Synchronized biphotonic process triggering CeC coupling catalytic

Activation of aryl(Ar)-halides for CeC coupling catalytic reactions using visible light has become one of the most

challenging tasks in organic synthesis since it offers effective and safer alternatives to traditional dehalogenation

protocols. The insufficient energy provided by visible light to cleave such strong CeH alogen bonds certainly

makes necessary the development of new protocols to overcome this limitation. We report here the application

of photon upconversion (UC) technology based on triplet-triplet annihilation (TTA) to a CeC coupling catalytic

reaction, a possibility that has not been investigated to date. This synchronized biphotonic process (TTA-UC)

activates successfully Ar-halides with visible light. Based on product analysis and spectroscopic experiments, a

cascade process combining photophysical and photochemical steps is proposed for the mechanism rationalization.

Visible light, ambient temperature and pressure, low-loading metal-free photocatalysts and no additives

make this protocol very attractive for applications to the synthesis of fine chemical building blocks, pharmaceuticals,

agrochemicals or new materials.