Method for synthesizing quinoline derivative by oxidizing and cyclizing acetophenone and aniline compounds
Technical Field
The invention relates to a method for synthesizing a quinoline derivative, in particular to a method for generating the quinoline derivative by performing air oxidation one-step reaction on acetophenone, aniline compounds and dimethyl sulfoxide under the catalysis of copper salt, and belongs to the field of synthesis of drug intermediates.
Background
As an important N-heterocyclic fine chemical raw material, the quinoline compound has wide application in the aspects of medicines, pesticides, spices, foods, dyes, synthetic feed additives, auxin and the like. The quinoline compound is widely existed in nature, but the separation and purification from nature not only has various operation steps, complicated separation devices, large energy consumption, higher process cost and serious environmental pollution, such as: quinoline was first extracted from wash oil of coal tar or naphthalene oil. Washing the naphthalene oil fraction and the wash oil fraction with dilute sulfuric acid to obtain quinoline sulfate base solution, steaming to remove impurities such as neutral oil, and decomposing with alkali or ammonia. The separated crude quinoline and the homologue thereof are rectified by a high-yield distillation tower after being dehydrated, and the distillation section with the boiling range of 237.5-239.5 ℃ is cut to obtain the crude quinoline containing 83% of quinoline and 15% of isoquinoline.
At present, the synthesis method of quinoline compounds becomes a hotspot of research of researchers, the most representative method for industrially synthesizing quinoline in early stage is a Skraup synthesis method, aromatic amine, concentrated sulfuric acid and glycerol are heated together with a mild oxidant, the glycerol is dehydrated into acrolein under the action of the concentrated sulfuric acid at high temperature, then condensed with aniline into dihydroquinoline, and finally oxidized to obtain quinoline, the reaction has the defects that the reaction is carried out in a concentrated sulfuric acid environment and under the high temperature condition, the reaction condition is harsh, and the yield is not high.
For example, Chinese patent Nos. CN 102134219A and CN 102070521A both disclose a method for preparing quinoline derivatives, specifically disclose that substituted aniline reacts with α unsaturated aldehyde, ketone or ester compounds in the presence of rare earth catalysts to obtain the target product (reaction formula 1 below), or aniline derivatives react with α, β -unsaturated aldehyde and ketone in acidic ionic liquid under the catalysis of iodine or iodide to obtain quinoline derivatives (reaction formula 2 below), which has the disadvantages of expensive ketene compounds and expensive rare earth metals in acidic ionic liquid, and high production cost, for example, Chinese patent No. CN103554020A discloses a method for synthesizing quinoline derivatives, specifically, imine and alkyne are used as substrates in organic solvents to react under iron catalysis to obtain quinoline compounds (reaction formula 3 below), which has the disadvantages of poor stability, and requires a sealed reaction of imine substrates under the conditions, and a method for preparing quinoline derivatives under the conditions of corrosion of triflic acid, which is not favorable for preparing quinoline derivatives under the conditions of trifluoro methanesulfonic acid, and requires the industrial corrosion of a novel method for preparing quinoline derivatives under the conditions of trifluoro methanesulfonic acid, and the disadvantages of the prior art (CN 106380463).
disclosure of Invention
Aiming at the defects of the existing method for synthesizing the quinoline derivative, the invention aims to provide a method for generating the quinoline derivative by oxidizing acetophenone, aniline compounds and dimethyl sulfoxide in one step through oxygen under the catalysis of copper salt.
In order to realize the technical purpose, the invention provides a method for synthesizing a quinoline derivative by oxidizing and cyclizing acetophenone and aniline compounds, wherein the acetophenone, the aniline compounds shown in the formula 1 and dimethyl sulfoxide are subjected to one-pot reaction in the presence of a copper salt catalyst in an oxygen-containing atmosphere to obtain a quinoline derivative shown in the formula 2;
wherein,
R1and R2Independently selected from hydrogen, alkyl, alkoxy, alkylthio, alkoxyacyl, halogenCyano, aryl or arylheterocyclyl.
In a preferred embodiment, the aniline compound is aniline, 4-isopropylaniline, 3-methylaniline, 3, 4-dimethylaniline, 2-phenylaniline, 4-chloroaniline, 3-chloroaniline or 3-bromoaniline.
In a preferable scheme, the concentration of the acetophenone in the dimethyl sulfoxide is 0.05-0.5 mol/L; more preferably 0.1 to 0.3 mol/L; most preferably 0.15 to 0.25 mol/L.
In a preferable scheme, the molar weight of the copper salt catalyst is 5-30% of that of the arylethanone compound; more preferably 8 to 20%.
In a more preferable scheme, the copper salt comprises at least one of copper sulfate, copper halide and copper acetate; preferred copper halides include copper chloride and/or copper bromide; most preferred is copper chloride.
In a preferable scheme, the molar weight of the aniline compound is 2-5 times of that of acetophenone; more preferably 2.5 to 3.5 times.
In a preferred embodiment, the reaction conditions are as follows: the reaction temperature is 90-140 ℃, and the reaction time is 18-30 h. More preferably, the reaction conditions are as follows: the reaction temperature is 100-130 ℃, and the reaction time is 20-28 h; the most preferable reaction time is 22-26 h at 115-125 ℃.
Preferably, the oxygen-containing atmosphere is air, oxygen, or other oxygen-containing atmosphere.
In the technical scheme of the invention, the copper salt is used as a catalyst, and the oxygen-containing gas is used as an oxidant. The pyridine ring contained in the quinoline derivative is formed by cyclizing one molecule of aniline compound, one molecule of acetophenone and one molecule of dimethyl sulfoxide, wherein a series of complex chemical reactions such as oxidative dehydrogenation, condensation cyclization and the like are carried out on one molecule of acetyl of the acetophenone compound, one molecule of amino of the aniline compound and one molecule of methyl of the dimethyl sulfoxide under the catalysis of a copper salt catalyst, so that the quinoline derivative is obtained.
Compared with the prior art, the technical scheme of the invention has the beneficial technical effects that:
1) according to the technical scheme, the acetophenone, the aniline compound and the dimethyl sulfoxide are subjected to oxidative cyclization to obtain the quinoline compound for the first time, and a brand new thought is provided for synthesizing the pharmaceutical intermediate of the quinoline compound.
2) The technical scheme of the invention adopts the conventional acetophenone, aniline compounds and dimethyl sulfoxide as raw materials, and the raw materials have wide sources and have the advantage of low cost compared with keto-alkene compounds.
3) The technical scheme of the invention has simple steps and mild reaction conditions, can realize the synthesis of the quinoline compound by a one-pot method, has high reaction yield and is beneficial to large-scale production.
4) The quinoline compound synthesized by the technical scheme of the invention contains aryl and other groups which are easy to modify again, and has obvious advantages when being used as a quinoline drug synthesis intermediate.
5) The catalyst of the invention is common copper salt, and has wide source and low cost.
Drawings
FIG. 1 is a 1H NMR spectrum of the quinoline derivative in example 1;
FIG. 2 is a 13C NMR spectrum of the quinoline derivative in example 1;
FIG. 3 is a 1H NMR spectrum of the quinoline derivative in example 3;
FIG. 4 is a 13C NMR spectrum of the quinoline derivative in example 3;
FIG. 5 is a 1H NMR spectrum of the quinoline derivative in example 4;
FIG. 6 is a 13C NMR spectrum of the quinoline derivative in example 4;
FIG. 7 is a 1H NMR spectrum of the quinoline derivative in example 6;
FIG. 8 is a 13C NMR spectrum of the quinoline derivative in example 6.
Detailed Description
The following examples are intended to further illustrate the present disclosure, but not to limit the scope of the claims.
The substrate starting materials, solvents and the like mentioned in the following examples were all commercial products (analytical reagents) on the market and were not further purified.
The product is separated by chromatography, column silica gel (300-400 mesh).
1H NMR (400MHz), 13C NMR (100MHz), in CDCl3As solvent, TMS was used as internal standard.
Multiplicity is defined as follows: s (singlet); d (doublet); t (triplet); q (quartet) and m (multiplet). Coupling constant J (Hertz).
Condition optimization experiment: the optimal reaction conditions were found by the following control experimental groups: the reaction is exemplified by using acetophenone, aniline and dimethyl sulfoxide as reaction raw materials, and using excessive dimethyl sulfoxide as a reaction solvent, and the specific reaction is as follows:
the catalyst, acetophenone and aniline were dissolved in DMSO in a 25mL Schlenk tube and stirred in the presence of an oxidant at a temperature for 24 hours. After the reaction is finished, cooling the obtained solution to room temperature; the solution was diluted with ethyl acetate (10mL), washed with water (5mL), extracted with ethyl acetate (3X 5mL), and extracted with anhydrous Na2SO4Dried and concentrated in vacuo. The crude product was purified by flash column chromatography on silica gel to give the desired product.
Reaction conditions of a control experiment group 1-12 are acetophenone (0.5mmol), DMSO (2.5mL), aniline (1.5mmol), catalyst (10 mol%), oxygen (1 atm)/oxidant (1.0mmol), the reaction temperature is 120 ℃, and the reaction time is 24 h.
The reaction temperature of the control experiment group 13 was 100 deg.C, and other conditions were the same as those of the experiment group 1.
The reaction temperature of the control experiment group 14 was 130 deg.C, and other conditions were the same as those of the experiment group 1.
CuCl of control experiment group 152·2H2O (5 mol%), other conditions were the same as in Experimental group 1.
CuCl for control experiment group 162·2H2O (20 mol%), other conditions were the same as in Experimental group 1.
As can be seen from comparison experiment groups 1-8 in the table, the reaction can be smoothly carried out under the catalysis of copper salt and iron salt, and the catalytic reaction effect is lower than that of corresponding copper salt, iron salt and the like although cobalt salt and nickel salt have certain catalytic activity. Experiments show that the catalytic effect of copper salt is the best in all the catalysts, and the yield of the quinoline derivative is higher correspondingly.
As can be seen from comparison of experimental groups 1 and 9-12 in the table, except that oxygen can enable the reaction to be carried out smoothly, higher yield is obtained, other conventional oxidants such as hydrogen peroxide and K2S2O8And peroxide TBHP and the like are difficult to synthesize quinoline derivatives, and only low yield or target products cannot be obtained.
As can be seen from the comparison of experimental groups 1 and 13-14 in the table, the yield is correspondingly reduced when the reaction temperature is too high or too low, and the optimal reaction effect can be achieved at about 120 ℃.
In summary, the optimal reaction conditions can be obtained by comparing the experimental groups 1-16: acetophenone (0.5mmol), aniline (1.5mmol), DMSO (2.5mL), CuCl2·2H2O (10 mol%), oxygen (1atm), reaction temperature 120 ℃ and reaction time 24 h.
The following examples 1 to 9 and comparative examples 1 and 2 were reacted under the optimized reaction conditions as described above:
example 1
AnilineA compound of the following class:
yield: 78 percent.
1H NMR(400MHz,CDCl3)δ8.23(d,J=8.6Hz,1H),8.17(d,J=8.5Hz,1H),8.13(d,J=8.1Hz,2H),7.85(d,J=3.6Hz,1H),7.83(d,J=3.0Hz,1H),7.74(t,J=7.7Hz,1H),7.57-7.48(m,3H).13C NMR(100MHz,CDCl3)δ156.0,148.2,138.0,137.1,135.6,129.9,129.7,129.0,128.9,127.5,127.2,126.6,118.6.
Example 2
yield: 66 percent.
1H NMR(400MHz,CDCl3)δ8.19-8.04(m,4H),7.81(d,J=8.6Hz,1H),7.56-7.49(m,4H),7.44(t,J=7.2Hz,1H),2.53(s,3H).13C NMR(100MHz,CDCl3)δ156.5,146.8,139.8,136.2,136.2,132.0,129.4,129.2,128.8,127.5,127.2,126.4,119.0,21.6.
Example 3
yield: 68 percent.
1H NMR(400MHz,CDCl3)δ8.20-8.07(m,4H),7.83(d,J=8.5Hz,1H),7.65-7.58(m,2H),7.51(t,J=7.5Hz,2H),7.44(t,J=7.1Hz,1H),1.36(d,J=6.9Hz,6H).13C NMR(100MHz,CDCl3)δ156.7,147.0,139.9,136.5,129.6,129.5,129.1,128.8,127.5,127.2,123.6,122.8,119.0,34.1,23.9.
Example 4
yield: 51 percent.
1H NMR(400MHz,CDCl3)δ8.27(d,J=7.6Hz,2H),8.20(d,J=8.5Hz,1H),7.91(d,J=8.5Hz,1H),7.67(d,J=8.1Hz,1H),7.60-7.51(m,3H),7.49–7.40(m,2H),2.92(s,3H).13CNMR(100MHz,CDCl3)δ155.6,147.0,139.7,137.6,137.2,129.9,129.3,128.8,127.6,127.1,126.1,125.4,118.3,17.9.
Example 5
yield: and 63 percent.
1H NMR(400MHz,CDCl3)δ8.31(d,J=8.7Hz,1H),8.15(d,J=7.6Hz,2H),7.88-7.76(m,2H),7.51(t,J=7.4Hz,2H),7.45(t,J=7.1Hz,1H),7.19(s,1H),2.65(s,3H),2.52(s,3H).13C NMR(100MHz,CDCl3)δ156.8,148.8,139.7,139.6,134.0,133.1,129.2,128.9,128.8,127.5,126.9,124.6,117.8,21.9,18.5.
Example 6
yield: and 47 percent.
1H NMR(400MHz,CDCl3)δ8.25(d,J=8.6Hz,1H),8.16(d,J=7.8Hz,2H),7.95(d,J=8.6Hz,1H),7.86(d,J=7.8Hz,2H),7.83-7.76(m,2H),7.60-7.40(m,7H).13C NMR(100MHz,CDCl3)δ156.0,145.6,140.8,139.5,139.4,137.1,131.2,130.4,129.3,128.8,127.7,127.4,127.2,126.2,118.1.
Example 7
yield: 71 percent.
1H NMR(400MHz,CDCl3)δ8.14(d,J=7.6Hz,2H),8.10(d,J=8.8Hz,2H),7.87(d,J=8.7Hz,1H),7.78(s,1H),7.64(d,J=8.9Hz,1H),7.49(dt,J=14.0,7.6Hz,3H).13C NMR(100MHz,CDCl3)δ157.6,146.6,139.2,135.9,132.0,131.3,130.6,129.6,128.9,127.7,127.6,126.2,119.8.
Example 8
yield: 75 percent.
1H NMR(400MHz,CDCl3)δ8.20-8.11(m,4H),7.85(d,J=8.6Hz,1H),7.73(d,J=8.6Hz,1H),7.54-7.45(m,4H).13C NMR(100MHz,CDCl3)δ158.2,148.6,139.1,136.6,135.5,131.0,129.7,128.9,128.7,127.6,127.3,125.5,119.1.
Example 9
quinoline derivativesBiology:
yield: and 69 percent.
1H NMR(400MHz,CDCl3)δ8.37(s,1H),8.16(t,J=8.5Hz,3H),7.88(d,J=8.5Hz,1H),7.68(d,J=8.6Hz,1H),7.60(d,J=8.6Hz,1H),7.55-7.48(m,3H).13C NMR(100MHz,CDCl3)δ158.2,148.9,139.1,136.7,132.0,129.8,129.7,128.9,128.7,127.6,125.8,123.8,119.3.
Comparative example 1
yield: none.
Comparative example 2
yield: none.