2D-MoS2 photocatalyzed cross dehydrogenative coupling reaction synchronized with hydrogen evolution reaction

Abstract

The chemically exfoliated 2D-MoS₂ has a mixture of 1T (metallic) and 2H (semiconducting) phases. It has shown a considerably good catalytic activity for hydrogen evolution reaction (HER), proceeding via electrochemical as well as photochemical pathways. Experimentalists have utilized triethanolamine or other sacrificial donors along with Eosin Y as a photosensitizer. But the potential of this reaction has not yet been fully explored as the sacrificial donor is wasted in the oxidation process. The oxidation cycle of this process can be used in many organic transformation(s). Herein, we report the use of the oxidative cycle for efficient cross dehydrogenative coupling (CDC) reaction with tetrahydroisoquinoline and indole substrates as well as their derivatives, parallel to HER. The reaction results in good to excellent yield of the corresponding product under visible light irradiation at room temperature. The mechanistic investigation has also been carried out. This study is a potential example of how to fully harness the oxidation and reduction cycles of many semiconductor based photocatalysts.