Reaktion #1558828

Reaktionsgleichung

NH4Cl

1-bromo-3-(bromomethyl)-5-fluorobenzene

(R)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine

n-BuLi

→

(2S,5R)-2-(3-bromo-5-fluorobenzyl)-5-isopropyl-3,6-dimethoxy-2,5-dihydropyrazine

Ausbeute 85.4%

Lösungsmittel

H2O

EtOAc

THF

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturto warm to ambient temperature
2. 2
   workup.STIRRINGAfter stirring for 16 h
3. 3
   SonstigeThe THF was removed in vacuo
4. 4
   Sonstigethe remaining organics were separated
5. 5
   Trocknendried over sodium sulfate
6. 6
   SonstigeAfter removal of solvent
7. 7
   Sonstigethe crude product was purified by silica gel chromatography

Vorschrift

To (R)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine (2 mL, 11.03 mmol) in THF (90 mL) at −78° C. was added n-BuLi (1.6 M in hexanes solution, 7.5 mL, 12 mmol). After stirring for 30 min, 1-bromo-3-(bromomethyl)-5-fluorobenzene (2.68 g, 10 mmol) in THF (10 mL) was added dropwise over 30 min. The temperature was maintained at −78° C. for 30 min then allowed to warm to ambient temperature. After stirring for 16 h, saturated aqueous NH4Cl (30 mL) was added followed by dilution with EtOAc and H2O. The THF was removed in vacuo and the remaining organics were separated and dried over sodium sulfate. After removal of solvent, the crude product was purified by silica gel chromatography to provide (2S,5R)-2-(3-bromo-5-fluorobenzyl)-5-isopropyl-3,6-dimethoxy-2,5-dihydropyrazine (3.17 g, 77%). MS (m/z) 371 [M+H]+.

Quelle