TETRACYCLIC INDOLE-DERIVATIVES FROM THE REACTION OF METHYL 2,4-DIOXO-6,6-DIMETHOXYHEXANOATE WITH TRYPTAMINE - INDOLO[2,3-A]QUINOLIZIDINE VS 3,7A-DIAZACYCLOHEPTA[JK]FLUORENE
Depending on the acid used for cyclization, reaction of methyl 6,6-dimethoxy-2,4-dioxohexanoate (4) with tryptamine yielded indoloquinolizidine (8) (AcOH) or diazacycloheptafluorene (10) (TFA). Treatment of 8 with TFA gave 10.