Photoredox-Catalyzed Deaminative Alkylation via C–N Bond Activation of Primary Amines

Primary
amines are often cheap, naturally occurring, and chemically
diverse starting materials. For these reasons, deaminative functionalization
of amines has emerged as an important area of research. Recent advances
in C–N activation transform simple α-1° and α-2°
amines into alkylating reagents via Katritzky pyridinium salts. We
report a complementary method that activates sterically encumbered
α-3° primary amines through visible light photoredox catalysis.
By condensing α-3° primary amines with electron-rich aryl
aldehyde, we enable an oxidation and deprotonation event, which generates
a key imidoyl radical intermediate. A subsequent β-scission
event liberates alkyl radicals for coupling with electron-deficient
olefins for the generation of unnatural γ-quaternary amino acids
and other valuable synthetic targets.