3.81(s,3H),3.51(q,J=15.7Hz,2H),1.26(s,9H).

[0064] 13 C NMR (101MHz, CDCl3) δ210.96,172.80,136.76,136.39,133.25,130.07,130.05,128 .29,127.74,127.11,126.67,125.71,119.39,104.62,35.19,32.05,29.04,19.00.

[0065] Implementation Case 6

[0066] Using 1,3-enyne compound 1a and aryl iodide 2f as raw materials ( Figure 7 )

[0067]

[0068] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2f (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), and cesium carbonate (3.0 equiv., 195 mg). 2 mL of ultra-dry DMSO was then added. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3f.

[0069] The product detection data are as follows: white solid, yield 64%, melting point: 114.6~115.7℃.

[0070] 1 H NMR (400MHz, CDCl3) δ12.11 (s, 1H), 7.27–7.15 (m, 3H), 7.15–7.02 (m, 7H), 3.48 (q, J = 15.6Hz, 2H), 2.84 (hept, J = 6.9Hz, 1H), 1.22–1.20 (m, 15H).

[0071] 13 C NMR (101MHz, CDCl3) δ211.68,172.94,146.91,135.99,133.38,129.04,128.34,12 7.83,127.14,126.16,119.77,104.39,35.20,34.14,33.70,29.12,24.16,23.96.

[0072] Implementation Case 7

[0073] Using 1,3-enyne compound 1a and aryl iodide 2g as raw materials ( Figure 8 )

[0074]

[0075] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), 2 g (2 equiv.) of aryl iodide, Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), and cesium carbonate (3.0 equiv., 195 mg). 2 mL of ultra-dry DMSO was then added. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain 3 g of allene carboxylic acid product.

[0076] The product detection data are as follows: white solid, yield 59%, melting point: 148.4~150.1℃.

[0077] 1 H NMR (400MHz, CDCl3) δ12.10 (s, 1H), 7.65–6.99 (m, 14H), 3.49 (q, J = 15.6Hz, 2H), 1.19 (s, 9H).

[0078] 13 C NMR (101MHz, CDCl3) δ211.67,172.84,140.99,139.24,137.78,133.24,129.53,128 .63,128.30,127.91,127.23,126.99,126.87,119.49,104.43,35.31,34.32,29.18.

[0079] Implementation Case 8

[0080] Using 1,3-enyne compound 1a and aryl iodide 2h as raw materials ( Figure 9 )

[0081]

[0082] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2h (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), cesium carbonate (3.0 equiv., 195 mg), and 2 mL of ultra-dry DMSO. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3h.

[0083] The product detection data are as follows: white solid, yield 58%, melting point: 106.4~108.1℃.

[0084] 1 H NMR (400MHz, CDCl3) δ11.97 (s, 1H), 7.75–6.95 (m, 9H), 3.53 (q, J = 15.6Hz, 2H), 1.22 (s, 9H).

[0085] 13 C NMR (101MHz, CDCl3) δ211.48,172.56,142.87,132.91,129.52,129.23,128.91,128.59,128.22,128.09,127.5 1,125.64,125.17,125.14,125.10,125.06,122.94,119.04,104.71,77.38,77.06,76.74,35.41,34.53,29.17.

[0086] 19 F NMR (377MHz, CDCl3) δ-62.33.

[0087] Implementation Case 9

[0088] Using 1,3-enyne compound 1a and aryl iodide 2i as raw materials ( Figure 10 )

[0089]

[0090] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2i (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), cesium carbonate (3.0 equiv., 195 mg), and 2 mL of ultra-dry DMSO. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3i.

[0091] The product detection data are as follows: white solid, yield 63%, melting point: 125.0.0~126.5℃.

[0092] 1 H NMR (400MHz, CDCl3) δ7.45–7.00 (m, 9H), 3.48 (q, J = 15.8Hz, 2H), 1.23 (s, 9H).

[0093] 13 C NMR (101MHz, CDCl3) δ211.44,172.62,137.06,133.01,132.11,130.49,129.15,128 .24,128.20,128.17,128.02,127.92,127.37,119.35,104.50,35.31,34.05,29.15.

[0094] Implementation Case 10

[0095] Using 1,3-enyne compound 1a and aryl iodide 2j as raw materials ( Figure 11 )

[0096]

[0097] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2j (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), and cesium carbonate (3.0 equiv., 195 mg). 2 mL of ultra-dry DMSO was then added. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3j.

[0098] The product detection data are as follows: white solid, yield 47%, melting point: 152.2~153.4℃.

[0099] 1 H NMR (400MHz, CDCl3) δ11.73 (s, 1H), 7.59 (d, J = 7.8 Hz, 2H), 7.37 (dd, J = 14.8, 7.4 Hz, 5H), 7.27 (d, J = 7.2 Hz, 2H), 3.96 (q, J = 15.6 Hz, 2H), 1.33 (s, 9H).

[0100] 13 C NMR (101MHz, CDCl3) δ211.18,172.33,144.25,132.86,132.54,132.47,131.89,129.92, 129.51,128.08,128.00,127.54,118.90,118.75,110.15,104.67,35.37,34.73,29.07.

[0101] Implementation Case 11

[0102] Using 1,3-enyne compound 1a and aryl iodide 2k as raw materials ( Figure 12 )

[0103]

[0104] In a glove box, a Schlenk tube (10 mL) equipped with a stirrer was charged with 1,3-enyne compound 1a (0.2 mmol), aryl iodide 2k (2 equiv.), Ir[(ppy)2(dtbbpy)]PF6 (1 mol%, 1.7 mg), DABCO (0.5 equiv., 11.2 mg), potassium formate (3.0 equiv., 50.5 mg), and cesium carbonate (3.0 equiv., 195 mg). 2 mL of ultra-dry DMSO was then added. The Schlenk tube was removed from the glove box, evacuated, and backfilled with carbon dioxide three times. The mixture was illuminated with a 40 W 460 nm Kessil Blue LED (at a distance of 3 cm, with a cooling fan maintaining the reaction temperature at room temperature). After 24 h of reaction, the reaction was quenched with hydrochloric acid (2 M) and extracted five times with ethyl acetate. The combined organic layers were washed with brine and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate / formic acid) to obtain the allene carboxylic acid product 3k.

[0105] The product detection data are as follows: white solid, yield 49%, melting point: 205.0~206.4℃.

[0106] 1 H NMR (400MHz, CDCl3) δ11.45(s,1H),7.88(d,J=8.2Hz,1H),7.78(d,J=7.9Hz,1H),7.72(d,J=7.4Hz,1 H),7.43–7.28(m,4H),7.13–7.04(m,3H),6.71(d,J=6.8Hz,2H),3.96(q,J=16.0Hz,2H),1.34(s,9H).

[0107] 13 C NMR (101MHz, CDCl3) δ211.26,171.89,134.64,133.67,132.83,131.95,128.41,127.99,127.64, 127.39,127.31,126.94,125.74,125.40,125.26,124.18,119.72,104.69,35.45,31.95,29.14.

[0108] Result Analysis

[0109] 1. Experimental results demonstrate that both 1,3-enynes and aryl iodide compounds provide high yields and excellent chemoselectivity for the synthesis of allenoic acid compounds. A wide range of functional groups, including methyl, methoxy, isopropyl, phenyl, trifluoromethyl, halogen, cyano, and fused rings, are compatible with this reaction. Iodides substituted at various positions on the phenyl group are also compatible with this system and converted into the desired allenoic acid products.

[0110] 2. The comparison of product yields of Experimental Example 1 is shown in Table 1.

[0111]

[0112]

[0113] Note: Table 1 shows the NMR yield, with dibromomethane as the internal standard, and the values ​​in brackets are the separation yields.

[0114] The data in Table 1 indicate that under the reaction conditions of this invention, the isolated yield reaches as high as 75%. A series of controlled experiments demonstrate that illumination, hydrogen transfer catalyst, base, formate, and photocatalyst play essential roles in the reaction; lacking any of these factors will result in the target product. The use of other photosensitizers or hydrogen atom transfer reagents can lead to varying degrees of yield decline, primarily due to excess raw materials or an increase in intermediate byproducts. Substituting different formate salts results in a slight decrease in yield and an increase in intermediate byproducts. Substituting MeCN or DMF as solvents results in a decrease in yield, primarily due to excess raw materials.

Claims

1. A method for synthesizing allene carboxylic acid based on CO2, characterized in that: The following steps are involved: 1,3-enyne, iodide, photocatalyst, hydrogen transfer catalyst, base, formate and solvent are added to a reaction vessel, and then carbon dioxide gas is introduced under normal pressure, reacted at room temperature under blue light and visible light, and after acidification, separated and purified to obtain an allene carboxylic acid compound; The general reaction formula is shown below: Where: R 1 is phenyl, R 2 is tert-butyl, R 3 is phenyl, 4-methylphenyl, 3-methylphenyl, 2-methylphenyl, 4-methoxyphenyl, 4-isopropylphenyl, 4-phenylphenyl, 4-trifluoromethylphenyl, 4-chlorophenyl, 4-cyanophenyl, 1-naphthyl; The photocatalyst is Ir[(ppy)2(dtbbpy)]PF6, 4DPAIPN; The hydrogen transfer catalyst is a mercaptan, a thiol or an amine; The base is cesium carbonate; The solvent is ultra-dry DMSO; The CO2 pressure in the reaction container is normal pressure.

2. The method for synthesizing allene carboxylic acid based on CO2 according to claim 1, characterized in that: The hydrogen transfer catalyst is DABCO, methyl thiosalicylate, cyclohexyl mercaptan, thiophenol or DIPEA.

3. The method for synthesizing allene carboxylic acid based on CO2 according to claim 1, characterized in that: The formate is potassium formate, sodium formate or cesium formate.

4. The method for synthesizing allene carboxylic acid based on CO2 according to claim 1, characterized in that: The distance between the light source and the reaction container is 0.1-10 cm, the wavelength of the light is 460 nm, and the power of the light source is 1-100 W.

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