4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano[3,4-f]indolizine-3,6,10(4H)-trione → (9S)-1-Acetylamino-9-ethyl-2,3-dihydro-9-hydroxy-1H, 12H-benzo[de]pyrano[3',4':6,7]indolizino[1,2-b]quinoline-10,13-(9H,15H)-dione

Participants

Reaction Steps

361 mg of (S) 4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano-[3,4-f]indolizine-3,6,10(4H)-trione (hereinafter abbreviated as “trione”) was added to the solution of 300 mg of the compound prepared in (4) above in 200 ml of toluene. The mixture was heated under reflux using a Deanstark apparatus for 10 minutes. To the mixture was added 1 mg of pyridinium-p-toluenesulfonate (hereinafter abbreviated as “PPTS”) and the mixture was refluxed while stirring for a further 24 hours. After cooling, the residue obtained by removing toluene by concentration was suspended into 300 ml of chloroform-methanol (10:1) solvent. Insoluble substances were removed and the residue was powdered with methanol to obtain 336 mg of the title compound. mp: above 240° C. (decomposed)

Provenance & Evidence