Assembly of Amino Acid Derivatives via Energy Transfer-Driven Photochemical Rearrangement

The development of synthetic methods to access amino
acid derivatives
remains a high priority. Herein, we report a photocatalytic strategy
based on triplet energy transfer that drives a photochemical rearrangement
to furnish diverse amino acid derivatives bearing epoxide functionality
in good yields. This operationally simple protocol employs a commercially
available organophotocatalyst and visible-light irradiation. Mechanistic
and computational studies corroborate a reaction pathway involving
diradical formation, a 1,4-nitrogen migration, and a 1,3-diradical
recombination. This oxa-di-π-methane (ODPM) rearrangement provides
a route to unnatural amino acid scaffolds and establishes a direction
for energy-transfer-driven photochemical synthesis.