A c3 arylcarbonyloxy group 4h-pyrido [1, 2-a] pyrimidine-4-ketone derivative and its synthesis method

Abstract

The application discloses a C3 aryl formyloxy 4H-pyrido[1,2-a]pyrimidin-4-one derivative and a synthesis method thereof, and belongs to the technical field of organic photocatalytic synthesis. In view of the problems that, in the current C3-H functionalization of 4H-pyrido[1,2-a]pyrimidin-4-one derivative and aryl formyloxylation of heterocyclic compounds, noble metal catalysts, strong oxidants, photosensitizers polluting the environment, and toxic solvents are used, the method of the application is characterized in that, under the condition of room temperature air and 410-415 nm violet light irradiation, 4H-pyrido[1,2-a]pyrimidin-4-one and peroxidized aryl formyl compound are reacted in dimethyl carbonate solvent to generate the C3 aryl formyloxy 4H-pyrido[1,2-a]pyrimidin-4-one derivative. The method of the application does not need to add any oxidant and photocatalyst, and has the advantages of simple operation, excellent substrate functional group compatibility, high reaction yield and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic photocatalytic synthesis, and particularly relates to a C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative and a synthesis method thereof. Background Art

[0002] Pyrido[1,2-a]pyrimidin-4-ones are common heterocyclic compounds with promising biological and pharmaceutical activities, making them important heterocyclic backbone structures in drug development. For example, 2,3-diaryl-4H-pyrimido[1,2-a]pyrimidin-4-one derivatives can act as inhibitors of endothelial cell dysfunction and smooth muscle cell activators. Furthermore, C3-arylated pyridino[1,2-a]pyrimidin-4-ones exhibit diverse biological activities, including as regulators of platelet activation and aggregation, anti-inflammatory agents, anti-tuberculosis agents, CXCR3 antagonists, anti-allergic activities, efflux pump inhibitors, and acetylcholinesterase, antioxidant, and antipsychotic agents. Currently, the main functionalization methods for the C3 position of 4H-pyrido[1,2-a]pyrimidin-4-ones include C3 aryl substitution, C3 dialkyl phosphite substitution, C3 arylthio(seleno)yl substitution, and C3 aryl substitution. However, the above-mentioned method for functionalizing the C3 position of 4H-pyrimidin[1,2-a]pyrimidin-4-one derivatives has the following problems: harsh reaction conditions, the need for the addition of noble metal catalysts (palladium acetate / silver nitrate, J. Org. Chem. 2015, 80, 8482–8488; Asian J. Org. Chem. 2021, 10, 1660–1664), strong oxidants (K2S2O8, PIFA / I2, J. Org. Chem. 2021, 10, 2911–2915; Adv. Synth. Catal. 2021, 363, 2148–2156), a narrow substrate range, the addition of environmentally polluting photosensitizers (J. Org. Chem., 2023, 88, 13: 9537–9542), and the use of environmentally unfriendly organic solvents (European Journal of Chemistry, 2015). ofOrganic Chemistry, 2023, 26(29), e202300268) and other deficiencies.

[0003] The C-H aryloxylation of heterocyclic compounds has attracted increasing attention due to its ability to directly prepare aryl carboxylate products, which have potential applications. For example, aryl carboxylates can be used as alternative electrophiles in palladium-free cross-coupling reactions and converted into potential phenolic compounds. Currently, C-H aryloxylation of heterocyclic compounds primarily involves the reaction of 8-aminoquinoline with aromatic acids or aryloxy compounds using catalytic methods such as ferric chloride or copper acetate (Org. Biomol. Chem., 2017, 15, 9200; Org. Lett., 2017, 19, 3636; Org. Biomol. Chem., 2017, 15, 531). However, these methods suffer from the use of transition metal catalysts, harsh reaction conditions, a narrow substrate range, low yields, and the use of toxic organic solvents. Summary of the Invention

[0004] In view of the problems existing in the current C3-H functionalization of 4H-pyrido[1,2-a]pyrimidin-4-one derivatives and the aryloxylation of heterocyclic compounds, such as the use of noble metal catalysts, strong oxidants, photosensitizers that pollute the environment, and the use of toxic solvents, the present invention provides a C3 aryloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative and a photocatalytic synthesis method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative, wherein the structure (I) of the C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative is as follows:

[0007] ( I )

[0008] R 1 = H, 6-methyl, 7-methyl, 8-methyl, 7-fluoro, 7-chloro, 7-bromo, 7-ester, 7-CF3; R 2 = methyl, phenyl, p-chlorophenyl; Ar = 2-methylphenyl, 3-methylphenyl, p-methoxyphenyl, p-fluorophenyl, 3-fluorophenyl, p-chlorophenyl, 3-chlorophenyl, p-bromophenyl, p-trifluoromethylphenyl, p-nitrophenyl.

[0009] A method for preparing a C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative comprises reacting 4H-pyrido[1,2-a]pyrimidin-4-one with a peroxide arylformyl compound in an organic solvent under room temperature and air conditions and irradiation with 410-415 nm violet light to produce a C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative. This method does not require the addition of any oxidant or photocatalyst and has the advantages of simple operation, mild conditions, readily available raw materials, environmental friendliness, excellent substrate functional group compatibility, and high reaction yield.

[0010] Furthermore, the 4H-pyrido[1,2-a]pyrimidin-4-one compound is represented by the following structural formula II:

[0011] ( II )

[0012] Among them, R 1 = H, 6-methyl, 7-methyl, 8-methyl, 7-fluoro, 7-chloro, 7-bromo, 7-ester, 7-CF3; R 2 = methyl, phenyl, p-chlorophenyl;

[0013] Furthermore, the aryl formyl peroxide compound is shown in the following structural formula III: ( III )

[0014] Wherein, Ar is 2-methylphenyl, 3-methylphenyl, p-methoxyphenyl, p-fluorophenyl, 3-fluorophenyl, p-chlorophenyl, 3-chlorophenyl, p-bromophenyl, p-trifluoromethylphenyl, or p-nitrophenyl.

[0015] Furthermore, the molar ratio of the 4H-pyrido[1,2-a]pyrimidin-4-one to the aryl formyl peroxide compound is 1:1 to 1:2.

[0016] Furthermore, the concentration of the 4H-pyrido[1,2-a]pyrimidin-4-one compound in the dimethyl carbonate solvent is 0.1 mol / L to 0.5 mol / L.

[0017] Furthermore, the organic solvent is one of ethyl acetate, dimethyl carbonate, ethanol, and DMSO, wherein dimethyl carbonate is preferred.

[0018] Furthermore, the wavelength of the violet light source is 410-415 nm, and the light intensity is 5-8 W, preferably 6 W.

[0019] The method of the present invention does not require the use of an external catalyst. Extensive research by the inventors has shown that dimethyl carbonate solutions of 4H-pyrido[1,2-a]pyrimidin-4-one and its derivatives exhibit good absorption of visible light in the 410-415 nm wavelength range, exhibiting photosensitivity and serving as excellent photosensitizers for the reaction. During the reaction, the 4H-pyrido[1,2-a]pyrimidin-4-one compound and the peroxyaryl formyl compound undergo a CH functionalization reaction under 410-415 nm violet light irradiation, initially yielding a small amount of 3-aryl formyloxy-4H-pyrido[1,2-a]pyrimidin-4-one compound. The 3-aryl formyloxy-4H-pyrido[1,2-a]pyrimidin-4-one compound then acts as a photosensitizer to promote the reaction, significantly improving reaction efficiency and shortening reaction time.

[0020] The present invention also proposes a reasonable reaction mechanism, which is illustrated by taking the reaction of a 2-phenyl 4H-pyrido[1,2-a]pyrimidin-4-one compound (1) and benzoyl peroxide (2) as an example. The 2-phenyl 4H-pyrido[1,2-a]pyrimidin-4-one compound 1a acts as a photosensitizer to catalyze the reaction. Under the action of light at 410 to 415 nm, the ground state compound 1a is excited and converted into a highly active excited state compound 1a*. Benzoyl peroxide 2a and the excited state compound 1a* generate a benzoate anion, a benzoyloxy free radical, and a 2-phenyl 4H-pyrido[1,2-a]pyrimidin-4-one free radical cation through electron transfer. The benzoyloxy free radical undergoes free radical addition with the ground state 2-phenyl 4H-pyrido[1,2-a]pyrimidin-4-one compound 1a to generate a free radical intermediate IM1. Radical intermediate A undergoes a single electron transfer reaction with the 2-phenyl-4H-pyrido[1,2-a]pyrimidin-4-one radical cation to form cationic intermediate IM2 and the ground state of 2-phenyl-4H-pyrido[1,2-a]pyrimidin-4-one compound 1a. Cationic intermediate IM2 undergoes dehydrogenative aromatization in the presence of a benzoate anion to produce the target product, 2-phenyl-3-arylcarboxylic acid-4H-pyrido[1,2-a]pyrimidin-4-one compound 3a. The resulting 2-phenyl-3-arylcarboxylic acid-4H-pyrido[1,2-a]pyrimidin-4-one compound 3a also acts as a photosensitizer.

[0021]

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0024] (1) The present invention uses an LED with a power of about 6W and a wavelength of 410-415 nm as a light source, which is safe, energy-saving, cheap and readily available;

[0025] (2) The aryl formyl peroxide compound used in the present invention is cheap and readily available, and the present invention has a wide selectivity for the aryl formyl peroxide compound and good functional group compatibility.

[0026] (3) The present invention does not use additives, transition metal catalysts, or external photosensitizers. It is simple to operate, has mild conditions, high reaction selectivity, and the product is easy to separate and purify with high yield. The prepared C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative is a new compound, which has certain feasibility for industrial production and provides an important reference for the photocatalytic CH functionalization of other heterocyclic compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention provides a roadmap for the photocatalytic synthesis of C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivatives.

[0028] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of 2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one.

[0029] Figure 3 This is the carbon NMR spectrum of 2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one.

[0030] Figure 4 This is the UV spectrum of 2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one 1a and 2-phenyl-3-aryloxy-4H-pyrido[1,2-a]pyrimidin-4-one compounds.

[0031] Figure 5 The fluorescence images of 2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one 1a and benzoyl peroxide compound 2a at different concentrations were shown.

[0032] Figure 6 This is the single crystal diffraction pattern of 7-methyl-2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one. DETAILED DESCRIPTION

[0033] To gain a deeper understanding of the present invention, we will provide a comprehensive and detailed description thereof. However, the present invention has various implementations and is not limited to the specific examples listed herein. These examples are presented to enhance a comprehensive understanding of the present disclosure.

[0034] Comparative Example: 1

[0035] The following control experimental groups 1 to 19 all react according to the following reaction equation:

[0036]

[0037] The specific procedure is as follows: 2-phenyl-4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol), benzoyl peroxide (0.3 mmol), and 1 mL of dimethyl carbonate were added sequentially to a 10 mL reaction tube. The reaction was allowed to proceed at room temperature under LED light. After the reaction was complete, the tube was cooled to room temperature and the yield was analyzed by GC-MS.

[0038]

[0039] Experiments 1 to 7 in the table above examined the effects of the reaction medium and the impact of different solvents on reaction yield. When the reaction solvents were dichloromethane (CH2Cl2), tetrahydrofuran (THF), acetonitrile (MeCN), ethanol (EtOH), and dimethyl sulfoxide (DMSO), the reaction yields were very low. Using ethyl acetate (EtOAc) as the reaction solvent increased the yield. Surprisingly, the green solvent dimethyl carbonate (DMC) yielded the highest yield of the target product, reaching 88%. Therefore, DMC was selected as the optimal reaction solvent. Experiments 8 to 12 in the table above examined the effects of different wavelengths of light on the reaction. As shown in the table, the yields obtained under other wavelengths of light were lower than those obtained under 410-415 nm light.

[0040] Experimental groups 13 to 14 in the table above investigated the effects of no light and nitrogen on the reaction. The experiments showed that the reaction could not occur under no light conditions and the reaction could not occur under nitrogen conditions.

[0041] Experiments 13 to 19 in the table above examined the effects of illumination power and reaction time. The experiments showed that 6W was the optimal illumination power. Lowering the power to 5W decreased the yield. Increasing the power to 8W also showed a downward trend in yield. The optimal reaction time was 3 hours; both shortening and extending the reaction time decreased the yield.

[0042] The synthetic route of the C3 aryl formyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative provided by the present invention is as follows: Figure 1 shown.

[0043] To a 10 mL reaction tube, add 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol), an aryl formyl peroxide (0.4 mmol), and 1 mL of dimethyl carbonate. Allow to react at room temperature under blue light for 2–5 hours. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to obtain the C3 aryl formyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative.

[0044] The present invention will be further described below with reference to specific Preparation Examples 1 to 23: Example 1

[0045] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = Ph), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under violet light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one as a white solid in 88% yield. The target product has the following structural formula:

[0046]

[0047] Mp = 108-109℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.04 (d, J =7.00 Hz, 1H), 8.21 (d, J = 7.00 Hz, 2H), 7.96-7.95 (m, 2H), 7.80 -7.76(m, 2H),7.64 (t, J = 7.50 Hz, 1H), 7.51 (t, J = 8.00 Hz, 2H), 7.44 (t, J = 8.00 Hz, 3H),7.19 (t, J = 6.75 Hz, 1H); 13C NMR (500 MHz, CDCl3): δ 164.1, 154.5, 153.9,148.1, 135.4, 135.3, 133.7, 130.5, 130.1, 129.0, 128.7, 128.5, 128.4, 127.7,127.3, 126.7, 115.4; HRMS(ESI-TOF)m / z:[M+H] + calcd for C 21 H 15 N2O3343.1077, found343.1076. Example 2

[0048] In a 10 mL reaction tube, 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 6-CH3, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = Ph), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under violet light (10 W, 6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 6-methyl-2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in 78% yield. The target product has the following structural formula:

[0049]

[0050] Mp = 105-106℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 8.94 (d, J =7.00 Hz, 1H), 8.20 (d, J = 8.00 Hz, 2H), 7.94 (t, J = 4.00 Hz, 2H), 7.63(t, J =7.25 Hz, 1H), 7.57 (s, 1H), 7.50 (t, J = 7.75 Hz, 2H), 7.44 (t, J = 6.00 Hz, 3H),7.01 (d, J = 7.50 Hz, 1H), 2.52 (s, 3H); 13C NMR (500 MHz, CDCl3): δ 164.2,154.8, 153.9, 148.1, 147.5, 135.4, 133.7, 130.5, 129.9, 128.9, 128.8, 128.5,128.4, 127.0, 126.6, 124.7, 118.2, 21.4; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 22 H 17 N2O3357.1234, found 357.1233. Example 3

[0051] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 7-CH3,R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = Ph), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford a yellow solid, 7-methyl-2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one, in a 75% yield. The target product has the following structural formula:

[0052]

[0053] Mp = 128-129 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 8.86 (s,1H), 8.20 (d, J = 8.00 Hz, 2H), 8.11 (d, J = 7.5 Hz, 1H), 7.94(d, J = 6.00 Hz, 1H),7.73 (d, J = 11.50 Hz, 1H), 7.63 (d, J = 8.50 Hz, 2H), 7.51 (d, J = 8.00 Hz, 3H),7.44 (d, J = 6.50 Hz, 2H), 2.47 (s, 3H); 13C NMR (500 MHz, CDCl3): δ 164.1,154.2, 153.7, 147.1, 138.5, 135.3, 133.7, 133.5, 131.8, 130.5, 130.1, 129.9,129.2, 128.9, 128.8, 128.5, 128.4, 127.9, 127.6, 126.1, 126.0, 125.8, 124.7,18.4; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 22 H 17 N2O3357.1234, found 357.1234.

[0054] Single crystal data: C 22 H 16 N2O3; Mr = 356.37, monoclinic, space group P 1 21 / c 1 , a =7.4520(2) Å, b = 20.1075(4) Å, c = 12.0021(3) Å; V = 1735.87(7) Å 3 ; T = 200.00K; Z = 4; Reflections collected / unique, 15457 / 3514, R int = 0.0945, R 1= 0.0388, wR 2= ​​0.1034; GOF = 1.042. Example 4

[0055] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 8-CH3,R 2=Ph), an aryl formyl peroxide (0.3 mmol, Ar = Ph), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford a yellow solid, 8-methyl-2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one, in a 77% yield. The target product has the following structural formula:

[0056]

[0057] Mp = 107-108 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 8.21 (d, J = 8.50 Hz, 2H), 7.97-7.95 (m, 2H), 7.62 (t, J = 6.75 Hz, 1H), 7.53-7.48 (m,3H), 7.44 (t, J = 5.75 Hz 4H), 6.68 (d, J = 7.00 Hz 1H), 3.12 (s, 3H); 13 C NMR (500MHz, CDCl3): δ164.2, 157.7, 152.3, 150.3, 143.9, 135.0, 134.5, 133.7, 130.5,130.0, 128.9, 128.8, 128.5, 128.4, 125.7, 118.0, 24.5; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 22 H 17 N2O3357.1234, found 357.1235. Example 5

[0058] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 7-F, R 2= Ph), peroxycarbonyl compound (0.3 mmol, Ar = Ph), 1 mL dimethyl carbonate. The reaction was carried out under blue light (6 W, 410~415 nm) at room temperature for 3 h. After the reaction was completed, the mixed solution was spin-dried, and column chromatography was performed to obtain yellow solid 7-fluoro-2-phenyl-3-phenylcarbonyloxy-4H-pyrido[l,2-a]pyrimidin-4-one with a yield of 71%. The structural formula of the target product is as follows:

[0059]

[0060] M.p. = 112-113 ℃; NMR and mass spectral data: 1 H NMR (500 MHz, CDCl3): d 8.94 (t, J = 7.50 Hz, 1H), 8.20 (d, J = 8.50 Hz, 2H), 7.94 (t, J = 3.75 Hz, 1H), 7.83-7.80(m, 1H), 7.70-7.63 (m, 2H), 7.51 (t, J = 8.00 Hz, 2H), 7.46 (d, J = 5.0 Hz, 2H),7.28 (s, 1H), 4.16-4.12 (m, 1H); 13 C NMR (500 MHz, CDCl3): δ 171.2, 163.9,155.0, 154.1, 153.4, 153.1, 146.0, 134.9, 133.9, 130.5, 128.9, 128.7, 128.6,128.5, 128.2, 128.0, 127.8, 113.6, 113.2, 89.78 ; 19 F NMR (400 MHz, CDCl3): δ -132.4; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 21 H 14 FN2O3361.0983, found 361.0981. Example 6

[0061] In a 10 mL reaction tube, 4H-pyrido[l,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 7-Cl,R 2= Ph), peroxycarbonyl compound (0.3 mmol, Ar = Ph), 1 mL dimethyl carbonate. The reaction was carried out under blue light (6 W, 410~415 nm) at room temperature for 3 h. After the reaction was completed, the mixed solution was spin-dried, and column chromatography was performed to obtain 7-chloro-2-phenyl-3- benzoyloxy-4H-pyrido[l,2-a]pyrimidin-4-one as a yellow oily liquid with a yield of 73%. The structural formula of the target product is as follows:

[0062]

[0063] NMR and mass spectral data: 1 H NMR (500 MHz, CDCl3): d 9.05 (d, J = 2.50 Hz, 1H),8.20 (d, J = 7.00 Hz, 2H), 8.12 (d, J = 8.00 Hz, 2H), 7.96-7.94(m, 2H), 7.74 (d, J = 9.50 Hz, 1H), 7.68-7.61 (m, 2H), 7.52-7.49 (m, 1H), 7.44 (t, J = 2.50 Hz,2H); 13 C NMR (500 MHz, CDCl3): δ 171.2, 163.9, 154.3, 153.1, 146.3, 137.5,136.7, 134.8, 133.9, 133.6, 130.5, 130.3, 130.1, 129.5, 129.0, 128.6, 128.5,128.4, 128.2, 127.6, 124.9, 124.3, 100.5; HRMS(ESI-TOF)m / z:[M+H] + calcd forC 21 H 14 ClN2O3377.0687, found 377.0686. Example 7

[0064] In a 10 mL reaction tube, 4H-pyrido[l,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 7-Br,R 2=Ph), an aryl formyl peroxide (0.3 mmol, Ar = Ph), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 7-bromo-2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one as a white solid in 79% yield. The structural formula of the target product is as follows:

[0065]

[0066] Mp = 110-111 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.15 (d, J = 2.50 Hz, 1H), 8.20 (d, J = 8.00 Hz, 2H), 7.95-7.93 (m , 2H), 7.78-7.75(m, 1H),7.66-7.63 (m, 2H), 7.51 (t, J = 7.75 Hz, 2H), 7.44 (t, J = 3.50 Hz, 3H); 13 C NMR(500 MHz, CDCl3): δ 163.9, 154.2, 153.0, 146.4, 138.7, 134.9, 133.9, 130.5,130.3, 129.0, 128.6, 128.5, 127.6, 127.3, 110.8, 100.5; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 21 H 14 BrN2O3421.0812, found 421.0811. Example 8

[0067] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 7-CF3,R 2=Ph), an aryl formyl peroxide (0.3 mmol, Ar = Ph), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 7-trifluoromethyl-2-phenyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one as a white solid in 69% yield. The target product has the following structural formula:

[0068]

[0069] Mp = 99-100 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.35 (s,1H), 8.21 (d, J = 8.00 Hz, 1H), 8.11 (d, J = 8.00 Hz, 1H), 7.99-7.97(m, 2H),7.85-7.79 (d, 2H), 7.66 (t, J = 7.50 Hz ,1H), 7.52 (t, J = 7.75 Hz,2H), 7.48-7.46 (m, 3H); 13 C NMR (500 MHz, CDCl3): δ 163.8, 154.6, 153.8, 147.5, 134.6,134.0, 133.6, 130.6, 130.5, 130.4, 130.1, 129.1, 128.8, 128.6, 128.5, 128.4,128.0, 126.8, 126.7, 125.8, 123.6, 121.5, 119.4, 119.1; 19 F NMR (400 MHz, CDCl3): δ -63.3; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 22 H 14 F3N2O3411.0951, found411.0950. Example 9

[0070] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 7-CO2Et, R 2= Ph), peroxoaroyl compound (0.3 mmol, Ar = Ph), 1 mL dimethyl carbonate. The reaction was carried out under blue light (6W, 410~415 nm) at room temperature for 3 h. After the reaction was completed, the mixed solution was spin-dried, and column chromatography was performed to obtain white solid 4-oxo-2-phenyl-3- benzoyloxy-4H-pyrido[l,2-a]pyrimidine-7-carboxylic acid ethyl ester in a yield of 70%. The structural formula of the target product is as follows:

[0071]

[0072] M.p. = 126-127 ℃; NMR and mass spectral data: 1 H NMR (500 MHz, CDCl3): d 9.70 (d, J = 3.50 Hz, 1H), 8.23-8.20 (m, 4H), 7.98 (t, J = 3.75 Hz, 2H), 7.76 (d, J = 9.00Hz, 1H), 7.66 (t, J = 7.50 Hz,1H), 7.54-7.46 (m, 6H), 7.29 (d, J = 3.50 Hz, 1H),4.48 (t, J = 7.25 Hz, 2H); 13 C NMR (500 MHz, CDCl3): δ 163.9, 163.4, 154.5,153.9, 148.1, 134.8, 134.1, 133.9, 131.4, 130.1, 129.1, 128.6, 128.5, 128.4,127.5, 126.5, 119.2, 62.2, 14.2; HRMS(ESI-TOF) m / z:[M+H] + calcd forC 24 H 19 N2O5415.1288, found 415.1289. Example 10

[0073] In a 10 mL reaction tube, 4H-pyrido[l,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2=4-ClC6H4), an aryl formyl peroxide (0.3 mmol, Ar = Ph), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-(4-chlorophenyl)-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one as a white solid in 84% yield. The target product has the following structural formula:

[0074]

[0075] Mp = 115-116 ℃; NMR and mass spectrometry data: d 9.10 (d, J = 8.5 Hz, 1H), 8.24 (d, J = 7.00 Hz, 2H), 8.10 (d, J = 8.00 Hz, 2H), 7.97-7.91 (m, 2H), 7.72 (d, J = 9.0Hz, 1H), 7.66-7.60 (m, 2H), 7.51-7.48 (m, 1H), 7.41 (t, J = 6.50 Hz, 2H); 13 C NMR(500 MHz, CDCl3): δ 171.0, 163.4, 154.4, 153.2, 146.5, 137.2, 136.4, 134.6,133.7, 133.4, 130.3, 130.0, 129.3, 129.0, 128.7, 128.4, 128.2, 127.5, 124.6,124.1, 100.0; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 21 H 14 ClN2O3377.0687, found377.0685. Example 11

[0076] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2=CH3), an aryl formyl peroxide (0.3 mmol, Ar = Ph), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 2 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-methyl-3-benzoyloxy-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in 68% yield. The target product has the following structural formula:

[0077]

[0078] Mp = 45-46 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.02 (d, J =7.00 Hz, 1H), 8.29 (d, J = 7.00 Hz, 2H), 7.75 (t, J = 8.75 Hz, 2H), 7.68 (t, J =4.75 Hz, 2H), 7.55 (t, J = 8.00 Hz, 3H), 7.28 (s, 1H), 7.16 (t, J = 7.00 Hz, 1H); 13 C NMR (500 MHz, CDCl3): δ 165.3, 164.0, 156.6, 152.7, 148.0, 136.3, 135.3,133.9, 130.5, 128.6, 128.3, 127.4, 127.2, 125.9, 125.8, 115.2, 115.0, 103.3,19.5; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 16 H 13 N2O3281.0921, found 281.0922. Example 12

[0079] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 6-CH3,R 2= CH3), aryl benzoyl peroxide compound (0.3 mmol, Ar = Ph), 1 mL dimethyl carbonate. The reaction was carried out under blue light (6 W, 410~415 nm) at room temperature for 5 h. After the reaction was completed, the mixed solution was spin-dried, and column chromatography was performed to obtain yellow solid 2,6-dimethyl-3-phenylcarbonyloxy-4H-pyrido[l,2 -a ]pyrimidin-4-one with a yield of 72%. The structural formula of the target product is as follows:

[0080]

[0081] M.p. = 86-87 ℃; NMR and mass spectral data are as follows: 1 H NMR (500 MHz, CDCl3): d 8.89(d, J = 7.50 Hz, 1H), 8.27 (d, J = 8.50 Hz, 3H), 7.65 (t, J = 7.50 Hz, 2H), 7.52(t, J = 7.75 Hz, 4H), 7.43 (d, J = 1.00 Hz, 2H), 6.98 (d, J = 7.00 Hz, 2H); 13 C NMR(500 MHz, CDCl3): δ 164.1, 156.7, 152.7, 148.1, 147.6, 133.8, 130.5, 129.9,128.7, 128.6, 128.2, 127.6, 126.6, 123.9, 118.0, 21.4, 19.5; HRMS(ESI-TOF)m / z:[M+H] + calcd for C 17 H 15 N2O3295.1077, found 295.1076. Example 13

[0082] In a 10 mL reaction tube, 4H-pyrido[l,2-a]pyrimidin-4-one (0.2 mmol, R 1 = 7-CH3,R 2= CH3), aryl benzoyl peroxide compound (0.3 mmol, Ar = Ph), 1 mL dimethyl carbonate. The reaction was carried out under blue light (5 W, 410~415 nm) at room temperature for 3 h. After the reaction was completed, the mixed solution was spin-dried, and column chromatography was performed to obtain yellow solid 2,7-dimethyl-3-benzoyloxy-4H-pyrido[l,2-a]pyrimidin-4-one with a yield of 78%. The structural formula of the target product is as follows:

[0083]

[0084] M.p. = 110-111 ℃; NMR and mass spectral data are as follows 1 H NMR (500 MHz, CDCl3): d 8.80(s, 2H), 8.27 (d, J =7.00 Hz, 3H), 7.65 (t, J = 7.50 Hz, 2H), 7.59 (d, J = 2.00 Hz,3H), 7.52 (t, J = 7.75 Hz, 4H); 13 C NMR (500 MHz, CDCl3): δ164.0, 156.0, 152.5,147.0, 138.5, 133.8, 130.5, 129.9, 128.7, 128.6, 128.2, 125.6, 125.2, 124.7,19.4, 18.3; HRMS(ESI-TOF)m / z:[M+H] + calcd for C 17 H 15 N2O3295.1077, found295.1075. Example 14

[0085] In a 10 mL reaction tube, 4H-pyrido[l,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), aryl benzoyl peroxide compound (0.3 mmol, Ar = 4-CH3C6H4), 1 mL dimethyl carbonate. The reaction was carried out under blue light (6 W, 410~415 nm) at room temperature for 3 h. After the reaction was completed, the mixed solution was spin-dried, and column chromatography was performed to obtain white solid 2-phenyl-3-(4-methylbenzoyloxy)-4H-pyrido[l,2-a]pyrimidin-4-one with a yield of 81%. The structural formula of the target product is as follows:

[0086]

[0087] M.p. = 105-106 ℃; NMR and mass data: 1 H NMR (500 MHz, CDCl3): d 9.04 (d, J =7.00 Hz, 1H), 8.10 (d, J =8.00 Hz, 2H), 7.96-7.94 (m, 2H), 7.80-7.74 (m, 2H),7.44 (d, J = 5.50 Hz, 3H), 7.29 (t, J = 7.00 Hz, 2H), 7.18 (t, J = 7.00 Hz, 1H),2.45 (s, 3H); 13 C NMR (500 MHz, CDCl3): δ164.1, 154.5, 153.9, 148.0, 144.7,135.3, 130.6, 130.0, 129.3, 129.0, 128.4, 127.7, 127.3, 126.7, 125.9, 115.4,21.8; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 22 H 17 N2O3357.1234, found 357.1233. Example 15

[0088] In a 10 mL reaction tube, 4H-pyrido[l,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), aryl formyl peroxide compound (0.3 mmol, Ar = 3-CH3C6H4), 1 mL dimethyl carbonate. The reaction was carried out under blue light (6 W, 410~415 nm) at room temperature for 3 h. After the reaction was completed, the mixed solution was spin-dried, and column chromatography was performed to obtain white solid 2-phenyl-3-(3-methylbenzoyloxy)-4H-pyrido[l,2-a]pyrimidin-4-one with a yield of 76%. The structural formula of the target product is as follows:

[0089]

[0090] M.p. = 151-152 ℃; NMR and mass data: 1H NMR (500 MHz, CDCl3): d 9.05 (d, J =7.00 Hz, 1H), 8.02 (d, J =9.00 Hz, 2H), 7.96-7.94 (m, 2H), 7.81-7.74 (m, 2H),7.44 (t, J = 4.00 Hz, 4H), 7.39 (t, J = 7.75 Hz, 1H), 7.20-7.17 (m, 1H), 2.44 (s,3H); 13 C NMR (500 MHz, CDCl3): δ 164.3, 154.5, 153.9, 148.0, 138.4, 135.4,134.6, 131.0, 130.1, 129.0, 128.6, 128.4, 127.8, 127.7, 127.3, 126.7, 115.4,21.3; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 22 H 17 N2O3357.1234, found 357.1231. Example 16

[0091] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = 4-OCH3C6H4), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-phenyl-3-(4-methoxybenzoyloxy)-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in 71% yield. The target product has the following structural formula:

[0092]

[0093] Mp = 150-151 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): 1 H NMR (500MHz, CDCl3): d 9.04 (d, J =7.00 Hz, 1H), 8.17 (d,J =9.00 Hz, 2H), 7.95-7.94 (m,2H), 7.79-7.73 (m, 2H), 7.44 (d, J =6.00 Hz, 3H), 7.17 (t, J = 6.75 Hz, 1H), 6.98(d, J = 9.00 Hz, 2H), 3.90 (d, J =2.00 Hz, 3H); 13 C NMR (500 MHz, CDCl3): δ 164.0,163.8, 154.4, 154.0, 148.0, 135.3, 132.7, 130.0, 129.0, 128.4, 127.8, 127.3,126.7, 121.0, 115.4, 113.8, 55.5; HRMS(ESI-TOF)m / z:[M+H] + calcd for C 22 H 17 N2O4373.1183, found 373.1182. Example 17

[0094] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = 4-FC6H4), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-phenyl-3-(4-fluorobenzoyloxy)-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in 74% yield. The target product has the following structural formula:

[0095]

[0096] Mp = 103-104 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.02 (d, J =7.00 Hz, 1H), 8.24-8.21 (m, 2H), 7.93 (d, J = 5.00 Hz, 2H), 7.79-7.73 (m, 2H),7.45 (d, J=3.00 Hz, 3H), 7.17 (t, J = 8.50 Hz, 3H); 13 C NMR (500 MHz, CDCl3): δ167.3, 165.2, 163.1, 154.5, 153.8, 148.1, 135.5, 135.2, 133.2, 133.1, 130.1,128.9, 128.5, 127.5, 127.3, 126.7, 125.0, 124.9, 115.9, 115.7, 115.5; 19 F NMR(400 MHz, CDCl3): δ -103.8; HRMS(ESI-TOF)m / z:[M+H] + calcd for C 21 H 14 FN2O3361.0983, found 361.0982. Example 18

[0097] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = 3-FC6H4), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-phenyl-3-(3-fluorobenzoyloxy)-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in 70% yield. The target product has the following structural formula:

[0098]

[0099] Mp = 88-89 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.05 (d, J =7.00 Hz, 1H), 8.00 (d, J =7.50 Hz, 1H), 7.93-7.92 (m, 2H), 7.89-7.86 (m, 1H), 7.80-7.78 (m, 2H), 7.50-7.45 (m, 4H), 7.36-7.32 (m, 1H), 7.22-7.19 (m, 1H); 13CNMR (500 MHz, CDCl3): δ 163.5, 163.0, 161.5, 154.6, 153.7, 148.1, 135.6,135.1, 130.8, 130.2, 128.9, 128.5, 127.5, 127.3, 126.7, 126.3, 121.0, 120.9,117.4, 117.2, 115.6; 19 F NMR (400 MHz, CDCl3): δ -111.8; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 21 H 14 FN2O3361.0983, found 361.0985. Example 19

[0100] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = 4-ClC6H4), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-phenyl-3-(4-chlorobenzoyloxy)-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in 72% yield. The target product has the following structural formula:

[0101]

[0102] Mp = 120-121 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.04 (d, J =7.00 Hz, 1H), 8.13 (d, J =8.50 Hz, 2H), 7.92 (t, J = 3.75 Hz, 2H), 7.80-7.74 (m,2H), 7.48-7.44 (m, 5H), 7.19 (t, J = 6.75 Hz, 1H); 13C NMR (500 MHz, CDCl3): δ163.3, 154.6, 153.8, 148.1, 140.4, 135.6, 135.1, 131.8, 131.4, 130.2, 129.0,128.9, 128.7, 128.5, 127.5, 127.3, 127.1, 126.7, 115.6; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 21 H 14 ClN2O3377.0687, found 377.0688. Example 20

[0103] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl peroxide (0.3 mmol, Ar = 2-ClC6H4), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and column chromatography yielded 2-phenyl-3-(2-chlorobenzoyloxy)-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow oily liquid in 73% yield. The target product has the following structural formula:

[0104]

[0105] NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.05 (d, J =9.00 Hz, 1H), 8.06(t, J =5.50 Hz, 1H), 7.95 (t, J = 6.00 Hz, 1H), 7.91-7.89 (m, 2H), 7.80-7.76 (m,2H), 7.48-7.45 (m, 4H), 7.37-7.33 (m, 1H), 7.20-7.17 (m, 1H); 13C NMR (500 MHz, CDCl3): δ 169.4, 162.7, 154.9, 153.7, 148.2, 135.6, 135.0, 134.7, 134.4, 133.4, 133.2, 132.3, 132.2, 131.3, 131.2, 130.1, 128.9, 128.8, 128.4, 127.4,126.7, 126.6, 115.6; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 21 H 14 ClN2O3377.0687,found 377.0686. Example 21

[0106] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = 4-BrC6H4), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-phenyl-3-(4-bromobenzoyloxy)-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in 78% yield. The target product has the following structural formula:

[0107]

[0108] Mp = 119-120 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.04 (d, J =7.00 Hz, 1H), 8.06 (d, J =8.50 Hz, 2H), 7.92-7.90 (m, 2H), 7.81-7.75 (m, 2H),7.65 (d, J =8.50 Hz, 2H), 7.46-7.44 (m, 3H), 7.20 (t, J = 6.50 Hz, 1H); 13C NMR (500 MHz, CDCl3): δ 163.4, 154.6, 153.8, 148.1, 135.6, 135.1, 131.9, 130.2,129.1, 128.9, 128.5, 127.6, 127.5, 127.3, 126.7, 115.6; HRMS(ESI-TOF)m / z:[M+H] + calcd for C 21 H 14 BrN2O3421.0182, found 421.0185. Example 22

[0109] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = 4-CF3C6H4), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410-415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-phenyl-3-(4-trifluoromethylbenzoyloxy)-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in 76% yield. The target product has the following structural formula:

[0110]

[0111] Mp = 163-164 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.03 (d, J =9.00 Hz, 1H), 8.30 (d, J =10.50 Hz, 2H), 7.91-7.88 (m, 2H), 7.76 (t, J =11.25Hz, 4H), 7.43 (t, J =4.50 Hz, 3H), 7.21-7.18 (m, 1H); 13 C NMR (500 MHz, CDCl3): δ162.9, 154.7, 153.7, 148.2, 135.7, 135.0, 131.9, 130.8, 130.2, 128.8, 128.5,127.4, 126.8, 125.6, 115.7; 19F NMR (400 MHz, CDCl3): δ -63.1; HRMS(ESI-TOF) m / z:[M+H] + calcd for C 22 H 14 F3N2O3411.0951, found 411.0950. Example 23

[0112] 4H-pyrido[1,2-a]pyrimidin-4-one (0.2 mmol, R 1 = H, R 2 =Ph), an aryl formyl peroxide (0.3 mmol, Ar = 4-NO₂C₆H₄), and 1 mL of dimethyl carbonate. The reaction was allowed to proceed under blue light (6 W, 410–415 nm) at room temperature for 3 h. After completion of the reaction, the mixed solution was spin-dried and purified by column chromatography to afford 2-phenyl-3-(4-nitrobenzoyloxy)-4H-pyrido[1,2-a]pyrimidin-4-one as a yellow solid in a 62% yield. The target product has the following structural formula:

[0113]

[0114] Mp = 144-145 ℃; NMR and mass spectrometry data: 1 H NMR (500 MHz, CDCl3): d 9.05 (d, J =7.00 Hz, 1H), 8.38-8.34 (m, 4H), 7.91-7.89 (m, 2H), 7.82 (d, J =5.50 Hz, 2H),7.46 (d, J =3.75 Hz, 3H), 7.25-7.22 (m, 1H); 13 C NMR (500 MHz, CDCl3): δ162.3,154.7, 153.6, 150.9, 148.3, 135.9, 134.9, 134.1, 131.6, 130.3, 128.8, 128.6,127.4, 127.2, 126.8, 123.7, 115.8; HRMS(ESI-TOF)m / z:[M+H] + calcd for C 21 H 14 N3O5388.0928, found 388.0927.

[0115] Any matters not described in detail in this specification are prior art known to those skilled in the art. Although the above description of the present invention is based on specific embodiments to facilitate understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the specific embodiments. As long as various modifications are within the spirit and scope of the present invention as defined and determined by the appended claims, such modifications will be obvious to those skilled in the art, and all inventions and creations utilizing the concepts of the present invention are protected.

Claims

1. A method for preparing a C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative, characterized by: Under room temperature and air conditions, 4H-pyrido[1,2-a]pyrimidin-4-one reacts with a peroxy aryl formyl compound in an organic solvent under 410-415 nm violet light irradiation to prepare a C3 aryl formyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative represented by structural formula (I); The structure (I) is as follows: （I）； R 1 = H, 6-methyl, 7-methyl, 8-methyl, 7-fluoro, 7-chloro, 7-bromo, 7-ester, 7-CF3; R 2 = methyl, phenyl, p-chlorophenyl; Ar = 2-methylphenyl, 3-methylphenyl, p-methoxyphenyl, p-fluorophenyl, 3-fluorophenyl, p-chlorophenyl, 3-chlorophenyl, p-bromophenyl, p-trifluoromethylphenyl, p-nitrophenyl; The 4H-pyrido[1,2-a]pyrimidin-4-one compound is shown in the following structural formula II: (II); Among them, R 1 = H, 6-methyl, 7-methyl, 8-methyl, 7-fluoro, 7-chloro, 7-bromo, 7-ester, 7-CF3; R 2 = methyl, phenyl, p-chlorophenyl; The aryl formyl peroxide compound is shown in the following structural formula III: (III); Wherein, Ar is 2-methylphenyl, 3-methylphenyl, p-methoxyphenyl, p-fluorophenyl, 3-fluorophenyl, p-chlorophenyl, 3-chlorophenyl, p-bromophenyl, p-trifluoromethylphenyl, or p-nitrophenyl; The organic solvent is one of ethyl acetate, dimethyl carbonate, ethanol and acetonitrile; The intensity of the purple light is 5 to 8 W.

2. The method for preparing a C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative according to claim 1, characterized in that: The molar ratio of the 4H-pyrido[1,2-a]pyrimidin-4-one to the aryl formyl peroxide compound is 1:1 to 1:

2.

3. The method for preparing a C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative according to claim 1, characterized in that: The concentration of the 4H-pyrido[1,2-a]pyrimidin-4-one compound in the dimethyl carbonate solvent is 0.1 mol / L to 0.5 mol / L.

4. The method for preparing a C3 arylformyloxylated 4H-pyrido[1,2-a]pyrimidin-4-one derivative according to claim 1, characterized in that: The reaction temperature is room temperature, and the reaction time is 2 to 5 hours.

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