We describe a facile approach for effectively constructing the pentacyclic framework of subincanadine B. The seven-step assembly of tetracyclic
ketone 14 featured Michael addition, Pictet−Spengler cyclization, and Dieckmann condensation. From this key ketone intermediate, two analogues
of subincanadine B, i.e., 20-deethylenylated subincanadine B (27) and 19,20-dihydrosubincanadine B (31), were synthesized in four steps,
respectively.