Reaction #351718

Reaction equation

(S)-1-amino-2-propanol

toluene

(RS)-2-(2-oxoethyl)-4-chromanone

water

toluene

→

(S)-1-(1,4-dihydro-[1]benzopyrano[4,3-b]pyrrol-1-yl)-propan-2-ol

Yield 76.0%

Conditions

Workup

1. 1
   OtherThe cooled reaction mixture
2. 2
   Otherwas purified by column chromatography on silica gel (ethyl acetate/toluene 2:3)

Procedure

A solution of 1.9 g of (RS)-2-(2-oxoethyl)-4-chromanone and 80 mg of p-toluenesulfonic acid in 70 ml of anhydrous toluene was heated on a water separator. A solution of 3.0 g of (S)-1-amino-2-propanol in 20 ml of anhydrous toluene was added dropwise to the boiling solution over a period of 5 minutes. Subsequently, the mixture was boiled for an additional 35 minutes, during which the solvent was reduced to a volume of 20 ml. The cooled reaction mixture was purified by column chromatography on silica gel (ethyl acetate/toluene 2:3). 1.73 g (76%) of (S)-1-(1,4-dihydro-[1]benzopyrano[4,3-b]pyrrol-1-yl)-propan-2-ol were obtained as a yellow oil.

Source