E/Z Isomerization-Enabled Conversion from Dual-Carbon to Single-Carbon Insertion into an Aromatic System

Divergent skeletal modification of aromatic systems is essential for generating molecular diversity, but it remains a significant challenge, typically relying on different individual strategies and starting materials. Herein, we report a tunable dual-to-single carbon insertion into an σ-aromatic metalla-cyclopropene. The key to this approach lies in an E/Z isomerization of two intermediates, in which the E-isomer undergoes dual-carbon insertion and the Z-isomer engages in single-carbon insertion of alkyne into the three-membered ring, proceeding via common [3+2] and unconventional [3+1] pathways, respectively. Both pathways originate from identical reagents, with E-to-Z isomerization of the intermediate achieved by easily modulating the timing of alkyne addition. This work highlights the pivotal role of E/Z isomerization in controlling the reaction selectivity and establishes a new paradigm for temporal control divergent skeletal editing.