Reaction #84029

Reaction equation

2-(3-ethoxy-4-methoxyphenyl)-1-(methylsulphonyl)-eth-2-ylamine

N-acetyl-L-leucine

→

(S)-2-(3-ethoxy-4-methoxyphenyl)-1-(methylsulphonyl)-eth-2-ylamine-N-acetyl-L-leucine salt

Yield 90.0%

Solvents

methanol

methanol

Conditions

Workup

1. 1
   OtherA 3 L 3-necked round bottom flask was equipped with a mechanical stirrer
2. 2
   TemperatureThe stirred slurry was heated
3. 3
   Temperatureto reflux for 1 hour
4. 4
   FiltrationThe slurry was filtered
5. 5
   Washwashed with methanol (250 L)
6. 6
   OtherThe solid was air-dried
7. 7
   Otherdried in vacuo at ambient temperature to a constant weight
8. 8
   Othergiving 109.5 g (98% yield) of the crude product (85.8% ee)
9. 9
   Temperatureto reflux for 1 hour
10. 10
    Temperaturecooled to room temperature
11. 11
    workup.STIRRINGstirred for an additional 3 hours at ambient temperature
12. 12
    FiltrationThe slurry was filtered
13. 13
    Washthe filter cake was washed with methanol (200 mL)
14. 14
    OtherThe solid was air-dried
15. 15
    Otherdried in vacuo at 30° C. to a constant weight

Procedure

A 3 L 3-necked round bottom flask was equipped with a mechanical stirrer, thermometer, and condenser and charged with 2-(3-ethoxy-4-methoxyphenyl)-1-(methylsulphonyl)-eth-2-ylamine (137.0 g, 500 mmol), N-acetyl-L-leucine (52 g, 300 mmol), and methanol (1.0 L). The stirred slurry was heated to reflux for 1 hour. The stirred mixture was allowed to cool to ambient temperature and stirring was continued for another 3 hours at ambient temperature. The slurry was filtered and washed with methanol (250 L). The solid was air-dried and then dried in vacuo at ambient temperature to a constant weight, giving 109.5 g (98% yield) of the crude product (85.8% ee). The crude solid (55.0 g) and methanol (440 mL) were brought to reflux for 1 hour, cooled to room temperature and stirred for an additional 3 hours at ambient temperature. The slurry was filtered and the filter cake was washed with methanol (200 mL). The solid was air-dried and then dried in vacuo at 30° C. to a constant weight, yielding 49.6 g (90% recovery) of (S)-2-(3-ethoxy-4-methoxyphenyl)-1-(methylsulphonyl)-eth-2-ylamine-N-acetyl-L-leucine salt (98.4% ee). Chiral HPLC (1/99 EtOH/20 mM KH2PO4 @pH 7.0, Ultron Chiral ES-OVS from Agilent Technologies, 150 mm×4.6 mm, 0.5 mL/min., @240 nm): 18.4 min (S-isomer, 99.2%), 25.5 min (R-isomer, 0.8%).

Source