β-Keto radicals can be readily generated from single-electron oxidation and ring opening
of cyclopropanols. Herein, we report new ways of trapping β-keto radicals derived
from Mn(III)-mediated oxidative cyclopropanol ring opening with biaryl isonitriles
and N-aryl acrylamides derived from anilines. Through tandem radical cyclization processes,
substituted phenanthridines and oxindoles can be synthesized in one step and good
to excellent yield. These new synthetic methods feature broad substrate scope and
mild reaction conditions, efficiently form two carbon–carbon bonds, and use cheap
and commercially available manganese salts as oxidants. Concomitant installation of
ketone functionality in the final products provides a handle for further functionalization
of these important and biologically relevant scaffolds.
Key words
cyclopropanol - radical - phenanthridine - oxindole - manganese
