Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• , attracts the attention of researchers involved in the study of various types of hydrogen bonds and the problem of superbasicity [7][8]. Indeed, the basicity of quinoline and simple azaarenes is rather low. At the same time, the correct structural organization of azaarenes, where unshared electron pairs are

• of the corresponding monoprotonated forms are given). Meanwhile, the very synthesis of polycondensed quinoline bases with a certain arrangement of nitrogen atoms is often a challenge for a synthetic scientist [9][10]. This greatly limits the possible use of such polynuclear azaarenes in organic

• dinitroacenaphthylene 12. Basicity of key compounds in acetonitrile. Comparison of basicity (in water scale) and synthetic availability of quinoline-type azaarenes and "proton sponge" 1. Formation of complex 9 and its slow hydrolytic degradation into protic salt 5·HCl. Dinitration of compound 5 and the initially

Direct C(sp³)–H allylation of 2-alkylpyridines with Morita–Baylis–Hillman carbonates via a tandem nucleophilic substitution/aza-Cope rearrangement

• Siyu Wang,
• Lianyou Zheng,
• Shutao Wang,
• Shulin Ning,
• Zhuoqi Zhang and
• Jinbao Xiang

Beilstein J. Org. Chem. 2021, 17, 2505–2510, doi:10.3762/bjoc.17.167

• allylic functionalization of 2-alkylazaarenes. Due to the high pKa value of alkyl azaarenes, the functionalization of benzylic C(sp3)–H was challengeable and pre-activation of the benzylic proton with suitable Lewis acids was often required prior to deprotonation of the alkyl chain by a stoichiometric

• reported C(sp3)–H allylic substitution reactions were mainly applied on the 2-alkyl-azaarenes containing strong electron-withdrawing groups. While the reactions with inactive alkyl-aza-arenes were rare [30][31]. Kim et al. have reported a K2CO3-promoted one-pot allylation reaction of 2-alkylpyridines with

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp³)–H bond functionalization under solvent- and catalyst-free conditions

• Divya Rohini Yennamaneni,
• Vasu Amrutham,
• Krishna Sai Gajula,
• Rammurthy Banothu,
• Murali Boosa and
• Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

• 19, Kamala Nehru Nagar, Ghaziabad, UP-201002, India 10.3762/bjoc.16.259 Abstract A convenient practical approach for the synthesis of 2-(pyridin-2-yl)ethanols by direct benzylic addition of azaarenes and aldehydes under catalyst- and solvent-free conditions is reported. This reaction is metal-free

• , green, and was carried out in a facile operative environment without using any hazardous transition metal catalysts or any other coupling reagents. Different aromatic aldehydes and azaarenes were monitored, and the yields of the resulting products were moderate to excellent. We accomplished several

• azaarene derivatives under neat conditions through a highly atom-economical pathway. To evaluate the preparative potential of this process, gram-scale reactions were performed up to a 10 g scale. Keywords: aldehydes; azaarenes; benzylic addition; green chemistry; solvent-free conditions; Introduction

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• (Scheme 17c) [63]. Interestingly, they found some of their examples required the more strongly reducing photocatalyst Ir(ppy)3 to achieve high yields, although the reason for this is unclear. Jiang et al. continued to explore the reactivity landscape of CPAs and azaarenes, demonstrating that ketone 128

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

• derivatives 3.3a–d upon rearomatization. Notably, the process offers a wide substrate scope and the products are obtained with complete regioselectivity [43]. 2 Synthesis of phenanthridines or related azaarenes Under photocatalyzed conditions, phenanthridines are mostly obtained via an intramolecular radical

• reaction could be scaled up to a 10 mmol amount, allowing to obtain grams of the desired phenanthridines, which could be isolated in a pure form by a simple filtration [74]. Azaarenes different from phenanthridines (e.g., benzo[f]quinolines) could be likewise prepared by photocatalytic means. Thus, a

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

Transition-metal-free [3 + 3] annulation of indol-2-ylmethyl carbanions to nitroarenes. A novel synthesis of indolo[3,2-b]quinolines (quindolines)

• Michał Nowacki and
• Krzysztof Wojciechowski

Beilstein J. Org. Chem. 2018, 14, 194–202, doi:10.3762/bjoc.14.14

• ]quinoline 3 in 59% yield. Under these conditions other nitrobenzene derivatives 2a–e reacted similarly, giving the condensed azaarenes (4–9) in good yields. The results are summarized in Table 1. In some cases, we observed in the reaction of sulfone 1a the formation of other products. This occurred in the

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• -trifluoromethylsulfenylation did not occur with 3-substituted substrates. Other azaarenes, such as pyrrole derivatives, as well as enamines or silyl enol ethers were also compatible with these conditions, and furnished the corresponding products in moderate to good yields. The key step of the reaction comprises the formation

• of CF3SO2Cl and tricyclohexylphosphine, the trifluoromethylsulfinylation of various indole and pyrrole derivatives featuring diverse functional groups, as well as other azaarenes could be achieved in low to excellent yields (Scheme 38a). Generally, indole derivatives provided better results than

• )arenes and thiols. PPh3/NaI-mediated trifluoromethylsulfenylation of indole derivatives. PPh3/n-Bu4NI mediated trifluoromethylsulfenylation of thiophenol derivatives. PPh3/Et3N mediated trifluoromethylsulfinylation of benzylamine. PCy3-mediated trifluoromethylsulfinylation of azaarenes, amines and