Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• toluene solvent. The synthesis and antiviral evaluation of 4'-(hydroxymethyl)oxathiolane nucleosides was reported by Chao and Nair [52]. The synthetic approach used 1,3-dihydroxyacetone dimer 3l (Scheme 14). This dimer, upon acetylation using acetic anhydride in pyridine, produced compound 47. Further

• -oxathiolane intermediates 65 and 66 could be controlled well (Scheme 22). The glycolaldehyde dimer 64 and 1,4-dithiane-2,5-diol (3q) were reacted in the presence of TEA and the acyl donor phenyl acetate. The presence of CAL-B allowed the formation of the intermediate 66 and ultimately the corresponding

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• alkyne (Scheme 18). Under visible-light irradiation, disulfides are easy transformed to thiyl radicals via the homolytic cleavage of the S–S bond [79]. In 2020, Anandhan and co-workers [80] explored the C(sp)–S coupling of terminal alkynes with 2-aminothiophenol dimer 38 as a radical precursor. Under

• photoexcitation the CuI acetylide A undergoes a SET process to form the CuII phenylacetylide species B and a superoxide radical anion. In parallel, under irradiation the homolytic S–S-bond cleavage in 2-aminothiophenol dimer 38 forms thiol radicals 40. The nucleophilic addition of the amino group in radical 40 to

Allylic alcohols and amines by carbenoid eliminative cross-coupling using epoxides or aziridines

• Matthew J. Fleming and
• David M. Hodgson

Beilstein J. Org. Chem. 2021, 17, 2385–2389, doi:10.3762/bjoc.17.155

• hexane (69%, E/Z = 62:38) and the amount of dimer 24 curtailed (8%) by reducing the amount of LTMP from 2 to 1.2 equiv. The viability of a benzyl ether (Scheme 10) in the carbenoid eliminative cross-coupling offered a straightforward way to probe any effect of the size of the leaving group on

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• Mn and PDI were 2900 Da and 1.22, respectively. The aminoazulene dimer 29 was also synthesized (Scheme 7B) in this study as a reference compound. When compared to the dimeric aminoazulene 29 (481 nm) and 2-aminoazulene (24, 394 nm), the polyaminoazulene 31 exhibited a far red-shifted broad absorption

• band spanning 400–800 nm in NMP solution with a maximum at 591 nm. Accordingly, the optical energy gap for the polymer 31 was the lowest (1.65 eV) in comparison to dimer 29 (2.15 eV) and monomer, 2-aminoazulene (24, 3.15 eV) emphasizing the advantage associated with inducing a 2,6-connectivity along

• forms of monomer 24, dimer 29, and polyazulene 31 were further red-shifted and their respective energy gaps were also reduced compared to their neutral forms. The oxidation potential for the neutral (−0.23 V) and protonated forms of polyaminoazulene 31 (0.70 V) was significantly different unlike the

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

• -trifluoroacetylation of peracetylated chitooligomers, could efficiently generate 1,2-(2-trifluoromethyloxazoline) donors. These reactive compounds were employed to construct different length COS, from dimer to hexamer [236]. Synthetic COS were prepared following chemical or enzymatic polymerization, albeit with poor

• used in a [2 + 2] glycosylation, affording the tetramer 74 with an alternated N-acetyl pattern (Scheme 11A) [257]. Partially N-acetylated COS dimer and tetramer were obtained exploiting the orthogonality of the azide and N-Troc groups [258]. β-Selectivity during the glycosylation with the C-2 azido

Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro[2.2]metaparacyclophanes

• Suraj Patel,
• Tyson N. Dais,
• Paul G. Plieger and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2021, 17, 1518–1526, doi:10.3762/bjoc.17.109

• archetypal cyclophane, with a strong interaction between the two aromatic rings, but it is readily available, being a ‘dimer’ for the polymer parylene [6][7]. Over the last twenty years, there has been a resurgence in interest in this compound as a scaffold for the synthesis of asymmetric catalysts, energy

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

• porphyrin dimer with a di-halogeno-substitution. Interestingly, this structure despite the extended dual-core and tilt of the porphyrin rings behaves quite like a 5,15-di-halo-substituted porphyrin. The bromine atoms are seen to interact with the tert-butyl and pyrrole hydrogen atoms in a head-to-tail

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

• synthesize the nucleoside dimer phosphoramidite with the appropriate amide linkage, which can then be introduced into the strand by solid-phase synthesis. These dimers are synthesized by using an amide coupling reagent to condense a 3'-carboxylic acid nucleoside with a 5'-amine nucleoside, where the

[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

• synthetic route to conjugates of C60 with cinnamaldehyde 206 and with chalcone 207. The synthetic route to conjugate C60 with a 2-nitrocinnamyl group. The synthetic route to a C60 dimer connected through a highly directional fourfold hydrogen bonding motif. The synthetic route to quadruple hydrogen‐bonded

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

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

• Zbigniew Malinowski,
• Emilia Fornal,
• Agata Sumara,
• Renata Kontek,
• Karol Bukowski,
• Beata Pasternak,
• Dariusz Sroczyński,
• Joachim Kusz,
• Magdalena Małecka and
• Monika Nowak

Beilstein J. Org. Chem. 2021, 17, 558–568, doi:10.3762/bjoc.17.50

• unit. Their geometry was fully optimized in vacuum using the DFT method with the crystal structure coordinates as the input geometry (optimized at the CAM-B3LYP/6–311++G(d,p)/LanL2DZ(Cu) level of theory). However, due to the convergence failure during the geometry optimization of the dimer of molecules

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

• upon interaction. These results demonstrated that the site-specific 19F signal of 5-FTrp187 could be directly employed as a reliable reporter to monitor the monomer/dimer exchange dynamics. Moreover, it could also be employed to characterize the ED helix–helix dimer interface in more detail by means of

• boosted the overall spectral sensitivity even when minimal protein concentrations were employed. The structural dynamics of the Myc-Max dimer formation were then evaluated by using intermolecular PREs between 19F‐Myc and three differently paramagnetic spin labelled MTSL ([(1-oxyl-2,2,5,5-tetramethyl-Δ3

Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• (cyclooctene)iridium dimer ([Ir(coe)2Cl]2) can act as the catalyst in combination with Et2SiH2 [15]. Surprisingly, they were able to obtain imines as well as amines using this methodology. Based on the works of Nagashima [16], an iridium-based protocol for tertiary amides was introduced by Dixon [17][18][19

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• -dependence is β-lactoglobulin. The protein forms a dimer at a low pH value, while it is a tetramer at a higher pH value [51]. In a salt-dependent binding mechanism, the binding interaction occurs due to the changes in the solvent exposure of the charges in the contact residues before and after binding. This

• . Different residues at the ‘a’ and ‘d’ positions give rise to different oligomeric states, with the yeast transcription factor GCN4 being a perfect example of this. GCN4 has isoleucine as ‘a’ and leucine as ‘d’ and forms a dimer (Figure 2b). When isoleucine and leucine are swapped via mutagenesis, a tetramer

Chiral anion recognition using calix[4]arene-based ureido receptors in a 1,3-alternate conformation

• Tereza Horáčková,
• Jan Budka,
• Vaclav Eigner,
• Wen-Sheng Chung,
• Petra Cuřínová and
• Pavel Lhoták

Beilstein J. Org. Chem. 2020, 16, 2999–3007, doi:10.3762/bjoc.16.249

• same time, the carbonyl groups from the neighbouring receptor urea moieties interacted with the C–H bonds of the DMSO methyl group (the C=O···H–C distances were 2.486 and 2.452 Å), thus forming the calixarene dimer with a head-to-tail mutual orientation. The overall supramolecular binding motif was

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• formation of a new derivative of caffeine. Keywords: adenine; caffeine; cyclic dimer of hexafluorothioacetone; hexafluoroisopropyl group; purine; 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane; theophylline; Introduction Despite significant progress in the last 20–30 years, the selective introduction of

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• only the cis isomer coordinates to the Ni(II) for steric reasons and 3. intermolecular coordination. At higher concentrations dimer formation or coordination oligomers between trans record player molecules occurs [35]. To compare the new molecules (1f–j) with previous systems (1a–d), the switching

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• exhibits an emission maximum peak at 329 nm upon excitation at 294 nm. This emission band is probably due to the formation of the ground-state dimer by interaction between the benzene rings upon excitation or excimer emission caused by the interaction between the aromatic rings [41][43]. As the

A new method for the synthesis of diamantane by hydroisomerization of binor-S on treatment with sulfuric acid

• Rishat I. Aminov and
• Ravil I. Khusnutdinov

Beilstein J. Org. Chem. 2020, 16, 2534–2539, doi:10.3762/bjoc.16.205

• of diamond-like hydrocarbons, diamantane, in 65% yield by hydroisomerization of the norbornadiene dimer, endo-endo-heptacyclo[8.4.0.02,12.03,8.04,6.05,9.011,13]tetradecane (binor-S) on treatment with concentrated sulfuric acid (98%). In the presence of H2SO4 of lower concentration (75–80%), the

• compounds for the preparation of diamantane are three isomeric polycyclic hydrocarbons C14H20 3а–с, which are obtained by hydrogenation of the norbornadiene dimer, heptacyclo[8.4.0.02,12.03,8.04,6.05,9.011,13]tetradecane (binor-S, 2). Binor-S is hydrogenated in the presence of a platinum catalyst (Н2PtCl6

NMR Spectroscopy of supramolecular chemistry on protein surfaces

• Peter Bayer,
• Anja Matena and
• Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

• interaction between the 14-3-3 protein and its phosphorylated cargo proteins [42][44][45]. Another ligand with just one GCP unit targets the central pore of the 14-3-3 dimer [43]. Unfortunately, these systems have not yet been studied by NMR. However, several other 14-3-3 inhibitors and stabilizers serve as

Hierarchically assembled helicates as reaction platform – from stoichiometric Diels–Alder reactions to enamine catalysis

• David Van Craen,
• Jenny Begall,
• Johannes Großkurth,
• Leonard Himmel,
• Oliver Linnenberg,
• Elisabeth Isaak and
• Markus Albrecht

Beilstein J. Org. Chem. 2020, 16, 2338–2345, doi:10.3762/bjoc.16.195

• of the stereoselectivity of the Diels–Alder reaction. In THF the stereochemically locked dimer of the hierarchical helicate was present. Here stereoselectivity was turned on. On the other hand, the highly dynamic and fast diastereomerizing/epimerizing monomer was the major species in DMF switching

• or rigid chiral ligands. In addition, a solvent screening was performed in which solvents were used which favor the dimer. This is imminent for good enantioselectivities because the presence of a high amount of stereolabile monomer switches off the selectivity [13]. Solvent dependence Initially the

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

• have attempted various combinations of Ti(IV) and reducing agents but Cp2TiCl2 with Zn powder provided the better results compared to the other combinations [14][40]. Additionally, they prepared benzyl–benzyl coupled sumanene dimer 48 by means of oxidative dimerization via sumanenyl monoanion

• (DFT) calculations. As we are aware that if the carbene formed is a singlet then a C–H bond inserted product is predominating whereas if the dimer is the major product along with the minor C–H bond inserted product then the triplet carbene is generated. During their study, they obtained the C–H

• inserted product 61 in 65% along with the dimer 62 in 18% yield with cyclohexane, confirming that the reaction precedes via the singlet state, albeit it was a triplet species in the ground-state. They further reported the applicability of the carbene precursor 59 by reacting it with different thiocarbonyl

Isolation and structure determination of a tetrameric sulfonyl dilithio methandiide in solution based on crystal structure analysis and ⁶Li/¹³C NMR spectroscopic data

• Jürgen Vollhardt,
• Hans Jörg Lindner and
• Hans-Joachim Gais

Beilstein J. Org. Chem. 2020, 16, 2057–2063, doi:10.3762/bjoc.16.172

• –dimer equilibrium. Bonding of the dianionic C atoms 6Li NMR spectroscopy of tetramer 2a-I had revealed a dianionic carbon atom, C1B, carrying two different Li atoms, a bonding situation which is reflected by the two different 6Li,13C coupling constants. It was thus of particular interest to see whether

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

• Sharna-kay Daley and
• Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

• aqueous conditions to prevent complexation of the reagent and the starting material. Of the Lewis acids used, stannic chloride proved to be the most effective oxidant for dimerization (Table 1). However, the hypervalent iodine reagents PIFA and PIDA gave better results overall, affording dimer 18 in 63