3-(2-Indolylthio)Propionic Acid → 2,3-Dihydrothiopyrano[2,3-b]indol-4(9H)-one

Participants

Reaction Steps

A mixture of 88.5 g (0.4 mol) of 3-(2-indolylthio)propionic acid and 300 g of polyphosphate ester in 3.5 liters of chloroform is stirred for 16 hours at room temperature and under a nitrogen atmosphere. The mixture is diluted with 3 liters of ice-cold water, the organic phase is separated after settling has occurred and the aqueous phase is extracted with chloroform. The organic phases are combined, washed with 10% strength aqueous sodium bicarbonate solution and then with water, dried and concentrated on a water bath under vacuum. The residue is recrystallized in ethanol, the crystals obtained are removed and the filtrate is concentrated.

Provenance & Evidence