Disclosure of Invention
The invention aims to provide a method for synthesizing a chiral 4- (2-propargyl) phenol compound by copper-catalyzed electron-rich phenol compound and propargyl compound through asymmetric propargyl Friedel-crafts reaction. The method has the characteristics of easily obtained raw materials, simple operation, high enantioselectivity and the like.
The invention provides a method for preparing chiral 4- (2-propargyl) phenol compounds, which is characterized in that under the existence of an alkali additive, a chiral copper catalyst catalyzes an electron-rich phenol compound and a propargyl compound to synthesize the compounds through an asymmetric propargyl Friedel-crafts reaction in a reaction medium, and the method comprises the following specific steps:
(1) preparation of chiral copper catalyst: under the protection of nitrogen, copper salt and P, N, N-ligand are stirred in a reaction medium for 0.5 to 2 hours according to the molar ratio of 1:0.1 to 10 to prepare a chiral copper catalyst;
(2) preparation of chiral 4- (2-propargyl) phenol compound: dissolving an electron-rich phenol compound, a propargyl compound and an alkali additive in a reaction medium, and then adding the solution into the stirred solution of the chiral copper catalyst under the protection of nitrogen, and stirring and reacting for 1-12 hours at the temperature of-20 ℃; after the reaction is finished, performing reduced pressure rotary evaporation and column separation to obtain a chiral para-propargyl phenol compound;
the molar ratio of the chiral copper catalyst to the propargyl compound is 0.001-1: 1;
the molar ratio of the alkali additive to the propargyl compound is 0.5-10: 1;
the molar ratio of the electron-rich phenol compound to the propargyl compound is 1-2: 1.
the reaction medium is at least one of methanol, ethanol, toluene, xylene, dichloromethane, dichloroethane, diethyl ether, tetrahydrofuran and ethyl acetate.
The chiral 4- (2-propargyl) phenol compound has one of the following structures:
i and II are enantiomers of each other, wherein: r1、R2Is C1-C40 alkyl, C3-C12 cycloalkyl or C3-C12 cycloalkyl with substituent, phenyl and substituted phenyl, benzyl and substituted benzyl, five-membered or six-membered heterocyclic aromatic group or ester group containing one or more than two oxygen, sulfur and nitrogen atoms; the substituent of the C3-C12 naphthenic base, the substituent of the phenyl or the substituent of the benzyl is C1-C40 alkyl, C1-C40 alkoxy, halogen, nitro, ester group or cyano respectively.
The phenolic compound has the following structure:
in the formula: r1Is the same as R in the structural formula I, II1The same groups.
The propargyl compound has the following structure:
in the formula: r2Is represented by the structural formula R in I, II2The same group; x is fluorine, chlorine, bromine, iodine, alkyl carboxylate, alkyl carbonate, alkyl sulfonate, alkyl phosphate, phenyl and substituted phenyl carboxylate, phenyl and substituted phenyl carbonate, phenyl and substituted phenyl sulfonate or phenyl and substituted phenyl phosphate.
The copper salt is hydrated copper acetate, hydrated copper sulfate, anhydrous copper acetate, anhydrous copper sulfate, copper triflate, copper chloride, cuprous acetate, cuprous chloride, cuprous iodide, cuprous perchlorate, copper triflate, Cu (CH)3CN)4BF4、Cu(CH3CN)4ClO4At least one of (1). Preferably hydrated copper acetate, trifluomethane sulfonate, Cu (CH)3CN)4BF4、Cu(CH3CN)4ClO4At least one of (1).
The structural formula of the chiral P, N, N-ligand is as follows:
in the formula: r3,R4Is alkyl in H, C1-C10, cycloalkyl in C3-C8, phenyl and substituted phenyl or benzyl and substituted benzyl;
R5,R6is H, halogen, alkyl and cycloalkyl, phenyl and substituted phenyl, alkoxy, phenoxy, acyl or nitro;
R7is alkyl, cycloalkyl, phenyl and substituted phenyl, naphthyl and substituted naphthyl or a five-membered or six-membered heterocyclic aromatic group containing one or more oxygen, sulfur and nitrogen atoms.
The base additive is various inorganic bases or organic bases, preferably N, N-diisopropylethylamine, triethylamine, DBU, K3PO4、K2CO3、Cs2CO3、Na2CO3Or NaHCO3。
The catalytic reaction conditions in the step (2) are preferably as follows: the temperature is-20 ℃; the reaction medium is methanol; the pressure is normal pressure; the time period required was 12 hours.
The molar ratio of the chiral copper catalyst to the propargyl compound is preferably 0.01-0.1: 1;
the molar ratio of the alkali additive to the propargyl compound is preferably 1.2: 1;
the molar ratio of the phenol compound to the propargyl compound is preferably 1.2: 1.
The reaction equation of the invention is as follows:
the invention has the following advantages:
1. the starting materials are cheap and easy to obtain.
2. The chiral ligand is simple and convenient to synthesize, the catalyst is cheap and easy to obtain, and the dosage is small.
3. Good reaction activity and high stereoselectivity.
4. The method can conveniently synthesize various substituted chiral 4- (2-propargyl) phenol compounds by using an asymmetric catalysis method for the first time.
Detailed Description
The following examples further illustrate the invention but are not intended to limit the invention thereto. NMR was measured by Bruker400M NMR spectrometer and High Performance Liquid Chromatography (HPLC) was measured by Agilent 1100 series high performance liquid chromatography.
Example 1
Cu(OAc)2.H2And catalyzing and reacting the O and the L-2-1 serving as catalysts to generate a product (S) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol I-1.
Adding Cu (OAc)2.H2O (0.015mmol, 5 mol%) and chiral ligand L-2-1(0.0165mmol, 5.5 mol%), adding 1.0 ml of anhydrous methanol under the protection of nitrogen, and stirring at room temperature for 1 hour. Mixing propargyl alcohol ester IV-1 (0.3mmol, 1equiv),3, 5-dimethylOxyphenol III-1 (0.36mmol, 1.2equiv) and N, N-diisopropylethylamine (0.36mmol, 1.2equiv) were dissolved in 2.0 ml of anhydrous methanol, and the solution was added to the stirred solution of the catalyst under nitrogen protection, and the reaction was stirred at room temperature for 12 hours. After the reaction was completed, the reaction mixture was rotary-distilled under reduced pressure to about 0.5 ml, separated by silica gel column (petroleum ether/ethyl acetate: 5:1), concentrated under reduced pressure, and dried in vacuo to give compound i-1 as a pale yellow oil in 82% yield and 87% ee.
The hydrogen nuclear magnetic resonance spectrum and the carbon nuclear magnetic resonance spectrum of (S) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol I-1 are respectively shown in the following figures 1 and 2:
1H NMR(400MHz,DMSO):δ9.53(s,1H),7.34(d,J=7.6Hz,2H),7.26(d,J=7.5Hz,2H),7.15(t,J=7.1Hz,1H),6.10(s,2H),5.50(s,1H),3.66(s,6H),2.97(d,J=0.7Hz,1H).13C NMR(101MHz,DMSO):δ158.8,158.5,141.4,128.2,127.4,126.3,108.3,93.0,85.0,71.8,56.0,30.5.HPLC(Chiralcel AD-H,n-hexane/i-PrOH=70/30,0.8ml/min,230nm,40℃):tR(major)=8.7min,tR(minor)=10.0min。
the structural formula of III-1, IV-1, I-1, L-2-1 is as follows:
example 2
L-2-2 is used as a ligand to prepare (S) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol I-1.
The ligand L-2-1 in example 1 was replaced with ligand L-2-2, and the procedure was otherwise the same as in example 1. The reaction gave compound II-2 in 51% yield and 62% ee.
The structural formula of L-2-2 is as follows:
example 3
L-2-3 is used as a ligand to prepare (R) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol II-1.
The ligand L-2-1 in example 1 was replaced with ligand L-2-3, and the procedure was otherwise the same as in example 1. The reaction gave compound II-1 in 22% yield and 52% ee.
The structural formula of L-2-3, II-1 is as follows:
example 4
NEt3(S) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol I-1 was prepared as a base.
The base N, N-diisopropylethylamine from example 1 was used with NEt3Instead, the rest is the same as example 1. The reaction gave compound I-1 in 55% yield and 87% ee.
Example 5
K2CO3(S) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol I-1 was prepared as a base.
The base N, N-diisopropylethylamine from example 1 was substituted with K2CO3Instead, the rest is the same as example 1. The reaction gave compound I-1 in 93% yield and 87% ee.
Example 6
Cu(OTf)2And L-2-1 is used as a catalyst to catalyze and react to generate a product (S) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol I-1.
Cu (OAc) in example 52·H2Replacement of O by Cu (OTf)2. The remainder of the procedure is as in example 5 to give compound I-1 in 84% yield and 88% ee.
Example 7
Cu(OTf)·1/2C6H6And L-2-1 is used as a catalyst to catalyze and react to generate a product (S) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol I-1.
Cu (OAc) in example 52·H2Replacement of O by Cu (OTf) 1/2C6H6. The remainder of the procedure is as in example 5 to give compound I-1 in 67% yield and 85% ee.
Example 8
The reaction at-20 ℃ produces the product (S) -3, 5-dimethoxy-4- (1-phenyl-2-propargyl) phenol I-1.
The reaction temperature in example 6 was changed to-20 ℃. The remainder of the procedure is as in example 6 to give compound I-1 in 96% yield and 93% ee.
Example 9
Propargyl alcohol ester IV-2 is used as a substrate to react to generate a product (S) -3, 5-dimethoxy-4- (1-p-chlorophenyl-2-propargyl) -phenol I-2.
The procedure in example 8 was repeated except for substituting propargyl alcohol ester IV-1 in example 8 with IV-2 to give the compound (S) -3, 5-dimethoxy-4- (1-p-chlorophenyl-2-propargyl) -phenoxide I-2 in 88% yield and 92% ee.
The hydrogen nuclear magnetic resonance spectrum and the carbon nuclear magnetic resonance spectrum of (S) -3, 5-dimethoxy-4- (1-p-chlorophenyl-2-propargyl) -phenol I-2 are respectively shown in the following figures 3 and 4:
1H NMR(400MHz,DMSO):δ9.56(s,1H),7.31(s,4H),6.10(s,2H),5.47(s,1H),3.66(s,6H),3.04(s,1H).13C NMR(101MHz,DMSO):δ159.0,158.4,140.4,130.9,129.2,128.2,107.8,93.0,84.5,72.3,56.0,30.0.HPLC(Chiralcel AD-H,n-hexane/i-PrOH=85/15,0.8ml/min,230nm,40℃):tR(major)=13.8min,tR(minor)=15.2min。
the structural formula of IV-2 and I-2 is as follows:
example 10
Propargyl alcohol ester IV-3 is used as a substrate to react to generate a product (S) -3, 5-dimethoxy-4- (1-p-fluorophenyl-2-propargyl) -phenol I-3.
The procedure in example 8 was repeated except for substituting propargyl alcohol ester IV-1 in example 8 with IV-3 to give the compound (S) -3, 5-dimethoxy-4- (1-p-fluorophenyl-2-propargyl) -phenoxide I-3 in 90% yield and 90% ee.
The hydrogen nuclear magnetic resonance spectrum and the carbon nuclear magnetic resonance spectrum of the product (S) -3, 5-dimethoxy-4- (1-p-fluorophenyl-2-propargyl) -phenol I-3 are respectively shown in the following figures 5 and 6:
1H NMR(400MHz,DMSO):δ9.54(s,1H),7.33(s,2H),7.08(d,J=8.9Hz,2H),6.09(s,2H),5.46(s,1H),3.66(s,6H),3.01(d,J=2.3Hz,1H).13C NMR(101MHz,DMSO):δ161.0(d,J=241.7Hz),158.8,158.4,137.5(d,J=2.9Hz),129.1(d,J=8.1Hz),115.0,114.8,108.1,93.0,84.8,72.1,56.0,29.9.HPLC(Chiralcel AD-H,n-hexane/i-PrOH=90/10,0.8ml/min,230nm,40℃):tR(major)=20.1min,tR(minor)=21.8min。
the structural formula of IV-3 and I-3 is as follows:
example 11
Propargyl alcohol ester IV-4 is used as a substrate to react to generate a product (S) -3, 5-dimethoxy-4- (1-p-methoxyphenyl-2-propargyl) -phenol I-4.
The procedure in example 8 was repeated except for substituting propargyl alcohol ester IV-1 in example 8 with IV-4 to give the compound (S) -3, 5-dimethoxy-4- (1-p-methoxyphenyl-2-propargyl) -phenoi-4 in 89% yield and 97% ee.
The hydrogen nuclear magnetic resonance spectrum and the carbon nuclear magnetic resonance spectrum of (S) -3, 5-dimethoxy-4- (1-p-methoxyphenyl-2-propargyl) -phenol I-4 are respectively shown in the following figures 7 and 8:
1H NMR(400MHz,DMSO):δ9.50(s,1H),7.24(d,J=8.3Hz,2H),6.81(d,J=8.5Hz,2H),6.09(s,2H),5.43(s,1H),3.68(d,J=12.1Hz,9H),2.94(d,J=1.7Hz,1H).13C NMR(101MHz,DMSO):δ158.6,158.4,157.9,133.3,128.4,113.6,108.6,93.0,85.4,71.5,56.0,55.4,29.7.HPLC(Chiralcel AD-H,n-hexane/i-PrOH=80/20,0.8ml/min,230nm,40℃):tR(minor)=20.7min,tR(major)=26.3min。
the structural formula of IV-4 and I-4 is as follows:
example 12
Propargyl alcohol ester IV-5 is used as a substrate to react to generate a product (S) -3, 5-dimethoxy-4- (1-naphthyl-2-propargyl) -phenol I-5.
The procedure in example 8 was repeated except for substituting propargyl alcohol ester IV-1 in example 8 with IV-5 to give the compound (S) -3, 5-dimethoxy-4- (1-naphthyl-2-propargyl) -phenoxide I-5 in 84% yield and 93% ee.
The hydrogen nuclear magnetic resonance spectrum and the carbon nuclear magnetic resonance spectrum of the product (S) -3, 5-dimethoxy-4- (1-naphthyl-2-propargyl) -phenol I-5 are respectively shown in the following figures 9 and 10:
1H NMR(400MHz,DMSO):δ9.56(s,1H),8.05–7.73(m,4H),7.44(dd,J=13.4,7.1Hz,3H),6.12(s,2H),5.67(s,1H),3.67(s,6H),3.10(d,J=2.5Hz,1H).13C NMR(101MHz,DMSO)δ158.9,158.6,139.0,133.2,132.1,128.0,127.8,127.7,126.5,126.4,125.8,125.3,108.1,93.0,84.9,72.4,56.1,30.7.HPLC(Chiralcel AD-H,n-hexane/i-PrOH=80/20,0.8ml/min,230nm,40℃):tR(major)=8.8min,tR(minor)=10.1min。
the structural formula of IV-5 and I-5 is as follows:
example 13
Propargyl alcohol ester IV-6 is used as a substrate to react to generate a product (S) -3, 5-dimethoxy-4- (1-o-chlorophenyl-2-propargyl) -phenol I-6.
The procedure in example 8 was repeated except for substituting propargyl alcohol ester IV-1 in example 8 with IV-6 to give the compound (S) -3, 5-dimethoxy-4- (1-o-chlorophenyl-2-propargyl) -phenoi-6 in 86% yield and 76% ee.
The hydrogen nuclear magnetic resonance spectrum and the carbon nuclear magnetic resonance spectrum of the product (S) -3, 5-dimethoxy-4- (1-o-chlorophenyl-2-propargyl) -phenol I-6 are respectively shown in the following figures 11 and 12:
1H NMR(400MHz,DMSO):δ9.53(d,J=4.6Hz,1H),7.86(d,J=6.6Hz,1H),7.31(t,J=7.9Hz,2H),7.22(d,J=7.6Hz,1H),6.06(d,J=6.8Hz,2H),5.62(dd,J=8.4,2.4Hz,1H),3.62(d,J=2.8Hz,6H),3.05(d,J=2.7Hz,1H).13C NMR(101MHz,DMSO):δ159.0,158.8,138.2,132.5,131.8,129.4,128.5,126.5,106.3,93.0,84.4,72.4,55.9,29.6.HPLC(Chiralcel AD-H,n-hexane/i-PrOH=80/20,0.8ml/min,230nm,40℃):tR(major)=8.7min,tR(minor)=10.3min。
the structural formula of IV-6 and I-6 is as follows:
example 14
Propargyl alcohol ester IV-7 is used as a substrate to react to generate a product (S) -3, 5-dimethoxy-4- (1-p-methylphenyl-2-propargyl) -phenol I-7.
The procedure in example 8 was repeated except for substituting propargyl alcohol ester IV-1 in example 8 with IV-7 to give the compound (S) -3, 5-dimethoxy-4- (1-p-methylphenyl-2-propargyl) -phenoi-7 in 90% yield and 93% ee.
The hydrogen nuclear magnetic resonance spectrum and the carbon nuclear magnetic resonance spectrum of the product (S) -3, 5-dimethoxy-4- (1-p-methylphenyl-2-propargyl) -phenol I-7 are respectively shown in the following figures 13 and 14:
1H NMR(400MHz,DMSO):δ9.50(s,1H),7.20(d,J=8.0Hz,2H),7.04(d,J=8.0Hz,2H),6.08(s,2H),5.43(d,J=2.1Hz,1H),3.65(s,6H),2.95(d,J=2.7Hz,1H),2.24(s,3H).13C NMR(101MHz,DMSO):δ158.6,158.4,138.3,135.2,128.8,127.3,108.4,92.9,85.2,71.7,56.0,30.1,21.0.HPLC(Chiralcel AD-H,n-hexane/i-PrOH=90/10,0.8ml/min,230nm,40℃):tR(major)=17.4min,tR(minor)=18.9min。
the structural formulas of IV-7 and I-7 are as follows:
examples 15 to 25
Reaction substrate suitability
The method has wide substrate applicability, and a plurality of substrates can participate in the reaction according to the reaction conditions in the example 8, so that the chiral 4- (1-phenyl-2-propargyl) -phenol compound can be obtained with high yield and high stereoselectivity, and the reaction formula is as follows:
in examples 15 to 25, when R is1And R2Respectively, and the yields and enantiomeric excess values thereof are shown in table 1.
TABLE 1
The invention can conveniently synthesize various chiral 4- (2-propargyl) phenol compounds with substituent groups, and the enantiomeric excess percentage of the chiral 4- (2-propargyl) phenol compounds is as high as 95%. The method has the characteristics of simple operation, easily obtained raw materials, wide application range of the substrate, high enantioselectivity and the like.