Tetrahydrofuran → 8-Acetyl-2-(dipropylamino)tetralin

Participants

Reaction Steps

A solution of n-butyllithium (1.6M in hexane, 15.1 ml, 24.2 mmol) was added to a solution of 8-bromo-2-di-n-propylamino-1,2,3,4-tetrahydronaphthalene (5.0 g, 16.1 mmol) in THF (50 ml) at -78° and the reaction stirred at -78° for one hour. Gaseous carbon dioxide was bubbled through the reaction at -78° until the deep violet color which forms dissipates. Methyllithium (1.4M in ether, 23 ml) was added. The reaction was stirred at -78° for 30 minutes and warmed to room temperature. The reaction was stirred for an additional ten minutes at room temperature at which time the pink color had been lost. An additional 10 ml of the methyllithium solution was added and the reaction became pink once again. After 15 minutes, the pink color was lost and an additional 10 ml of the methyllithium solution added. The reaction was poured onto ice, made acidic with hydrochloric acid and extracted with ether. The aqueous layer was made basic and extracted with methylenechloride. The basic extracts were dried (Na2SO4) and concentrated to give 3.8 g of crude product. Purification by flash silica gel chromatography using 2:1 hexane:ether containing trace ammonium hydroxide provided 2-di-n-propylamino-8-acetyl-1,2,3,4-tetrahydronaphthalene as a yellow oil (2.7 g, 61%).

Provenance & Evidence