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

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• cationic entity in the crown ether-like cavity and an anion in the region close to the metalloporphyrin core (Figure 7). The studies showed that the cation binding in the hovering crown pockets of 9-Zn and 9-Cu included, but was not limited to, alkali metal cations, transition metal cations, and

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• –Cu(I) complexes 12 (Scheme 5). A variety of bases, namely metal alkoxides, alkali metal carbonates, n-butyllithium, and lithium bis(trimethylsilyl)amide have been employed for this purpose. In 2010, Diez-González et al. synthesized a variety of NHC–Cu(I) complexes 14 from imidazolium salts 13 using

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• context of deeply reductive reactions, dissolving alkali metal conditions have remained the most commonly employed both in academia and industry for over a century and even to date continue to be used despite their hazards, poor selectivity and chemical waste [7][8][9][10]. Nowadays, excellent alternative

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• highly selective hydration/acylation of tertiary bromopropargylic alcohols with carboxylic acids promoted by alkali metal carbonates [24]. The reaction proceeds via the ring-opening of 1,3-dioxolan-2-one intermediates formed with hydroxy and alkynyl groups of bromopropargylic alcohol and alkali metal

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

• -transfer step. This provides low amounts of reactive, nucleophilic fluoride in the nonpolar solution, circumventing thereby selectivity and reactivity issues owing to the high basicity of alkali metal fluorides [58][59][60][61][62]. By modifying the reaction conditions, the same group was also able to

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

• Ryan M. Alam and
• John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

• regioselectivity. Further variation of the alkali metal cation, through the use of strong hydride bases, such as LiH or KH in THF, to examine N-1 regioselectivity (Table 3, entries 5 and 6, respectively) revealed a high preference for the formation of N-1 regioisomer 10 (ratio N-1 (10):N:2 (11) = 28:1 and 11:1

• the use of DMF, may prompt indazole N-alkylation to fall predominantly under steric control, resulting in diminished N-alkylation regioselectivity. To further probe the potential influence of the alkali metal cation on the regioselective N-1 alkylation of indazole methyl ester 9, a control experiment

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• metal (complex) catalysts, methanolysis of PLA was recently described using alkali metal halides [271]. In an optimised experiment, PLA from various goods (cups, fork, spoons, containers, Mw 120000–260000 g⋅mol−1) was converted into Me-La in up to 97% yield using 2.5 mol % KF, 180 °C microwave heating

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

• Sergey V. Norkov,
• Anton V. Cherkasov,
• Andrey S. Shavyrin,
• Maxim V. Arsenyev,
• Viacheslav A. Kuropatov and
• Vladimir K. Cherkasov

Beilstein J. Org. Chem. 2021, 17, 273–282, doi:10.3762/bjoc.17.26

• -chloro-o-quinone (1) with alkali metal salts of dithiocarboxylic acids. In fact, this procedure is suitable for the synthesis of such annulated o-quinone derivatives including di-o-quinones bridged by tetrathiafulvalene or p-phenylene-extended tetrathiafulvalene spacers 3a–c (Scheme 1, route 1) [14][15

• reaction of 4,5-dichloro-3,6-di-tert-butyl-o-benzoquinone (4) [19] with alkali metal gem-dithiolates. This synthetic procedure allows us to significantly extend the range of substituents which could be potentially introduced to the final product. Gem-dithiolates are comparatively less studied than related

• -dithiolate and dithiocarboxilate are trithiocarbonate salts. Synthesis and characterization of new o-quinone derivatives In this work we used sodium gem-dithiolates in the reactions with o-quinone 4. Alkali metal gem-dithiolates are relatively unstable species, so that they are commonly freshly prepared in

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

• Henrik Hupatz,
• Marius Gaedke,
• Hendrik V. Schröder,
• Julia Beerhues,
• Arto Valkonen,
• Fabian Klautzsch,
• Sebastian Müller,
• Felix Witte,
• Kari Rissanen,
• Biprajit Sarkar and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

• alkali metal ions [2]. Crown ethers and their binding properties nowadays find frequent application, e.g., as cation sensors [4][5][6][7], as phase-transfer catalysts [8][9][10], or as drug delivery systems [11][12][13]. Already at the early stages of crown ether research, considerable effort has been

• electrochemical output. For example, crown ethers containing tetrathiafulvalene (TTF) derivatives, which enable two reversible oxidation processes from the neutral to the dicationic state, were applied to sense various cations, e.g., alkali metal ions, Pb2+, and Ba2+ [18][19][20][21]. Furthermore, with the first

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

• . In contrast, not much is reported related to the η5-coordinated alkali metal complexes though the first report came around 120 years ago. To this context, in 2015, Hirao and Petrukhina’s group have reported the first alkali metal–sumanene complex K7(C21H102−)2(C21H93−)·8THF (137) having di- and

On the hydrolysis of diethyl 2-(perfluorophenyl)malonate

• Ilya V. Taydakov and
• Mikhail A. Kiskin

Beilstein J. Org. Chem. 2020, 16, 1863–1868, doi:10.3762/bjoc.16.153

• -(perfluorophenyl)acetic acid (12). This new method is shorter and much safer than the classical one based on the hydrolysis of 2-(perfluorophenyl)acetonitrile [38][39], because utilization of both toxic 1-(bromomethyl)-2,3,4,5,6-pentafluorobenzene and alkali metal cyanides is avoided. Conclusion To summarize, we

Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

• Sachin S. Burade,
• Sushil V. Pawar,
• Tanmoy Saha,
• Navanath Kumbhar,
• Amol S. Kotmale,
• Manzoor Ahmad,
• Pinaki Talukdar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2019, 15, 2419–2427, doi:10.3762/bjoc.15.234

• alkali metal cations in the transport process. However, variation of extravesicular anions demonstrated the changes in the transport behaviour with the following selectivity sequence: Cl– >> AcO– ≈ SCN– ≈ F– > NO3– >> Br– ≈ I–, showing highest selectivity for the Cl– ion (Figure 7B). Overall, anion

Tautomerism as primary signaling mechanism in metal sensing: the case of amide group

• Vera Deneva,
• Georgi Dobrikov,
• Aurelien Crochet,
• Daniela Nedeltcheva,
• Katharina M. Fromm and
• Liudmil Antonov

Beilstein J. Org. Chem. 2019, 15, 1898–1906, doi:10.3762/bjoc.15.185

• alkali metal determination is still a challenge. In the case of alkaline earth metal ions, the reagents with reasonable selectivity are still not commonly accepted since they compete with transitional metal ions [4]. The discovery of crown ethers [5] and 3D-based ligands [6] unquestionably helped the

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• thermodynamic driving forces, intra-alkali metal exchange is one of the most challenging metathetical exchanges to attempt, especially when conducted without solvent. Nevertheless, grinding together the bulky potassium allyl [KA']∞ (A' = [1,3-(SiMe3)2C3H3]–) and CsI produces the heterometallic complex [CsKA'2

• between M'X and MX becomes particularly small? Here we describe the application of mechanochemistry in an organometallic context to examine alkali metal halide exchange unassisted by solvents. The organic group used is the bulky 1,3-bis(trimethylsilyl)allyl anion, [1,3-(SiMe3)2C3H3]− ([A']−) [13][14], for

• which alkali metal complexes are known, including those of Li [15], Na [16], K [17][18], and Cs [18]. These have been formed via traditional solvent-based routes, by deprotonation of the substituted propene precursor with a metal alkyl or hydride (Equation 2) or with the metal itself (Equation 3) [18

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• presence of alkali metal and ammonium ions. Sakata et al. reported the synthesis of peripherally functionalized DBTAAs with the two benzo-15-crown-5 scaffolds appended to the meso-benzoyl substituents [27]. Both crown ether-capped macrocycles in a form of free base and nickel(II) and cobalt(II) complexes

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• NHPI-catalyzed C–H acetoxylation reaction yielded the ester product 3a in moderate (42%) yield. This contrasts with orthoperiodic acid (H5IO6), which yielded only electrophilic arene iodination. The use of alkali metal iodate salts such as lithium, sodium, and potassium iodate as the terminal oxidant

Dynamic light scattering studies of the effects of salts on the diffusivity of cationic and anionic cavitands

• Anthony Wishard and
• Bruce C. Gibb

Beilstein J. Org. Chem. 2018, 14, 2212–2219, doi:10.3762/bjoc.14.195

• titration with various halide salts. The fifteen salts studied were a matrix of the alkali metal cations Li+, Na+, K+, and Cs+ in combination with the halides F− through I−, the one omission being poorly soluble lithium fluoride (maximum solubility = 0.134 g mL−1). Unsurprisingly, given the pKa values of

• see no evidence of specific complexation here. More generally, despite the high charge density of 1, monovalent alkali metal ions cannot associate with it sufficiently to induce significant aggregation and a reverse Hofmeister effect. This was not, however, the case with divalent metal ions, which are

• strongly solvated, it is interesting to contemplate the idea that the prevalence of alkali metal ions in the environment exerted evolutionary pressures on biomacromolecules to select carboxylate, phosphates and sulfates and hence minimize ion pairing, charge neutralization, and deleterious precipitation

Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

• Dennis Hiltrop,
• Steffen Cychy,
• Karina Elumeeva,
• Wolfgang Schuhmann and
• Martin Muhler

Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120

• reactions over Pt single crystal, polycrystalline Pt and Pt/C electrodes. They proposed two different adsorbate structures of hydrated alkali metal cations on the electrode, either via a hydrogen bonding between hydrating water and two OHad groups (1) or direct ion–dipole interactions between two OHad and

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• . However, this pathway is shut down under solvent-free conditions, making everything in the system a contact ion pair. The traditional solution-based mechanism of the Wittig reaction proceeds via a four-membered oxaphosphetane intermediate. However, by incorporating the halide anion and the alkali metal

• cation into the mechanism, a six-membered ring, similar to that proposed in Scheme 2, would result (Figure 3). Based on this hypothesis, in addition to the oxygen and phosphorous forming a stable bond, the alkali metal and halide must form a stable contact ion pair as well. These interactions and the

• alkali metal and halide pairs would be most favourable. For example, bromide is a borderline soft anion, so based on the proposed mechanism we would expect more product to form if the counter ion is Cs+(soft) than if it was Li+ (hard). Using the Jones–Dole viscosity B coefficient, we could also predict

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• [26]. Previously, we obtained molecular clips containing diphenylglycoluril and benzocrown ether fragments 1–5, and studied their complexation with alkali metal [27][28]. In this report, we discuss the interaction of given molecular clips and the model clip based on veratrole 6 with paraquat (7) and

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• thiacalix[4]arene variously substituted at the lower rim form 1,2-, 1,3-di- and trisubstituted macrocycles [42], depending on the nature of the alkali metal carbonates and solvent. In this paper, we describe the regioselective synthesis of p-tert-butylthiacalix[4]arene monosubstituted at the lower rim by N

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• ], Ullmann coupling [13][14], Buchwald–Hartwig amination [15] or N-alkylation of carbazole in the presence of alkali metal carbonates under MW irradiation [16]. In our case, the N-arylation was realized under phase transfer conditions using triethylbenzylammonium chloride (TEBA) as a catalyst [17][18

Adsorption of RNA on mineral surfaces and mineral precipitates

• Elisa Biondi,
• Yoshihiro Furukawa,
• Jun Kawai and
• Steven A. Benner

Beilstein J. Org. Chem. 2017, 13, 393–404, doi:10.3762/bjoc.13.42

• not due to impurities in the natural species. To complete the analysis, we then co-precipitated various pairs of synthetic carbonates by mixing the appropriate aqueous solutions of the alkali metal chlorides with an aqueous solution of sodium carbonate in a 1:1 ratio (Figure 2). These were then easily

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• the reductive decyanation reaction that focuses on more modern methods. Review Alkali-metal-promoted decyanation Since the article by Arapakos in 1967 [10], decyanations using alkali metal dissolving conditions, typically Li or Na/NH3, are widely used in organic synthesis [11][12][13][14][15]. The