A Build, Couple, Pair (B/C/P) Strategy in the Synthesis of Diindole Fused Diazamacrocycles: An Attempt to a Green Synthetic Approach

An efficient build/couple/pair (B/C/P) strategy toward the synthesis of diindole-fused diazamacrocycles was demonstrated. The water-mediated reactions of aryl aldehydes and 2-sulfonamidoindoles in the presence of a catalytic amount of tetrabutylammonium iodide (TBAI) afforded an excellent yield of <i>bis</i>(aminoindolyl)-methanes with a broad substrate scope and a good functional group tolerance. Furthermore, the bisconjugation of the free N-H groups of <i>bis</i>(aminoindolyl)-methane scaffolds with the dibromo spacers of varied chain lengths via the universal dialkylation protocol furnished diindole-fused diazamacrocycles. The obtained products were characterized by NMR, IR, and mass spectral analysis and were confirmed by single-crystal X-ray diffraction analysis. The corresponding macrocycles obtained through this protocol are new and could be potent scaffolds, and the methodology adopted in this work will be of great interest to researchers.