Organo-Soluble MoS₂ Quantum Dots Mediated Photocatalytic Generation of Imminium Intermediate for Effective Synthesis of Bis(indolyl)Methanes Derivatives

Abstract

Iminium intermediates play a pivotal role in the synthesis of diverse organic molecules due to their exceptional reactivity and capacity to participate in a wide range of transformative reactions. However, their inherent instability in aqueous media, commonly employed in nanomaterial-based catalysis presents a significant challenge. Even though there are few reports of organo-soluble nanophotocatalysis, it has never been explored for iminium ion-mediated pharmaceutically important bis(indolyl)methanes (BIMs) synthesis. In this study, we report the use of organo-soluble MoS₂ quantum dots (QDs) as photocatalysts for the in situ generation of stable iminium ions, which serve as key intermediates in the synthesis of bis(indolyl)methanes (BIMs). Leveraging the unique electronic properties and high surface area of MoS₂ QDs, we achieve efficient substrate activation under mild, environmentally benign conditions, eliminating the need for harsh reagents or elevated temperatures. The in situ generated iminium ions undergo nucleophilic attack by indoles, affording bisindoline derivatives, structural motifs commonly found in biologically active natural products and pharmaceutical agents. Our findings highlight the potential of MoS₂ QDs as sustainable and versatile photocatalysts in organic synthesis, offering a novel and efficient strategy for constructing bisindoline frameworks. This approach not only advances synthetic methodologies but also opens new avenues for the design of catalytic systems aimed at accelerating the discovery of therapeutic agents and bioactive molecules.