Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• ) derivative (Figure S2 in Supporting Information File 1). The lower yield of 2b compared to 2a is probably due to the [2 + 2 + 2] homocoupling cycloaddition of the corresponding starting diyne, which is more favorable when the tether is a malonate rather than an NTs-sulfonamide. Among the four different [6,6

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• copper(I) iodide in DMF/DIPEA solution at 55 °C with subsequent desilylation with potassium carbonate. Finally, butadiyne 6 was prepared by a homocoupling reaction of 5 with 80% yield. Derivatives containing two dicyanopyridyl moieties, 7 and 8, were prepared starting with a Sonogashira coupling of

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• the reaction used to complete rotaxane synthesis, hence the name “active template”. This strategy was first applied by Saito and co-workers [35], using a Cu(I) template to catalyze a Glaser coupling reaction. The method has been extended for other reactions, for example Ni-catalyzed homocoupling of

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• yields (Scheme 28). In this reaction, Grignard reagent 148 was used as arylation source in excess amount as the reagent underwent homocoupling leading to the formation of biaryl systems under the reaction conditions. 1,2-Dichloro-2-methylpropane (149) was found to be an effective oxidant under the

• reaction conditions. Also, the additive KF was employed in order to minimize the oxidative iron-catalyzed homocoupling of 148. An imine directing group at the para-position in pyridine 147 lead to activated ortho-position products 150 within 15 minutes. The imine group of the products can further be

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• shows the most positive oxidation potential and rate of the first oxidation as well as the lowest rate of reduction. However, the relatively small differences may simply be due to the different local solvation of the CF3 substituent. Conclusion Glaser–Hay homocoupling of 2-ethynyl-7-(arylethynyl)-1,8

Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry

• Eric Gayon,
• Guillaume Lefèvre,
• Olivier Guerret,
• Adrien Tintar and
• Pablo Chourreu

Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15

• described an elegant aryl–aryl cross-coupling procedure suppressing the formation of Grignard homocoupling byproducts relying on the use of FeF3 as catalyst, associated with strong N-heterocyclic carbenes (NHCs) and a source of fluoride anions [28]. A similar procedure involving sodium alkoxide additives

Electrochemical formal homocoupling of sec-alcohols

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masashi Shiota,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2022, 18, 1062–1069, doi:10.3762/bjoc.18.108

• ][16][17][18]. In addition to the reductive coupling of carbonyl compounds, oxidative homocoupling reactions of benzyl alcohols under transition metal- or semiconductor-based photoredox catalysis have been demonstrated as attractive approaches to access vic-1,2-diols [19][20][21][22][23

• formal homocoupling of benzhydrol did not occur under Kim’s reaction conditions. Thus, the development of an environmentally benign and efficient electrochemical protocol to access vic-1,2-diols would be still highly desirable. Herein, we report the sacrificial anode-free electrochemical synthesis of vic

• -1,2-diols through the formal homocoupling of sec-alcohols using platinum electrodes in an undivided cell (Scheme 1c). Results and Discussion We commenced the optimization study for the electrochemical formal homocoupling of sec-alcohols by using 1-phenylethanol (1a) as a model substrate. The results

Synthesis, optical and electrochemical properties of (D–π)₂-type and (D–π)₂Ph-type fluorescent dyes

• Kosuke Takemura,
• Kazuki Ohira,
• Taiki Higashino,
• Keiichi Imato and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106

• with two (diphenylamino)carbazole-thiophene units as D (electron-donating group)–π (π-conjugated bridge) moiety and the (D–π)2Ph-type fluorescent dye OTK-2 with the two D–π moieties connected through a phenyl ring were derived by oxidative homocoupling of a stannyl D–π unit and Stille coupling of a

• fluorescence quantum yield (Φfl) of OTK-2 are comparable to those of the (D–π)2A-type fluorescent dyes. More recently, we found that the (D–π)2-type fluorescent dye OTT-2 consisting of two D–π moieties is derived by oxidative homocoupling of a stannyl D–π unit. There is an obvious structural difference between

• 1 with 1,3-diiodobenzene and oxidative homocoupling of 1, respectively (Scheme 1). The photoabsorption and fluorescence spectra of OTK-2 and OTT-2 in toluene are shown in Figure 1a,b, and their optical data are summarized in Table 1. As shown in insets of Figure 1a,b, the toluene solutions of OTK-2

Synthesis of novel alkynyl imidazopyridinyl selenides: copper-catalyzed tandem selenation of selenium with 2-arylimidazo[1,2-a]pyridines and terminal alkynes

• Mio Matsumura,
• Kaho Tsukada,
• Kiwa Sugimoto,
• Yuki Murata and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 863–871, doi:10.3762/bjoc.18.87

• of Cu(I). As an alternative route, we also surmise that Cu–acetylide E attacks intermediate A to produce intermediate D. Although this reaction was performed under aerobic conditions, Glaser-type homocoupling of terminal alkynes did not occur, and no diynes were observed as byproducts. Moreover, the

Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry

• Koji Kubota,
• Emiru Baba,
• Tamae Seo,
• Tatsuo Ishiyama and
• Hajime Ito

Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86

• no homocoupling product of 1a was formed, or only trace amounts (<1%) were formed in all cases. Under the optimized reaction conditions (Table 1, entry 1), we explored the substrate scope of aryl bromides for the solid-state borylation (Scheme 2). The reactions of aryl bromides bearing electron

Unexpected chiral vicinal tetrasubstituted diamines via borylcopper-mediated homocoupling of isatin imines

• Marco Manenti,
• Leonardo Lo Presti,
• Giorgio Molteni and
• Alessandra Silvani

Beilstein J. Org. Chem. 2022, 18, 303–308, doi:10.3762/bjoc.18.34

• products we disclosed the efficient homocoupling of oxindole-based N-tert-butanesulfinyl imines, with the generation of chiral, quaternary 1,2-diamines in a mild and completely stereoselective way. The obtained 3,3′-bisoxindole derivatives were fully characterized by NMR and single-crystal X-ray

• diffraction analysis and proved to be single diastereoisomers and atropisomers. A plausible mechanism for the one-pot Cu(II)-catalyzed Bpin addition to the isatin-derived ketimine substrate and subsequent homocoupling is described. Keywords: atropoisomer; bis(pinacolato)diboron; 3,3′-bisoxindole; N-tert

• -butanesulfinyl ketimine; homocoupling; Introduction As bioisosteres of carboxylic acid derivatives, boronic acids have recently emerged as a novel chemotype in drug design, with a number of boron-containing compounds recently being approved by the FDA [1][2][3][4]. In particular, α- and β-aminoboronic acids are

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• various acetylenes. With regard to alkynes, 1-chloro-4-ethynylbenzene and 1-bromo-4-ethynylbenzene were found suitable substrates, which provided good to excellent yields of the products, and no homocoupling was observed in any reaction. Shim and co-workers demonstrated an efficient iron powder/CuI

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• catalyst amount. Several attempts were performed showing that a low concentration of the catalyst was required to avoid the formation of elevated amounts of homocoupling and side products. We found that reducing the amount of Pd(PPh3)4 from 5 mol % to 1 mol % gave higher yields of 2,4-diphenyl-9-chloro

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• the sulfur species 102 takes place to generate copper sulfide complex 103. An oxidative homocoupling gives the bis(indol-3-yl)sulfide 101. Simultaneously, an oxidative homocoupling of the copper sulfide complex can take place to afford disulfide 104, that reacts with N-methylindole again under

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• (R)-tylocrebrine (32) and (R)-tylophorine (33), which were found to display antiproliferative activity in the nanomolar range against human colorectal carcinoma, human breast carcinoma and drug-resistant human ovarian adenocarcinoma cell lines. Methods for the oxidative homocoupling of phenolic

• molecules of substrate together. In addition, the high enantiopurity was ascribed to a chiral environment that presents three elements of asymmetry. Other examples of vanadium-mediated oxidative homocouplings of phenolic substrates include regioselective and asymmetric homocoupling of phenols and 2

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• initial studies showed the formation of significant amounts of protodeborylation products, small amounts of boronic acid homocoupling products, and the corresponding phenols as boronic acid oxidation products. To optimise the yields, the amount of the boronic acid was increased to 3 equiv, which was added

• was chosen DMF, although the use of polar aprotic solvents usually leads to products of the oxidative Heck reaction. The authors noticed a significant reduction of Pd(II) to Pd(0) (by secondary processes such as oxidative homocoupling or oxidation of boronic acid to the corresponding phenol). The Pd(0

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• oxidative hetero- and homocoupling of 217, respectively. It is also noted that dumbbell-like fullerene-containing compound 219 is the first example of a dimeric fullerene that was fully characterized. Conclusion Summarizing our analysis of scientific literature on [2 + 1] cycloaddition reactions to C60

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• subsequently cross-linked by oxidative homocoupling to form a highly cross-linked polymer [138]. Zhang and co-workers recently demonstrated that the dispersibility of polymer nanoparticle-supported benzothiadiazole photocatalysts could be improved in a range of different solvents by copolymerising classical

Distinctive reactivity of N-benzylidene-[1,1'-biphenyl]-2-amines under photoredox conditions

• Shrikant D. Tambe,
• Kwan Hong Min,
• Naeem Iqbal and
• Eun Jin Cho

Beilstein J. Org. Chem. 2020, 16, 1335–1342, doi:10.3762/bjoc.16.114

• ]. Among these diverse applications, the Rueping group has reported excellent examples of the reductive umpolung homocoupling of imines and heterocoupling with α-amino radicals for the synthesis of symmetrical and unsymmetrical vicinal diamines (Scheme 1b) [23][26]. Notably, 1,2-diamines have widespread

• the formation of mixtures of several types of amine compounds. A photochemical quantum yield, determined by using the standard ferrioxalate actinometry, was 83% for the radical cross-coupling between 1a and Cy2NMe (see Supporting Information File 1 for details). Next, the homocoupling reactions of

• electron density or position of the substituent on the benzylidene moiety. Interestingly, the homocoupling process was highly stereoselective, resulting in the formation of only one diastereomer, probably due to the bulky substitution pattern of the substrates. The structure of the homocoupled 1,2-diamine

Palladium-catalyzed regio- and stereoselective synthesis of aryl and 3-indolyl-substituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones

• Valeria Nori,
• Antonio Arcadi,
• Armando Carlone,
• Fabio Marinelli and
• Marco Chiarini

Beilstein J. Org. Chem. 2020, 16, 1084–1091, doi:10.3762/bjoc.16.95

• , various functional groups such as amino, acetamido, F, Cl, OMe, CF3, and CN moieties were found to be compatible with these reaction conditions, and only the homocoupling of the arylboronic acids was observed as side reaction to some extent [42]. The best results were obtained with arylboronic acids

Synthesis and anticancer activity of bis(2-arylimidazo[1,2-a]pyridin-3-yl) selenides and diselenides: the copper-catalyzed tandem C–H selenation of 2-arylimidazo[1,2-a]pyridine with selenium

• Mio Matsumura,
• Tsutomu Takahashi,
• Hikari Yamauchi,
• Shunsuke Sakuma,
• Yukako Hayashi,
• Tadashi Hyodo,
• Tohru Obata,
• Kentaro Yamaguchi,
• Yasuyuki Fujiwara and
• Shuji Yasuike

Beilstein J. Org. Chem. 2020, 16, 1075–1083, doi:10.3762/bjoc.16.94

• experiments, a plausible double selenation mechanism is shown in Scheme 2 and Scheme 3. The first step of the reaction involves the generation of the intermediate B via A by the Cu-mediated electrophilic substitution of 1 with selenium. The oxidative homocoupling of the intermediate B then proceeds to give

Palladium-catalyzed Sonogashira coupling reactions in γ-valerolactone-based ionic liquids

• László Orha,
• József M. Tukacs,
• László Kollár and
• László T. Mika

Beilstein J. Org. Chem. 2019, 15, 2907–2913, doi:10.3762/bjoc.15.284

• the product isolation procedure. In addition, it is well-established that the presence of Cu(I) salt can promote the in situ formation of some Cu(I) acetylides, which can readily undergo oxidative homocoupling of alkynes even in their slight excess in the reaction mixture [15][38][39]. Thus, the

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• high level of functional group compatibility, intramolecular alkylations, inter and intramolecular C–H bond activation and regio/stereoselective homocoupling of alkynes [71][72][73]. Group of Cho and Chang have unprecedentedly reported a Rh catalytic system for facile addition of heteroarenes to both

• this methodology resulted in homocoupling of bromoalkynes. Among the examined Cu(I) and Cu(II) salts, Cu(OTf)2 was proven to be the optimal one. Both EW and EDGs were well tolerated except 2-amino-6-methylpyridine which might be sterically hindered due to methyl group at 6-position. The use of

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• minor amount of homometathesis. Fortunately, the product of homocoupling could be easily separated from the desired CM products. The presence of the carborane clusters was shown to enhance the thermal stability of the materials. Absorption and emission data of carborane–POSS hybrids indicate a large red