Hydrochloric Acid → Diethyl-(2-quinoxalin-2-yl-ethyl)amine

Participants

Reaction Conditions

Reaction Steps

A solution of diethylamine hydrochloride (3.82 g, 35 mmol) and triethylamine (0.23 ml) in ethanol (1.75 ml) and water (1.75 ml) was added dropwise, at 60° C., to a mixture of 2-methyl-quinoxaline (5.0 g, 35 mmol), formaldehyde (2.81 g of 37% solution, 35 mmol), triethylamine (0.17 ml) and ethanol (4.6 ml). The pH was adjusted to 7–7.5 by mean of dilute aqueous hydrochloric acid. Stirring was maintained 16 hours at 60° C. The solvent was concentrated, the residue was diluted with water and extracted with diethyl ether to remove the unreacted quinoxaline. The aqueous phase was basified with 20% aqueous sodium hydroxide (10 ml) and extracted with ethyl acetate. The organic phase was dried over magnesium sulfate and concentrated. The residue was chromatographed on silica gel eluting with dichloromethane-methanol (first 95-5 then 90-10 and finally 90-10 plus 0.1% of ammonia) to give diethyl-(2-quinoxalin-2-yl-ethyl)-amine (2.67 g, 37%).

Provenance & Evidence