Carbon Dots as Nano-Photocatalysts: A Green Tool for Indole and Heteroarenes Alkylation.

Abstract

Taking into account the hurdles of climate change and environmental pollution, through the years, the development of sustainable protocols in catalysis stands as a cornerstone to answer those issues. Carbon dots (CDs) have recently proven to be efficient in various types of catalysis, including photocatalytic reactions, while being a green and economic alternative for metal catalysts. In this paper, we present a new catalytic system for the photoredox functionalization of indoles and heteroarenes derivatives based on CDs as nano-photocatalysts. This reaction, based on the cooperation between our catalyst and 2,6-lutidine, shows the ability to functionalize these compounds up to 88%, it is effective on 1 mmol scale, and shows a recyclability potential at least to 5 cycles. This system also demonstrated the capacity of obtaining rare types on indoles, having two electron withdrawing groups (EWG), both on the carbon 2 (C2) and carbon 3 (C3). Furthermore, careful studies led to the partial resolution of the mechanism, and to explanations on the regioselectivity of the reaction, which has been studied through the nature of both reagents and substrates, but also through the light's wavelength used in the reaction.