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

• benzannulation of diacetylene 42 in an 85% yield. The final NG 44 formed by treating compound 43 with DDQ/TfOH at 0 °C and the overall structure exhibits interesting photophysical and antiaromatic properties [45]. During the final Scholl reaction, an monoiodide structure 101 was also isolated (Scheme 11). In the

Synthesis of N-phenyl- and N-thiazolyl-1H-indazoles by copper-catalyzed intramolecular N-arylation of ortho-chlorinated arylhydrazones

• Yara Cristina Marchioro Barbosa,
• Guilherme Caneppele Paveglio,
• Claudio Martin Pereira de Pereira,
• Sidnei Moura,
• Cristiane Storck Schwalm,
• Gleison Antonio Casagrande and
• Lucas Pizzuti

Beilstein J. Org. Chem. 2022, 18, 1079–1087, doi:10.3762/bjoc.18.110

• cycloaddition reaction of α-diazomethylphosphonates with o-(trimethylsilyl)phenyl triflate in the presence of CsF [13], Cu2+-mediated N−N bond formation from ketimines in the presence of oxygen [14], Pd2+-mediated oxidative benzannulation from pyrazoles and internal alkynes [15], Pd-catalyzed Aza–Nenitzescu

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• substituted anthracenes by the regioselective oxidative benzannulation of 1-adamantyl-1-naphthylamines 10 with internal alkynes 11 (Scheme 2) [35]. To the best of our knowledge, this was the first successful example of rhodium-catalyzed benzannulation reactions of N-adamantyl-1-naphthylamines. Reactions of 10

• -phenanthrene derivatives 152, also in excellent yields (91–98%) [68]. In 2015, Gribble et al. published a new method to synthesize dibenzo[a,c]anthracene (158) based on a triple benzannulation of naphthalene derivative 153 via a 1,3,6-naphthotriyne synthetic equivalent 155 (Scheme 35) [69]. First, reaction of

• oxidative benzannulation reactions of 1-adamantoyl-1-naphthylamines with internal alkynes. Gold/bismuth-catalyzed cyclization of o-alkynyldiarylmethanes. [2 + 2 + 2] Cyclotrimerization reactions with alkynes/nitriles in the presence of nickel and cobalt catalysts. Cobalt-catalyzed [2 + 2 + 2

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• only slightly red-shifted. The effect of benzannulation in 19 compared to H-SN4 13 as well results only in small differences, which, however, become larger in comparison to hexacyclic heteroacene 22 showing the largest bathochromic shift in the series (Figure S6, Supporting Information File 1). The

• , but substantially higher than this for SN6 (Epox1 = 0.06 V) [7][37] clearly showing the effect of the two-fold benzannulation. From the optoelectronic data a schematic energy level diagram of the frontier orbitals and the optical transitions in the series can be derived (Figure 3). The HOMO energy

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• synthesis of phenanthridines. Synthesis of phenanthrenes by a photo-Pschorr reaction. Synthesis of phenanthrenes by a benzannulation reaction. Photocatalytic cyclization of α-bromochalcones for the synthesis of phenanthrenes. General scheme describing the synthesis of phenanthridines from isocyanides via

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• twofold [3 + 2] cyclopentannulation and subsequent twofold [4 + 2] benzannulation. The structure of 1 is unambiguously confirmed by X-ray crystallography; 1 adopted a twisted geometry due to the steric hindrance of the phenyl rings and the hydrogen substituents at the bay regions. Notably, compound 1

• [4 + 2] benzannulation, instead of the desired tetracyclopenta[cd,fg,jk,mn]pyrene (2). The selective formation of 1 could be rationalized by the steric hindrance of the phenyl rings after the twofold [3 + 2] alkyne pentannulated intermediate (Scheme S2, Supporting Information File 1), and the sequent

• the narrower energy gap of 1 (2.24 eV). Conclusion In summary, we demonstrated the first synthesis and characterization of a dicyclopenta-fused peropyrene 1 starting from pyrene in four steps in which the twofold pentannulation and subsequent twofold benzannulation based on 1,3,6,8-tetrabromo-2,7

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• . Benzotropolones Benzannulation to the tropolone scaffold can give numerous tautomeric hydroxybenzotropones or benzotropolenes. Figure 10 shows 238A (or 241A–240) as single tautomers, whereas 239 and 174 are depicted as a mixture of tautomers. Moreover, benzenoid structures as 238A are more stable than o-quinoidal

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• synthesis of 2,3-disubstituted furans 210 (Scheme 60) [330]. The benzannulation of indoles 211 can be performed with γ-carbonyl tert-butyl peroxides 212 catalyzed by trifluoromethanesulfonic acid to give carbazoles 213. The key step of this approach is based on the acid-catalyzed rearrangement of tert-butyl

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• ) using the McMurry coupling (Figure 8). Pd(0)-catalyzed cross-coupling reaction: In 1997, Yamamoto and co-workers [122] have synthesized the exomethylene paracyclophane 108 via intramolecular benzannulation of conjugated enynes in the presence of palladium(0). In this regard, dibromoalkane 103 was

• -workers [188] have reported the synthesis of the naphthalene-diimide-based cyclophane 311 for understanding supramolecular interactions by metal ions (Figure 11). [3 + 2 + 1] Cycloaddition (Dötz benzannulation): In 2003, Wulff and co-workers [189] synthesized cyclophane derivatives using the Dötz

• benzannulation as a key step. They found that the Fischer carbene complex 314 in a coordinating solvent such as THF lead to the products 312 (15%) and 313 (42%) whereas a non-coordinating solvent like benzene delivered products 315 (40%) and 316 (21%, Scheme 54). Wulff and Wang [190] have synthesized [6,6

Synthesis and structure of tricarbonyl(η⁶-arene)chromium complexes of phenyl and benzyl D-glycopyranosides

• Thomas Ziegler and
• Ulrich Heber

Beilstein J. Org. Chem. 2012, 8, 1059–1070, doi:10.3762/bjoc.8.118

• reactions [9][10][11][12]. Tricarbonylchromium complexes of type C and D were obtained via benzannulation of glucal-derived pentacarbonylchromium carbenes or by reaction of alkynyl C-glycosides with pentacarbonylchromium carbenes [13]. Further syntheses and characterizations of more examples of carbohydrate

Valence isomerization of cyclohepta-1,3,5-triene and its heteroelement analogues

• Helen Jansen,
• J. Chris Slootweg and
• Koop Lammertsma

Beilstein J. Org. Chem. 2011, 7, 1713–1721, doi:10.3762/bjoc.7.201

• the computed structure of cyclohepta-1,3,5-triene (1; α = 52.9°, β = 25.4°) [14]; The MP2/6-31G(d) optimized geometry of the parent thiepine (5) (α = 50.3° and β = 30.8°) [40] is similar to that of the molecular structure of 17 [76]. Benzannulation of the thiepine ring on both sides results in the

• decomposition of the bicyclic phosphanorcaradiene (10) into benzene and phosphinidene R–P [100]. However, the 7-membered ring can be stabilized by phosphorus oxidation (30; see Figure 4) [95], the introduction of bulky substituents at the 2 and 7 positions (31) [101], or benzannulation (e.g., 3H

• +G(d,p) level [7]. Also for the phosphepine system [108], benzannulation leads to interesting targets. Namely, the thermal lability of the transition-metal-complexed 3H-benzophosphepine 33 was explored by Lammertsma et al. for the synthesis of a variety of organophosphorus compounds by means of [1

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• evolves through different pathways depending on the catalyst and on the reaction components. The reaction therefore can provide a variety of interesting polycyclic systems. For example, Yamamoto reported in 2002 a AuCl3-catalyzed formal (4 + 2) [23] benzannulation between ortho-alkynylbenzaldehydes of

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• benzannulation of 3-alkoxy-1,5-enynes 236 to produce functionalized benzenes 237 [112]. The reaction occurs selectively through a 6-endo-dig pathway to give tri- and tetrasubstituted benzenes efficiently. Cyclization reactions of 1,6-diynes (2,2-dipropargylmalonates 238) could be achieved with gold(I) catalysts

Gold film- catalysed benzannulation by Microwave- Assisted, Continuous Flow Organic Synthesis (MACOS)

• Gjergji Shore,
• Michael Tsimerman and
• Michael G. Organ

Beilstein J. Org. Chem. 2009, 5, No. 35, doi:10.3762/bjoc.5.35

• of catalysing benzannulation reactions. The cycloaddition precursors are flowed through these capillaries while the metal film is being heated to high temperatures using microwave irradiation. The transformation can be optimized rapidly, tolerates a wide number of functional groups, is highly

• regioselective, and proceeds in good to excellent conversion. Keywords: benzannulation; flow synthesis; gold catalysis; microwave; thin metal film; Introduction Microwave-assisted organic synthesis (MAOS) has had a significant impact on organic and medicinal chemistry by dramatically shortening reaction times

• exploring complex, multi-step catalytic processes in flow. The benzannulation reaction between aromatic carbonyls and alkynes has received increasing attention since 2002 [29][30]. This transformation has been shown to be promoted by Lewis acids, copper complexes [31] and various gold species, including Au