| 66% |
With chlorosulfonic acid; sodium hydroxide; carbonic acid dimethyl ester; In cyclohexane; at 20 - 72℃; for 1.25h; |
To a 3-necked, round-bottomed flask was added <strong>[4179-19-5]3,5-dimethoxytoluene</strong> (6.088 g, 40 mmol) and cyclohexane (28 mL) under nitrogen. Dimethyl carbonate (30.3 g, 336 mmol) was added and the reaction mixture was heated at 60 C. Excess chlorosulfonic acid was added over a period of 15 min. The liberated HCl gas was removed by inserting a tube into solid sodium hydroxide. On completion of the addition, the reaction mixture was heated to 70-72 C. for 1 h and then cooled to room temperature. The solid was filtered off and washed with dimethyl carbonate/cyclohexane (1:1, 20 mL). The solid was dried in vacuo to obtain pure material (6.13 g, 66%). To a mixture of the sulfonic acid (product from above, 4.65 g, 20 mmol) and triethyl amine (2.03 g, 2.79 mL) in acetone (40 mL) was added 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride, 3.69 g, 20 mmol). The reaction mixture was heated under reflux for 20 h before being cooled to room temperature. The solution was passed through a Celite pad and evaporated in vacuo to leave a solid, which was filtered off and washed with hexane. The mixture of product and salt of cyanuric hydroxide and triethyl amine (7.58 g) was used for the next step without further purification.To a 3-necked, round-bottomed flask, equipped with a condenser (acetone-dry ice cooling), was added the mixture from the step above (7.58 g) and acetone (100 mL). The reaction mixture was cooled to -78 C. and ammonia gas was bubbled through the solution for 0.5 h. The reaction mixture was kept standing overnight, allowing slow evaporation of ammonia gas, followed by the evaporation of solvent. Water was added and the product was extracted with DCM. The solvent was dried and evaporated to leave a mixture of solid and a dense liquid. The solid was filtered off and washed with hexane to leave pure sulfonamide (3.23 g, 70%).To a round-bottomed flask was added 3,5-dimethyl-4-hydroxybenzoic acid (2.99 g, 18 mmol). Anhydrous DMF (20 mL) was added, followed by sodium hydride (1.8 g, 45 mmol). The reaction mixture was stirred at room temperature for 1 h. p-Methoxybenzyl chloride (6.20 g, 39.6 mmol) was added and the mixture was stirred at room temperature overnight (20 h). The reaction mixture was poured into water, acidified with 1 N HCl and stirred for 1 h. The precipitated solid was filtered off, washed with water and hexane to obtain pure B-ring building block (6.93 g, 95%).The B-ring building block (6.93 g, 17.1 mmol) was dissolved in a mixture of methanol (50 mL) and tetrahydrofuran (50 mL). Potassium hydroxide (1.25 g, 22.2 mmol) in water (20 mL) was added. The reaction mixture was refluxed at 70 C. for 24 h. The solvent was evaporated in vacuo. Water was added and the reaction mixture was acidified with 1 N HCl (pH 4-5). The solid was filtered off, washed with water and hexane. The yield was 4.61 g (94%). The product (1.932 g, 6.75 mmol) and the sulfonamide from above (1.04 g, 4.5 mmol) were taken in a 3-necked, round-bottomed flask under nitrogen. Dichloromethane (100 mL) was added with stirring. To this stirred mixture was added N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDCl. HCl, 1.36 g, 7.09 mmol), followed by N,N-dimethylaminopyridine (2.06 g, 16.9 mmol). The reaction mixture was stirred at room temperature for 24 h before being washed with 1 N HCl, 2.5% NaOH and saturated sodium bicarbonate solutions. The organic layers were dried and evaporated in vacuo to leave a residue, which was purified by silica gel (100 g) column chromatography, employing 20-50% ethyl acetate in hexane and 5% methanol in dichloromethane as eluents. Fractions 30-66 were combined to obtain pure materials (1.35 g, 60%). The compound from the step above (0.105 g, 0.21 mmol) was dissolved in tetrahydrofuran under nitrogen and cooled to -78 C. n-Butyllithium was added and the reaction mixture was allowed to warm to room temperature slowly and stirred overnight (14 h). TLC showed incomplete conversion. The reaction mixture was quenched with saturated ammonium chloride solution and extracted with ethyl acetate. The solvent was evaporated in vacuo to leave a residue that was purified by silica gel (15 g) column chromatography, employing 20-50% ethyl acetate in hexane as eluents. The product was not pure enough, so another column was used, employing 0.5% methanol in hexane as eluent, and finally preparative TLC was employed to purify the material. The compound from the step above (0.277 g) was dissolved in trifluoroacetic acid (10 mL) under nitrogen and the reaction mixture was refluxed (bath temperature 80 C.) for 4 d. The solvent was evaporated in vacuo and the residue was dissolved in 0.25 N NaOH (20 mL), and acidified with acetic acid. The solid had precipitated out at this point. The solid was filtered off and washed with water, hexane and dried. From one batch, 0.005 g of pure material was isolated. From another batch, 0.060 g compound was isolated, which was not pure enough. This compound was further purified by preparat... |
| 66% |
|
A 3-necked round bottom flask was added <strong>[4179-19-5]3,5-dimethoxytoluene</strong> (6.088g, 40mmol) and cyclohexane(28mL) under nitrogen.Was added dimethyl carbonate (30.3g,336mmol), at 60 deg.] Cand the reaction mixture was heated. After 15 minutes was added an excess of chlorosulfonic acid. By inserting the tubeof solid sodium hydroxide to remove HCl gas release. After the addition wascomplete, the reaction mixture was heated at 70-72 for one hour, then cooled toroom temperature. The solid was filtered off, washed with dimethyl carbonate /cyclohexane (1:1,20mL)and washed. The solid was dried under vacuum to give pure material (6.13g, 66%). To sulfonic acid (product fromthe above, 4.65g, 20mmol) and triethylamine(2.03g, 2.79mL) was added 2,4,6-trichloro-1,3,5triazine (cyanuric chloride, 3.69g, 20mmol)in (40 mL) in amixture of acetone-.The reaction mixture was heated at reflux for 20 hours, then cooled to room temperature. Thesolution was passed through a pad of Celite, and evaporated in vacuo to leave asolid, which was filtered off, washed with hexane. The product of cyanuric acidand hydroxides (cyanuric hydroxide) in a mixture of salt and triethylamine (was7.58 g) used in the next step without further purification. Fitted to acondenser (acetone - cooled with dry ice), 3-neck round bottom flask was addedthe mixture from step (was 7.58 g) and acetone (100mL). Thereaction mixture was cooled to -78 , ammonia gas intothe solution for 0.5hours. The reaction mixture was allowed to stand overnight, so that theammonia was slowlyevaporated, and then the solvent was evaporated. Water was added, the productwas extracted with DCM. The solvent was dried and evaporated to a mixture ofthe remaining solid and thick liquids. The solid was filtered off, washed withhexane, the remaining pure sulfonamide (3.23g,70%). To a round bottomflask was added 3,5-dimethyl-4-hydroxybenzoicacid (2.99g, 18mmol). Was added anhydrous DMF (20mL), and sodium hydride (1.8g, 45mmol). The reaction mixturewas stirred at roomtemperature for 1hour. Was added p-methoxybenzyl chloride (6.20g,39.6mmol), and the mixture was stirred at room temperature overnight (20 hours). Thereaction mixture was poured into water, acidified with 1N HCl and stirred for 1hour. The precipitated solid was filtered off, washed with water and hexane togive the pure B- cyclic structural unit (6.93g, 95%). The structural unitof the B- ring (6.93g, 17.1mmol) was dissolvedin a mixture of methanol(50mL) and tetrahydrofuran(50 mL) of. Waterwas added (20 mL) of potassium hydroxide (1.25g,22.2mmol). At 70 deg.] Cand the reaction mixture was refluxed for 24 hours. The solvent was evaporated in vacuo.Water was added, the reaction mixture was acidified with 1N HCl (pH4-5). Thesolid was filtered off, washed with water and hexanes. The yield was 4.61g (94%). Under nitrogen,above product (1.932g, 6.75mmol), and sulfonamidefrom above (1.04g, 4.5mmol) was added to a 3-neck round bottom flask. Dichloromethane was addedunder stirring (100mL). To this stirred mixture was addedN-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDCI.HCl, 1.36g, 7.09mmol), followed by addition of N, N- dimethylaminopyridine(2.06g, 16.9mmol). At roomtemperature the reaction mixture was stirred for 24 hours, then washed with 1N HCI, 2.5%NaOH and saturated sodium bicarbonate solution. The organic layer was dried andevaporated in vacuo to leave a residue, which was purified by silica gel (100g)column chromatography using 20-50% hexane in ethyl acetate in methylenechloride and methanol as the eluting 5% purification agent. Fractions 30-66afforded pure material (1.35g, 60%). Under nitrogen,compounds from the previous step(0.105g, 0.21mmol) was dissolved in tetrahydrofuran, cooled to -78 . N-butyllithium was added, and the reaction mixture wasslowly warmed to roomtemperature and stirredovernight (~ 14 hours).TLC showed incomplete conversion. The reaction mixture was quenched withsaturated ammonium chloride solution, extracted with ethyl acetate. The solventwas evaporated in vacuo, the remaining residue, which was purified by silicagel (15g) column chromatography adopt in 20-50% ethyl acetate in hexanes aseluent. Product was not pure enough, thus making use of another pillar, the useof hexane in 0.5% methanol as eluent. Finally, the material was purified bypreparative TLC. Under nitrogen compounds from the previous step(0.277 g of) was dissolved in trifluoroacetic acid (10mL), and the reaction mixture was refluxed (bath temperature 80 ) 4 days. The solvent wasevaporated in vacuo, the residue was dissolvedin 0.25N NaOH (20mL), and acidified with acetic acid. At this time, the solidhas precipitated. The solid was filtered off, washed with water, washed withhexane, and dried. 0.005g of pure substances isolated from the batch. 0.060gcompound isolated from another batch, which is not enough pure. The compoundwas further purified by preparative HPLC, to give pure 6,8-dimethoxy-3-(4-hydroxy-3,5-dimethylphenyl) -2H-1,2- benzothiazine 1,1-... |
| 66% |
With chlorosulfonic acid; carbonic acid dimethyl ester; In cyclohexane; at 60 - 72℃; for 1.25h; |
To a 3-necked, round-bottomed flask was added 3,5- dimbetathoxytoluene (6.088 g, 40 mmol) and cyclohexane (28 mL) under nitrogen. Dimethyl carbonate (30.3 g, 336 mmol) was added and the reaction mixture was heated at 60C. Excess chlorosulfonic acid was added over a period of 15 min. The liberated HCI gas was removed by inserting a tube into solid sodium hydroxide. On completion of the addition, the reaction mixture was heated to 70-72C for 1 h and then cooled to room temperature. The solid was filtered off and washed with dimethyl carbonate/cyclohexane (1:1, 20 mL). The solid was dried in vacuo to obtain pure material (6.13 g, 66%). To a mixture of the sulfonic acid (product from above, 4.65 g, 20 mmol) and tribetathyl amine (2.03 g, 2.79 mL) in acetone (40 mL) was added 2,4,6-trichloro-i ,3,5-triazine (cyanuric chloride, 3.69 g, 20 mmol). The reaction mixture was heated under reflux for 20 h before being cooled to room temperature. The solution was passed through a Celite pad and evaporated in vacuo to leave a solid, which was filtered off and washed with hexane. The mixture of product and salt of cyanuric hydroxide and triethyl amine (7.58 g) was used for the next step without further purification.[0156] To a 3-necked, round-bottomed flask, equipped with a condenser (acetone-dry ice cooling), was added the mixture from the step above (7.58 g) and acetone (100 mL). The reaction mixture was cooled to -78C and ammonia gas <n="93"/>was bubbled through the solution for 0.5 h. The reaction mixture was kept standing overnight, allowing slow evaporation of ammonia gas, followed by the evaporation of solvent. Water was added and the product was extracted with DCM. The solvent was dried and evaporated to leave a mixture of solid and a dense liquid. The solid was filtered off and washed with hexane to leave pure sulfonamide (3.23 g, 70%).[0157] To a round-bottomed flask was added 3.5-dimethyl-4- hydroxybenzoic acid (2.99 g. 18 mmol). Anhydrous DMF (20 rnL) was added, followed by sodium hydride (1.8 g, 45 mmol). The reaction mixture was stirred at room temperature for 1 h. p-Methoxybenzyl chloride (6.20 g, 39.6 mmol) was added and the mixture was stirred at room temperature overnight (-20 h). The reaction mixture was poured into water, acidified with 1 N HCI and stirred for 1 h. The precipitated solid was filtered off, washed with water and hexane to obtain pure B-ring building block (6.93 g, 95%).[0158] The B-ring building block (6.93 g, 17.1 mmol) was dissolved in a mixture of methanol (50 ml) and tetrahydrofuran (50 mL). Potassium hydroxide (1.25 g, 22.2 mmol) in water (20 mL) was added. The reaction mixture was refluxed at 709C for 24 h. The solvent was evaporated in vacuo. Water was added and the reaction mixture was acidified with 1 N HCI (pH 4-5). The solid was filtered off, washed with water and hexane. The yield was 4.61 g (94%). The product (1.932 g, 6.75 mmol) and the sulfonamide from above (1,04 g, 4.5 mmol) were taken in a 3-necked, round-bottomed flask under nitrogen. Dichloromethane (100 mL) was added with stirring. To this stirred mixture was added N-(3- dimethylaminopropyl)-W-ethylcarbOdiimide hydrochloride (EDCI. HCI, 1.36 g,7.09 mmol), followed by lambda/,W-dimethylaminopyridine (2.06 g, 16.9 mmol). The <n="94"/>reaction mixture was stirred at room temperature for 24 h before being washed with 1 N HCI, 2.5% NaOH and saturated sodium bicarbonate solutions. The organic layers were dried and evaporated in vacuo to leave a residue, which was purified by silica gel (100 g) column chromatography, employing 20-50% ethyl acetate in hexane and 5% methanol in dichloromethane as eluents. Fractions 30-66 were combined to obtain pure materials (1.35 g, 60%). The compound from the step above (0.105 g, 0.21 mmol) was dissolved in tetrahydrofuran under nitrogen and cooled to -78C. n-Butyllithium was added and the reaction mixture was allowed to warm to room temperature slowly and stirred overnight (~14 h). TLC showed incomplete conversion. The reaction mixture was quenched with saturated ammonium chloride solution and extracted with ethyl acetate. The solvent was evaporated in vacuo to leave a residue that was purified by silica gel (15 g) column chromatography, employing 20-50% ethyl acetate in hexane as eluents. The product was not pure enough, so another column was used, employing 0.5% methanol in hexane as eluent, and finally preparative TLC was employed to purify the material. The compound from the step above (0.277 g) was dissolved in trifiuoroacetic acid (10 mL) under nitrogen and the reaction mixture was refluxed (bath temperature 809C) for 4 d. The solvent was evaporated in vacuo and the residue was dissolved in 0.25 N NaOH (20 mL), and acidified with acetic acid. The solid had precipitated out at this point. The solid was filtered off and washed with water, hexane and dried. From one batch, 0.005 g of pure material was isolated. From another batch, 0.060 g compound was isolated, which was not pure enough... |
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