1-Bromopentane → 1-Pentyl-1H-indole-3-carboxylic acid

Reaction equation

[NH:1]1[C:9]2[C:4](=[CH:5][CH:6]=[CH:7][CH:8]=2)[C:3]([C:10]([OH:12])=[O:11])=[CH:2]1.[H-].[Na+].Br[CH2:16][CH2:17][CH2:18][CH2:19][CH3:20]>CN(C=O)C>[C:10]([C:3]1[C:4]2[C:9](=[CH:8][CH:7]=[CH:6][CH:5]=2)[N:1]([CH2:16][CH2:17][CH2:18][CH2:19][CH3:20])[CH:2]=1)([OH:12])=[O:11]

Participants

Procedure

Indole 3-carboxylic acid (3 g, 18.62 mmol) was added to a suspension of sodium hydride (60% in oil) (1.11 g, 1.5 eq) in dry DMF (30 ml) under a nitrogen atmosphere. The mixture was stirred at room temperature for 45 min (H2 evolving has ceased) and to this was added 1-bromopentane (4.62 ml, 2 eq) in dry DMF (10 ml) dropwise. The mixture was stirred at room temperature overnight. The solvents were removed in vacuo and to the residue was added water (30 ml) and ethyl acetate (30 ml). The ethyl acetate portion was separated, dried over sodium sulphate, filtered and evaporated to dryness. The crude residue was purified by column chromatography (silica gel: 20% ethyl acetate in hexane) to give the title compound (2.12 g, 49%) as a cream solid.