Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• precursors of S- and Se-inserted HBCs. The subsequent Scholl reaction allowed the formation of four new C–C bonds, but failed to afford the fully cyclized chalcogen-embedded HBC whatever the conditions tested, presumably due to large strain in line with the size of S and Se atoms as compared with O. The

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• chiral nanographenes. Keywords: chiral nanographene; helicene; racemization barrier; Scholl reaction; single-crystal X-ray diffractometry; Introduction Graphene, an allotrope of carbon, has captured widespread attention since it was first experimentally demonstrated as a monolayer of carbon atoms [1

• % yield. The Scholl reaction of compound 3 in the presence of FeCl3 and nitromethane led to the [5]helicene containing, seco-HBC-based chiral NG 4 in an 80% yield [33]. Miao and co-workers reported a twisted chiral NG 7 by a partially cyclized Scholl reaction. By treating compound 6 in 2,3-dichloro-5,6

• Scholl reaction conditions (DDQ, H+; or FeCl3, CH3NO2), the aza-[5]helicenes 22 and 24 were obtained respectively with 60% and 23% yields [38]. It was noted that with the installation of two adjacent pyrimidines in this hexarylbenzene precursor, a fully cyclized planar NG was formed toward Scholl

Direct borylation of terrylene and quaterrylene

• Haruka Kano,
• Keiji Uehara,
• Kyohei Matsuo,
• Hironobu Hayashi,
• Hiroko Yamada and
• Naoki Aratani

Beilstein J. Org. Chem. 2020, 16, 621–627, doi:10.3762/bjoc.16.58

• with AlCl3 reproducibly provided a pure terrylene [8]. Scholl reaction using a superacid catalyst in combination with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant provides a scalable preparation of quaterrylene [9], but unfortunately the low solubility prevents 1H NMR characterization

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• via 1,4-cobalt migration. The resulting 7-hydroxybenzo[b]phosphole derivative was used for further π-extension through Suzuki–Miyaura couplings and a Scholl reaction, the latter closing the triphenylene ring. The absorption and emission spectra of the thus-synthesized compounds illustrated their

• furnished the phosphole-fused ortho-teraryl products 7a–c in moderate to high yields. With the phosphole-fused ortho-teraryl compounds 7 in hand, we next examined their cyclization into triphenylene derivatives by the Scholl reaction (Scheme 3) [30]. The reaction of 7a (0.1 mmol) in the presence of [bis

• (trifluoroacetoxy)iodo]benzene] (PIFA) and BF3·OEt2 in dichloromethane at −78 °C afforded, after 12 h, the desired cyclized product 8a in 59% yield. The reaction could be performed on a 0.5 mmol scale in a similar yield of 58%. Note that other typical reagents used for the Scholl reaction, such as DDQ/CF3CO2H

Six-fold C–H borylation of hexa-peri-hexabenzocoronene

• Mai Nagase,
• Kenta Kato,
• Akiko Yagi,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2020, 16, 391–397, doi:10.3762/bjoc.16.37

• functionalizing poorly soluble compounds, functionalized HBC is typically synthesized by dehydrogenative cyclization, which is called Scholl reaction, of precursors having solubilizing substituents [12][13]. However, the Scholl reaction sometimes causes unexpected rearrangement such as 1,2-aryl shift, and

• , diethyl ether, ethanol, CH2Cl2 and CHCl3. To compare the efficiency of the current method, the stepwise synthesis of 1 was also examined. The synthesis of hexaiodoinated HBC 3 was conducted through Scholl reaction according to a literature procedure [19]. The subsequent Miyaura–Ishiyama borylation [22

• mg, 27%). 1H NMR (600 MHz, CDCl3) δ 9.78 (s, 1H), 1.61 (s, 6H). Stepwise synthesis of 1 from 3 The Scholl reaction of 2 was performed according to a literature procedure [19]. To a 1 L two-necked round bottom flask containing a magnetic stirring bar were added dichloromethane (400 mL) and compound 2