Reaktion #45170

Reaktionsgleichung

ethyl 5-bromothiophene-2-carboxylate

homopiperazine

(rac)-(−)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl

sodium tert-butoxide

→

ethyl 5-(4-ethylpiperazin-1-yl)thiophene-2-carboxylate

Ausbeute 17.0%

Lösungsmittel

MeOH

toluene

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeThe cooled reaction mixture
2. 2
   Sonstigethe crude product was purified by ion exchange chromatography
3. 3
   WaschenThe desired product was eluted from the column
4. 4
   workup.ADDITIONcontaining the desired product
5. 5
   Sonstigewere evaporated to dryness
6. 6
   Sonstigeto afford impure product as a brown oil
7. 7
   SonstigeThe crude product was purified by silica column chromatography
8. 8
   Wascheneluting with a gradient of 0 to 5% 7N NH3/MeOH in DCM
9. 9
   SonstigePure fractions were evaporated to dryness

Vorschrift

Palladium(II) acetate (52.1 mg, 0.23 mmol) followed by sodium tert-butoxide (624 mg, 6.49 mmol) was added to a stirred solution of ethyl 5-bromothiophene-2-carboxylate (1090 mg, 4.64 mmol), homopiperazine (511 mg, 5.10 mmol) and (rac)-(−)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (289 mg, 0.46 mmol) in toluene (20 mL) at 25° C. under nitrogen. The resulting suspension was stirred at 110° C. for 3 h. The cooled reaction mixture was diluted with MeOH and the crude product was purified by ion exchange chromatography, using an SCX column. The desired product was eluted from the column using 7M NH3/MeOH and fractions containing the desired product were evaporated to dryness to afford impure product as a brown oil. The crude product was purified by silica column chromatography, eluting with a gradient of 0 to 5% 7N NH3/MeOH in DCM and then 0 to 3% NH3/MeOH in DCM. Pure fractions were evaporated to dryness to afford ethyl 5-(4-ethylpiperazin-1-yl)thiophene-2-carboxylate (195 mg, 17%) as a yellow oil.

Quelle