Reaktion #566830

Reaktionsgleichung

iodoethane

ethyl 7-benzyloxychromane-2-carboxyate

hexamethylphosphoramide

sodium bis(trimethylsilyl)amide

→

title compound

Ausbeute 96.0%

Ethyl 7-benzyloxy-2-ethylchromane-2-carboxylate

Ausbeute 96.0%

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturUpon cooling in a dry ice-acetone bath
2. 2
   workup.ADDITIONwas added via syringe
3. 3
   SonstigeThe solvent was removed under reduced pressure
4. 4
   workup.ADDITIONthe residue was diluted with AcOEt and aqueous NU4Cl (NH4Cl 7.2 g/200 ml water)
5. 5
   SonstigeThe organic layer was separated
6. 6
   Extraktionthe aqueous layer was extracted with AcOEt twice
7. 7
   TrocknenThe combined organic layers were dried over anhydrous Na2SO4
8. 8
   Filtrationfiltered
9. 9
   Einengenconcentrated
10. 10
    Sonstigechromatographed on silica gel eluting with 7.5% EtOAc/hexanes

Vorschrift

To a 320 ml anhydrous THF solution of ethyl 7-benzyloxychromane-2-carboxyate 14.6 g (46.6 mmol) were added hexamethylphosphoramide (10.5 ml, 60.4 mmol). Upon cooling in a dry ice-acetone bath, sodium bis(trimethylsilyl)amide (1.0M/THF) (60.5 ml, 60.5 mmol) was added via syringe over 15 min period. The resulting orange solution was stirred at that temperature for 30 min before iodoethane (18.6 ml , 233 mmol) was added via syringe. The reaction was slowly warmed to rt and stirred overnight. The solvent was removed under reduced pressure, and the residue was diluted with AcOEt and aqueous NU4Cl (NH4Cl 7.2 g/200 ml water). The organic layer was separated, and the aqueous layer was extracted with AcOEt twice. The combined organic layers were dried over anhydrous Na2SO4, filtered, concentrated, and chromatographed on silica gel eluting with 7.5% EtOAc/hexanes to give the title compound 15.2 g (96%).

Quelle