1, 2-dioxodiene as well as efficient preparation method and application thereof

Abstract

The invention relates to the technical field of organic synthesis, and particularly discloses 1, 2-dioxodiene, the structural formula of which is # imgabs0 #, and R1 and R2 are hydrogen, aryl, alkyl, alkoxy, chloroalkyl or naphthenic base. The 1, 2-dioxodiene has Diels-Alder cycloaddition reaction properties, can be used as a novel synthon for DA reaction research, is a key intermediate for preparation of important compounds such as polysubstituted phenol, can be subjected to a decarboxylation DA aromatization reaction with alkyne or benzoquinone to synthesize polysubstituted phenol, and has certain commercial application value and scientific research value.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a 1,2-dioxodiene and an efficient preparation method and synthetic application thereof. Background Art

[0002] The Diels-Alder (DA) cycloaddition reaction is one of the most useful reactions in organic synthesis. Since its discovery, it has been widely applied in the synthesis of natural products, pharmaceuticals, and materials. Therefore, the design and synthesis of useful heteroatom-functionalized dienes allows DA cycloadditions to proceed under mild conditions with high regio- and stereoselectivity. Furthermore, the incorporation of readily convertible heteroatom groups into the cycloaddition products can greatly expand the synthetic applications of DA cycloadditions. Numerous heteroatom-substituted dienes, such as 1,3-disubstituted and monosubstituted dienes, have been developed and widely used in cycloaddition reactions with various dienophiles. Currently, due to the lack of novel and easily convertible 1,2-dioxodienes, research on DA reactions of these dienes and their synthetic applications has been largely stagnant.

[0003] Only two examples of 1,2-dioxodienes have been reported in the literature. In 1988, Fétizon and his collaborators reported the synthesis and DA properties of etherified 1,2-dioxodienes (M. Fétizon, P. Goulaouic, I. Hanna, et al. J. Org. Chem., 1988, 53, 5672-5679). These dienes exhibited excellent DA reactivity and could undergo DA reactions with various dienophiles under mild conditions. However, the 1,2-dioxane ring structure in the products was difficult to remove, rendering these dienes of little synthetic application value. In 1989, Lee's group reported the DA reaction of 1,2-dioxodienes containing benzo-1,4-dioxane (TV Lee, AJ Leigh, CB Chapleo. Synlett, 1989, 30-32). This diene also exhibits broad DA reactivity, but the benzo-1,4-dioxane in the product cannot be removed, rendering this diene of synthetic application value. Therefore, the synthesis of novel and easily convertible 1,2-dioxodienes as synthons for DA reactions will lay a solid foundation for research on DA reactions and their synthetic applications, and provide new methods for the synthesis of important compounds such as substituted phenols, thus possessing significant academic and practical value. Summary of the Invention

[0004] In response to the reported difficulty in removing 1,2-dioxodienes, the present invention provides a 1,2-dioxodiene that can be removed or diversified and subjected to a DA cycloaddition reaction, thereby overcoming the removal difficulties existing in the prior art. The specific technical solution is as follows:

[0005] A 1,2-dioxadiene having the structural formula:

[0006]

[0007] Among them, R 1 、R 2 is hydrogen, aryl, alkyl, alkoxy, chloroalkyl or cycloalkyl.

[0008] On the other hand, the present invention also provides an efficient preparation method of the above-mentioned 1,2-dioxodiene, comprising the following steps: dissolving a palladium catalyst and a ligand in an organic solvent, then adding vinylene carbonate, an alkenyl halide and a base, stirring for reaction, and after the reaction is completed, filtering, concentrating under reduced pressure, and purifying to obtain 1,2-dioxodiene.

[0009] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxodiene, the organic solvent is one of dichloromethane, 1,2-dichloroethane, chloroform, trifluoroethanol, and hexafluoroisopropanol.

[0010] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxadiene, the organic solvent is dichloromethane.

[0011] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxadiene, the reaction temperature is 60-120° C., and the reaction time is 12-24 h.

[0012] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxadiene, the reaction temperature is 80°C.

[0013] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxadiene, the ligand is triphenylphosphine (PPh3), methyldiphenylphosphine (MePPh2), ethyldiphenylphosphine (EtPPh2), propyldiphenylphosphine ( n PrPPh2), isopropyldiphenylphosphine ( i PrPPh2) or cyclohexyldiphenylphosphine (CyPPh2).

[0014] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxodiene, the ligand is methyldiphenylphosphine.

[0015] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxodiene, the palladium catalyst is one of tetrakistriphenylphosphine palladium, Pd(dba)2, Pd / carbon, palladium acetate, palladium chloride, palladium bromide, palladium iodide or palladium trifluoroacetate.

[0016] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxadiene, the ligand is palladium acetate.

[0017] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxadiene, the base is one of potassium bicarbonate, potassium carbonate, sodium phosphate, potassium phosphate, dipotassium hydrogen phosphate, sodium acetate, and potassium acetate.

[0018] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxadiene, the base is potassium bicarbonate.

[0019] Preferably, in the above-mentioned efficient preparation method of 1,2-dioxodiene, the molar amount of the palladium catalyst is 8 to 12% of the amount of the alkenyl halide, the molar amount of the ligand is 18 to 22% of the molar amount of the alkenyl halide, the molar amount of the vinylene carbonate is 7 to 9 times the molar amount of the alkenyl halide, and the molar amount of the base is 2 to 3 times the molar amount of the alkenyl halide.

[0020] On the other hand, the present invention also provides the use of the above-mentioned 1,2-dioxadiene in a DA cycloaddition reaction.

[0021] Preferably, in the above application, the 1,2-dioxodiene is used in the preparation of polysubstituted phenols.

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

[0023] 1. The 1,2-dioxadiene of the present invention has the properties of Diels-Alder cycloaddition reaction, can be used as a novel synthon for DA reaction research, is a key intermediate for the preparation of important compounds such as polysubstituted phenols, and can undergo decarboxylation DA aromatization reaction with alkynes or benzoquinones to synthesize polysubstituted phenols, and has certain commercial application value and scientific research value.

[0024] 2. In the efficient preparation method of 1,2-dioxodienes of the present invention, a series of 1,2-dioxodienes with novel structures and easy removal or conversion are synthesized by palladium-catalyzed olefination reaction of olefin halides and vinylene carbonate, which have certain commercial application value and scientific research value.

[0025] 3. In the efficient preparation method of 1,2-dioxadiene of the present invention, the functional groups of the substrate are well tolerated, including hydrogen, aryl, alkyl, alkoxy, chloroalkyl, cycloalkyl, etc., which enriches the substrate range. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Unless otherwise defined, all technical terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

[0027] Example 1

[0028] A 1,2-dioxadiene having the structural formula:

[0029]

[0030] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0031]

[0032] This embodiment also provides an efficient preparation method of 1,2-dioxadiene, comprising the following steps:

[0033] A 35 mL reaction tube was placed in a drying oven and dried. After cooling, a magnetic stirrer, 2a (1.6 mmol, 8.0 equiv), MePPh2 (0.04 mmol, 20 mol%), Pd(OAc)2 (0.02 mmol, 10 mol%), 1a (0.2 mmol, 1.0 equiv), ultra-dry dichloromethane (2 mL), and potassium bicarbonate (0.5 mmol, 2.5 equiv) were added in sequence. Argon was introduced and vacuum was evacuated three times, then the tube was quickly capped with a rubber stopper and reacted at 80°C for 24 h. After completion of the reaction, the tube was diluted with EA, and the inorganic material was filtered out with a filter column. The filtrate was spin-dried and purified by silica gel column chromatography to obtain the corresponding 1,2-dioxadiene 3a in a yield of 71% (26.6 mg, 0.14 mmol).

[0034] The NMR and high-resolution data of 3a are:

[0035] 1 H NMR (400MHz, CDCl3) δ7.51-7.33(m,5H),6.85(s,1H),5.74(s,1H),5.43(s,1H).

[0036] 13 C NMR (101MHz, CDCl3) δ152.79,143.92,136.37,134.05,129.52,129.29,128.25,127.99,117.15.

[0037] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 11 H9O3,189.0552; found,189.0547.

[0038] Example 2

[0039] A 1,2-dioxadiene having the structural formula:

[0040]

[0041] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0042]

[0043] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1b (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3b in a yield of 52% (21 mg, 0.1 mmol).

[0044] The NMR and high-resolution data of 3b are:

[0045] 1 H NMR (400MHz, CDCl3) δ7.25(d,J=8.1Hz,2H),7.20(d,J=8.1Hz,2H),6.84(s,1H),5.68(s,1H),5.38(s,1H),2.37(s,3H).

[0046] 13 C NMR (101MHz, CDCl3) δ152.54,143.78,139.24,133.62,133.19,129.64,127.81,127.62,116.35,21.32.

[0047] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 12 H 11 O3,203.0708;found,203.0703.

[0048] Example 3

[0049] A 1,2-dioxadiene having the structural formula:

[0050]

[0051] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0052]

[0053] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1c (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3c in a yield of 40% (19.5 mg, 0.08 mmol).

[0054] The 3c NMR and high-resolution data are:

[0055] 1 H NMR (400MHz, CDCl3) δ7.42(d,J=8.5Hz,2H),7.30(d,J=8.5Hz,2H),6.89(s,1H),5.71(s,1H),5.42(s,1H),1.35(s,9H).

[0056] 13 C NMR (101MHz, CDCl3) δ152.56,152.44,143.74,133.57,133.14,127.69,127.62,125.90,116.39,34.82,31.43,31.42,31.38.

[0057] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 15 H 17 O 3, 245.1178; found, 245.1171.

[0058] Example 4

[0059] A 1,2-dioxadiene having the structural formula:

[0060]

[0061] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0062]

[0063] The efficient preparation method of 1,2-dioxodienes in this example is the same as that in Example 1, except that 1d (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodienes 3a in 64% yield (27.8 mg, 0.13 mmol).

[0064] The 3D NMR and high-resolution data are:

[0065] 1 H NMR (400MHz, CDCl3) δ7.20(d,J=8.8Hz,2H),6.82(d,J=8.8Hz,2H),6.77(s,1H),5.56(s,1H),5.27(s,1H),3.73(s,3H).

[0066] 13 C NMR (101MHz, CDCl3) δ160.24,152.46,143.77,133.09,129.04,128.28,127.49,115.86,114.23,55.38.

[0067] HRMS (ESI-TOF) m / z: [MH] + calcd for C 12 H 11 O4,217.0506;found,217.0505

[0068] Example 5

[0069] A 1,2-dioxadiene having the structural formula:

[0070]

[0071] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0072]

[0073] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1e (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3e in a yield of 61% (25.2 mg, 0.12 mmol).

[0074] The 3e NMR and high-resolution data are:

[0075] 1H NMR (400MHz, CDCl3) δ7.35 (dd, J = 8.7, 5.3Hz, 2H), 7.08 (s, 2H), 6.84 (s, 1H), 5.72 (s, 1H), 5.39 (s, 1H).

[0076] 13 C NMR (101MHz, CDCl3) δ 164.42, 161.95, 152.33, 143.47, 132.71, 132.05 (d, J = 3.03Hz), 129.74 (d, J = 8.08Hz), 127.64, 117.00, 115.96 (d, J = 22.22Hz).

[0077] 19 F NMR (377MHz,CDCl3)δ-112.01.

[0078] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 11 H8FO3,207.0457; found,207.0453.

[0079] Example 6

[0080] A 1,2-dioxadiene having the structural formula:

[0081]

[0082] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0083]

[0084] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1f (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3f in a yield of 65% (28.9 mg, 0.13 mmol).

[0085] The 3f NMR and high-resolution data are:

[0086] 1 H NMR (400MHz, CDCl3) δ7.28(d,J=8.6Hz,2H),7.22(d,J=8.6Hz,2H),6.77(s,1H),5.64(s,1H),5.33(s,1H)

[0087] 13C NMR (101MHz, CDCl3) δ152.30,143.32,135.31,134.49,132.72,129.30,129.27,127.65,117.37.

[0088] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 11 H8ClO3,223.0162; found,223.0155.

[0089] Example 7

[0090] A 1,2-dioxadiene having the structural formula:

[0091]

[0092] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0093]

[0094] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1 g (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv). 3 g of the corresponding 1,2-dioxodiene is obtained with a yield of 69% (30.7 mg, 0.14 mmol).

[0095] The 3g NMR and high-resolution data are:

[0096] 1 H NMR (400MHz, CDCl3) δ7.36(dd,J=7.9,1.2Hz,1H),7.29–7.24(m,1H),7.21(td,J=7.4,1.9Hz,2H),6.49(s,1H),5.82(s,1H),5.27(s,1H).

[0097] 13 C NMR (101MHz, CDCl3) δ152.31,142.72,134.34,133.18,131.20,130.98,130.35,130.12,127.57,127.16,118.72.

[0098] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 11 H8CLO3,223.0162; found,223.0158.

[0099] Example 8

[0100] A 1,2-dioxadiene having the structural formula:

[0101]

[0102] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0103]

[0104] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1h (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3h in a yield of 72% (32.1 mg, 0.14 mmol).

[0105] The 3h NMR and high-resolution data are:

[0106] 1 H NMR (400MHz, CDCl3) δ7.27(t,J=5.3Hz,3H),7.18(dd,J=5.2,3.6Hz,1H),6.80(s,1H),5.67(s,1H),5.36(s,1H).

[0107] 13 C NMR (101MHz, CDCl3) δ152.19,143.01,137.70,134.82,132.52,130.24,129.28,128.02,127.71,126.09,117.58.

[0108] HRMS (ESI-TOF) m / z: [MH] + calcd for C 11 H6ClO3,221.0011; found,221.0010.

[0109] Example 9

[0110] A 1,2-dioxadiene having the structural formula:

[0111]

[0112] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0113]

[0114] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1i (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3i in a yield of 71% (36.4 mg, 0.14 mmol).

[0115] 3i's NMR and high-resolution data are:

[0116] 1 H NMR (400MHz, CDCl3) δ7.68 (d, J = 8.3Hz, 2H), 7.51 (d, J = 8.1Hz, 2H), 6.86 (s, 1H), 5.82 (s, 1H), 5.49 (s, 1H).

[0117] 13 C NMR (101MHz, CDCl3) δ152.19, 143.03, 139.63, 132.72, 131.55 (q, J = 33.33Hz), 128.45, 127.75, 126.04 (q, J = 4.04Hz), 122.58 (q, J = 171.7Hz), 118.20.

[0118] 19F NMR (377MHz, CDCl3) δ-62.77,-62.82,-62.98.

[0119] HRMS (ESI-TOF) m / z: [MH] + calcd for C 12 H6F3O3,255.0275; found,255.0276.

[0120] Example 10

[0121] A 1,2-dioxadiene having the structural formula:

[0122]

[0123] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0124]

[0125] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1j (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3j in a yield of 63% (31 mg, 0.12 mmol).

[0126] The NMR and high-resolution data of 3j are:

[0127] 1 H NMR (400MHz, CDCl3) δ8.06(d,J=8.4Hz,2H),7.44(d,J=8.4Hz,2H),6.85(s,1H),5.81(s,1H),5.49(s,1H),3.93(s,3H).

[0128] 13 C NMR (101MHz, CDCl3) δ166.48,152.22,143.04,140.42,133.03,130.94,130.24,127.99,127.73,117.95,52.42.

[0129] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 13 H 11 O5,247.0606;found,247.0601.

[0130] Example 11

[0131] A 1,2-dioxadiene having the structural formula:

[0132]

[0133] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0134]

[0135] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1k (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3k in a yield of 74% (31.6 mg, 0.15 mmol).

[0136] The 3k NMR and high-resolution data are:

[0137] 1 H NMR (400MHz, CDCl3) δ7.69 (d, J = 8.4Hz, 2H), 7.50 (d, J = 8.4Hz, 2H), 6.89 (s, 1H), 5.82 (s, 1H), 5.50 (s, 1H).

[0138] 13C NMR (101MHz, CDCl3) δ152.01,142.61,140.51,132.84,132.43,128.74,127.76,118.82,118.22,113.20.

[0139] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 12 H8NO3,214.0504; found,214.0498.

[0140] Example 11

[0141] A 1,2-dioxadiene having the structural formula:

[0142]

[0143] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0144]

[0145] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1l (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3l in a yield of 63% (29.4 mg, 0.12 mmol).

[0146] The NMR and high-resolution data of 3l are:

[0147] 1 H NMR (400MHz, CDCl3) δ8.25(d,J=8.8Hz,2H),7.57(d,J=8.8Hz,2H),6.91(s,1H),5.88(s,1H),5.55(s,1H).

[0148] 13 C NMR (101MHz, CDCl3) δ151.98,148.30,142.53,142.33,132.10,128.99,127.85,124.24,119.14.

[0149] HRMS (ESI-TOF) m / z: [MH] + calcd for C 11 H6NO 5, 232.0251;found,232.0252

[0150] Example 12

[0151] A 1,2-dioxadiene having the structural formula:

[0152]

[0153] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0154]

[0155] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1m (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3m in a yield of 72% (39.2 mg, 0.14 mmol).

[0156] The 3m NMR and high-resolution data are:

[0157] 1 H NMR (400MHz, CDCl3) δ7.34 (d, J = 8.7Hz, 2H), 7.18 (d, J = 8.3Hz, 2H), 6.78 (s, 1H), 5.69 (s, 1H), 5.36 (s, 1H).

[0158] 13 C NMR (101MHz, CDCl3) δ152.29, 149.88, 143.30, 134.70, 132.55, 130.48, 129.55, 127.70, 121.63 (q, J = 38.38Hz), 117.67.

[0159] 19 F NMR (377 MHz, CDCl3) δ-57.85.

[0160] HRMS (ESI-TOF) m / z: [MH] + calcd for C 12 H6F3O4,271.0224; found,271.0224.

[0161] Example 13

[0162] A 1,2-dioxadiene having the structural formula:

[0163]

[0164] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0165]

[0166] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1n (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3n in a yield of 70% (26.5 mg, 0.14 mmol).

[0167] The 3n NMR and high-resolution data are:

[0168] 1 H NMR (400MHz, CDCl3) δ8.68–8.61(m,2H),7.72–7.65(m,1H),7.35(ddd,J=7.9,4.9,0.6Hz,1H),6.86(s,1H),5.84(s,1H),5.48(s,1H).

[0169] 13 C NMR (101MHz, CDCl3) δ152.12,150.52,148.89,143.02,135.41,131.93,130.61,127.67,123.73,118.53.

[0170] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 10 H8NO3,190.0504; found,190.0499.

[0171] Example 14

[0172] A 1,2-dioxadiene having the structural formula:

[0173]

[0174] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0175]

[0176] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1o (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3o in a yield of 39% (18.8 mg, 0.08 mmol).

[0177] The 3o NMR and high-resolution data are:

[0178] 1 H NMR (400MHz, CDCl3) δ7.92–7.83(m,4H),7.54(dd,J=6.1,3.4Hz,2H),7.46(dd,J=8.5,1.7Hz,1H),6.88(s,1H),5.83(s,1H),5.55(s,1H).

[0179] 13 C NMR (101MHz, CDCl3) δ152.48,143.66,133.74,133.51,133.39,133.25,128.78,128.22,127.86,127.79,127.22,126.95,126.91,125.55,117.25.

[0180] HRMS (ESI-TOF) m / z: [MH] + calcd for C 15 H9O3,237.0557; found,237.0556.

[0181] Example 15

[0182] A 1,2-dioxadiene having the structural formula:

[0183]

[0184] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0185]

[0186] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1p (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3p in a yield of 63% (24.6 mg, 0.12 mmol).

[0187] The 3p NMR and high-resolution data are:

[0188] 1 H NMR (400MHz, CDCl3) δ6.98 (s, 1H), 5.49 (s, 1H), 5.18 (s, 1H), 2.16 (dd, J = 11 .3,4.0Hz,2H),1.55–1.46(m,2H),1.34–1.24(m,6H),0.88(t,J=6.9Hz,3H).

[0189] 13 C NMR (101MHz, CDCl3) δ152.64,144.27,132.03,125.44,114.59,31.66,31.13,28.97,28.13,22.67,14.15.

[0190] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 11 H 17 O3,197.1178;found,197.1171.

[0191] Example 16

[0192] A 1,2-dioxadiene having the structural formula:

[0193]

[0194] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0195]

[0196] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1q (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3q in a yield of 44% (16.1 mg, 0.09 mmol).

[0197] The 3q NMR and high-resolution data are:

[0198] 1 H NMR(400MHz, CDCl3)δ6.98(s,1H),5.49(s,1H),5.18(s,1H),2.20–2.10(m,2H),1. 51(dd,J=9.8,5.2Hz,2H), 1.30(td,J=6.9,3.1Hz,4H), 0.89(dd,J=7.0,6.2Hz,3H).

[0199] 13 C NMR (101MHz, CDCl3) δ152.63,144.25,132.03,125.44,114.57,31.45,31.08,27.84,22.51,14.06.

[0200] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 10H 15 O3,183.1021;found,183.1017.

[0201] Example 17

[0202] A 1,2-dioxadiene having the structural formula:

[0203]

[0204] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0205]

[0206] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1r (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3r in a yield of 72% (28 mg, 0.14 mmol).

[0207] The 3r NMR and high-resolution data are:

[0208] 1 H NMR (400MHz, CDCl3) δ7.01 (s, 1H), 5.49 (s, 1H), 5.20 (s, 1H), 1.82 (d, J = 9.2Hz, 5H), 1.39–1.15 (m, 6H).

[0209] 13 C NMR (101MHz, CDCl3) δ152.57,144.13,137.87,125.12,112.61,39.51,32.78,26.62,26.05.

[0210] HRMS (ESI-TOF) m / z: [MH] + calcd for C 11 H 13 O3,193.0870;found,193.0868.

[0211] Example 18

[0212] A 1,2-dioxadiene having the structural formula:

[0213]

[0214] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0215]

[0216] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1s (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3s in a yield of 65% (28.2 mg, 0.13 mmol).

[0217] The 3s NMR and high-resolution data are:

[0218] 1 H NMR (400MHz, CDCl3) δ7.29(t,J=7.3Hz,2H),7.25–7.14(m,3H),6.90(s,1H),5.53(s,1H),5.19(s,1H),2.89–2.79(m,2H),2.51–2.40(m,2H).

[0219] 13 C NMR (101MHz, CDCl3) δ152.49,143.97,140.67,131.24,128.64,128.40,126.47,125.55,115.18,34.54,32.88.

[0220] HRMS (ESI-TOF) m / z: [MH] + calcd for C 13 H 11 O3,215.0714;found,215.0713.

[0221] Example 19

[0222] A 1,2-dioxadiene having the structural formula:

[0223]

[0224] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0225]

[0226] This embodiment also provides an efficient preparation method of 1,2-dioxadiene, comprising the following steps:

[0227] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1t (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3t in a yield of 70% (28 mg, 0.14 mmol).

[0228] The 3T NMR and high-resolution data are:

[0229] 1 H NMR (400MHz, CDCl3) δ7.02(s,1H),5.52(s,1H),5.21(s,1H),3.56(t,J=6.4Hz,2H),2.20(t,J=7.6Hz,2H),1.86–1.74(m,2H),1.74–1.61(m,2H).

[0230] 13 C NMR (101MHz, CDCl3) δ152.49,143.93,131.32,125.58,115.08,44.63,31.83,30.31,25.27.

[0231] HRMS (ESI-TOF) m / z: [M+H] + calcd for C9H 12 ClO3,203.0475; found,203.0470.

[0232] Example 20

[0233] A 1,2-dioxadiene having the structural formula:

[0234]

[0235] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0236]

[0237] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1u (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3u in a yield of 68% (25.7 mg, 0.13 mmol).

[0238] The NMR and high-resolution data of 3u are:

[0239] 1H NMR (400MHz, CDCl3) δ7.06(s,1H),5.57(s,1H),5.24(s,1H),3.58(t,J=6.1Hz,2H),2.41–2.32(m,2H),1.99(ddd,J=12.9,8.3,6.3Hz,2H).

[0240] 13 C NMR (101MHz, CDCl3) δ152.44,143.74,130.48,125.75,115.64,44.04,30.96,28.05.

[0241] HRMS (ESI-TOF) m / z: [M+H] + calcd for C8H 10 ClO3,189.0318; found,189.0313.

[0242] Example 21

[0243] A 1,2-dioxadiene having the structural formula:

[0244]

[0245] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0246]

[0247] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1v (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3v in a yield of 46% (21.4 mg, 0.09 mmol).

[0248] The 3V NMR and high-resolution data are:

[0249] 1 H NMR (400MHz, CDCl3) δ7.40–7.35(m,2H),7.35–7.29(m,3H),7.13(s,1H),5.67(s,1H),5.42(s,1H),4.49(s,2H),4.20(d,J=0.6Hz,2H).

[0250] 13C NMR (101MHz, CDCl3) δ152.33,142.20,137.29,129.46,128.74,128.23,128.08,127.34,117.31,72.14,69.85.

[0251] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 13 H 13 O4,233.0814;found,233.0808.

[0252] Example 22

[0253] A 1,2-dioxadiene having the structural formula:

[0254]

[0255] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0256]

[0257] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1w (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3w in a yield of 54% (21.4 mg, 0.11 mmol).

[0258] The 3w NMR and high-resolution data are:

[0259] 1 H NMR (400MHz, CDCl3) δ6.99(s,1H),5.52(s,1H),5.19(s,1H),3.41(t,J=6.7Hz,2H ),2.18(t,J=7.2Hz,2H),1.93–1.83(m,2H),1.52(ddd,J=22.9,15.5,8.7Hz,4H).

[0260] 13 C NMR (101MHz, CDCl3) δ152.54,144.08,131.57,125.47,114.90,33.64,32.48,30.92,27.78,27.25.

[0261] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 10 H15 O4,199.0970;found,199.0961.

[0262] Example 23

[0263] A 1,2-dioxadiene having the structural formula:

[0264]

[0265] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0266]

[0267] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1x (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3x in a yield of 63% (23.2 mg, 0.12 mmol).

[0268] The 3x NMR and high-resolution data are:

[0269] 1 H NMR (400MHz, CDCl3) δ7.02 (s, 1H), 5.53 (s, 1H), 5.21 (s, 1H), 3.43 (t, J = 6.5Hz ,2H),2.21(t,J=7.6Hz,2H),1.89(dd,J=14.7,6.6Hz,2H),1.78–1.64(m,2H).

[0270] 13 C NMR (101MHz, CDCl3) δ152.48,143.94,131.30,125.58,115.17,33.26,31.97,30.25,26.56.

[0271] HRMS (ESI-TOF) m / z: [MH] - calcd for C9H 13 O4C9H 11 O4,183.0663;found,183.0663.

[0272] Example 24

[0273] A 1,2-dioxadiene having the structural formula:

[0274]

[0275] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0276]

[0277] The efficient preparation method of 1,2-dioxodienes in this example is the same as that in Example 1, except that 1y (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodienes 3y in a yield of 26% (15.6 mg, 0.05 mmol).

[0278] The NMR and high-resolution data of 3y are:

[0279] 1 H NMR (400MHz, CDCl3) δ7.82 (dd, J=5.4, 3.1Hz, 2H), 7.71 (dd, J=5.5, 3.0Hz, 2H), 7.02 (s, 1H ),5.51(s,1H),5.25(s,1H),3.71(t,J=7.1Hz,2H),2.29–2.18(m,2H),1.98–1.87(m,2H).

[0280] 13 C NMR (101MHz, CDCl3) δ168.44,152.40,143.76,134.19,132.04,130.69,125.66,123.38,115.07,37.41,28.23,26.76.

[0281] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 16 H 14 NO5,300.0872; found,300.0866.

[0282] Example 25

[0283] A 1,2-dioxadiene having the structural formula:

[0284]

[0285] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0286]

[0287] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1z (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3z in a yield of 60% (22.6 mg, 0.12 mmol).

[0288] The 3z NMR and high-resolution data are:

[0289] 1 H NMR (400MHz, CDCl3) δ7.48–7.42(m,2H),7.36(ddd,J=13.5,8.4,4.2Hz,3H),7.07(s,1H),7.02(d,J=16.2Hz,1H),6.55(d,J=16.2Hz,1H).

[0290] 13 C NMR (101MHz, CDCl3) δ152.42,142.86,135.33,132.54,129.23,129.06,127.01,126.58,109.50.

[0291] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 11 H9O3,189.0552; found,189.0546.

[0292] Example 26

[0293] A 1,2-dioxadiene having the structural formula:

[0294]

[0295] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0296]

[0297] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1aa (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3aa in a yield of 41% (17.9 mg, 0.08 mmol).

[0298] The NMR and high-resolution data of 3aa are:

[0299] 1H NMR (400MHz, CDCl3) δ7.21 (d, J = 8.7Hz, 2H), 6.82 (dd, J = 6.7, 2.0Hz, 3H), 6.60 (d, J = 12.5Hz, 1H), 5.84 (d, J = 12.5Hz, 1H), 3.75 (s, 3H).

[0300] 13 C NMR (101MHz, CDCl3) δ159.91,152.37,141.68,134.40,129.97,128.15,127.61,114.08,110.35,55.41.

[0301] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 11 H8FO3,207.0457; found,207.0453.

[0302] Example 27

[0303] A 1,2-dioxadiene having the structural formula:

[0304]

[0305] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0306]

[0307] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1ab (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3ab in a yield of 64% (26.4 mg, 0.12 mmol).

[0308] The NMR and high-resolution data of 3ab are:

[0309] 1 H NMR (400MHz, CDCl3) δ7.32(dd,J=8.5,5.5Hz,2H),7.06(t,J=8.7Hz,2H),6.86(s,1H),6.70(d,J=12.5Hz,1H),6.01(d,J=12.5Hz,1H).

[0310] 13C NMR (101MHz, CDCl3) δ163.97, 161.49, 152.16, 141.34, 133.32, 131.80 (d, J = 3.03Hz), 130.35 (d, J = 8.08Hz), 128.10, 115.70 (d, J = 21.21Hz), 111.88.

[0311] 19 F NMR (377MHz,CDCl3)δ-112.33.

[0312] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 11 H8FO3,207.0457; found,207.0453.

[0313] Example 28

[0314] A 1,2-dioxadiene having the structural formula:

[0315]

[0316] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0317]

[0318] The efficient preparation method of 1,2-dioxodienes in this example is the same as that in Example 1, except that 1ac (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3ac in 30% yield (12.2 mg, 0.06 mmol).

[0319] The NMR and high-resolution data of 3ac are:

[0320] 1 H NMR (400MHz, CDCl3) δ7.11(dd,J=21.1,8.1Hz,4H),6.76(s,1H),6.64(d,J=12.5Hz,1H),5.88(d,J=12.5Hz,1H),2.27(s,3H).

[0321] 13 C NMR (101MHz, CDCl3) δ152.32,141.53,138.67,134.73,132.93,129.35,128.26,127.73,111.35,21.38.

[0322] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 12 H 11 O3,203.0708;found,203.0704.

[0323] Example 29

[0324] A 1,2-dioxadiene having the structural formula:

[0325]

[0326] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0327]

[0328] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1ad (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3ad in a yield of 51% (18.2 mg, 0.1 mmol).

[0329] The NMR and high-resolution data of 3ad are:

[0330] 1 H NMR (400MHz, CDCl3) δ7.75(s,1H),7.54(d,J=1.6Hz,1H),6.58(d,J=3.4Hz,1H ), 6.50 (dd, J = 3.4, 1.8Hz, 1H), 6.37 (d, J = 13.3Hz, 1H), 5.80 (d, J = 13.3Hz, 1H).

[0331] 13 C NMR (101MHz, CDCl3) δ152.56,150.99,143.77,141.69,129.08,118.86,114.38,112.44,106.81.

[0332] HRMS (ESI-TOF) m / z: [M+H] + calcd for C9H7O4,179.0374; found,179.0386.

[0333] Example 30

[0334] A 1,2-dioxadiene having the structural formula:

[0335]

[0336] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0337]

[0338] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1ae (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3ae in a yield of 53% (23.8 mg, 0.11 mmol).

[0339] The NMR and high-resolution data of 3ae are:

[0340] 1 H NMR (400MHz, CDCl3) δ6.91 (s, 1H), 5.60 (t, J = 7.3Hz, 1H), 2.26–2.13 (m, 4H), 1.43–1.27 (m, 8H), 0.90 (ddd, J = 7.2, 5.7, 1.5Hz, 6H).

[0341] 13 C NMR (101MHz, CDCl3) δ152.91,143.48,135.08,126.90,123.62,33.90,31.91,31.18,29.11,22.44,22.31,14.01,13.93.

[0342] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 13 H 21 O3,225.1491;found,225.1486.

[0343] Example 31

[0344] A 1,2-dioxadiene having the structural formula:

[0345]

[0346] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0347]

[0348] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1af (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3af in a yield of 51% (31.7 mg, 0.1 mmol).

[0349] The NMR and high-resolution data of 3af are:

[0350] 1 H NMR (400MHz, CDCl3) δ7.30–7.24(m,2H),7.13(t,J=8.6Hz,2H),6.97(s,1H),6.90(d,J=8.9Hz,2H),6.72–6.66(m,2H),6.47(s,1H),3.75(s,3H).

[0351] 13 C NMR (101MHz, CDCl3) δ164.23, 161.76, 159.76, 152.57, 145.60, 131.64 (d, J = 8.08Hz), 131.30, 130.31(d,J=3.03Hz),128.92,127.35,126.56,122.06,116.85(d,J=21.21Hz),113.97,55.35.

[0352] 19 F NMR (377 MHz, CDCl3) δ-112.02.

[0353] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 18 H 14 FO4,313.0876; found,313.0870.

[0354] Example 32

[0355] A 1,2-dioxadiene having the structural formula:

[0356]

[0357] The synthetic route of 1,2-dioxadiene in this embodiment is:

[0358]

[0359] The efficient preparation method of 1,2-dioxodiene in this example is the same as that in Example 1, except that 1ag (0.2 mmol, 1.0 equiv) is used instead of 1a (0.2 mmol, 1.0 equiv) to obtain the corresponding 1,2-dioxodiene 3ag in a yield of 47% (32 mg, 0.09 mmol).

[0360] The NMR and high-resolution data of 3ag are:

[0361] 1 H NMR (400MHz, CDCl3) δ7.25 (dd, J=4.5, 1.5Hz, 3H), 7.18–7.13 (m, 2H), 7.11 (d, J=7 .3Hz,5H),6.99(d,J=7.1Hz,3H),6.85(dd,J=6.8,1.3Hz,2H),6.31–6.28(m,1H).

[0362] 13 C NMR (101MHz, CDCl3) δ152.44,146.63,144.77,142.16,141.11,137.25,130.94,1 30.86,129.62,129.49,128.59,128.44,128.42,128.10,127.90,127.67,123.95.

[0363] HRMS (ESI-TOF) m / z: [M+H] + calcd for C 23 H 17 O3,341.1178;found,341.1172.

[0364] Comparative Examples 1 to 9

[0365] The preparation method of this comparative example is different from that of Example 1 in that the ligand is different (see Table 1 for details), and the other steps and parameters are the same as those of Example 1, see Table 1 for details.

[0366] Table 1 Reaction conditions and yields of Example 1 and Comparative Examples 1 to 9

[0367]

[0368]

[0369] Comparative Examples 10-18

[0370] The preparation method of this comparative example is different from that of Example 1 in that the organic solvent is different (see Table 2 for details), and the other steps and parameters are the same as those of Example 1, see Table 2 for details.

[0371] Table 2 Reaction conditions and yields of Example 1 and Comparative Examples 10 to 18

[0372]

[0373] Comparative Examples 19 to 25

[0374] The preparation method of this comparative example is different from that of Example 1 in that the palladium catalyst is different (see Table 3 for details), and the other steps and parameters are the same as those of Example 1, see Table 3 for details.

[0375] Table 3 Reaction conditions and yields of Example 1 and Comparative Examples 19 to 25

[0376]

[0377]

[0378] Comparative Examples 26 to 38

[0379] The preparation method of this comparative example is different from that of Example 1 in that the base is different (see Table 4 for details), and the other steps and parameters are the same as those of Example 1, see Table 4 for details.

[0380] Table 4 Comparison of reaction conditions and yields between Example 1 and Comparative Examples 10 to 23

[0381]

[0382] In summary, in the efficient preparation method of 1,2-dioxadiene of the present invention, the ligand, base, organic solvent, etc. will affect the synthesis of 1,2-dioxadiene.

[0383] Application Example 1 Synthesis of Polysubstituted Phenols by DA Reaction of 1,2-Dioxadiene

[0384] The synthetic route of the substituted phenol in this application example is:

[0385]

[0386] This application example also provides the DA reaction of 1,2-dioxadiene to synthesize substituted phenols, including the following steps:

[0387] The mixture was dried in a drying oven. After cooling, a magnetic stirrer, 3f (0.1 mmol), 4a (0.3 mmol), and benzene (2 mL) were added in sequence. Argon was introduced and vacuumed three times, then the mixture was quickly capped with a rubber stopper. The reaction was allowed to proceed at 100°C for 24 h. After completion of the reaction, the mixture was diluted with EA, and the inorganic matter was filtered out with a filter column. The filtrate was then dried and purified by silica gel column chromatography to obtain the corresponding product 5a in a yield of 71% (49 mg, 0.07 mmol).

[0388] Application Example 2

[0389] The synthetic route of the substituted phenol in this application example is:

[0390]

[0391] This embodiment also provides a method for synthesizing substituted phenols by the DA reaction of 1,2-dioxadiene, comprising the following steps:

[0392] The mixture was dried in a drying oven. After cooling, a magnetic stirrer, 3d (0.1 mmol), 4b (0.3 mmol), and THF (2 mL) were added in sequence. Argon was introduced and vacuumed three times, then the mixture was quickly capped with a rubber stopper. The reaction was continued at 130°C for 36 h. After completion of the reaction, the mixture was diluted with EA, and the inorganic matter was filtered out using a filter column. The filtrate was then dried and purified by silica gel column chromatography to obtain the corresponding product 5b in a 75% yield (27 mg, 0.075 mmol).

[0393] Application Example 3

[0394] The synthetic route of the substituted phenol in this application example is:

[0395]

[0396] This application example also provides the DA reaction of 1,2-dioxadiene to synthesize substituted phenols, including the following steps:

[0397] The mixture was dried in a drying oven. After cooling, a magnetic stirrer, 3v (0.1 mmol), 4c (0.3 mmol), and THF (2 mL) were added in sequence. Argon was introduced and vacuumed three times, then the mixture was quickly capped with a rubber stopper and allowed to react at 130°C for 36 h. After completion of the reaction, the mixture was diluted with EA, and the inorganic matter was filtered out using a filter column. The filtrate was then dried and purified by silica gel column chromatography to obtain the corresponding product 5c in a 70% yield (36 mg, 0.07 mmol).

[0398] The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and obviously, many modifications and variations are possible in light of the above teachings.

Claims

1. A 1,2-dioxadiene, characterized in that The structural formula of the 1,2-dioxadiene is: Among them, R 1 、R 2 is hydrogen, aryl, alkyl, alkoxy, chloroalkyl or cycloalkyl.

2. A method for preparing 1,2-dioxodiene, characterized in that: The method comprises the following steps: dissolving a palladium catalyst and a ligand in an organic solvent, adding vinylene carbonate, an alkenyl halide and a base, stirring for reaction, filtering, concentrating under reduced pressure and purifying after the reaction is completed to obtain 1,2-dioxadiene.

3. The efficient preparation method of 1,2-dioxodiene according to claim 2, characterized in that, The organic solvent is one of dichloromethane, 1,2-dichloroethane, chloroform, trifluoroethanol, and hexafluoroisopropanol.

4. The efficient preparation method of 1,2-dioxodiene according to claim 2, characterized in that, The reaction temperature is 60-120° C., and the reaction time is 12-24 hours.

5. The efficient preparation method of 1,2-dioxodiene according to claim 2, characterized in that, The ligand is one of methyl diphenyl phosphine, ethyl diphenyl phosphine, propyl diphenyl phosphine and isopropyl diphenyl phosphine.

6. The efficient preparation method of 1,2-dioxodiene according to claim 2, characterized in that: The palladium catalyst is one of tetrakistriphenylphosphine palladium, Pd(dba)2, Pd / carbon, palladium acetate, palladium chloride, palladium bromide, palladium iodide or palladium trifluoroacetate.

7. The efficient preparation method of 1,2-dioxodiene according to claim 2, characterized in that: The base is one of potassium bicarbonate, potassium carbonate, sodium phosphate, potassium phosphate, dipotassium hydrogen phosphate, and potassium acetate.

8. The efficient preparation method of 1,2-dioxodiene according to claim 2, characterized in that: The molar amount of the palladium catalyst is 8 to 12% of the molar amount of the alkenyl halide, the molar amount of the ligand is 18 to 22% of the molar amount of the alkenyl halide, the molar amount of the vinylene carbonate is 7 to 9 times the molar amount of the alkenyl halide, and the molar amount of the base is 2 to 3 times the molar amount of the alkenyl halide.

9. The efficient preparation method of 1,2-dioxodiene according to any one of claims 5 to 7, characterized in that: The ligand is methyldiphenylphosphine, the palladium catalyst is palladium acetate, and the base is potassium bicarbonate.

10. Use of the 1,2-dioxodiene according to claim 1 in a DA cycloaddition reaction.

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