Diversity-oriented synthesis of nanographenes enabled by dearomative annulative π-extension

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.

Rapid access to polycyclic N-heteroarenes from unactivated, simple azines via a base-promoted Minisci-type annulation

“…Furthermore, we also conducted additional substrate scope studies using quinoxaline (see also the Supplementary Information, Section 1.6.2 ). The desired products were observed, and interestingly the reactivity pattern of this radical APEX strategy involving the azine-moiety activation within the quinoxaline framework is complementary to Itami’s M -region APEX 46 that operates through a two-step dearomatization-annulation approach. This annulation protocol not only is compatible with simple azines but can also be amended to unactivated benzene to produce the PACs 25 – 32 .…”

Acenaphthenoannulation Induced by the Dual Lewis Acidity of Alumina

“…However, this method frequently suffers from unexpected rearrangements leading to undesired products [8] . Although several other methods can provide rapid π‐extension through inter‐ or intramolecular C−C coupling reactions, most developed reactions lead to alternant PAHs containing exclusively hexagons [9–16] . Meanwhile, only a handful of synthetic instruments enable the rapid synthesis of non‐alternant PAHs [17–23] …”

“…[8] Although several other methods can provide rapid π-extension through inter-or intramolecular CÀ C coupling reactions, most developed reactions lead to alternant PAHs containing exclusively hexagons. [9][10][11][12][13][14][15][16] Meanwhile, only a handful of synthetic instruments enable the rapid synthesis of non-alternant PAHs. [17][18][19][20][21][22][23] Thus, the incorporation of pentagons into the hexagonal lattice is accompanied by strain energies related to the deviation of the valence angles leading to the positive Gaussian curvature.…”

Diels–Alder Cycloaddition with CO, CO2, SO2, or N2 Extrusion: A Powerful Tool for Material Chemistry

“…The application possibilities listed above have been discussed in this review. Particular attention is paid to nanographenes, including functionalized and heteroatoms-doped ones, which preparation and new applications constitute a “hot topic” in science and technology [ 6 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ]. Currently, only bottom-up methods, where nanographene is constructed from smaller entities by stepwise organic synthesis, allow the preparation of nanographenes, including functionalized and doped ones, with perfect control of shapes and sizes and, therefore, perfectly defined properties [ 2 , 5 , 6 , 11 , 12 ,…”

“…The reactions presented in this review fit perfectly into the previously mentioned synthetic strategy. It should be added that nanographenes (graphenoids), obtained via reactions discussed in this review, can be planar or otherwise distorted, that is, non-planar, one- (1D), two- (2D), and three-dimensional (3D) [ 6 , 11 , 12 , 17 , 23 , 24 , 25 , 26 , 36 , 38 , 40 , 43 , 46 , 47 , 49 , 52 ]. Graphenoids with planar sheets of varying size, shape, and periphery have made great progress in practical applications of electronics, energy storage, catalysis, and biosensing [ 6 , 11 , 12 , 14 , 15 , 16 , 17 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 42 , 44 , 47 , 50 , 52 , 53 ].…”