| 90% |
Stage #1: With triethylamine In methanol at 30℃; for 0.166667 h;
Stage #2: at 20℃; for 3.5 h;
Stage #3: With sodium tetrahydroborate In methanol at 5℃; for 2 h; |
In a 2 1 four necked round bottom flask, equipped with mechanical stirrer, thermometer, reflux condenser and under a flow of nitrogen, L-alaninamide hydrochloride (124.6 g, 0.49 mol) and methanol (840 mL) are charged and stirred for 15 min at 20 °C. Triethylamine (49.5 g, 0.49 mol) is added at such a rate that the temperature remains below 30 °C. The mixture is stirred for 10 min, whereupon solid 4-(3-fluorobenzyloxy)benzaldehyde (100 g) , prepared in Es. 10 b), is added portion wise in about 30 min. After stirring for 3 hours at 20 °C, the mixture is cooled to 5 °C and solid NaBIHU (16.4 g, 0.44 mol) is added in ten portion with caution over a period of 1.5 hours. After the end of the addition, the mixture is stirred for 30 min at 5 °C. The mixture is concentrated at reduced pressure to a volume of 100- 150 mL. To the residue, toluene (550 mL) and water (750 mL) are added and the temperature raised to 75 °C. After stirring for 30 min phases are separated and the organic phase is washed with water (140 mL). After phase separation, the organic phase is cooled to 68 °C, seeded and stirred at this temperature for 1 hour. The mixture is cooled to 20 °C in about 2 hours and stirred at this temperature for 2 hours. The solid is isolated by filtration, washed with toluene (2x40 mL) and dried under vacuum to yield 1 18 g of white solid; 90percent yield.The HPLC purity of the obtained product is 99.95 (area percent, see Example 25A) and the content of C,O-dialkylated (S)-2-[3-(3-fluorobenzyl)-4-(3- fluorobenzyloxy)-benzylamino]propanamide is 0.008percent by weight (see Example 25B).The enantiomeric purity of safinamide determined with a chiral HPLC column is 100percent (area percent, see Example 27A).1H-NMR (D2O) (Bruker A V300) δ (ppm, with respect to H2O at 4.7 ppm): <n="63"/>1.43 (3H, d, J = 7 Hz, CH3); 2.66 (3H, s, CH3SO3H); 3.87 (IH, q, J = 7 Hz, H-2); 3.97 (2H, bs, CH2NR); 4.89 (2H, s, CH2OR); 6.88 and 7.23 (4H, AA'XX' aromatic p-disubstituted system,; 6.90 il .11 (4H, aromatic H)13C-NMR (D2O) (Bruker AV300) δ ppm: 15.68 (CH3); 38.27 (CH3SO3H); 48.99 (CH2NR); 54.81 (CH); 69.00 (OCH2); 1 14.15 (d, Jc F = 21 Hz, aromatic CH); 1 14.76 (d, Jc F = 20 Hz, aromatic CH); 1 15.38 (aromatic CH); 123.06 (d, Jc F = 24 Hz, aromatic CH); 123.24; 130.29 (d, Jc F = 6 Hz, aromatic CH); 131.54 (aromatic CH); 138.76 (d, JC F = 7 Hz, aromatic CH); 158.52; 162.89 (d, Jc F = 245 Hz, C-F); 171.92 (CO) |
| 90% |
Stage #1: With triethylamine In methanol at 20 - 25℃; for 1 h;
Stage #2: With hydrogen In methanol at 20 - 35℃; for 5 h; |
EXAMPLE 6 <n="32"/>Preparation of fS)-2-f4-(3-fluorobenzyloxy)benzylamino1propanamide (safinamide, Ia) of high purity degree (one pot reaction)An autoclave is loaded with, 4-(3-fluorobenzyloxy) benzaldehyde (2.0 kg, 8.69 mol) prepared as in Example 4, and then a solution, prepared apart, of L-alaninamide hydrochloride (1.2 kg, 9.63 mol) and triethylamine (0.97 kg, 9.63 mol) in methanol (7.1 kg) is added thereto.The mixture is stirred at 20-25 0C for 1 hour and, after seeding with few grams of (S)-2-[4-(-3-fluorobenzyloxy)benzylideneamino]propanamide, stirring is continued for additional 15 minutes. To the stirred heterogeneous mixture, methanol (1.8 kg) and, wet (50percent H2O) Pt/C 5percent (Engelhard cod. Escat 22 )(0.3 kg) are then added, at 20-250C. The air is purged from the autoclave with nitrogen and then hydrogen is introduced at 5.0 bars. After 5 hours at 30-350C, the mixture is cooled to 15 0C, methanol (4.8 kg) is added and the mixture is heated to 40-45 0C; finally the solid is filtered out and washed with methanol (1.6 kg).The solvent is eliminated under reduced pressure approximately at 30 0C and then a mixture of ethyl acetate (23.0 kg) and water (18.0 kg) is added to the residue. After stirring for 15 minutes, the aqueous phase is separated and extracted with ethyl acetate (7.0 kg). The collected organic phases are concentrated until a residue of approximately 6.0 kg is obtained. To this residue n-heptane (10.8 kg) is added and the mixture is stirred at 20 0C for about 2 hours. The solid is then collected by filtration and washed with n-heptane. After drying the solid under reduced pressure, 2.41 kg (91.8percent yield) of the title compound are obtained with a HPLC purity of 98.4 (area percent, see Example 17A), and a content of C,O-dibenzylated (S)-2-[3-(3-fluorobenzyl)- 4-(3-fluorobenzyloxy)-ben2ylamino]propanamide) of 0.005percent by weight (see Example 17B).
6.2 Preparation of (S)-2-[4-(3-fluorobenzyloxy)benzylamino] propanamide (Ia) of high purity degree by hydroge nation at 1 barA mixture of (S)-2-[4-(2-fluorobenzyloxy)benzaldehyde, L-alaninamide hydrochloride and triethylamine is hydrogenated according to the same procedure of Example 6, but at 1 bar/ H2 instead of 5 bar/ H2. The yield of (S)-2-[4-(3-fluorobenzyloxy)benzylamino]propanamide is 90percent with a HPLC purity of 98.7 (area percent, see Example 17A) and a content of (S)- 2-[3-(3-fluorobenzyl)-4-(3-fluorobenzyloxy)benzylamino]propanamide of0.005percent by weight determined by HPLC (see Example 17B ). |
| 88.5% |
Stage #1: With triethylamine In methanol at 30℃; for 0.166667 h;
Stage #2: at 30℃; for 3.5 h;
Stage #3: With sodium hydroxide; sodium tetrahydroborate In methanol; water at 5℃; for 2 h; |
As an alternative procedure, the reduction is carried out by using a methanolic solution of NaBH4, instead of solid NaBH4. A methanolic solution of NaBH4 is prepared by adding under stirring and under nitrogen at 0 - 5 °C NaBH4 (16.4 g) to a mixture of methanol (12OmL) and NaOH 30percent aqueous solution (5.8mL).In a 2 L four necked round bottomed flask, equipped with mechanical stirrer, thermometer, reflux condenser and under a flow of nitrogen, L- alaninamide hydrochloride (124.6 g, 0.49 mol) and methanol (720 mL) are charged and stirred for 15 min at 20 °C. Triethylamine (49.5 g, 0.49 mol) is added at such a rate that the temperature remains below 30 °C. The mixture is stirred for 10 min, whereupon solid 4-(3-fluorobenzyloxy) benzaldehyde (100 g), prepared in Example 1Ob)), is added portion wise in about 30 min. After stirring for 3 hours at 20 °C, the mixture is cooled to 5 °C and the previously prepared solution of NaBH4 is cautiously added through a dropping funnel over a period of 1.5 hours. After the end of the addition, the mixture is stirred for 30 min at 5 °C. The mixture is concentrated at reduced pressure to a volume of 100- 150 mL. To the residue, toluene (550 mL) and water (750 mL) are added and the temperature raised to 75 °C. After stirring for 30 min phases are separated and the organic phase is washed with water (140 mL). After phase separation, the organic phase is cooled to 68 °C, seeded and stirred at this temperature for 1 hour. The mixture is cooled to 20 °C in about 2 hours <n="64"/>and stirred at this temperature for 2 hours. The solid is isolated by filtration, washed with toluene (2x40 mL), dried at 40°C under vacuum: 116 g of white solid, 88.5percent yield.The HPLC purity of the product is 100.0 percent (area percent, see Example 25A) and the content of C,O-dialkylated (S)-2-[3-(3-fluorobenzyl)-4-(3- fluorobenzyloxy)-benzylamino]propanamide is 0.009percent by weight (see Example 25B).The enantiomeric purity of safinamide determined with a chiral HPLC column is 100percent (area percent, see Example 27A). |
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