Synthesis of Nano Conducting Poly(N-ethylaniline) and its Function as Reusable Catalyst for Bis-benzpyrrole Synthesis

The present work demonstrates the effectiveness of poly(N-ethylaniline) salts derived from FDA approved bifunctional diprotic organic acid (DL-tartaric acid); in order to execute a practical route to bisindole synthesis. Poly(N-ethylaniline) salts (DL-tartaric acid) were prepared by chemical polymerization. Many of the early efforts performed in the quest of making the synthesis more practical are doomed to failure owing to their inconveniences. The work reported in our laboratory shows the usefulness of DL-tartaric acid doped Poly(N-ethylaniline) salts to accomplish the synthesis of bisindole class of compounds. Efficient electrophilic substitution of indoles (2 mmol) with aromatic aldehydes (1 mmol) equipped with various constituents were carried out employing a catalytic amount of poly(N-ethylaniline) salt (DL-tartaric acid) in methanol to obtain symmetrical (and unsymmetrical) bisindoles in good to excellent yields. The method is practical simple, efficient, cost-effective and affords good yields in short reaction run time. The catalyst employed is recyclable, eco-friendly, highly active, and stable and requires low loading. The catalyst and bisindole products were characterized by XRD, UV-Vis, 1H-NMR and FT-IR spectroscopy. By this method, reproducible yields of bisindoles were attainable. The present work permits easy and effective bisindole synthesis.