Catalytic Desymmetric Cycloaddition of Diaziridines with Metalloenolcarbenes: The Role of Donor–Acceptor Cyclopropenes

A chiral copper(I) complex catalyzes reactions of symmetric diaziridines with enol diazo compounds, which react through N−N bond ring opening in a formal [3+3] cycloaddition to form four chiral centers with high stereocontrol. A broad spectrum of bridged dinitrogen heterocycles were obtained in high yields and excellent diastereo‐ and enantioselectivities from γ‐substituted enol diazoacetates, while their geometrical isomers gave different enantioselectivities. Donor–acceptor cyclopropenes formed from the geometrical isomers of the γ‐substituted enol diazoacetates underwent catalytic ring opening to give only the Z isomer of the metalloenolcarbene intermediate, provided excellent yields and selectivities for the 1,5‐diazabicyclo[n.3.1]non‐2‐ene derivatives.