Highly Ambiphilic Room Temperature Stable Six-Membered Cyclic (Alkyl)(amino)carbenes

Cyclic (alkyl)­(amino)­carbenes with
a six-membered backbone were
prepared. Compared to their five-membered analogues, they feature
increased %Vbur and enhanced donor and
acceptor properties, as evidenced by the observed n → π*
transition trailing into the visible region. The high ambiphilic character
even allows for the intramolecular insertion of the carbene into an
unactivated C­(sp3)–H bond. When used as ligands,
they outcompete the five-membered analogues in the palladium-mediated
α-arylation of ketones with aryl chlorides.