Development of an imidazole salt catalytic system for the preparation of bis(indolyl)methanes and bis(naphthyl)methane

Abstract

Imidazolium salts are shown to catalyze the rapid room temperature reaction of indoles or naphthol with aldehydes to provide bis(indolyl)methanes or bis(naphthol)methane in excellent yields and the reaction proceeds optimally in dichloromethane with no base additives. The reaction exhibits a broad substrate tolerance and occurs through nucleophilic activation of the indoles and naphthols through a cation–π interaction.

Differential Chromogenic Response towards F− and H2PO4−: Hydrogen Bonding vs Deprotonation

“…This was also supported by 1 H-NMR studies. The NMR signal corresponds to the proton 'a', present adjacent to indolyl nitrogen center, experienced upfield shift when R =À NMe 2 and downfield shift when R =À NO 2 than that of observed for 1 (R = À CH 3 ) (Figure S20).…”

“…Though shift in absorption maximum from 430 nm to 446 nm was also observed with H 2 PO 4 À , but no absorption band was appeared at 535 nm region (Figure S18b-S21). 1 H-NMR titration of 3 showed a sharp upfield change in δ of aromatic protons with each of 1.0 equiv. F À and H 2 PO 4 À anion (Figure S22-S23).…”

“…Bis(indolyl)methanes (BIM) and their derivatised adducts are often been found and isolated from various terrestrial and marine species. [1] The BIM molecules readily undergo oxidation due to presence of labile CÀ H bond at the meso position, resulting formation of conjugated, highly colored BIM molecule. [2] The photophysical properties as well as ion-binding efficiency of BIM molecules depend on the overall π-conjugation length of the molecule and the electronic nature of the central aryl moiety (Figure 1a).…”

Valorization of discarded face mask for bioactive compound synthesis and photodegradation of dye

“…Various types of catalysts have been developed for BIM syntheses such as the amberlyst-15, molecular iodine, metal nanoparticles, acid and base, NbCl 5 , cellulose sulphuric acid, zeolite and ceric ammonium nitrate. However, some of these catalysts employed hazardous and expensive reagents which hampered their practical use, for instance, the utilization of imidazolium salt as catalysts in chloroform ( Wang and Aldrich, 2019 ) and scandium (III) triflate ( Tanemura, 2021 ) in addition with the use of non-reusable thiourea catalysts in harsh reaction condition ( Rivas-Loaiza et al, 2019 ). As part of our continuous efforts in green and sustainable chemistry, herein, we report the transformation of discarded masks into mask waste ash catalyst (MWAC) via direct burning in a furnace for use in BIM synthesis.…”

Metal-Ion-Responsive Chromogenic Probe for Rapid, On-Location Detection of Foodborne Bacterial Pathogens in Contaminated Food Items

“…Bis­(indolyl)­methanes (BIMs) and their derivatives, isolated from various terrestrial and marine natural sources, are naturally available, bioactive aza-heterocycles . The hydrogen atom at the meso position of the BIM skeleton is unstable, and therefore, they spontaneously undergo oxidation to produce a highly conjugated “colored” product .…”