Fast Pd- and Pd/Cu-Catalyzed Direct C–H Arylation of Cyclic Nitrones. Application to the Synthesis of Enantiopure Quaternary α‑Amino Esters

Cocatalysis by pivalic acid or copper bromide allows
a very fast,
clean, and high-yielding palladium-catalyzed coupling of a large array
of aryl, thienyl, and pyridyl halides with cyclic nitrones, including
DMPO. The study of the reaction conditions, scope, and mechanism is
presented. Applied to the chiral nitrone MiPNO, this transformation
provides a straightforward access to enantiopure α-methyl α-arylglycine
esters.