Reaktion #69984

Reaktionsgleichung

2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl

sodium tert-butoxide

4-(5-bromopyridin-2-yl)-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester

4-(benzyloxycarbonyl)piperazine

→

4-[5-(4-(benzyloxycarbonyl)piperazin-1-yl)pyridin-2-yl]-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester

Ausbeute 74.1%

Lösungsmittel

Ethyl acetate

toluene

Reaktionsbedingungen

Aufarbeitung

1. 1
   Waschenthe mixture is washed once with water and once with a saturated aqueous sodium chloride solution
2. 2
   TrocknenThe organic phase is dried over magnesium sulphate
3. 3
   Einengenconcentrated under reduced pressure
4. 4
   SonstigeThe crude product obtained
5. 5
   Sonstigeis chromatographed on silica gel, elution
6. 6
   workup.ADDITIONbeing carried out with a gradient of a mixture of heptane/ethyl acetate (90/10 to 0/100)

Vorschrift

10.12 g of 4-(5-bromopyridin-2-yl)-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester and 5.7 g of 4-(benzyloxycarbonyl)piperazine are placed in 118 ml of toluene and then 0.95 g of tris(dibenzylideneacetone)dipalladium(0), 1.7 g of 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl and 3.5 g of sodium tert-butoxide are added. The reaction medium is heated at 110° C. for 3 h. Ethyl acetate is subsequently added and the mixture is washed once with water and once with a saturated aqueous sodium chloride solution. The organic phase is dried over magnesium sulphate and concentrated under reduced pressure. The crude product obtained is chromatographed on silica gel, elution being carried out with a gradient of a mixture of heptane/ethyl acetate (90/10 to 0/100). 10.16 g of 4-[5-(4-(benzyloxycarbonyl)piperazin-1-yl)pyridin-2-yl]-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester are obtained.

Quelle