Synthesis of indolo[2,3-a]quinolizine and hexahydro-1H-indolizino[8,7-b]indole derivatives by cascade condensation, cyclization, and Pictet–Spengler reaction: an application to the synthesis of (±)-harmicine

Synthesis of indole alkaloid related compounds using Schiff base formation, intramolecular cyclization (or N-alkylation), and Pictet–Spengler reaction as a cascade one pot condensation has been reported. The cascade chemistry has been applied to the synthesis of (±)-harmicine as a key step.