Reaction #2069969

Reaction equation

4-hydroxyindole

2-chloroethanol

triphenylphosphine

diethyl azodicarboxylate

→

title compound

4-(2-Chloroethoxy)-1H-Indole

Solvents

diethyl ether

tetrahydrofuran

Et2O hexane

Conditions

Workup

1. 1
   Concentrationconcentrated in vacuo
2. 2
   Otherto give a residue
3. 3
   Otherthe solid triphenylphosphine oxide is precipitated
4. 4
   Otherremoved by filtration
5. 5
   ConcentrationThe filtrate is concentrated
6. 6
   Otherpurified by flash chromatography (silica gel, EtOAc/hexane: 1.5/8.5)
7. 7
   Otherto give an oil

Procedure

A solution of 4-hydroxyindole (3.99 g, 30 mmol), 2-chloroethanol (6.03 ml, 90 mmol) and triphenylphosphine (23.6 g, 90 mmol) in tetrahydrofuran is treated with diethyl azodicarboxylate (14.1 ml, 90 mmol) under nitrogen at room temperature, stirred for 2 hr at room temperature and concentrated in vacuo to give a residue. Cooled diethyl ether is added to the residue and the solid triphenylphosphine oxide is precipitated and removed by filtration. The filtrate is concentrated and purified by flash chromatography (silica gel, EtOAc/hexane: 1.5/8.5) to give an oil. After trituration with Et2O/hexane (1/10), the title compound is obtained as a white solid, 4.8 g (82%) mp 60° C., identified by NMR and mass spectral analyses.

Source