Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• diols can be carried out in the presence of basic (e.g., tertiary phosphines and amines, alkali metal hydroxides, alkoxides, halides, carbonates, alkali metal exchanged faujasites and hydrotalcites) or acidic catalysts or co-catalysts, and under thermal (non-catalytic) conditions. All applicable

One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

• Roman Yu. Peshkov,
• Elena V. Panteleeva,
• Wang Chunyan,
• Evgeny V. Tretyakov and
• Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

• such as pharmacy [22]. Because of the above-mentioned shortcomings of cross-coupling methods, we applied the method based on the direct C–H arylation of unactivated monocyanoarene 2 by the terephthalonitrile (12−) dianion [23]. It was shown that the interaction of 12− alkali metal salt with

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• by photolysis of 1a, the reaction was performed in different solvents in the absence or presence of a base. As solvents, alcohols and aqueous organic solvent mixtures were tested and alkali metal hydroxides, carbonates or acetates were screened as the base. All reactions were carried out by

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• as homo-benzoin reaction and that of two different aldehydes is known as crossed benzoin reaction. Mechanistically the reaction involves polarity reversal (umpolung) of one aldehyde to generate an acyl anion equivalent and this event is mediated by the catalyst. Alkali metal cyanides and N

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF₅-substituted phenylboronic esters and iodobenzenes

• George Iakobson,
• Junyi Du,
• Alexandra M. Z. Slawin and
• Petr Beier

Beilstein J. Org. Chem. 2015, 11, 1494–1502, doi:10.3762/bjoc.11.162

• for an efficient reaction. Alkali metal acetates are known to facilitate decomposition of aryldiazonium salts by the formation of diazoacetates and diazo anhydrides, which decompose to aryl radicals [76]. These additives were used in Meerwein arylation of isopropenyl acetate [77]. In our case, two

Deproto-metallation of N-arylated pyrroles and indoles using a mixed lithium–zinc base and regioselectivity-computed CH acidity relationship

• Mohamed Yacine Ameur Messaoud,
• Ghenia Bentabed-Ababsa,
• Madani Hedidi,
• Aïcha Derdour,
• Floris Chevallier,
• Yury S. Halauko,
• Oleg A. Ivashkevich,
• Vadim E. Matulis,
• Laurent Picot,
• Valérie Thiéry,
• Thierry Roisnel,
• Vincent Dorcet and
• Florence Mongin

Beilstein J. Org. Chem. 2015, 11, 1475–1485, doi:10.3762/bjoc.11.160

• the course of these deproto-metallation reactions complete previously reported studies using alkali metal bases with similar substrates [36][37][38][39][40][41]. The calculations of the CH acidities in THF (Figure 5) allow us to comment on the regioselectivities observed in the different studies. To

2-(1-Hydroxypropyn-2-yl)-1-vinylpyrroles: the first successful Favorsky ethynylation of pyrrolecarbaldehydes

• A. V. Ivanov,
• V. S. Shcherbakova,
• I. A. Ushakov,
• L. N. Sobenina,
• O. V. Petrova,
• A. I. Mikhaleva and
• B. A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 228–232, doi:10.3762/bjoc.11.25

• :1.6:13.6) and a temperature of 7–10 °C (Table 1), which is by ca. ten degrees higher than recommended in the patent [22], are appropriate for the efficient ethynylation of 1-vinylpyrrole-2-carbaldehydes with acetylene. As alkali metal hydroxide for the superbase composition we have chosen NaOH since

Highly selective electrochemical fluorination of dithioacetal derivatives bearing electron-withdrawing substituents at the position α to the sulfur atom using poly(HF) salts

• Bin Yin,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2015, 11, 85–91, doi:10.3762/bjoc.11.12

• was achieved by direct and indirect anodic oxidation in the presence of the poly(HF) salts [12][13][14][15][16][23][24][25] or alkali-metal fluorides like KF and CsF with PEG 200 [17]. The anodic fluorination of a dithioacetal derived from an aliphatic aldehyde provided the fluorodesulfurization

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• for the hazardous synthesis via alkali metal cyanides [137][145][146]. Derivatives of cyanoacetic acid are precious starting materials in pharmaceutical and agrochemical synthesis [137]. When the anodic reaction is the oxidation of a halide, lower current efficiencies can be attributed to a successive

• the acquired double bond. Sodium carbonate is a suitable proton scavenger, providing the required alkalinity and being a convenient source of sodium ions. Crown ethers are added to dissolve the alkali metal salts in the organic solvent system. After reaction, anolyte and catholyte are filtered and

Exploration of C–H and N–H-bond functionalization towards 1-(1,2-diarylindol-3-yl)tetrahydroisoquinolines

• Michael Ghobrial,
• Marko D. Mihovilovic and
• Michael Schnürch

Beilstein J. Org. Chem. 2014, 10, 2186–2199, doi:10.3762/bjoc.10.226

• ) leading to decomposition as well. Thus, an alternative N-arylation method had to be established, employing milder conditions, especially at lower reaction temperature. Phillips et al. demonstrated that N-arylation can be carried out using CsF instead of strong alkali metal bases at 60 °C employing various

Efficient CO₂ capture by tertiary amine-functionalized ionic liquids through Li⁺-stabilized zwitterionic adduct formation

• Zhen-Zhen Yang and
• Liang-Nian He

Beilstein J. Org. Chem. 2014, 10, 1959–1966, doi:10.3762/bjoc.10.204

• CO2 capture, by simple mixing of equimolar amounts of alkanolamines with LiNTf2 [38]. The strong complexation of alkali metal cations by crown ethers could be used to achieve equimolar CO2 absorption in systems containing crown ethers and easily available alkali metal salts of amino acids, resulting

Carbenoid-mediated nucleophilic “hydrolysis” of 2-(dichloromethylidene)-1,1,3,3-tetramethylindane with DMSO participation, affording access to one-sidedly overcrowded ketone and bromoalkene descendants^§

• Rudolf Knorr,
• Thomas Menke,
• Johannes Freudenreich and
• Claudio Pires

Beilstein J. Org. Chem. 2014, 10, 307–315, doi:10.3762/bjoc.10.28

• a very strong nucleophile R–Mt (Mt = alkali metal) to give 7 may appear problematic, because the first intermediate 9 expected with the usual ARE (addition–rotation–elimination) [12] mechanism would suffer from poor stabilization of the negative charge at C-2 which is flanked by two tert-alkyl

Host–guest complexes of mixed glycol-bipyridine cryptands: prediction of ion selectivity by quantum chemical calculations, part V

• Svetlana Begel,
• Ralph Puchta and
• Rudi van Eldik

Beilstein J. Org. Chem. 2013, 9, 1252–1268, doi:10.3762/bjoc.9.142

• ]2+ exist as local minima. The complexation energies computed in this way are shown in Table 3 and Table 4, and are plotted against the ionic radii, see Figure 10 and Figure 11. The first and second places in the stability order of the endohedral complexes of [2.2.bpy] with the studied alkali metal

• than [2.2.2]. Both cryptands prefer to bind Tl3+ as earth metal and K+ as alkali metal ions, although [2.2.bpy] favors Rb+ as the next best and [2.bpy.bpy] favors Na+. However, it is the selectivity of the alkaline-earth metal ions that is more significant if one wants to ascertain the cavity size of a

Methylidynetrisphosphonates: Promising C₁ building block for the design of phosphate mimetics

• Vadim D. Romanenko and
• Valery P. Kukhar

Beilstein J. Org. Chem. 2013, 9, 991–1001, doi:10.3762/bjoc.9.114

• than methylenebisphosphonic acid and its alkali-metal salts and also sequester more calcium and magnesium ions, for example, than does H2C(PO3H2)2 [50][51]. The complexation behavior of the polydentate ligand Me2NC(PO3Et2)3 toward Co2+ ion has shown that the trisphosphonate molecule is coordinated in

Synthesis of SF₅-containing benzisoxazoles, quinolines, and quinazolines by the Davis reaction of nitro-(pentafluorosulfanyl)benzenes

• Petr Beier and
• Tereza Pastýříková

Beilstein J. Org. Chem. 2013, 9, 411–416, doi:10.3762/bjoc.9.43

• Davis and Pizzini [7] and probably proceeds through the formation of σH adducts that give nitroso compounds, which upon deprotonation enter an intramolecular addition–elimination process as shown in Scheme 1. Typical reaction conditions are an excess of alkali metal hydroxide in a low-boiling-point

Metal-mediated aminocatalysis provides mild conditions: Enantioselective Michael addition mediated by primary amino catalysts and alkali-metal ions

• Matthias Leven,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2013, 9, 155–165, doi:10.3762/bjoc.9.18

• -hydroxycoumarin (1) to prochiral α,β-unsaturated ketones. Instead of acid additives, which sometimes lead to decomposition of sensitive components [18], alkali-metal ions are employed as very mild Lewis acids (Scheme 1). The activation of Michael acceptors by iminium ions enables asymmetric additions of 4

• seems to be clear that the zwitterionic chelate shown in Figure 1 is too inert to form imines with carbonylic compounds. The choice of alkali metal does not affect the ee very markedly and the ee’s obtained in Table 1 are in the moderate range (up to 47%). In order to elucidate if Lewis acid free imines

• could also react as Michael acceptors, experiments employing triethylammonium salts of the catalysts 5 and 7 (pH 9) were performed, and no conversions could be detected in all cases. Because lithium was identified as the most appropriate alkali-metal ion for application in the catalysis (Table 1), the

Low-generation dendrimers with a calixarene core and based on a chiral C₂-symmetric pyrrolidine as iminosugar mimics

• Marco Marradi,
• Stefano Cicchi,
• Francesco Sansone,
• Alessandro Casnati and
• Andrea Goti

Beilstein J. Org. Chem. 2012, 8, 951–957, doi:10.3762/bjoc.8.107

• of a considerable number of iminosugar-like moieties in a reduced volume and in a well-defined geometry. The inclusion of alkali-metal ions (sodium and potassium) in the polar cavity defined by the acetamide moieties at the lower rim of the calixarene was demonstrated, which allows also the

• water. The presence of acetamide moieties at the lower rim of the dendrimers 2 and 3 prompted us to explore the possibility to use alkali metal salts as allosteric effectors in the modulation of the shape and rigidity of the iminosugar presentation by the calixarene scaffold. A common way, in fact, used

• to rigidify the “mobile cone” structure of tetraalkoxycalix[4]arenes is to introduce strong donating groups, such as amide or ester [32][33], on the phenolic oxygen atoms and an alkali-metal ion. The cation, strongly coordinated by eight oxygen atoms in the polar region created at the lower rim

Discovery of practical production processes for arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides): Beginning of a new era of “super-trifluoromethyl” arene chemistry and its industry

• Teruo Umemoto,
• Lloyd M. Garrick and
• Norimichi Saito

Beilstein J. Org. Chem. 2012, 8, 461–471, doi:10.3762/bjoc.8.53

• an alkali metal fluoride, and (step 2) treatment of the resulting arylsulfur chlorotetrafluoride with a fluoride source, such as ZnF2, HF, and Sb(III/V) fluorides. The intermediate arylsulfur chlorotetrafluorides were isolated by distillation or recrystallization and characterized. The aspects of

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• , derivatives containing carbonyl groups (ester, acid, amide and ketone) and heteroatoms, such as nitrogen and phosphorous, have been obtained. In 1993, Shinkai et al. [29] reported the synthesis of the first ethyl ester derivative 12a. In the belief that the alkali-metal template effect would lead

• -butyl ether 10 derivatives toward alkali-metal cations were estimated by extraction experiments from alkaline aqueous picrate solutions to CH2Cl2 [24], with the latter showing some preference for K+ (59% E) over Na+ (6%) and Cs+ (35%). Replacement of the alkyl groups by residues with additional binding

• was investigated by Masci in 1995 [54] who found that Kassoc values in CDCl3 were modest, ranging from 38 M−1 for N,N,N-trimethylanilinium to 90 M−1 for N,N-dimethylpyrrolidinium, but significantly greater than those of the dihomocalix[4]arene and tetrahomooxacalix[4]arene analogues. 4.1.2 Alkali

On the control of secondary carbanion structure utilising ligand effects during directed metallation

• Andrew E. H. Wheatley,
• Jonathan Clayden,
• Ian H. Hillier,
• Alison Campbell Smith,
• Mark A. Vincent,
• Laurence J. Taylor and
• Joanna Haywood

Beilstein J. Org. Chem. 2012, 8, 50–60, doi:10.3762/bjoc.8.5

• authenticated tertiary carbanions, significant similarities are seen insofar as the connectivity of the alkali metal is concerned when changing tridentate Lewis bases. Thus, whereas 6-Lil·PMDTA fails to show a Li–(α-C) interaction in the solid state, in Lil·DGME the corresponding distance (2.406(6) Å) suggests

PEG-embedded KBr₃: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

• Sanny Verma,
• Suman L. Jain and
• Bir Sain

Beilstein J. Org. Chem. 2011, 7, 1334–1341, doi:10.3762/bjoc.7.157

• alkali metal cations, as shown in Scheme 1. The developed catalyst 3 was readily prepared by the mixing of equimolar amounts of PEG400 (1) and KBr to give [K+PEG]Br− 2, which on subsequent reaction with Br2 resulted in a dark orange-red colored viscous liquid (see Experimental). The liquid was dried

Combined directed ortho-zincation and palladium-catalyzed strategies: Synthesis of 4,n-dimethoxy-substituted benzo[b]furans

• Verónica Guilarte,
• M. Pilar Castroviejo,
• Estela Álvarez and
• Roberto Sanz

Beilstein J. Org. Chem. 2011, 7, 1255–1260, doi:10.3762/bjoc.7.146

• compounds and different directing groups have been used to facilitate the deprotonation reaction [1][2][3][4][5]. Various strong bases such as alkyl lithiums and their derivatives (for instance, TMEDA-activated complexes [6] and heavier alkali metal tert-butoxide-complexed alkyl lithium reagents, known as

• ), the introduction in the last years of new organometallic “ate” complexes [8][9], which combine an alkali metal with either magnesium, zinc, aluminium, or copper, has allowed more selective metallation reactions. The milder reaction conditions required make these deprotonation reactions tolerant to the

• , as well as of meta-functionalized haloaromatics. In particular, the alkali metal mediated zincation reactions have turned out to be very useful processes and the structures and reaction pathways of TMP-zincates (TMP = 2,2,6,6-tetramethylpiperidine) have been studied in detail [15][16][17][18][19]. On

Meta-metallation of N,N-dimethylaniline: Contrasting direct sodium-mediated zincation with indirect sodiation-dialkylzinc co-complexation

• David R. Armstrong,
• Liam Balloch,
• Eva Hevia,
• Alan R. Kennedy,
• Robert E. Mulvey,
• Charles T. O'Hara and
• Stuart D. Robertson

Beilstein J. Org. Chem. 2011, 7, 1234–1248, doi:10.3762/bjoc.7.144

• -) metallation was favoured by direct sodium-mediated zincation. Keywords: alkali metal; crystal structure; isomerisation; metallation; zincation; Introduction While the metallation reaction remains an essential tool for constructing substituted aromatic compounds [1][2], the quest for new improved reagents

• typically at ambient temperature [11] and on the multi-gram scale with metallation rates comparable to those obtained for small scale processes [12]. Alkali metal zincates have also been given consideration, principally two-component dialkyl-amido zincates MZn(NR2)R′2. The reagent “(LiZn(TMP)(t-Bu)2

• enabled such reagents to perform special metallation reactions that cannot be reproduced by either of the single-metal components that constitute the mixed-metal reagent. While the alkali metal component is essential for the synergic metallation to follow its course, it is the less electropositive zinc

Intramolecular hydroxycarbene C–H-insertion: The curious case of (o-methoxyphenyl)hydroxycarbene

• Dennis Gerbig,
• David Ley,
• Hans Peter Reisenauer and
• Peter R. Schreiner

Beilstein J. Org. Chem. 2010, 6, 1061–1069, doi:10.3762/bjoc.6.121

• was computed to be 262 kcal mol–1, which is comparable to those of alkali metal hydroxides, this seems a viable possibility. Conclusion The formation of a 2,3-dihydrobenzofuran derivative from carbene 5 in the gas phase is the first C–H insertion reaction observed for a hydroxycarbene derivative

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32