-Scission of Secondary Alcohols via Photosensitization: Synthetic Utilization and Mechanistic Insights

An efficient metal-free photocatalytic method for the alkylation of alkenes using accessible aliphatic alcohols as redox auxiliaries is presented. C-centered radicals can be generated under mild conditions and subsequently employed in a C(sp(3))-C(sp(3)) bond-forming process, which overall provides a C1 tethering strategy of nucleophiles and electrophiles. The optimized conditions accommodate various electron-deficient alkenes and secondary/tertiary alcohols, with applications in late-stage functionalization of natural products and pharmaceutically relevant compounds. Mechanistic investigations revealed a complex mechanistic manifold, including non-PCET fragmentation and concerted/stepwise PCET. Even though the previously thought PCET type mechanism is compatible with our observations, the non-PCET mechanism most probably constitutes a main pathway.