Sulfuric Acid → (4S)-4-Ethyl-7,8-dihydro-4-hydroxy-1H-pyrano(3,4-f)indolizine-3,6,10(4H)-trione

Participants

Reaction Steps

Dissolved in 15 ml of dimethoxyethane was 815 mg of the compound (VI) obtained in the above procedure (1), followed by an addition of 5 ml of 2N H2SO4. The thus-prepared solution was heated with stirring for 20 hours under a nitrogen gas stream. After completion of the reaction, 150 ml of dichloromethane was added and the resultant mixture was washed with water. The organic layer was then dried over anhydrous sodium sulfate and the solvent was distilled off. The residue was recrystallized from a mixed solvent of ethanol and petroleum ether to obtain 315 mg of the title compound as colorless needle-like crystals.

Provenance & Evidence