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

• alcohol derivatives. The present transformations smoothly proceed in a simple undivided cell under constant current conditions without the use of external chemical oxidants/reductants, and transition-metal catalysts. Keywords: alcohols; dimerization; electrooxidation; electroreduction; paired

New azodyrecins identified by a genome mining-directed reactivity-based screening

• Atina Rizkiya Choirunnisa,
• Kuga Arima,
• Yo Abe,
• Noritaka Kagaya,
• Kei Kudo,
• Hikaru Suenaga,
• Junko Hashimoto,
• Manabu Fujie,
• Noriyuki Satoh,
• Kazuo Shin-ya,
• Kenichi Matsuda and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2022, 18, 1017–1025, doi:10.3762/bjoc.18.102

• nitrogen radical coupling mechanism in the biosynthesis of azoxymycins [12][13], which are aromatic azoxy natural products. A similar mechanism has been envisioned for the autoxidation and spontaneous dimerization of aliphatic hydroxylamines via the azoxy linkage in malleobactin D biosynthesis [14]. A

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• ). Therefore, the 32% chemical yield (with respect to starting IL) is comparable with the yield of the batch process. Electrogenerated NHC organocatalysis. Dimerization of trans-cinnamaldehyde: synthesis of 4-phenyl-5-styryldihydrofuran-2(3H)-one Having demonstrated that NHCs could be generated and accumulated

• of the electrogenerated carbene was used to promote dimerization and oxidative esterification reactions of cinnamaldehyde. Under the flow conditions investigated, a higher rate of NHC production was achieved, compared to previously reported batch reactions, which is an important consideration for

• (s, 3H), 1.70–1.59 (m, 2H), 1.42–1.24 (m, 2H), 0.92 (t, J = 7.2 Hz, 3H) ppm; 13C NMR (CDCl3) δ 153.1, 111.3, 110.2, 43.5, 31.1, 30.5, 19.9, 13.6 ppm. General procedure for dimerization of trans cinnamaldehyde Constant current electrolyzes (I = 134 mA) were carried out using a parallel plate divided

Unusual highly diastereoselective Rh(II)-catalyzed dimerization of 3-diazo-2-arylidenesuccinimides provides access to a new dibenzazulene scaffold

• Anastasia Vepreva,
• Alexander S. Bunev,
• Andrey Yu. Kudinov,
• Grigory Kantin,
• Mikhail Krasavin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2022, 18, 533–538, doi:10.3762/bjoc.18.55

• , the formation of the spirocyclic benzoxepine was not observed. Instead, the principal product of the reaction was compound 2 (as unequivocally confirmed by the single-crystal X-ray analysis of a representative, compound 2a, see Supporting Information File 1), presumably resulting from the dimerization

• benzylidene fragment (1g) led to the deactivation of the diazo substrate ‒ after 1 hour the conversion did not exceed 30% and even after 3 days the starting DAS 1g was still present in the mixture. At the same time, only a trace amount of the expected dimerization product 2g was detected along unidentified

• showed pronounced cytotoxocity against the A549 human lung adenocarcinoma cell line while N-aryl analogs were non-cytotoxic. Previously reported transformations of DAS (1) and their unusual dimerization investigated in this work. Cytotoxicity of N-alkyl-substituted dibenzoazulenodipyrroles 2 against the

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

• Sayan Pramanik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 469–478, doi:10.3762/bjoc.18.49

• dimerization produces dispirocyclopentanebisoxindoles in a transition-metal-free protocol (Scheme 1). Results and Discussion There is extensive application of 3-phenacylideneoxindoles generating diverse reaction strategies following the regioselective and diastereoselective synthesis of carbocyclic and

• solution in the presence of K2CO3 as base. After the reaction was completed, we observed that the reductive cyclo-dimerization occurs smoothly to give the corresponding dispirocyclopentanebisoxindole 3a in 68% isolated yield with good diastereoselectivity (>95:5 dr) (Table 1). NMR and HRMS analyses confirm

Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides

• Md Imran Hossain,
• Md Imdadul H. Khan,
• Seong Jong Kim and
• Hoang V. Le

Beilstein J. Org. Chem. 2022, 18, 446–458, doi:10.3762/bjoc.18.47

• prevalent scaffold in biomedical research and drug discovery programs. We also proposed a plausible mechanism for the selectivity of the [3 + 2]-cycloaddition reaction to produce 3,4,5-trisubstituted isoxazoles. Not to be overlooked are our optimized reaction conditions for the dimerization of hydroximoyl

• . There are many possible products formed through the reaction between nitrile oxides and 1,3-diketones (Figure 2), such as the homo-coupled product (dimerization) of the nitrile oxides (Figure 2, path A) and dioxazoles through a hetero [3 + 2] cyclization as another possibility [30] (Figure 2, path B

• donors have shown important biological activities due to their unique electronic and coordination ability [37][38], such as antitumor [39] and antiparasitic [40][41]. Previously, furoxans were synthesized via dimerization of hydroximoyl chlorides in the presence of a base, such as trimethylamine in ether

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• -workers synthetized 10 using a much simpler way (Scheme 1) [80]. These authors reported the methylation and alkylation of 1,4-naphthoquinone (1) in the presence of (NH4)2S2O8 and AgNO3 as catalyst to obtain 10 in 60% yield. Recently, Onuki and co-workers conducted dimerization reactions of 10, exploring

• an interesting artifice to track the dimerization reaction path: they synthesized 2-(methyl-13C)-1,4-naphthoquinone (10) (Scheme 1) [81]. For that, sodium acetate-2-13C was used as the source of the methyl radical, generated by its treatment with K2S2O8 and AgNO3. After 3 hours at 60 °C, the 13C

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

• )indole (111). As the sulfur in 111 is methyl-protected, no dimerization occurs. Oxidation of sulfur by oxone followed by repetition of the previous steps afford the diindol-3-ylsulfonium salt 114, which in the presence of a base gives product 105a. Li et al. used 2-(fluorosulfonyl)difluoroacetic acid

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• viride, afforded xylans containing exclusively β(1–4) linkages in 72% yield [203]. Compounds with DP higher than 23 constituted the insoluble fraction (37% yield) (Scheme 7B). The combination of XynB2-catalyzed dimerization of α-ᴅ-xylopyranosyl fluoride and subsequent polymerization by XynA helped to

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• products in very low yields, varying from 27% to 3% depending on the substrate. The fluorinations were accompanied by tar formation and dimerization. Scheme 57 illustrates some representative examples. 1-26. Perfluoro-(N-fluoro-2,2,6,6-tetramethylpiperidine) and its 2,6-dimethyl analogue In 1999, the Banks

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• RNA–RNA kissing loop dimerization and RNA–protein binding [138]. Ly and co-workers developed Janus-wedge nucleobases that invade both dsDNA and dsRNA Watson–Crick base pairs from the minor groove side. At the time of writing, three Janus nucleobases, E, F, and I (Figure 9) have been reported for

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• catalyst in the reductive dimerization of aryl olefins 32 reported by van der Donk in 2002 [71]. This group showed the formation of a new C–C bond between benzylic carbons, affording compounds 33 with two vicinal quaternary carbon centers (Scheme 17). The occurrence of a radical pathway was proposed based

• tend to recombine and eventually generate benzylcobalamin in a parasite pathway. However, the presence of Ti(III) citrate reduces the Co(II) radical, thereby overcoming the “persistent radical effect” observed in cobalt-mediated radical reactions and allowing benzylic radical dimerization to afford 33

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• bisporophyrin via reaction of the starting material with PhLi followed by in situ oxidation to a radical anion and dimerization [55]. While formation of 5,10,15-trisubstituted porphyrins and 5,10,15,20-tetrasubstituted porphyrins was anticipated as side products, the detection of the title compound 4 was

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• hexamethyldisilazide was the base of choice to perform the deprotonation, and it must be added very slowly to the reaction mixture in order to suppress self-dimerization of the butenolide [72]. The structures as well as the absolute and relative stereochemistry of reaction products 30 and 31 were also unambiguously

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• Sakurai macrocyclization/dimerization strategy to produce 150 in the presence of TMSOTf, as shown in Scheme 35 [70]. Hoye and Hu utilized camphor sulfonic acid (CSA) to construct a cis-2,6-disubstituted tetrahydropyran 153 via an intramolecular Sakurai cyclization reaction between the enal 151 and an

• dimerization/macrolactonization reaction for the synthesis of cyanolide A. Hoye and Hu’s synthesis of (−)-dactyloide by intramolecular Sakurai cyclization. Minehan and co-workers’ strategy for the synthesis of THPs 157. Yu and co-workers’ allylic transfer strategy for the construction of tetrahydropyran 161

[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

• butyric acid 209. Based on this, fullerene dimer 210 with four hydrogen bonds having a very high dimerization constant was obtained (Scheme 43). Diethyl 4-oxopimelate was used as the precursor of polymer 213. The former was converted via diacid 211 to the target methanofullerene 212, the solution of which

Breakdown of 3-(allylsulfonio)propanoates in bacteria from the Roseobacter group yields garlic oil constituents

• Anuj Kumar Chhalodia and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 569–580, doi:10.3762/bjoc.17.51

• from 9, followed by a series of proposed spontaneous reactions [5][8]. Through these transformations, acid 10 can undergo a dimerization with elimination of water to allicin (5). The hydrolysis of 5 results in allylsulfinic acid (12) and allyl thiol (13), the latter of which can react with another

• molecule of 5 to yield 10 and 2. Alternatively, 5 can decompose to 10 and thioacroleine (14) by a Cope elimination, which explains the formation of the heterocycles 6 and 7 by dimerization through a [4 + 2] cycloaddition [5]. Compounds 6 and 7 were also reported to be formed from 5 during gas

• chromatographic (GC) analysis by an unknown mechanism [9] (7 was confused with its double bond regioisomer 3-vinyl-3,6-dihydro-1,2-dithiine (8) in this study [5]). Under these conditions the formation of the heterocyclic disulfides 7 and 8 may not involve a dimerization of 14, as a [4 + 2] cycloaddition is not a

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• , Vasilyev and Khoroshilova investigated the superacid-promoted activation of α-(trifluoromethyl) silyl ethers exhibiting a thiophene core [73]. At 0 °C, thiophenes 72-Cl and 72-Br undergo electrophilic dimerization, affording a mixture of 73-Cl and 73-Br (Scheme 20). When the reaction was cooled to −60 °C

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• ] and (ii) spontaneous oxidation and subsequent dimerization forming the insoluble blue 5-bromo-4-chloro-substituted indigo dye [15]. In an alternative demonstration, 1a was also used for colony level detection of FAE using yeast cells (Yarrowia lipolytica [30]) that actually coexpressed AnFaeA and

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• characterization of intermolecular dynamic processes such as protein dimerization, oligomerization and fibrillation, even within large and especially complex systems [62][63]. In a recent study, Aramini et al. employed 19F NMR to investigate the conformational dynamics within the interacting interface of non

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• instantly be disassembled by a volume-expanding photocyclodimerization and recycled for repeated use via the dimerization of 1:1 complexes. In 2018, Wu, Yang, et al. also reported the photocyclodimerization of AC with the aid of 6A,6X-diguanidio-γ-CDs [26]. The γ-CDs and AC could form stable 1:2 ternary

Supramolecular polymers with reversed viscosity/temperature profile for application in motor oils

• Jan-Erik Ostwaldt,
• Christoph Hirschhäuser,
• Stefan K. Maier,
• Carsten Schmuck and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2021, 17, 105–114, doi:10.3762/bjoc.17.11

• VII system requires a BU with strong dimerization tendency and a LU with precoordinating properties. For our purpose, we initially employed the guanidiniocarbonyl pyrrole (GCP) motif as a binding unit [19]. The GCP unit is a self-complementary zwitterion, which forms dimers with high association

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• are often difficult to separate. Another drawback of this method is the difficulty of scaling, since the reaction requires strong dilution to prevent the [2π + 2π] dimerization of the starting stilbene. Among other approaches to the carbazole-based helicenes are the Diels–Alder reaction of silyl enol

UV resonance Raman spectroscopy of the supramolecular ligand guanidiniocarbonyl indole (GCI) with 244 nm laser excitation

• Tim Holtum,
• Vikas Kumar,
• Daniel Sebena,
• Jens Voskuhl and
• Sebastian Schlücker

Beilstein J. Org. Chem. 2020, 16, 2911–2919, doi:10.3762/bjoc.16.240

• strong dimerization based on zwitterion formation at neutral pH, as described for GCP (Kdim >102 in water) [29] as well as for a GCI derivative [30], which would interfere with the anion binding. Solid benzoic acid and RGD were purchased from Fluka Analytical and Sigma-Aldrich, respectively. Both