Reaktion #216391

Reaktionsgleichung

HCl

Ethyl difluoroacetate

sodium methoxide

2-acetyl-5-bromothiophene

→

needles

Ausbeute 73.3%

4,4-difluoro-1-[5-bromo-2-thienyl]-butane-1,3-dione

Ausbeute 73.3%

Lösungsmittel

THF

ether

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeAfter two hours a precipitate formed
2. 2
   workup.STIRRINGThe reaction was stirred at room temperature 6.2 hours
3. 3
   SonstigeThe organic layer was collected
4. 4
   Waschenwashed with brine
5. 5
   Trocknendried over MgSO4
6. 6
   Einengenconcentrated in vacuo
7. 7
   Sonstigeto give a yellow oil which
8. 8
   Sonstigewas crystallized from methylene chloride/isooctane

Vorschrift

Ethyl difluoroacetate (2.43 g, 19.6 mmol) was placed in a 100 mL round bottom flask, and dissolved in ether (15 mL). To the stirred solution was added 25 weight % sodium methoxide (4.23 g, 19.5 mmol) followed by 2-acetyl-5-bromothiophene (3.59 g, 17.5 mmol). After two hours a precipitate formed and THF (15 mL) was added to allow stirring to continue. The reaction was stirred at room temperature 6.2 hours, then treated with 3N HCl (20 mL). The organic layer was collected and washed with brine, dried over MgSO4, and concentrated in vacuo to give a yellow oil which was crystallized from methylene chloride/isooctane to give yellow needles (3.63 g, mp 83.5°-85° C., 73% ). 1H NMR (CDCl3) 300 MHz 14.60 (br s, 1H), 7.53 (d, J=4.0 Hz, 1H), 7.15 (d, J=4.0 Hz, 1H), 7.19 (m, 1H), 6.32 (s, 1H), 6.04 (t, J=54.2 Hz, 1H); 19F NMR (CDCl3) 300 MHz: -127.00 (d) ; M+282.

Quelle