A new class of N-doped ionic PAHsviaintramolecular [4+2]-cycloaddition between arylpyridines and alkynes

Abstract

Reported herein, for the first time, is a copper-promoted intramolecular [4+2]-cycloaddition cascade to access ionic N-doped polycyclic aromatic hydrocarbons (PAHs) with tunable emission wavelengths.

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

“… Reagents and conditions: (a) 514 EtOH, reflux, 1 h; (b) N 2 H 4 ·H 2 O, EtOH, reflux, 8 h; (c) 515 Cu(OTf) 2 (100 mol %), MeCN, 80 °C, 12 h; (d) Cu(OTf) 2 (10 mol %), Selectfluor (1.0 equiv), MeCN, 80 °C, 12 h; (e) 517 ortho -phenylenediamine (2.5 equiv), Na 2 CO 3 (3 equiv), Cu(OAc) 2 (0.1 equiv), i -PrOH/ethylene glycol (9:1), argon, reflux, 16 h; (f) TsOH·H 2 O (0.1 equiv), EtOH, reflux. …”

“…In 2018, Patil et al developed a library of cationic nitrogen-doped polycyclic arenes via copper-promoted intramolecular [4 + 2] cycloaddition cascade. 515 Upon heating with an equimolar amount of Cu(OTf) 2 in acetonitrile, 274.5 was transformed to the doubly cyclized quaternary ammonium salt [ 274.6 ][OTf] in 60% yield ( Scheme 274 ). When an external oxidant (Selectfluor) was added, the use of a catalytic amount of Cu(OTf) 2 sufficed to mediate the same bicyclization to give [ 274.6 ][BF 4 ] in a similar yield.…”

1,2‐Aminofunctionalization Reactions of Pyridino‐Alkynes via Carbophilic Activation

“…[38] Drawing an analogy from these reports, we understood that our designed substrate 39 (R = Ar') is acting as an azadiene surrogate and undergoing an intramolecular copper-mediated ). [39] Having a constructive conception from our previous achievements, we have proposed that the substrate 41 could undergo a carbophilic activation by Cu(OTf) 2 and thereby, instigate a nucleophilic attack from the pyridyl nitrogen atom in 5-exo-dig fashion to generate vinyl copper intermediate 43 (Scheme 14). This intermediate then activates the CÀ H bond of the proximal aryl ring and a subsequent generation of a seven-membered cyclic copper(II) intermediate 44 takes place with the removal of TfOH.…”

Bottom-Up Synthesis of Nitrogen-Doped Polycyclic Aromatic Hydrocarbons

“…Therefore, this N-doped motif results in a cationic nitrogen species, which alters the electron density at the Fermi level and has a tremendous influence on tailoring the optical and electronic structures of graphene. [76][77][78][79][80][81][82][83][84] Cationic N-doped nanographenes (CNDNs) with planar structures have been synthesized as mentioned in section 2, such as PAMY, 4…”