1,2-Benzothiazine Schiff base derivatives and preparation methods thereof

Abstract

The present invention belongs to the technical field of heterocyclic compounds, and specifically relates to a 1,2-benzothiazine Schiff base derivative and a preparation method thereof. 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide and hydrazine hydrate are refluxed to obtain 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid hydrazide-1,1-dioxide; 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid hydrazide-1,1-dioxide is reacted with potassium ferrocyanide to obtain 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid hydrazide-1,1-dioxide; 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid hydrazide-1,1-dioxide is refluxed with o-anisidine to obtain 1,2-benzothiazine Schiff base derivative. The present invention has good anti-tumor activity.

Description

Technical Field

[0001] The invention belongs to the technical field of heterocyclic compounds, and specifically relates to a 1,2-benzothiazine Schiff base derivative and a preparation method thereof. Background Art

[0002] Piroxicam, its chemical formula is as follows:

[0003] .

[0004] Piroxicam is a non-steroidal anti-inflammatory drug with a 1,2-benzothiazine ring as its parent nucleus. Piroxicam exerts its pharmacological effects by inhibiting the activity of cyclooxygenase, reducing the synthesis of prostaglandins, inhibiting the chemotaxis of leukocytes and the release of lysosomes. The drug can selectively inhibit the activity of COX-2, and its adverse reactions are mainly gastrointestinal reactions. Food can also reduce the absorption rate of the drug.

[0005] 1,2-Benzothiazines, represented by piroxicam, have good pharmacokinetic properties, such as:

[0006] (1) Oral absorption: Piroxicam is well absorbed after oral administration. Although food can reduce the absorption rate, it does not affect the total amount absorbed.

[0007] (2) Metabolism and excretion: Piroxicam is mainly metabolized by the liver, and its metabolites are mainly piroxicam and 5'-hydroxypiroxicam conjugates with glucuronic acid; 66% of the drug is excreted by the kidneys and 33% by the feces, of which less than 5% is the original form;

[0008] (3) Stability: Due to the long half-life of piroxicam, a single dose can maintain a relatively stable blood concentration for 24 hours.

[0009] One of the current research directions of piroxicam is to modify its structure in order to obtain new functional effects. Summary of the invention

[0010] The purpose of the present invention is to provide a 1,2-benzothiazine Schiff base derivative, which has good anti-tumor activity and has broad research prospects in treating tumors; the present invention also provides a preparation method of the 1,2-benzothiazine Schiff base derivative.

[0011] The 1,2-benzothiazine Schiff base derivative of the present invention has the following structural formula:

[0012] .

[0013] The method for preparing the 1,2-benzothiazine Schiff base derivative of the present invention comprises the following steps:

[0014] (1) In a solvent, 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide and hydrazine hydrate are refluxed to obtain 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid hydrazide-1,1-dioxide;

[0015] (2) in a solvent, 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxyhydrazide-1,1-dioxide reacts with potassium ferrocyanide to obtain 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide;

[0016] (3) In a solvent, 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide is reacted with o-anisidine under reflux to obtain a 1,2-benzothiazine Schiff base derivative.

[0017] In step (1), the solvent is one or more of methanol, ethanol, n-propanol or isopropanol; the ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide to the solvent is 1:4.9-5, wherein 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide is measured in g and the solvent is measured in ml.

[0018] In step (1), the molar ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide to hydrazine hydrate is 1:3-12.

[0019] In step (1), the reflux reaction temperature is 64-83° C., and the reflux reaction time is 8-16 h.

[0020] In step (2), the solvent is a mixture of chloroform and aqueous ammonia, the volume ratio of chloroform to aqueous ammonia is 2-4:1; the ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxyhydrazide-1,1-dioxide to the solvent is 1:12-16, wherein the amount of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxyhydrazide-1,1-dioxide is measured in g and the amount of solvent is measured in mL.

[0021] In step (2), the molar ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxyhydrazide-1,1-dioxide to potassium ferrocyanide is 1:2-3.

[0022] In step (2), the reaction temperature is 18-30°C and the reaction time is 2-4h.

[0023] In step (3), the solvent is a mixture of alcohol and glacial acetic acid, the alcohol is one or more of methanol, ethanol, n-propanol or isopropanol, and the volume ratio of the alcohol to the glacial acetic acid is 60-64:1; the ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide to the solvent is 1:25-26, wherein the 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide is measured in g and the solvent is measured in ml.

[0024] In step (3), the molar ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide to o-anisidine is 1:1-1.5; the reflux reaction temperature is 64-83° C., and the reflux reaction time is 4-8 h.

[0025] The synthetic route of the present invention is as follows:

[0026]

[0027] In the present invention, 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide (piroxicam methyl compound) is reacted with hydrazine hydrate by reflux reaction to obtain 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid hydrazide-1,1-dioxide (piroxicam hydrazide), and then 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid hydrazide-1,1-dioxide is reacted with potassium ferricyanide to obtain 4-hydroxy- 2-Methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide (piroxicam C-3 aldehyde), and finally 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide is reacted with o-anisidine under reflux to obtain 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-(((2-methoxyphenyl)imino)methyl)-1,1-dioxide, i.e., 1,2-benzothiazine Schiff base derivative.

[0028] The anti-inflammatory effect of non-steroidal anti-inflammatory drugs such as arylacetic acid anti-inflammatory drugs and arylpropionic acid anti-inflammatory drugs is related to the acidity of the drug itself. The acidity of arylacetic acid anti-inflammatory drugs and arylpropionic acid anti-inflammatory drugs is provided by the carboxyl group contained in their structure. Piroxicam is also a non-steroidal anti-inflammatory drug. The anti-inflammatory effect of piroxicam is related to the acidity provided by the enol hydroxyl group contained in its 1,2-benzothiazine ring structure. In addition, 1,2-benzothiazine drugs such as piroxicam, meloxicam, isoxicam, tenoxicam, etc., all have anti-inflammatory effects, but the magnitude of the anti-inflammatory effect is different, which is related to the substituent at the 3rd position. The substituent at the 3rd position only affects the strength of the drug activity. The 1,2-benzothiazine ring structure is closely related to the anti-inflammatory effect. The present invention modifies the structure of piroxicam, retains the 1,2-benzothiazine ring structure, and further retains the acidity provided by the enol hydroxyl group at the 4-position of the 1,2-benzothiazine ring structure.

[0029] Inflammation has a tendency to promote tumor development. Inflammation is one of the characteristic reactions of tumors. Reducing the occurrence of inflammation can delay tumor growth to a certain extent. The 1,2-benzothiazine ring in the structure of the present invention has an anti-inflammatory effect, and can thereby delay tumor growth to a certain extent.

[0030] Studies have shown that Schiff base compounds have certain anti-tumor activity. Therefore, the present invention introduces a Schiff base at the C-3 position of the 1,2-benzothiazine ring to make it have better anti-tumor activity.

[0031] The 1,2-benzothiazine ring structure and the Schiff base structure in the present invention can synergistically improve the anti-tumor activity. In addition, the drug with the 1,2-benzothiazine ring structure has good pharmacokinetic properties in vivo. The present invention effectively utilizes the 1,2-benzothiazine ring structure so that the prepared 1,2-benzothiazine Schiff base derivative also has good pharmacokinetic properties in vivo.

[0032] The beneficial effects of the present invention are as follows:

[0033] The present invention introduces an aldehyde group at the C-3 position of the 1,2-benzothiazine ring and then reacts with corresponding amines to obtain a 1,2-benzothiazine Schiff base derivative which has good anti-tumor activity and is expected to be used as an anti-tumor drug, and has broad research prospects in the treatment of tumors. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the H NMR spectrum of piroxicam hydrazide in Example 1.

[0035] Figure 2 It is the H NMR spectrum of piroxicam C-3 aldehyde in Example 1.

[0036] Figure 3This is the H NMR spectrum of the 1,2-benzothiazine Schiff base derivative prepared in Example 1. DETAILED DESCRIPTION

[0037] The present invention is further described below with reference to the embodiments.

[0038] Example 1

[0039] (1) Add 16.230 g of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide, 11 ml of 80% hydrazine hydrate solution and 80 ml of anhydrous ethanol into a 250 ml three-necked flask, heat, and reflux at 78°C for 12 h to obtain a yellow clear solution; evaporate the solvent under reduced pressure to obtain a light yellow viscous substance, add 30 ml of anhydrous ethanol, and heat at 78°C to completely dissolve it; cool naturally, filter, collect the filter cake, and air dry at 50°C to obtain 14.582 g of a yellow solid (piroxicam hydrazide), with a yield of 89.85%; the H NMR spectrum of piroxicam hydrazide is shown in Figure 1 ;

[0040] (2) Add 13.447 g of piroxicam hydrazide, 135 mL of chloroform and 50 mL of ammonia water into a 500 mL three-necked flask, stir evenly, then slowly add a saturated aqueous solution of potassium ferrocyanide (containing 35 g of potassium ferrocyanide), stir at 30 °C for 2 h, and after the reaction is complete, separate the chloroform layer, wash it with water three times, add 30 g of anhydrous sodium sulfate to the chloroform layer, dry it overnight, filter it, and spin dry it to obtain 5.317 g of piroxicam C-3 aldehyde, with a yield of 44.5%; the H NMR spectrum of piroxicam C-3 aldehyde is shown in Figure 2 ;

[0041] (3) In a 100 mL single-mouth bottle, 1.205 g of piroxicam C-3 aldehyde, 0.704 g of o-anisidine, 30 mL of anhydrous ethanol and 0.5 mL of glacial acetic acid were added. The mixture was heated to reflux at 78 °C for 6 h. The reaction was completed by TLC. After the reaction was completed, the mixture was cooled and filtered, washed with anhydrous ethanol and dried to obtain 1.358 g of the target compound 1,2-benzothiazine Schiff base derivative. The yield was 78.32%.

[0042] The H NMR spectrum of 1,2-benzothiazine Schiff base derivatives is shown in Figure 3 , the hydrogen spectrum data are as follows:

[0043] 1 H-NMR (DMSO- d 6 , 400 MHz): 2.834 ( s ,3H,-NCH 3 ), 3.834 ( s , 3H, -OCH 3), 6.858-8.545 ( m , 8H, Ph-H), 9.675 ( s , 1H, -N=CH-), 11.784 (s, 1H, -OH).

[0044] Example 2

[0045] (1) Add 20.212 g of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide, 27.5 ml of 80% hydrazine hydrate solution and 100 ml of methanol into a 250 ml three-necked flask, heat, and reflux at 64°C for 8 h to obtain a yellow clear solution; evaporate the solvent under reduced pressure to obtain a light yellow viscous substance, add 38 ml of anhydrous ethanol, and heat at 78°C to completely dissolve it; cool naturally, filter, collect the filter cake, and air dry at 50°C to obtain 12.247 g of a yellow solid (piroxicam hydrazide) with a yield of 60.59%.

[0046] (2) In a 500-mL three-necked flask, 15.264 g of piroxicam hydrazide, 160 mL of chloroform and 80 mL of aqueous ammonia were added. After stirring evenly, a saturated aqueous solution of potassium ferrocyanide (containing 40 g of potassium ferrocyanide) was slowly added. The mixture was stirred at 25°C for 3 h. After the reaction was completed by TLC, the chloroform layer was separated and washed with water three times. 35 g of anhydrous sodium sulfate was added to the chloroform layer and dried overnight. The layer was filtered and dried by spin drying to obtain 5.643 g of piroxicam C-3 aldehyde with a yield of 41.62%.

[0047] (3) In a 100 mL single-mouth bottle, 1.263 g of piroxicam C-3 aldehyde, 0.65 g of o-anisidine, 32 mL of anhydrous methanol and 0.5 mL of glacial acetic acid were added. The mixture was heated to reflux at 64 °C for 8 h. The reaction was completed by TLC. After the reaction was completed, the mixture was cooled and filtered, washed with anhydrous ethanol and dried to obtain 1.032 g of the target compound 1,2-benzothiazine Schiff base derivative. The yield was 56.77%.

[0048] Example 3

[0049] (1) Add 23.385 g of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide, 52 ml of 80% hydrazine hydrate solution and 115 ml of isopropanol into a 250 ml three-necked flask, heat, and reflux at 83°C for 16 h to obtain a yellow clear solution; evaporate the solvent under reduced pressure to obtain a light yellow viscous substance, add 45 ml of anhydrous ethanol, and heat at 78°C to completely dissolve it; cool naturally, filter, collect the filter cake, and air dry at 50°C to obtain 14.575 g of a yellow solid (piroxicam hydrazide) with a yield of 62.33%.

[0050] (2) Add 17.695 g of piroxicam hydrazide, 180 mL of chloroform and 45 mL of aqueous ammonia to a 500 mL three-necked flask. After stirring evenly, slowly add a saturated aqueous solution of potassium ferrocyanide (containing 46 g of potassium ferrocyanide). Stir and react at 18 °C for 4 h. After the reaction is complete, separate the chloroform layer, wash it with water three times, add 40 g of anhydrous sodium sulfate to the chloroform layer, dry it overnight, filter it, and spin dry it to obtain 6.149 g of piroxicam C-3 aldehyde with a yield of 39.12%.

[0051] (3) In a 100 mL single-mouth bottle, 1.231 g of piroxicam C-3 aldehyde, 0.947 g of o-anisidine, 31 mL of isopropanol and 0.5 mL of glacial acetic acid were added and refluxed at 83 °C for 4 h. The reaction was completed by TLC. After the reaction was completed, the mixture was cooled and filtered, washed with anhydrous ethanol and dried to obtain 1.084 g of the target compound 1,2-benzothiazine Schiff base derivative in a yield of 61.17%.

[0052] The anti-tumor activity test method is as follows:

[0053] Human pancreatic cancer cells Capan-1, human liver cancer cells SMMC-7721 and mouse leukemia cells L1210 in the logarithmic growth phase were inoculated in a 96-well plate (90 µL culture medium / well) at a cell number of 8000 cells / well. After culturing for 24 hours, 6 wells were divided into a blank control group, a normal group, an experimental group, a positive control group, a piroxicam methyl group, a piroxicam hydrazide group and a piroxicam C-3 aldehyde group; the culture medium was added to the blank control group, and the amount of the culture medium added was 10 µL / well; DMSO was added to the normal group, and the amount of DMSO added was 10 µL / well; different concentrations (12.5 µM, 25 µM, 50 µM, 100 µM, 200 µM, 500 µM) of aqueous solutions of 1,2-benzothiazine Schiff base derivatives prepared in Example 1 were added to the 6 wells of the experimental group, and the amount of the aqueous solution of 1,2-benzothiazine Schiff base derivatives added was 1 0µL / well; in the reference experimental group, the aqueous solution of 1,2-benzothiazine Schiff base derivatives was replaced by doxorubicin aqueous solution as the positive control group; in the reference experimental group, the aqueous solution of 1,2-benzothiazine Schiff base derivatives was replaced by piroxicam methyl aqueous solution as the piroxicam methyl group; in the reference experimental group, the aqueous solution of 1,2-benzothiazine Schiff base derivatives was replaced by piroxicam hydrazide aqueous solution as the piroxicam hydrazide group; in the reference experimental group, the aqueous solution of 1,2-benzothiazine Schiff base derivatives was replaced by piroxicam C-3 aldehyde aqueous solution as the piroxicam C-3 aldehyde group; after 48h of culture, 1mg / mL MTT solution was added; after continuing to culture for 4h, the supernatant was discarded, 100µL DMSO was added to each well, shaken for 15min to dissolve, and the OD value was detected at 570nm with an enzyme reader. The cell inhibition rate was calculated according to the following formula, and the experiment was repeated three times. The calculation method of cell proliferation inhibition rate is as follows:

[0054] .

[0055] Obtain OD by experiment 570 The corresponding cell inhibition rate was calculated using the SPSS 20.0 software, and then the IC of 1,2-benzothiazine Schiff base derivatives against L1210, Capan-1 and SMMC-7721 cell lines was calculated. 50 The results are shown in Table 1.

[0056] .

[0057] As shown in Table 1, the IC values ​​of the 1,2-benzothiazine Schiff base derivatives prepared by the present invention are 50 IC value of the anticancer drug doxorubicin 50The values ​​are similar, indicating that the 1,2-benzothiazine Schiff base derivatives prepared by introducing a Schiff base structure at the C-3 position of the 1,2-benzothiazine ring in the present invention exhibit an inhibitory effect on the growth of L1210, Capan-1 and SMMC-7721 cells and have good anti-tumor activity.

Claims

1. A 1,2-benzothiazine Schiff base derivative, characterized in that The structural formula is as follows: 。 2. A method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 1, characterized in that The steps include: (1) In a solvent, 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide and hydrazine hydrate are refluxed to obtain 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid hydrazide-1,1-dioxide; (2) in a solvent, 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxyhydrazide-1,1-dioxide reacts with potassium ferrocyanide to obtain 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide; (3) In a solvent, 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide is reacted with o-anisidine under reflux to obtain a 1,2-benzothiazine Schiff base derivative.

3. The method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 2, characterized in that In step (1), the solvent is one or more of methanol, ethanol, n-propanol or isopropanol; the ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide to the solvent is 1:4.9-5, wherein 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide is measured in g and the solvent is measured in ml.

4. The method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 2, characterized in that In step (1), the molar ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylic acid methyl ester-1,1-dioxide to hydrazine hydrate is 1:3-12.

5. The method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 2, characterized in that In step (1), the reflux reaction temperature is 64-83° C., and the reflux reaction time is 8-16 h.

6. The method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 2, characterized in that In step (2), the solvent is a mixture of chloroform and aqueous ammonia, the volume ratio of chloroform to aqueous ammonia is 2-4:1; the ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxyhydrazide-1,1-dioxide to the solvent is 1:12-16, wherein the amount of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxyhydrazide-1,1-dioxide is measured in g and the amount of solvent is measured in mL.

7. The method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 2, characterized in that In step (2), the molar ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxyhydrazide-1,1-dioxide to potassium ferrocyanide is 1:2-3.

8. The method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 2, characterized in that In step (2), the reaction temperature is 18-30°C and the reaction time is 2-4h.

9. The method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 2, characterized in that In step (3), the solvent is a mixture of alcohol and glacial acetic acid, the alcohol is one or more of methanol, ethanol, n-propanol or isopropanol, and the volume ratio of the alcohol to the glacial acetic acid is 60-64:1; the ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide to the solvent is 1:25-26, wherein the 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide is measured in g and the solvent is measured in ml.

10. The method for preparing the 1,2-benzothiazine Schiff base derivative according to claim 2, characterized in that In step (3), the molar ratio of 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxaldehyde-1,1-dioxide to o-anisidine is 1:1-1.5; the reflux reaction temperature is 64-83° C., and the reflux reaction time is 4-8 h.

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