Hydrogen Atom Transfer for C(sp3)-H Functionalization Enabled by Photoredox/Thianthrene/Methanol Synergistic Catalysis

A synergetic catalytic system of organophotocatalyst 4CzIPN, thianthrene, and methanol was developed for visible-light-induced Giese reactions of various alkanes and alkenes, upon using alkoxy radicals as hydrogen atom transfer reagents. The reaction can be performed under mild conditions to provide the alkylated products in moderate to excellent yields, avoiding the use of any strong oxidants and transition metal reagents. Different from the known LMCT and PCET processes, the key to success of this approach is the in situ thianthrenation of methanol by thianthrene radical cation to trigger the generation of methoxy radical.

Automated summary

A synergetic catalytic system utilizing organophotocatalyst 4CzIPN, thianthrene, and methanol was developed for visible-light-induced Giese reactions of various alkanes and alkenes. The use of alkoxy radicals as hydrogen atom transfer reagents allows the reaction to proceed under mild conditions, providing alkylated products in moderate to excellent yields without the need for strong oxidants and transition metal reagents. The success of this approach relies on the in situ thianthrenation of methanol by thianthrene radical cation, triggering the generation of methoxy radical.