Reaktion #79350

Reaktionsgleichung

iodoethane

ethyl 7-(3-benzyloxypropoxy)-chromane-2-carboxylate

hexamethylphosphoramide

sodium bis(trimethylsilyl) amide

→

title compound

Ausbeute 70.0%

Ethyl 7-(3-benzyloxypropoxy)-2-ethylchromane-2-carboxylate

Ausbeute 70.0%

Lösungsmittel

THF

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added
2. 2
   Temperaturupon cooling in a dry ice-acetone bath
3. 3
   SonstigeThe cooling bath was removed
4. 4
   SonstigeThe solvent was removed under reduced pressure
5. 5
   workup.ADDITIONThe residue was diluted with AcOEt and sat. NH4Claq
6. 6
   SonstigeThe organic layer was separated
7. 7
   Extraktionthe aqueous layer was extracted twice with AcOEt
8. 8
   TrocknenThe combined organic layers were dried over anhydrous Na2SO4
9. 9
   Filtrationfiltered
10. 10
    Einengenconcentrated
11. 11
    Sonstigechromatographed on silica gel eluting with 10% methyl-tert-butyl ether/hexanes

Vorschrift

To a 85 ml anhydrous THF solution of ethyl 7-(3-benzyloxypropoxy)-chromane-2-carboxylate (5.0 g, 13.5 mmol) and hexamethylphosphoramide (3.1 ml, 17.8 mmol) was added sodium bis(trimethylsilyl) amide 1.0M/THF solution (16.2 ml, 16.2 mmol) was added upon cooling in a dry ice-acetone bath. After stirring for 30 min at that temperature, to it was added iodoethane (3.3 ml, 41.3 mmol). The cooling bath was removed allowing the reaction mixture to warm to rt overnight. The solvent was removed under reduced pressure. The residue was diluted with AcOEt and sat. NH4Claq. The organic layer was separated, and the aqueous layer was extracted twice with AcOEt. The combined organic layers were dried over anhydrous Na2SO4, filtered, concentrated, and chromatographed on silica gel eluting with 10% methyl-tert-butyl ether/hexanes to give the title compound as a clear oil 3.76 g (70%).

Quelle