Dimethylamine → N-(Dimethylaminomethyl)-indole

Participants

Reaction Steps

Formaldehyde (37% in water, 0.19 mL, 2.6 mmol) was added to cooled (ice/water bath) aqueous dimethylamine (40% in water, 0.32 mL, 2.6 mmol). The mixture was stirred for 10 min and then indole 31 (0.3 g, 2.6 mmol) was added. The suspension was stirred for 1 h in an ice/water bath and then 24 h at RT. Indole was not completely dissolved. Dichloromethane (10 mL) was added and the organic layer was separated. The solvent was evaporated and the residue was chromatographed on a Chromatotron with dichloromethane/hexanes, 5:2 mixture as eluent to remove non-polar impurities. This was followed by elution with dichloromethane/EtOAc, 5:1 to 1:1. Appropriate fractions were collected to give indole Mannich base 32 as an oil (0.25 g, 57%) which was pure by TLC.

Provenance & Evidence