Abstract
Nanographenes and polycyclic aromatic hydrocarbons (PAHs) are among the most important classes of compounds, with potential applications in nearly all areas of science and technology. While the theoretically possible number of nanographene structures is extraordinary, most of these molecules remain synthetically out of reach due to a lack of programmable and diversity-oriented synthetic methods, and their potentially huge structure-property diversity has not been fully exploited. Herein we report a diversity-oriented, growth-from-template synthesis of nanographenes enabled by iterative annulative π-extension (APEX) reactions from small PAH starting materials. The developed dearomative annulative π-extension (DAPEX) reaction enables π-elongation at the less-reactive M-regions of PAHs, and is successfully combined with complementary APEX reactions that occur at K- and bay-regions to access a variety of previously untapped nanographenes.
Highlights
Nanographenes and polycyclic aromatic hydrocarbons (PAHs) are among the most important classes of compounds, with potential applications in most areas of science and technology
While nature provides a tremendous variety of PAHs as components of fuel, coal, and tar, as well as side-products in combustion, interstellar dust, and meteorites[4,7], only an extremely limited number of pure PAHs can be reliably accessed from these natural sources due to challenges in isolation
The regioselective and direct construction of fused aromatic rings on a peripheral region of an unfunctionalized aromatic template would result in the formation of another, larger aromatic template, and repeating this protocol would grant access to diverse nanographene structures
Summary
Nanographenes and polycyclic aromatic hydrocarbons (PAHs) are among the most important classes of compounds, with potential applications in most areas of science and technology. Programmable, and potentially diversity-oriented synthetic strategy would be the “growth-fromtemplate” approach, in which nanographenes are built up from small PAH templates by regioselective, template-elongating annulative π-extension (APEX) reactions (Fig. 1b)[15]. Rearomatization of these intermediates successfully afforded the desired M-region APEX products 5aa–5ga in 59–96% yield (Step 2).
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