Cascade Synthesis of New Indole‐Containing Pentacyclic Scaffolds Mediated by Aryl and Iminyl Radicals

Abstract

A five‐step approach, starting from simple 1,5‐disubstituted indoles, has been implemented for the synthesis of diversely substituted indole‐pyrido‐indene pentacyclic compounds up to 54% yield via domino radical‐mediated processes in the presence of the radical reagents DLP/TTMSS and AIBN/TTMSS. Reactions proceeded with diverse key starting radical cyano‐precursors strategically synthesized which were subsequently transformed into the target pentacyclic compounds through an aryl/iminyl radical‐mediated domino reactions sequence. In addition to the routine spectroscopic techniques, the structure of radical precursors, as well as, the target pentacyclic products were unequivocally established by single crystal X‐ray diffraction, confirming the effectiveness of the proposed synthetic sequence.