<p>The
Birch reduction is a powerful synthetic methodology that uses solvated
electrons to convert inert arenes to 1,4-cyclohexadienes—valuable intermediates
for building molecular complexity. This reaction historically requires
dangerous alkali metals and cryogenic liquid ammonia as the solvent, severely
limiting application potential and scalability. Here, we introduce
benzo[ghi]perylene imides as new organic photoredox catalysts for Birch
reductions performed at ambient temperature and driven by visible light. Using
low catalyst loadings (<1 mole percent), benzene and other functionalized
arenes can be selectively transformed to 1,4-cyclohexadienes in good yields.
Mechanistic studies support that this unprecedented visible light induced
reactivity is enabled by the ability of the organic photoredox catalyst to
harness the energy from two visible light photons to affect a single, high
energy chemical transformation, likely proceeding through a solvated electron.</p>
Organocatalyzed Birch Reduction Driven by Visible Light
