Method for synthesizing dihydrofuranonetetrahydroquinoline derivative by optical excitation of arylamine and 2 (5H)-furanone

Abstract

The invention belongs to the technical field of organic synthesis, and particularly relates to a method for synthesizing a dihydrofuranonetetrahydroquinoline derivative by optical excitation of arylamine and 2 (5H)-furanone. The invention provides a method for synthesizing a dihydrofuranone tetrahydroquinoline derivative by photoexcitation of arylamine and 2 (5H)-furanone, which comprises the following steps: in an inert atmosphere, performing single electron transfer on an arylamine compound and benzophenone (BP) in an excited state through light irradiation to form free radical positive ions of nitrogen, and then performing deprotonation to synthesize the dihydrofuranone tetrahydroquinoline derivative. And then carrying out intermolecular free radical addition and further cyclization reaction on the alpha-amino alkyl free radical intermediate and 2 (5H)-furanone, so as to finally obtain the dihydrofuranone tetrahydroquinoline derivative disclosed by the invention. No transition metal catalyst or oxidant is needed in the reaction process, operation is easy and convenient, and conditions are mild.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis and more specifically relates to a method for synthesizing dihydrofuranone and tetrahydroquinoline derivatives by using photoexcited aromatic amine and 2(5H)-furanone. Background Art

[0002] Tetrahydroquinoline derivatives are a class of quinoline alkaloids with high content in Zanthoxylum bungeanum. Studies have found that this alkaloid, as a common nitrogen-containing heterocyclic natural product, shows outstanding anti-plant pathogenic fungi, insecticides and antiviral activities in agriculture. Especially in the development of environmentally friendly pesticides and antibacterial agents, this class of compounds has shown outstanding potential and has attracted widespread attention. The Povarov reaction is a method for synthesizing tetrahydroquinoline derivatives by reacting aromatic amines with olefins. The two-component aromatic amines and electron-donating olefins can be cyclized to efficiently construct a tetrahydroquinoline skeleton structure (Sridharan V, Suryavanshi PA, Menéndez J C. Chemical Reviews, 2011, 111, 7157-7259; Muthukrishnan I, Sridharan V, Menéndez J C. Chemical Reviews, 2019, 119, 5057-5191). However, these methods are only effective for olefins containing electron-donating groups, which limits the application of electron-deficient olefins to some extent. At present, the synthesis of tetrahydroquinoline derivatives from electron-deficient olefins generally requires the addition of metal catalysts or oxidants. For example, Sakai et al. developed a method for synthesizing tetrahydroquinoline derivatives under cobalt metal catalyst conditions and synthesized a variety of N-succinamide tetrahydroquinoline derivatives (Tetrahedron Letters, 2016, 57, 5449-5452); Hu et al. used potassium persulfate as an oxidant and achieved the intermolecular reaction of aromatic tertiary amines and N-substituted maleimides under metal-free conditions, and synthesized tetrahydroquinoline derivatives with high stereoselectivity (Organic Letters, 2023, 25, 1252-1256).

[0003] Therefore, it is of great significance to provide a simple, mild, inexpensive and efficient preparation method to synthesize tetrahydroquinoline from electron-deficient olefins and aromatic tertiary amines. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the prior art that the synthesis of tetrahydroquinoline derivatives using electron-deficient olefins generally requires the additional addition of metal catalysts or oxidants, and to provide a method for synthesizing dihydrofuranone and tetrahydroquinoline derivatives with photoexcited aromatic amines and 2(5H)-furanone.

[0005] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0006] A method for synthesizing dihydrofuranone and tetrahydroquinoline derivatives by photoexcited aromatic amine and 2(5H)-furanone, comprising the following steps:

[0007] The compound represented by formula (I) and 2(5H)-furanone are mixed, an organic solvent and benzophenone are added, the mixture is reacted under an inert atmosphere and light, and post-treated to obtain the compound represented by formula (II);

[0008] The specific synthesis route is as follows:

[0009]

[0010] Wherein R1 is hydrogen, C 1～6 Alkyl; R2 is C 1～6 Alkyl, phenyl; R3 is hydrogen, C 1～6 Alkyl, C 1～6 Alkoxy, cyano, halogen, C 1～6 Ester group, C 1～7 Acyl.

[0011] The inventors have found through experiments that, under an inert atmosphere, the compound of formula (I) can be excited by light irradiation to undergo single electron transfer with excited benzophenone (BP), forming a nitrogen free radical cation, which is then deprotonated to form an α-aminoalkyl free radical intermediate, which then undergoes intermolecular free radical addition and further cyclization reaction with 2(5H)-furanone, and finally obtains a dihydrofuranone tetrahydroquinoline derivative shown in formula (II). The reaction process of the present invention does not require the participation of a transition metal catalyst or an oxidant, is simple to operate, and has mild conditions.

[0012] Preferably, R1 is hydrogen, C 1～3 Alkyl; R2 is C 1～3 Alkyl, phenyl; R3 is hydrogen, C 1～3 Alkyl, C 1～3 Alkoxy, cyano, halogen, C 1～3 Ester group, C 1～7 Acyl.

[0013] Preferably, R1 is hydrogen or methyl; R2 is methyl, ethyl or phenyl; R3 is hydrogen, methyl, methoxy, cyano, fluorine, chlorine, bromine, acetyl, benzoyl or methyl formate.

[0014] Specifically, the compound of formula (I) is N,N-dimethylaniline, N,N-diethylaniline, N,N-dipropylaniline, N-methyldiphenylamine, 4-methyl-N,N-dimethylaniline, 3-methoxy-N,N-dimethylaniline, 4-bromo-N,N-dimethylaniline, 4-chloro-N,N-dimethylaniline, 4-fluoro-N,N-dimethylaniline, 3-bromo-N,N-dimethylaniline, 3-cyano-N,N-dimethylaniline, 4-acetyl-N,N-dimethylaniline, 4-benzoyl-N,N-dimethylaniline, and 4-methylformyl-N,N-dimethylaniline.

[0015] Preferably, a base is also added to the reaction, that is, the compound represented by formula (I) and cyclopentenyl ester are mixed, an organic solvent, a base and benzophenone are added, and the mixture is reacted under an inert atmosphere and light, and post-treated to obtain the compound represented by formula (II); the base is one or both of acetate and tertiary amine. The inventors have found through extensive research that adding a specific base to the entire reaction is beneficial to improving the yield of the dihydrofuranone tetrahydroquinoline derivative represented by formula (II).

[0016] Preferably, the acetate is sodium acetate. Compared with other acetates, sodium acetate as a base has a better yield.

[0017] Preferably, the tertiary amine is triethylenediamine or triethylamine.

[0018] Preferably, the molar ratio of the compound represented by formula (I) to the base is 1:(1-3).

[0019] Preferably, the reaction under illumination refers to the reaction under the irradiation of visible light or ultraviolet light. In some non-limiting examples, the reaction can be carried out under sunlight. More specifically, the wavelength of the illumination is 350-475nm; more specifically, the wavelength of the illumination is 375-450nm; more specifically, the wavelength of the illumination is 375-420nm. Under the illumination range of this wavelength, the compound of formula (II) has a higher yield.

[0020] Preferably, the organic solvent is one or more of acetonitrile, dioxane, tetrahydrofuran, toluene, ethanol, and dichloroethane.

[0021] Preferably, the molar ratio of the compound represented by formula (I) to benzophenone is 1:(0.2-1).

[0022] Preferably, the reaction temperature is 20-25°C.

[0023] Preferably, the reaction time is 12 to 48 hours.

[0024] Preferably, the post-treatment is separation and purification.

[0025] The separation and purification described in the present invention is a commonly used separation and purification method in the field of compound synthesis. As a reference, the present invention provides a separation and purification method: removing the organic solvent, and subjecting the residue to silica gel column chromatography using a mixed solvent of petroleum ether and ethyl acetate as an eluent.

[0026] Preferably, the method for removing the organic solvent is distillation under reduced pressure.

[0027] Preferably, the volume ratio of petroleum ether to ethyl acetate is 2 to 20:1.

[0028] The present invention has the following beneficial effects:

[0029] The present invention provides a method for synthesizing a dihydrofuranone tetrahydroquinoline derivative by photoexcited aromatic amine and 2(5H)-furanone. In an inert atmosphere, a compound of formula (I) can be excited by light irradiation to undergo single electron transfer with excited benzophenone (BP), forming a nitrogen free radical positive ion, which is then deprotonated to form an α-aminoalkyl free radical intermediate, which then undergoes intermolecular free radical addition and further cyclization reaction with 2(5H)-furanone, and finally obtains the dihydrofuranone tetrahydroquinoline derivative of the present invention. The reaction process of the present invention does not require the participation of a transition metal catalyst or an oxidant, and is simple to operate and has mild conditions. DETAILED DESCRIPTION

[0030] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0031] In the present invention, C 1-6 Alkyl refers to a saturated alkyl group having 1 to 6 carbon atoms, including C 1-6 Straight chain alkyl, C 1-6 for example, a straight chain alkyl group having 1, 2, 3, 4, 5 or 6 carbon atoms, or a branched chain alkyl group having 1, 2, 3, 4, 5 or 6 carbon atoms. 1-3 Alkyl groups have a similar explanation, except that the number of carbon atoms is different.

[0032] C 1-6 Alkoxy refers to an alkoxy group having 1 to 6 carbon atoms, including C 1-6 Straight chain alkoxy, C 1-6 for example, a straight chain alkoxy group having a total number of carbon atoms of 1, 2, 3, 4, 5 or 6, or a branched chain alkoxy group having a total number of carbon atoms of 1, 2, 3, 4, 5 or 6. 1-3 Alkoxy groups have a similar interpretation, except that the number of carbon atoms is different.

[0033] C 1～6 The ester group refers to an ester group having a total carbon atom number of 1 to 6, for example, methyl formate, ethyl formate, methyl acetate, methyl propionate, methyl butyrate, ethyl butyrate and the like.

[0034] C 1～7 The acyl group refers to an acyl group having 1 to 7 carbon atoms, for example, acetyl, formyl, propionyl, butyryl, benzoyl, etc.

[0035] In the present invention, the room temperature is 20-25°C.

[0036] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0037] Example 1

[0038]

[0039] In a 10mL quartz test tube, add N,N-dimethylaniline (36.3mg, 0.3mmol), 2(5H)-furanone (25.2mg, 0.3mmol), BP (Benzophenone, 36.3mg, 0.15mmol), acetonitrile (2mL), sodium acetate (49.2mg, 0.6mmol), nitrogen atmosphere, irradiation under 425nm light, and stirring at room temperature for 36 hours. After the reaction is completed, acetonitrile is removed by pressure distillation, and the product (48.6mg, yield 73%) is separated by silica gel column chromatography using a mixed solvent of petroleum ether and ethyl acetate (volume ratio of petroleum ether and ethyl acetate is 5:1) as the eluent.

[0040] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ7.49 (d, J = 7.4Hz, 1H), 7.23 (t, J = 7.6Hz, 1H), 6.86 (t, J = 7.4Hz, 1H), 6.74 (d, J = 8.2Hz, 1H), 4.50 (dd, J = 9.2, 6.6Hz, 1H),4.24(dd,J=9.2,3.6Hz,1H),3.74(d,J=8.2Hz,1H),3.25(dd,J=11.6,4.6Hz,1H),3.17-3.06(m,1H),2.99-2.93(m,1H),2.91(s,3H). 13 C NMR (100MHz, CDCl3) δ176.66,146.63,130.51,128.53,118.36,116.73,112.13,69.39,51.15,40.68,39.54,34.05.

[0041] Example 2

[0042]

[0043] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by N,N-diethylaniline (44.8 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (44.3 mg, yield 64%) is finally obtained.

[0044] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ7.53 (d, J=7.4Hz, 1.40H), 7.24-7.15 (m, 1.49H), 6.81 (t, J=7.4Hz, 1H), 6.74 (ddd, J=7.4, 3.8, 1. 2Hz,1.42H),6.67(d,J=8.4Hz,0.49H),4.48(dt,J=8.3,6.8Hz,1.50H),4.27(ddd,J=18.2,9.4,5.8Hz,1.55H),3.77(d ,J=9.0Hz,0.51H),3.69(d,J=8.6Hz,0.95H),3.59-3.42(m,2.61H),3.28(qd,J=6.4,2.8Hz,0.56H),3.23-3.06(m,2.6 2H), 2.99 (ddd, J=17.6, 9.4, 2.6Hz, 0.54H), 1.23 (q, J=7.2Hz, 4.62H), 1.16 (d, J=6.4Hz, 1.57H), 1.04 (d, J=6.8Hz, 3H). 13 C NMR (100MHz, CDCl3) δ177.38,176.87,143.71,143.07,130.43,129.61,128.72,128.49,117.33,117.11,115.66,11 5.13,112.50,112.08,69.84,68.58,51.87,51.38,44.00,43.30,41.95,38.83,38.53,38.32,17.08,13.19,12.82.

[0045] Example 3

[0046]

[0047] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by N-methyldiphenylamine (55.2 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (44.5 mg, yield 58%) is finally obtained.

[0048] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR(400MHz, CDCl3) CDCl3) δ7.58(d,J=7.4Hz,1H),7.39(dd,J=8.4,7.2Hz,2H),7.21(dd,J =8.6,1.2Hz,2H),7.17(t,J=7.2Hz,1H),7.09-7.04(m,1H),6.91(td,J=7.4,1.2Hz,1H),6.7 9(dd,J=8.2,1.2Hz,1H),4.51(dd,J=9.4,6.8Hz,1H),4.26(dd,J=9.4,3.8Hz,1H),3.84(d,J =8.4Hz,1H),3.77(dd,J=12.2,4.4Hz,1H),3.43(dd,J=12.2,8.8Hz,1H),3.21-3.11(m,1H). 13 C NMR (100MHz, CDCl3) δ176.51,146.92,144.40,130.78,129.64,127.95,124.42,124.39,119.89,117.81,115.93,69.12,49.51,40.68,34.35.

[0049] Example 4

[0050]

[0051] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 4-methyl-N,N-dimethylaniline (40.5 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (48.8 mg, yield 75%) is finally obtained.

[0052] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1H NMR (400MHz, CDCl3) δ7.31(s,1H),7.04(d,J=7.7Hz,1H),6.66(d,J=8.2Hz,1H),4.49(dd,J=9.2,6.8Hz,1H),4.24(dd,J=9.2,3 .8Hz,1H),3.70(d,J=8.4Hz,1H),3.20(dd,J=11.4,4.5Hz,1H),3.14-3.04(m,1H),2.94-2.89(m,1H),2.88(s,3H),2.31(s,3H). 13 C NMR (100MHz, CDCl3) δ176.74,144.57,130.90,129.14,127.67,116.77,112.26,69.43,51.39,40.68,39.68,34.31,20.37.

[0053] Example 5

[0054]

[0055] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 3-methoxy N,N-dimethylaniline (45.3 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (54.5 mg, yield 78%) is finally obtained.

[0056] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ7.18(t,J=8.2Hz,1H),6.46(d,J=8.2Hz,1H),6.40(d,J=8.2Hz,1H),4.51(dd,J=9.2,5.4Hz,1H),4.14 (d,J=8.4Hz,2H),3.89(s,3H),3.20(ddd,J=11.6,5.0,1.2Hz,1H),3.01(t,J=11.2Hz,1H),2.93(s,3H),2.90-2.82(m,1H). 13 C NMR (100MHz, CDCl3) δ175.34,158.81,146.93,128.87,105.36,105.07,101.32,69.57,56.07,51.41,39.78,37.32,32.48.

[0057] Example 6

[0058]

[0059] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 4-bromo-N,N-dimethylaniline (60.0 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (68.5 mg, yield 81%) is finally obtained.

[0060] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ7.57(dd,J=2.4,0.8Hz,1H),7.29(dd,J=8.6,2.6Hz,1H),6.59(d,J=8.8Hz,1H),4.49(dd,J=9.2,6.6Hz ,1H),4.21(dd,J=9.2,3.2Hz,1H),3.67(d,J=8.2Hz,1H),3.24(dd,J=11.6,4.6Hz,1H),3.12-3.02(m,1H),2.94-2.87(m,4H). 13 C NMR (100MHz, CDCl3) δ175.94,145.61,132.89,131.26,118.65,113.78,110.23,69.32,50.98,40.48,39.56,33.71.

[0061] Example 7

[0062]

[0063] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 4-chloro-N,N-dimethylaniline (46.5 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (63.9 mg, yield 90%) is finally obtained.

[0064] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1H NMR (400MHz, CDCl3) δ7.46(dd,J=2.4,0.6Hz,1H),7.16(dd,J=8.8,2.4Hz,1H),6.65(d,J=8.8Hz,1H),4.50(dd,J=9.2,6.6Hz,1H),4.22( dd,J=9.4,3.2Hz,1H),3.68(d,J=8.2Hz,1H),3.24(dd,J=11.2,4.2Hz,1H),3.09(dd,J=11.2,4.2Hz,1H),2.95-2.91(m,1H),2.90(s,3H). 13 C NMR (100MHz, CDCl3) δ175.92,145.17,130.11,128.40,123.22,118.23,113.34,69.31,51.10,40.56,39.64,33.79.

[0065] Example 8

[0066]

[0067] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 4-fluoro-N,N-dimethylaniline (41.7 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (59.0 mg, yield 89%) is finally obtained.

[0068] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ7.23 (dd, J=9.2, 3.2Hz, 1H), 6.93 (td, J=8.4, 2.8Hz, 1H), 6.65 (dd, J=9.0, 4.6Hz, 1H), 4.49 (dd, J=9. 2,6.6Hz,1H),4.23(dd,J=9.2,3.4Hz,1H),3.69(d,J=8.4Hz,1H),3.24-3.18(m,1H),3.14-3.05(m,1H),2.92-2.85(m,4H). 13 C NMR (100MHz, CDCl3) δ176.12,155.87(d, 1 J C-F =235.8Hz),143.29(d, 4 J C-F =3.3Hz),118.27(d, 3 J C-F=7.5Hz),116.91(d, 2 J C-F =23.0Hz),155.00(d, 2 J C-F =21.8Hz),112.99(d, 3 J C-F =7.5Hz),69.43,51.52,40.77(d, 4 J C-F =1.3Hz),39.90,34.07.

[0069] Example 9

[0070]

[0071] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 3-bromo-N,N-dimethylaniline (60.0 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (52.4 mg, yield 62%) is finally obtained.

[0072] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ7.08(s,1H),7.06(d,J=3.2Hz,1H),6.65(dd,J=6.4,3.2Hz,1H),4.56(dd,J=9.4,5.2Hz,1H),4.23 (dd,J=7.2,1.2Hz,1H),4.18(d,J=9.4Hz,1H),3.25(ddd,J=11.8,5.2,1.2Hz,1H),3.11-3.04(m,1H),3.00-2.89(m,4H). 13 C NMR (100MHz, CDCl3) δ174.09,147.73,129.49,126.56,122.35,116.39,110.83,69.71,51.66,42.86,39.63,32.87.

[0073] Example 10

[0074]

[0075] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 3-cyano-N,N-dimethylaniline (43.8 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (47.7 mg, yield 70%) is finally obtained.

[0076] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ7.28 (d, J=8.0Hz, 1H), 7.14 (dd, J=8.0, 1.2Hz, 1H), 6.90 (d, J=8.0Hz, 1H), 4.57 (dd, J=9. 6,5.2Hz,1H),4.20(d,J=9.2Hz,1H),4.07(d,J=6.8Hz,1H),3.34-3.30(m,1H),3.05-2.97(m,2H),2.96(s,3H). 13 C NMR (100MHz, CDCl3) δ173.78,146.48,128.98,122.14,121.29,119.22,115.81,114.90,69.57,51.03,41.11,39.44,32.29.

[0077] Embodiment 11

[0078]

[0079] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 4-acetyl-N,N-dimethylaniline (48.9 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (52.9 mg, yield 72%) is finally obtained.

[0080] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ8.03(d,J=1.6Hz,1H),7.84(dd,J=8.8,2.2Hz,1H),6.70(d,J=8.8Hz,1H),4.51(dd,J=9.4,5.8Hz,1H) ,4.19(dd,J=9.6,2.0Hz,1H),3.73(d,J=7.2Hz,1H),3.36(d,J=8.2Hz,1H),3.05(d,J=8.6Hz,2H),3.01(s,3H),2.55(s,3H). 13C NMR (100MHz, CDCl3) δ196.51,175.95,149.83,131.78,129.45,127.12,115.14,111.20,69.19,50.46,40.63,39.39,33.06,26.19.

[0081] Example 12

[0082]

[0083] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 4-benzoyl-N,N-dimethylaniline (67.5 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with those of the embodiment, and the product (80.1 mg, yield 87%) is finally obtained.

[0084] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ7.96(d,J=2.2Hz,1H),7.80(d,J=7.2Hz,3H),7.56(t,J=7.4Hz,1H),7.49(t,J=7.4Hz,2H),6.75(d,J=8.6Hz,1H),4 .50(dd,J=9.4,5.2Hz,1H),4.20(d,J=9.4Hz,1H),3.72(d,J=6.6Hz,1H),3.37(d,J=7.0Hz,1H),3.06(dd,J=5.8,3.4Hz,2H),3.03(s,3H). 13 C NMR (100MHz, CDCl3) δ195.04,175.87,149.64,138.61,133.97,131.59,129.77 ,128.14,128.11,126.67,115.10,111.15,69.15,50.58,40.66,39.43,33.02.

[0085] Example 13

[0086]

[0087] The preparation method of this embodiment is different from that of Example 1 in that N,N-dimethylaniline (36.3 mg, 0.3 mmol) is replaced by 4-methylformate-N,N-dimethylaniline (53.8 mg, 0.3 mmol), and the remaining reaction conditions and preparation steps are consistent with the embodiment, and the product (61.1 mg, yield 78%) is finally obtained.

[0088] The hydrogen spectrum data and carbon spectrum data of the product are shown below: 1 H NMR (400MHz, CDCl3) δ8.10(d,J=2.0Hz,1H),7.89(dd,J=8.8,2.1Hz,1H),6.69(d,J=8.8Hz,1H),4.50(dd,J=9.4,5.6Hz,1H ),4.18(dd,J=9.4,2.0Hz,1H),3.88(s,3H),3.72(d,J=7.2Hz,1H),3.33(d,J=8.0Hz,1H),3.10-3.01(m,2H),2.99(s,3H). 13 C NMR (100MHz, CDCl3) δ175.92,167.06,149.69,132.34,130.58,119.15,115.34,111.17,69.18,51.70,50.55,40.65,39.39,33.08.

[0089] Examples 14, 15 and Comparative Example 1

[0090] The difference between Examples 14, 15 and Comparative Example 1 and Example 1 is only the amount of benzophenone added, as shown in the following table:

[0091] Table 1 Yields of dihydrofuranone and tetrahydroquinoline derivatives under different benzophenone addition amounts

[0092]

[0093] Note: “ / ” indicates that no benzophenone was added.

[0094] As shown in Table 1, the yield of Comparative Example 1 is significantly reduced without adding benzophenone, which indicates that the synthesis method of the present invention requires the participation of benzophenone.

[0095] Examples 16 to 19 and Comparative Examples 2 to 3

[0096] The difference between Examples 16 to 19 and Comparative Examples 2 to 3 and Example 1 is only in the type and amount of the base added, as shown in the following table:

[0097] Table 2 Yields of dihydrofuranone and tetrahydroquinoline derivatives under different alkaline conditions

[0098]

[0099] Note: “ / ” indicates no alkali was added.

[0100] As shown in Table 2, the reaction of the present invention can also generate the target product in the absence of alkali, and the yield can reach 40%. The yield of the target product can be significantly improved under specific alkali conditions, but for Comparative Example 3 where the alkali is the strong alkali sodium hydroxide, no reaction occurs, and the yield of the target product is 0; for the alkali is potassium carbonate, the yield of the target product is <5%. The above results show that potassium carbonate and sodium hydroxide are not suitable for the synthesis method of the present invention.

[0101] Examples 20 to 24 and Comparative Example 4

[0102] The difference between Examples 20 to 24 and Comparative Example 4 and Example 1 is only that the wavelength of the light is different, as shown in the following table:

[0103] Table 3 Yields of dihydrofuranone and tetrahydroquinoline derivatives under different alkaline conditions

[0104]

[0105] Note: The reaction under sunlight conditions refers to the reaction under direct sunlight.

[0106] It can be seen from Table 3 that the reaction of the present invention must be carried out under light conditions, and no reaction occurs in comparative example 4 under light protection, and no target product is generated.

[0107] Comparative Example 5

[0108] The only difference between Comparative Example 5 and Example 1 is that the reaction in this comparative example is carried out under an oxygen atmosphere. The experimental results show that in an oxygen atmosphere, no reaction occurs and no target product is generated.

[0109] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for synthesizing dihydrofuranone and tetrahydroquinoline derivatives by photoexcited aromatic amine and 2(5H)-furanone, characterized in that: The following steps are involved: The compound represented by formula (I) and 2(5H)-furanone are mixed, an organic solvent and benzophenone are added, the mixture is reacted under an inert atmosphere and light, and post-treated to obtain the compound represented by formula (II); The specific synthesis route is as follows: Wherein R1 is hydrogen, C 1～6 Alkyl; R2 is C 1～6 Alkyl, phenyl; R3 is hydrogen, C 1～6 Alkyl, C 1～6 Alkoxy, cyano, halogen, C 1～6 Ester group, C 1～7 Acyl.

2. The method according to claim 1, characterized in that: R1 is hydrogen, C 1～3 Alkyl; R2 is C 1～3 Alkyl, phenyl; R3 is hydrogen, C 1～3 Alkyl, C 1～3 Alkoxy, cyano, halogen, C 1～3 Ester group, C 1～7 Acyl.

3. The method according to claim 2, characterized in that: The R1 is hydrogen or methyl; R2 is methyl, ethyl or phenyl; R3 is hydrogen, methyl, methoxy, cyano, fluorine, chlorine, bromine, acetyl, benzoyl or methyl formate.

4. The method according to claim 1, characterized in that: A base is also added in the reaction; the base is one or both of acetate and tertiary amine.

5. The method according to claim 4, characterized in that: The acetate is sodium acetate.

6. The method according to claim 4, characterized in that: The tertiary amine is triethylenediamine or triethylamine.

7. The method according to claim 4, characterized in that: The molar ratio of the compound represented by formula (I) to the base is 1:(1-3).

8. The method according to claim 1, characterized in that: The organic solvent is one or more of acetonitrile, dioxane, tetrahydrofuran, toluene, ethanol, and dichloroethane.

9. The method according to claim 1, characterized in that: The molar ratio of the compound represented by formula (I) to benzophenone is 1:(0.2-1).

10. The method according to claim 1, characterized in that: The reaction temperature is 20-25°C.

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