Tedatioxetine Revisited

Tedatioxetine chemical name 4- (2- (4-methylphenyl group)) phenylpiperidine by Lundbeck developed for the treatment of severe depression, it is a monoamine reuptake inhibitor, a monoamine reuptake transporter inhibitors, 5-HT3 antagonists and 5-HT2c receptor antagonist. For the treatment of major depressive disorder and generalized anxiety, II clinical study in. Tedatioxetine has the following structure:

According to the literature, the current synthesis routes are the following:

WO 2003/029232 discloses Tedatioxetine first preparation method, as shown in the following Scheme,

The method of low yield, the product is not easy purification by column chromatography requires; more important is the preparation of the compound N-Boc- piperidin-4-ol of the need to use butyl lithium, and reaction was carried out at lower temperatures, not conducive to industrial production.

WO 2009109541 provides a, as shown in the above-described method for improved routes following synthetic route,

Bn- replaced with Boc-, dehydroxylation switch to TFA and Et ₃ of SiH, yield improved despite increased. But there are many shortcomings.Deficiencies mainly reflected in the following aspects: the compound used in the expensive starting 2-bromo benzene iodine source and a catalyst of palladium and a bidentate phosphine ligand 3, an increase of production cost; preparation of compound needed 4:00 butyl lithium reagent to the more dangerous, the need at a low temperature reaction. This will bring in the production of a big security risk, is not conducive to the operation; when dehydroxylation

Preparation of 2- (4-methyl-phenyl mercapto) phenylpiperidine hydrobromide, to use a lot of trifluoroacetate (15eq), post-processing is too much trouble and the environment have a greater pollution.

Given 4- [2- (4-methylphenyl) phenyl] piperidine and salts thereof possess excellent pharmacological properties, and deficiencies of the prior processes, is necessary to develop a suitable industrial production, easy to operate and environmentally friendly preparation process.

2- (4-methyl-phenylthio) benzaldehyde prepared as in Example 1

Direction of Na ₂ CO. ₃ stirred mixture (11g, 105mmol) and 30mlDMF added 4-methyl-thiophenol (12.4g, 100mmol), stirred for 20 minutes. To the mixture was slowly added 2-bromobenzaldehyde (18.4g, 100mmol); a pending completion of the addition, under nitrogen, was heated to 100 deg.] C for 6 hours. After completion of the reaction, the reaction solution was cooled to room temperature, 100ml of water was added and stirred for 30 minutes. Filtered, washed with water (30ml) and dried in vacuo to give the filter cake was washed with 20.5g pale green solid; After n-hexane to give 18.5g pale yellow solid was recrystallized from 2- (4-phenylthio) benzaldehyde (mp: 52- 54 ℃), 81% yield. 2- (4-methyl-phenylthio) benzaldehyde Example 2 Preparation of

To the K ₂ CO. ₃ stirred mixture (15g, 110mmol) and 30mlDMA added 4-methyl-thiophenol (12.6g, 102mmol), stirred for 20 minutes. To the mixture was slowly added 2-chlorobenzaldehyde (14g, 100mmol); a pending completion of the addition, under nitrogen, the reaction was heated to 100 deg.] C for 7 hours. After completion of the reaction, the reaction solution was cooled to room temperature, 100ml of water was added and stirred for 30 minutes. Filtered, washed with water (30ml) and dried in vacuo to give the filter cake was washed with 19.7g pale green solid; After n-hexane to give 17g as a pale yellow solid was recrystallized from 2- (4-phenylthio) benzaldehyde (melting point: 51-53 ℃), a yield of 77.5%

2- (4-methyl-phenylthio) benzaldehyde Example 3 Preparation of

Ask NaOH (4.2g, 105mmol) and stirred 50ml 1,4-dioxane was added 4-methyl-thiophenol (12.4g, 100mmol), stirred for 30 minutes. To the mixture was slowly added 2-iodo-benzaldehyde (23.1g, 100mmol); a pending completion of the addition, under nitrogen, was heated under reflux for 5 hours.After completion of the reaction, the reaction solution was cooled to room temperature, 50ml of water was added, extraction separated; the organic phase was washed with 50ml of ethyl acetate, and the combined organic phases were washed with 20% aqueous ammonium chloride solution and saturated brine, dried over anhydrous magnesium sulfate, filtration and concentration gave 21g viscous liquid, and cooled to solidify; after n-hexane to give 18.1g pale yellow solid was recrystallized from 2- (4-phenylthio) benzaldehyde (m.p.: 53-54 ℃), close rate of 79%.

Example 4 Preparation of 3- [2 (4-methyl) phenyl] pentanedioic acid

1) Preparation of ethyl-2-cyano-3- (2- (4-methyl) phenyl) acrylate

2- (4-methylphenyl thio) benzaldehyde (4g, 17.5mmol), ethyl cyanoacetate (2.4g 21mmol) and toluene (30ml) was added a mixture of glacial acetic acid (5ml) and piperidine (0.3 ml of) stirred for 10 minutes; heated to reflux, and isolating the resulting water trap. Completion of the reaction, cooled to room temperature; the reaction was washed with 30ml water and 30ml saturated sodium bicarbonate solution, dried over anhydrous magnesium sulfate; filtered, and concentrated to give 5.0g yellow liquid (solidifies on cooling), yield 86%. It was used directly in the next reaction without purification.

2) Preparation of Diethyl 2,4-diethyl-3- (2- (4-methyl) phenyl) glutarate

Sodium methoxide (1.9g, 35mmol) and dry THF (30ml) was stirred and cooled to mix 0-5 ℃, was added dropwise diethyl malonate (4.6g, 35mmol), stirred for 15 minutes at room temperature dropwise Bi; dropwise obtained above in step 2-cyano-3- (2- (4-methyl) phenyl) acrylate (5g, 15.4mmol) and dry tetrahydrofuran (40ml) solution; BI dropwise, at room temperature stirred for 13 hours. Completion of the reaction, the reaction mixture was added 150ml20% aqueous ammonium chloride solution, followed by extraction separated; the aqueous phase was extracted with ethyl acetate, the combined organic phase was dried over anhydrous magnesium sulfate; filtered, and concentrated to give 5.4 g of a viscous liquid, yield 78%. It was used directly in the next reaction without purification.

Was added 6N hydrochloric acid (70ml), was heated at reflux for 3 days the material obtained in the above step (5.4 g of); completion of the reaction, slowly cooled to room temperature, added 50ml of ethyl acetate, stirred for 30 minutes to precipitate a solid from the solution, filtered and washed with 20ml washed with ethyl acetate, and dried in vacuo at 50 ℃ 10 hours to give 2.7g of white solid 3- [2 (4-methylphenyl) phenyl] glutaric acid (melting point: 191-195 ℃), in 58% yield.

Example 5 Preparation of 3- [2- (4-phenylthio) phenyl] pentanedioic acid

To ethyl acetoacetate (13g, 100mmol) and piperidine (1.7g, 10mmol) was added a mixture of 2- (4-methyl-phenylthio) benzaldehyde (11.5g, 50mmol), room temperature for 1 day to give a yellow viscous semi-solid, 2.7g of sodium methoxide was added. after stirring for 1 hour cure, stand for 2 days.To the above mixture was added ethanol (180ml) and 40% aqueous sodium hydroxide (140ml) was stirred and heated to reflux for 4-5 hours the reaction. Completion of the reaction the heating was stopped, and after cooling to room temperature, the solvent was distilled off under reduced pressure; the residue after distillation under cooling in an ice water bath, and treated dropwise with concentrated hydrochloric acid (150ml) adjusted to pH 1-2. 300ml ethyl acetate was added, the aqueous phase was extracted with 300ml of ethyl acetate, and the combined organic phases were washed with 300ml water; the organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated to 500ml of the solvent. The residue was cooled to room temperature, stirred for 2 hours. The title compound was isolated by filtration through with ethyl acetate (20ml) and was washed and dried at 50 deg.] C in vacuo overnight to give 21.5g of white solid 3- [2 (4-methylphenyl) phenyl] glutaric acid (melting point: 194-196 ℃) yield 65%.

¹HNMR(DMSO‐d6):δ2.28(S,3H),2.54‐2.65(m,4H),4.09‐4.16(m,1H),7.08‐7.17(m,4H),7.21‐7.26(m,3H),7.39(d,J＝8.1Hz,1H),12.15(s,2H).ESI‐MS(m/z):353.10[M+Na]⁺.

Example 6 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine-2,6-dione

Mixing the compound 3- [2 (4-methyl) phenyl] glutaric acid (10g, 30mmol) and urea (5.4g, 90mmol) prepared in Step stirred and heated to 146 deg.] C for 4 hours ; after completion of the reaction was monitored by TLC, cooled to 80 deg.] C, was slowly added 70ml of water and 70ml of ethanol was stirred for 30 minutes; cooled to room temperature and stirred for 1 hour. The title compound was filtered absolute ethanol (170ml) and recrystallized from 50 deg.] C overnight and dried in vacuo to give 8.0g white solid 4- [2- (4-methylphenyl) phenyl] piperidine-2,6-di -one (mp: 164-166 ℃), yield 86%

¹HNMR(CDCl₃):δ2.33(S,3H),2..86(dd,J＝17.2,4.4Hz,2H),2.69‐2.76 (m,2H),3.99‐4.08(m,1H),7.10‐7.15(m,4H),7.18‐7.30(m,4H),8.78(brs,1H).ESI‐MS(m/z):312.1[M+H]⁺.

7 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine-2,6-dione Example

In four of 250ml equipped with a condenser reaction flask was added 3- [2 (4-methyl) phenyl] glutaric acid (10g, 30mmol) and urea (14.4g, 240mmol) and the mixture was stirred and heated to 146 deg.] C for 4 hours; TLC monitoring completion of the reaction, cooled to 100 deg.] C, was slowly added 70ml of water and 70ml of ethanol was stirred for 30 minutes; cooled to room temperature and stirred for 1 hour. The title compound was filtered absolute ethanol (170ml) and recrystallized from 50 deg.] C overnight and dried in vacuo to give 7.8g white solid 4- [2- (4-methylphenyl) phenyl] piperidine-2,6-di -one (mp: 165-166 ℃), yield 84%.

8 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine-2,6-dione Example

In four of 250ml equipped with a condenser reaction flask was added 3- [2 (4-methyl) phenyl] pentanedioic acid (5g, 15mmol) and urea (1.8g, 30mmol) and the mixture was stirred and heated to 143 deg.] C for 4 hours; cool to 100 deg.] C, was slowly added 35ml of water and 35ml of ethanol was stirred for 30 minutes; cooled to room temperature and stirred for 1 hour. The title compound was filtered absolute ethanol (70ml) and recrystallized from 50 deg.] C overnight and dried in vacuo to give an off-white solid 2.9g of 4- [2- (4-methylphenyl) phenyl] piperidine-2,6-dione (Melting point: 163-166 ℃), a yield of 63%.

9 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine-2,6-dione Example

The compound prepared in the step of 3- [2 (4-methyl) phenyl] glutaric acid (10g, 30mmol) and urea (3.6g, 60mmol) were mixed and stirred and heated to 146 deg.] C for 4 hours ; after completion of the reaction was monitored by TLC, cooled to 80 deg.] C, was slowly added 70ml of water and 70ml of ethanol was stirred for 30 minutes; cooled to room temperature and stirred for 1 hour. The title compound was filtered, absolute ethanol (45 ml of) and recrystallized from 50 deg.] C overnight and dried in vacuo to give 8.0g white solid 4- [2- (4-methylphenyl) phenyl] piperidine-2,6 dione (melting point: 164-166 ℃), yield 86%.

10 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine-2,6-dione Example

A step of preparing the compound 3- [2 (4-methylphenyl) phenyl] glutaric acid (19.8g, 60mmol) and urea (21.6g, 360mmol) were mixed and stirred and heated to 144 deg.] C for 4 hours; after completion of the reaction was monitored by TLC, cooled to 100 deg.] C, slowly added water 140ml 140ml ethanol and stirred for 30 min; cooled to room temperature and stirred for 1 hour. The title compound was filtered, absolute ethanol (350ml) and recrystallized from 50 deg.] C overnight and dried in vacuo to give a white solid 16.5g of 4- [2- (4-methylphenyl) phenyl] piperidine-2,6 dione (melting point: 164-166 ℃), yield 88%.

Example 11 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine

Tetrahydro lithium aluminum (5.1g, 39mmol) with 140ml of tetrahydrofuran were mixed and stirred ice bath cooled to 8 ℃, under nitrogen, was added dropwise 4- (2-mercapto-methylphenyl) piperidine-2,6-phenyl one (7g) in tetrahydrofuran (140ml) solution, so that the temperature does not exceed 20 ℃; dropping was completed, the reaction at room temperature for 5 hours. The reaction solution was cooled in an ice-water bath, was slowly added dropwise 30ml of water, stirred for 20 minutes. The reaction mixture was added sodium sulfate (20g), stirred for 30 minutes. Filtered and the filtrate was concentrated to give a colorless liquid (4.5g), cooled to solidify to a white solid of 4- [2- (4-methylphenyl) phenyl] piperidine.

Example 12 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine

The reaction flask was added 100ml four 1mol / l borane tetrahydrofuran solution (40ml, 40mmol), cooled to ice bath 5 ℃; under nitrogen was added dropwise 4- (2-mercapto-methylphenyl) piperidine-2-phenyl , 6-dione (3.1g) in tetrahydrofuran (40ml) solution, so that the temperature does not exceed 10 ℃; dropping was completed, the reaction at room temperature for 20 hours. The reaction solution was cooled to 0 deg.] C, and slowly added dropwise 1mol / l HCl (30mL), dropwise finished warming at reflux for 5 hours; of THF was removed and concentrated, 30ml of ethyl acetate and washed with an aqueous solution, a saturated aqueous sodium bicarbonate was added to adjust the pH> 10 , followed by addition of 50ml of ethyl acetate, the organic phase was dried, filtered and concentrated to give 1.8g of a colorless liquid, and cooled to solidify to a white solid of 4- [2- (4-methyl) phenyl] piperidine.

Example 13 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine

The a 2 mol / L the BH ₃ .CH ₃ the SCH ₃ (20 mL) and diethylene glycol dimethyl ether 20ml were mixed and stirred ice bath cooled to 10 ℃, solution of 4- (2-mercapto-methyl-phenyl) phenylpiperidine pyridine 2,6-dione (3.1g) in diethylene glycol dimethyl ether (60ml) solution, so that the temperature does not exceed 20 ℃; dropping was completed, the reaction at room temperature 0.5 hours, then slowly heated to 120 deg.] C for 10 hours. The reaction solution was cooled to 0 deg.] C, and slowly added dropwise 30ml of methanol, a dropping was completed, the mixture was stirred overnight at room temperature; was added 4mol / l HCl / EA (10ml ), was heated to 100 deg.] C for 4 hours; the resulting residue was distilled under reduced pressure was dissolved in 30ml water, saturated aqueous sodium bicarbonate was added to adjust the pH> 10, followed by addition of 50ml of ethyl acetate, the organic phase was dried, filtered and concentrated to give a pale red liquid; after column chromatography (hexane – acetic acid – ethanol 10 : 1.5: 0.5) to give a white solid (0.9g) 4- [2- (4- methylphenylsulfanyl) phenyl] piperidine after purification.

14 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine hydrochloride Example

The step resulting 4- [2- (4-methylphenyl) phenyl] piperidine (4g, 14mmol) was added to absolute ethanol (30ml) and heated to 50 deg.] C to dissolve; 4mol slowly added dropwise / l hydrogen chloride – ethyl acetate solution (4ml), 40 minutes with the reaction temperature; cooled to 5-10 ℃ stirred for 2 hours, filtered through a cake when the ethanol (5ml) and washed with 44 ℃ overnight and dried in vacuo to give 3.2 g of white solid 4- [2- (4-methylphenyl) phenyl] piperidine hydrochloride (melting point: 222-225 ℃), 75% yield.

15 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine hydrochloride Example

Example 16 Preparation of 4- [2- (4-methylphenyl) phenyl] piperidine hydrochloride embodiment

Tetrahydro Lithium aluminum (19g, 500mmol) and 200ml of tetrahydrofuran were mixed and stirred at room temperature was added dropwise 4- (2-mercapto-methylphenyl) piperidine-2,6-dione phenyl (31.1g, 100mmol) and tetrahydrofuran ( 200ml) solution, the temperature does not exceed 35 ℃; dropping was completed, the reaction heated under reflux for 3 hours. The reaction solution was cooled in an ice-water bath, was slowly added dropwise 100ml of saturated aqueous sodium sulfate solution, stirred for 60 minutes. The reaction mixture was added ethyl acetate (200ml) and anhydrous magnesium sulphate (50g) was stirred for 60 minutes. Filtered and the filtrate was concentrated to give a colorless liquid. Was added to 80ml of acetone and heated to 40 ℃ dissolved, was added quickly 4mol / l hydrogen chloride – ethyl acetate solution (10ml), seeded, stirred for 20 minutes to precipitate a white solid. 40 ℃, slowly dropping the remaining hydrogen chloride – ethyl acetate solution (20ml). Drop Bi, 5-10 ℃ for 3 hours. The filtered cake in acetone (30ml) and washed with 44 ℃ when dried in vacuo overnight to give 20.8g of white solid 4- [2- (4-methylphenyl) phenyl] piperidine hydrochloride (melting point: 225-228 ℃), yield 66%.

TLC:Rf 0.15(chloroform:methanol＝9:1)；¹HNMR(CDCl₃):δ6.83(d,J＝8.1Hz,1H),6.74(d,J＝1.9Hz,1H),6.68(dd,J＝8.1,1.9Hz,1H),4.75(m,1H),3.68(s,3H),3.36(m,1H),3.31(br,2H),3.02‐2.94(m,2H),2.58‐2.52(m,2H),1.94‐1.39(m,12H).