Reaktion #1108769

Reaktionsgleichung

2-bromo-4-chloropyridine

lithium diisopropyl-amide

DMF

→

103a

Ausbeute 51.0%

2-Bromo-4-chloronicotinaldehyde

Ausbeute 51.0%

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGthe mixture was stirred for another 30 minutes
2. 2
   SonstigeIt was then quenched with saturated NH4Cl (30 mL)
3. 3
   Extraktionextracted with ethyl acetate (20 mL×3)
4. 4
   TrocknenThe combined organic layer was dried over anhydrous Mg2SO4
5. 5
   Filtrationfiltered
6. 6
   Sonstigeevaporated under reduced pressure
7. 7
   SonstigeThe residue was purified by silica-gel column chromatography
8. 8
   Wascheneluting with petroleum ether/ethyl acetate (20:1)

Vorschrift

To a solution of 2-bromo-4-chloropyridine (1.6 g, 8.0 mmol) in anhydrous tetrahydrofuran (40 mL) cooled at −70° C. was added the solution of lithium diisopropyl-amide (5.0 mL, 10.0 mmol, 2.0 M) over a period of 5 minutes and stirred at −70° C. for another 1 h. Anhydrous DMF (1.3 g) was introduced over a period of 3 minutes and the mixture was stirred for another 30 minutes. It was then quenched with saturated NH4Cl (30 mL) and extracted with ethyl acetate (20 mL×3). The combined organic layer was dried over anhydrous Mg2SO4, filtered, and evaporated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with petroleum ether/ethyl acetate (20:1) to afford 103a as a yellow solid (900 mg, 48%). 1H NMR (500 MHz, DMSO) δ 10.21 (s, 1H), 8.52 (d, J=5.5 Hz, 1H), 7.79 (d, J=5.0 Hz, 1H).

Quelle