Synthesis of Chiral Diazocine Derivatives via a Copper-Catalyzed Dearomative [5+3] Cycloaddition.

Copper-catalyzed [5+3] cycloaddition of N-aromatic zwitterions and enol diazoacetates produced enantio-enriched diazocine derivatives. A sterically encumbered BOX ligand and NaBArF additive played significant roles in driving the overall catalytic process via the unfavorable dearomatization to construct the desired eight-membered heterocyclic compounds. The induced stereoselectivity was preserved after further modifications of the skeleton, which demonstrates the potential applications of the developed asymmetric catalysis.