Divergent aryne regulation for polycyclic aromatic hydrocarbons.

Arynes are straightforward and effective synthons for π-extension accompanying by vicinal difunctionalization simultaneously, thereby being ideal building blocks for polycyclic aromatic hydrocarbons (PAHs) construction. However, CC triple bond in an aromatic system, with the distorted bond angle and shortened bond distance, arouses tremendous challenges for thermodynamic stability and kinetically reactive selectivity, especially for heteroarynes. Herein, controllable aryne generation was achieved for nitrogen-doped polycyclic aromatic hydrocarbons via designed cyclic pyridine-benzene λ3-iodanes, in which the iodine ensured the thermodynamic stability and kinetic site-selectivity via p→π* interaction with aryne for chemo- and regio-selectivity. The "pyridyne-benzyne" model enabled the preeminent ortho-selectivity with nucleophilic capture and consecutive [4+2]-cycloaddition for π conjugation extension, not only assembling for N-doped PAHs with adjustable Twisted Intramolecular Charge Transfer (TICT) and inverse Suppression of Proximity Effect (SOPE) phenomenon but also establishing a reliable empirical formula for regulating generation and release of arynes.