The direct utilization of native functional groups without the need for prefunctionalized holds considerable promise to revolutionize organic synthesis. While significant advances have been realized within the area of C-H activation, the functionalization of inert C-O bonds in aryl ethers is still at its infancy. Prompted by the natural abundance of aryl ethers in Lignin, the second most abundant biopolymer (30% of non-fossil organic carbon on earth), chemists have been challenged to devise, conceptuality and practicality aside, mild, general and widely applicable catalytic technologies for ethereal C-O functionalization. At present, however, these technologies remain confined to the use of rather activated extended p-systems, stoichiometric metal reagents and, in many instances, harsh conditions.
ET-PHOTOX aims at establishing a general platform that combines visible light photocatalysis with nickel catalysis for tackling the challenge of the functionalization of ubiquitous ethereal aryl C-OMe bonds via CT complexes. The successful accomplishment of this project will be of significant value for the synthetic community, as ethereal C–O bonds are commonly present in biomass-derived feedstocks such as Lignin, the second most abundant biopolymer on the earth. ET-PHOTOX has provided the fellow with new knowledge and skills to broaden his future career as an independent researcher at the European Community.
The main objective of ET-PHOTOX was to develop an efficient paradigm for forging C–C bonds via the functionalization of ethereal aryl C–OMe bonds by the merger of nickel catalysis and photocatalysis. The specific objectives were the following:
1. To synthesize a variety of π-acceptor catalysts that will form a CT complex with aryl ethers
2. To implement dual photochemical C–C bond-forming reactions of anisole derivatives with carbon-based nucleophiles
3. To develop a photocarboxylation technology of aryl ethers with CO2 en route to benzoic acids
