Reaktion #41724

Reaktionsgleichung

potassium carbonate

tert-butyl 4-chloropyridine-2-carboxylate

KHMDS

4-amino-3-nitrophenol

→

desired product

tert-butyl 4-(4-amino-3-nitrophenoxy)pyridine-2-carboxylate

Lösungsmittel

dimethylformamide

dimethylformamide

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeThe reaction was evaporated under reduced pressure
2. 2
   workup.ADDITIONdiluted with excess ethyl acetate and water
3. 3
   ExtraktionAn extraction of the aqueous layer
4. 4
   Waschenwashed 4 times with water
5. 5
   TrocknenThe organic layer was dried over anhydrous sodium sulfate
6. 6
   Sonstigeevaporated under reduced pressure
7. 7
   SonstigeThe crude material was purified by flash silica gel chromatography
8. 8
   workup.ADDITIONan eluent of 1:1 mixture of hexanes to ethyl acetate

Vorschrift

Solid anhydrous white powdered KHMDS (2 eq) was suspended in a solution of dimethylformamide. Red crystalline 4-amino-3-nitrophenol (1 eq) was charged to the rapidly stirring solution under an inert atmosphere and the heterogeneous solution was allowed to stir for 2 hours. Then a dimethylformamide solution of tert-butyl 4-chloropyridine-2-carboxylate (1 eq) was added dropwise. Anhydrous powdered potassium carbonate (1.2 eq) was charged to the reaction as an acid scavenger. The purple colored viscous mixture was heated to 80° C. for 12-15 hours until when it was determined to be complete by HPLC. The reaction was evaporated under reduced pressure and diluted with excess ethyl acetate and water. An extraction of the aqueous layer was made with ethyl acetate. The organic layers were combined and washed 4 times with water followed by brine. The organic layer was dried over anhydrous sodium sulfate and evaporated under reduced pressure. The crude material was purified by flash silica gel chromatography using an eluent of 1:1 mixture of hexanes to ethyl acetate to give the desired product. MS: MH+=332.

Quelle