Photocatalytic activation of alkyl chlorides by assembly-promoted single electron transfer in microheterogeneous solutions

Abstract

Photoredox catalysis has developed into a powerful tool for the synthesis of organic compounds with diverse structures. However, stable carbon–chloride bonds remain beyond the energetic limits of the outer-sphere photoreductive activation. Here, we demonstrate that the organization of the reacting species in microstructured, aqueous solutions allows generation of carbon-centred radicals from non-activated alkyl chlorides in the presence of double bonds via assembly-promoted single electron transfer. Photocatalytic systems consisting of a surfactant, organic substrates and additives have been designed, characterized and applied for radical dechlorination, addition and cyclization reactions. Cheap and commercially available blue light-emitting diodes are used as the irradiation source for the transformations. Mechanistic studies indicate the accumulation of the energy of two visible light photons in one catalytic cycle. Photocatalytic activation of alkyl carbon–chlorine bonds has constantly proven difficult due to the high energies needed to cleave this stable bond. Here a surfactant-based photocatalytic system is used, allowing for the radical dehalogenation and subsequent reactivity of unactivated alkyl chlorides.