Visible-light mediated installation of halogen functionality into aromatic systems

LEMIR, IGNACIO D; SCHMIDT LUCIANA C.; ARGÜELLO, JUAN E.

Encuentro; XIII ELAFOT; 2017

The development of new methods for introducing halogens into organic compounds hasconstantly attracted many research groups. Halogen substituted compounds are important buildingblocks in organic synthesis for conversion and introduction of more valuable functional groups bytransition metal catalysis[1] and nucleophilic substitution.[2] Furthermore, the interaction ofhalogen bonds with proteins or small molecules provide modulated physical and chemicalproperties such as lipophilicity and thermal/oxidative stability.The introduction of halogen functionalities into an aromatic system is a well-establishedmethod in organic chemistry. Most commonly activated aromatic rings are converted directlythrough reaction with excess of the diatomic halogens. However, this method suffers from criticaldrawbacks with handling of highly hazardous and volatile halogens and poor regioselectivity. Up todate, the most used bromination procedures involves the use N-Bromosuccinimide, transitionmetals catalyst or solutions of molecular bromine (Br2), these methodologies carry a high economiccost, high toxicity and requires the use of heat sources.In order to solve the above mentioned problems, visible-light photoredox catalysis hasarisen as alternative. In the present report, we propose the bromination of anilines using organicphotocatalysts and carbon tetrabromide (CBr4) as a source of bromine. ?in situ? Elemental bromideformation is possible using photocatalysts (FCs) such as Ru(bpy3) Cl2 and Eosin Y (EY)