Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• using metal complexes as switching units (Figure 20). This concept named “weak link approach” (WLA) [78] uses square planar d8-transition metal complexes with two hemilabile bidentate ligands composed of a strong binding site (phosphorus) and a weaker one (generally sulfur, oxygen, selenium, or nitrogen

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

• thiepines were progressively isolated as a result of very diverse synthetic strategies [46][47][48][49], which were further applied to the preparation of stable selenepines and tellurepines [50][51][52][53]. Extrusion reactions from sulfur-, selenium- and tellurium-containing compounds have long been

• helical S- and Se-doped seco-HBCs 28b and 28c were thus obtained as racemic mixtures in three steps from dibenzoheteropines 23b and 23c in 45% and 18% overall yield, respectively. To evaluate the impact of the heteroatom oxidation state on reactivity, the sulfur and selenium oxides were next prepared via

• design of pentacene’s soluble precursor, as reported by Müllen and Herwig [14], is depicted in the top left. Valence isomerization of chalcogen heteropines and subsequent cheletropic extrusion in the case of sulfur, selenium and tellurium derivatives. Early example of phenanthrene synthesis via a

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• cyclization transformation involving activation of the electrophilic sulfur reagent by PhSePh with the assistance of TMSOTf to form transition state I. Intermediate II formed through capturing of sulfonium by selenium. Then, II reacted with 136 to give regioselective cyclic thiiranium ion III. Nucleophilic

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

• . And the derivative 16 was also synthesized by allylic oxidation of compound 15 using selenium dioxide. As helical chiral NGs, helicene 14 and its derivatives 15 and 16 showed highly distorted helical conformation and also exhibited a relatively high isomerization barrier (over 28.9 kcal/mol determined

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• phenotellurazine 7c were isolated in lower yields of 16% and 6%, likely due to undesired oxidations of selenium and tellurium [38]. Substitutions with nitrogen nucleophiles were performed, giving the N-phenylphenazine 8 in 26% yield [39][40] and the N-tosyl derivative 9 in 18% yield [41]. Anion exchange reactions

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• drastically the radical stability, nucleophilicity, and selectivity of 139 [73]. Furnishing of the common scaffold 130 can be carried out via an attack of intermediates of this type (e.g., 139) on Michael acceptors. Tosyl group deprotection of 130, followed by selenium anhydride oxidation and catalytic

Dienophilic reactivity of 2-phosphaindolizines: a conceptual DFT investigation

• Nosheen Beig,
• Aarti Peswani and
• Raj Kumar Bansal

Beilstein J. Org. Chem. 2022, 18, 1217–1224, doi:10.3762/bjoc.18.127

• of 1-aza-2-phosphaindolizines 3 with DMB and isoprene occurred at rt, although slowly and were speeded up by the use of sulfur or selenium which oxidized the phosphorus atom of the initially formed product thereby pushing the reaction in the forward direction [14]. The difference in the reactivities

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

• reagents and 1,3-dipolar azide–alkyne cycloaddition based on the alkyne moiety. Keywords: alkynyl imidazopyridinyl selenide; copper catalyst; imidazo[1,2-a]pyridine; selenium; tandem reaction; terminal alkyne; Introduction Imidazo[1,2-a]pyridines are important heterocycles that serve as key functional

• . Experimental General procedure for the synthesis of alkynyl imidazopyridinyl selenides A solution of 2-phenylimidazo[1,2-a]pyridine (1a, 1.0 mmol), selenium powder (79 mg, 1.0 mmol, 1 equiv), CuI (14 mg, 0.1 mmol, 10 mol %) and 1,10-phenanthoroline (18 mg, 0.1 mmol, 10 mol %) in DMSO (3 mL) was heated at 130

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• , regioselective double oxidative photocyclization was observed during the construction of three S-shaped double helicenes DH-1–3 based on thiophene/selenophene. From DH-1 to DH-3, sulfur atoms in the molecular framework were gradually replaced by selenium atoms. The crystal structures of DH-1 and DH-2 and

• DH-1 and DH-2 are shown in Table 1. The replacement of sulfur with selenium in DH-1 and DH-2 leads to turn angles in-plane and helix climbs of [5]helicene and [6]helicene of DH-1 and DH-2 significantly change (Table 1, Figure 3). Each of the two DH-1 molecules (blue and red molecules in Figure S3 of

• occur with increasing number of selenium atoms. In band-I, compounds DH-1–3 show a maximum absorption peak at 232, 240, and 242 nm, respectively. In band-II and band-III, helical distortion and possible conjugation through heteroatoms (e.g., sulfur and selenium atoms) in DH-1–3 may increase π-electron

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

• catalytic activity of selenium mesoporous molecular sieves (SeMCM-41) in the oxidation of 16 (Table 1, entry 10). The approach was performed using H2O2 as oxidant in acetic acid over SeMCM-41 (Si/Se = 30) at 100 °C [56]. In this case, a conversion of 99% was achieved and menadione (10) was obtained with 68

• % selectivity. According to the authors, the reaction mechanism involves the formation of an active selenium peroxo species. Additionally, they mentioned that the catalyst was easily separated from the reaction mixture by simple filtration [56]. Serindağ and co-workers disclosed the bidentate tertiary

• respective ditellurides, a disulfide and a diselenide (Scheme 27). Recently, Ribeiro and co-workers used menadione as a nucleophile for the synthesis of 3-chloromethylated menadione 84, a key intermediate used to prepare selenium-menadione conjugates 86 [128]. In this work, compound 84 was prepared through

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• complex or active nucleophiles. In 2014, Jacobsen et al. developed a highly enantioselective selenocyclization reaction of olefins 26, using the chiral squaramide 28 as a dual hydrogen bond donor (Scheme 6) [16]. Although early-stage enantio-enrichment during the introduction of selenium is hard to

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

• , nitrogen, oxygen, silicon, phosphorus, sulfur, selenium, and tellurium. This review will skip the reports on the corresponding carbon-centered analogs. Boranes First discovered in 1894 [34], 2,2’-bisarylborinates are used for treating prostate cancers utilizing their property of inhibiting the transient

• the indoles are less studied compared to the same through their pyrrole counterpart. The corresponding compounds are investigated for boron, nitrogen, oxygen, sulfur, and selenium as the central connecting atom. Boranes The indole alkaloid dragmacidin D is a marine secondary metabolite which was

• obtaining diaryl sulfides [117]. Selenides Along with the oxygen insertion, Black et al. also performed the oxidative selenium insertion into the C-7 position of highly electrophilic 2-methylindole derivative 184. The dual role of selenium dioxide consists of activation of the C-7 position giving the

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• possibility of varying optoelectronic properties, and good solubility in a wide range of solvents [59][60][61]. In this regard, the most studied and promising are π-conjugated polymer structures based on sulfur, oxygen, nitrogen, and selenium heterocyclic compounds [62][63]. One of the systems for creating

• the conductivity with close values of μh = 0.68–0.83 cm2⋅V−1⋅s−1 [87][91]. It should be noted here that more detailed studies on selenium analogs of polymers 48 are promising since the latter showed moderate values of electronic mobility of μe = 1.28 cm2⋅V−1⋅s−1 [89]. It was shown that a significant

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

•  7D) monomer which has been shown to stabilize oligonucleotides similarly to unmodified LNA with a nuclease resistance greater than PS-modified oligonucleotides [157]. Incorporation of selenium at C2' in a thymine-bearing LNA nucleoside (Figure 7E) has been demonstrated to have a hybridization ability

• and a nuclease resistance that are highly reversible in response to redox changes of the selenium atom [158]. Recent work has also looked at this modification in LNA nucleosides bearing an adenine base [159], but this nucleoside was found to be highly sensitive to heat, making its incorporation into

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• piperidine (17). The synthetic sequence performed by the authors is described in Scheme 3. Oxidation of 17 in the presence of hydrogen peroxide, catalyzed by selenium dioxide provided tetrahydropyridine N-oxide 18 in 88% yield. 18 was treated with (R)-p-tolylsulfinylmethyllithium 25 in THF at −78 °C to

Metal-free nucleophilic trifluoromethylselenolation via an iodide-mediated umpolung reactivity of trifluoromethylselenotoluenesulfonate

• Kevin Grollier,
• Alexis Taponard,
• Arnaud De Zordo-Banliat,
• Emmanuel Magnier and
• Thierry Billard

Beilstein J. Org. Chem. 2020, 16, 3032–3037, doi:10.3762/bjoc.16.252

• . Metal-free nucleophilic trifluoromethylselenolations have been then performed with this in situ-generated anion. Perfluoroalkylselenolations have also been described. Keywords: fluorine; nucleophilic substitution; perfluoroalkylselenolation; selenium; trifluoromethylselenolation; Introduction Because

• particular by combining heteroatoms, such as chalcogens, and fluorinated moieties [16]. Despite, the negative reputation of selenium due to its toxicity at high doses, it is an essential trace element for human physiology and biochemistry [17][18][19][20]. Furthermore, selenolated compounds found valuable

• applications in materials [21][22][23], life sciences [19][20][24][25][26][27][28][29], and drug design [30][31][32][33]. Consequently, the merging of fluorinated moieties, such as CF3 with selenium could constitute an interesting motif in the design of new molecules, in particular in medicinal chemistry or

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• utilization of Deoxo-Fluor® in fluoroselenations. PhSeBr was selected to provide the phenylselenyl cation serving as the required electrophilic selenium species. This reagent combination was previously unknown in the literature. Preliminary experiments with the diester 4 demonstrated that the reaction is much

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

• followed by quenching the hexaanionic species with selenium powder to afford 159 containing one 1,2-diselenin ring and two selenophene rings. Compound 159 was later subjected to deselenation in the presence of copper nanopowder (80–100 nm grain size) to furnish the expected compound 160 in quantitative

• displayed in Scheme 43. Furthermore, when they subjected the tritellurasumanenes 162 and 163 with Br2 in CH2Cl2, they obtained the tris(Te,Te-dibromo)tritellurasumanenes 164 and 165 as covalent adducts in quantitative yield (Scheme 43). 3.4 Preparation of sulfur, selenium and tellurium-doped sumanenes The

• transformed to the ortho-quinones in the presence of FeCl3. From the experimentations, they noticed that heteroatoms also play a significant role in this reaction for instance with sulfur and selenium-doped systems, ortho-quinones 166 and 167 were obtained (Scheme 44). In sharp contrast, the tellurium-doped

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

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

• anticancer activity are described. The double C–H selenation of imidazo[1,2-a]pyridine with Se powder was catalyzed by CuI (10 mol %) ligated with 1,10-phenanthroline (10 mol %) at 130 °C under aerobic conditions. The selenides or diselenides were prepared almost selectively using selenium powder in an

• ]pyridin-3-yl] diselenide showed an excellent anticancer activity and low cytotoxicity toward noncancer cells, suggesting that this diselenide is a potential lead compound for anticancer therapy. Keywords: anticancer activity; copper catalyst; diselenide; imidazopyridine; selenide; selenium; Introduction

• selenium source in the presence of a transition metal catalyst, such as Cu or Ni [27][28][29][30][31][32]. In 2011, Zhou et al. reported the pioneering Cu-catalyzed C–H selenation of 2-arylimidazopyridine with diphenyl diselenide in the presence of CuI (10 mol %) [29]. Tandem reactions involving the

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• amides (Scheme 43) [93]. Singlet oxygen in heteroatom oxidations Singlet oxygen reacts readily with electron pairs of heteroatoms, such as sulfur, selenium, phosphorus, and nitrogen, due to their electrophilicity. The interaction between singlet oxygen and the heteroatom occurs in both physical and

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

• Svetlana V. Amosova,
• Andrey A. Filippov,
• Nataliya A. Makhaeva,
• Alexander I. Albanov and
• Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

• -thiaselenole; nucleophilic addition; nucleophilic substitution; rearrangement; seleniranium intermediate; Introduction The regio- and stereoselective synthesis of organoselenium compounds based on selenium-centered electrophilic reagents has been one of the most important and effective directions in

• organoselenium chemistry for half a century [1][2][3][4][5][6][7][8][9][10][11][12]. The important trend in the field of organoselenium chemistry within the last 15 years was the involvement of selenium dihalides in the synthesis of organoselenium compounds [13][14]. The first synthesis of organoselenium

• compound from selenium dihalides was the preparation of 1,4-selenasilafulvenes by cyclization reaction with diethynyldimethylsilane [15][16]. The creation of new methodologies for the synthesis of new classes of organoselenium compounds and especially selenium heterocycles, with promising biological

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• reactions using potassium tert-butoxide as promoter. Wu developed an efficient protocol for the KOt-Bu-promoted synthesis of 1-aminoisoquinolines from 2-methylbenzonitriles and benzonitriles [23], and the carbonylative cyclization of propargylic amines with selenium under CO gas-free conditions [24]. Based

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• tandem formation of C–Se and Se–fluoroalkyl bonds have emerged in the last five years. In 2014, Hor and Weng reported the trifluoromethylselenolation of (hetero)aryl iodides and alkyl bromides with the Ruppert–Prakash reagent, TMSCF3, elemental selenium, potassium fluoride, and silver carbonate under

• , which is in line with an SN2 mechanism. The authors proposed a mechanism where difluorocarbene is first generated upon thermal decomposition of the starting difluorophosphobetaine. The carbene then reacts with elemental selenium to yield difluoroselenophosgene, and in the presence of fluoride anions