posted on 2023-01-06, 18:09authored byDavid
M. Fischer, Henry Lindner, Willi M. Amberg, Erick M. Carreira
Intermolecular cyclopropanation of mono-, di-, and trisubstituted
olefins with α-bromo-β-ketoesters and α-bromomalonates under organophotocatalysis
is reported. The reaction displays broad functional group tolerance,
including substrates bearing acids, alcohols, halides, ethers, ketones,
nitriles, esters, amides, carbamates, silanes, stannanes, boronic
esters, as well as arenes, and furnishes highly substituted cyclopropanes.
The transformation may be performed in the presence of air and moisture
with 0.5 mol % of a benzothiazinoquinoxaline as organophotocatalyst.
Mechanistic investigations, involving Stern–Volmer quenching,
quantum yield determination, and deuteration experiments, are carried
out, and a catalytic cycle for the transformation is discussed.