Abstract

Radical halogenation is an important transformation in organic synthesis. Traditionally, radical halogenation has been accomplished using harsh reaction conditions like ultraviolet light and toxic reagents such as chlorine gas. Our research is exploring a new, more sustainable approach to traditional radical halogenation using photocatalysis. In photocatalysis, the reaction is exposed to visible light which excites the catalyst and allows the reaction to proceed. The current conditions being examined in the reaction are the use of a tungsten photocatalyst, TBADT, sclareolide as the substrate being halogenated, and a range of halogen sources in solution with acetonitrile. In the presence of visible light, the tungsten catalyst becomes excited and reacts with the sclareolide, forming a site-selective radical intermediate. The radical intermediate then reacts with the halogen source and forms a carbon halogen bond. The optimization of reaction conditions is the main point of investigation. One variable that is being examined is the effectiveness of the halogen radical source. So far, we have observed that different chlorine radical sources produce a chlorinated product at the site-selective carbon on sclareolide. The focal point of this investigation is to further optimize the conditions of the reaction, improve the yield, and apply it to flow chemistry.