Flash Communication: Exocyclic Alkenyl Tuning of Cyclic (Amino)carbene: Enhancing π‑Acceptor Property without Ring Unsaturation

A new type of ambiphilic singlet carbene, termed cyclic
(alkenyl)(amino)carbene
(exo-CAenAC), has been developed by replacing
the endocyclic sp3-alkyl group of classical
CAACs with an exocyclic alkenyl moiety. This structural
modification imparts enhanced π-acceptor character while preserving
a strong σ-donating ability, as supported by DFT studies. The
representative exo-CAenAC is generated in situ from a dibenzobarrelene-derived iminium salt and
can be trapped with selenium or group 9 and 11 metal precursors.