Base‐Mediated Generation of Ketenimines from Ynamides: [3+2] Annulation with Azaallyl Anions

Under basic conditions and heat, ynamides can serve as precursors to ketenimines, whose synthetic potential is often hampered by their difficulty of access. Herein, we report that they undergo a [3+2] cycloaddition with 2-azaallyl anions, obtained from benzylimines under the same reaction conditions. This between two highly reactive intermediates, both generated in situ bench stable starting materials, gives access various nitrogen-rich heterocycles. The usually proceeds excellent diastereoselectivity, favor cis adduct. Deuteration experiments DFT calculations helped rationalize regio- stereoselectivity process well formation side products.