Acyclic cucurbit[n]uril bearing alkyl sulfate ionic groups

• Christian Akakpo,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 717–726, doi:10.3762/bjoc.21.55

• [n])), and those prepared by metal ligands and H-bonding self-assembly processes [1][2][10][11][12][13][14][15][16][17][18][19][20]. Macrocycles have played key roles in important real-world products including the household deodorizer FebreezeTM, glucose monitors, and as solubilizing excipients [21

Origami with small molecules: exploiting the C–F bond as a conformational tool

• Patrick Ryan,
• Ramsha Iftikhar and
• Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

• attraction can still be significant in some contexts [102][103] and the intramolecular H-bond depicted in II (Figure 8) can have a significant impact upon the properties of vicinal fluorohydrins [97]. The possibility of intramolecular H-bonding in vicinal fluorohydrins has important consequences for the

• instance in highly-fluorinated alcohols (e.g., hexafluoroisopropanol) [107], or in rigid molecules where intramolecular H-bonding is not possible [104] (e.g., 56, Figure 8); but it is not a universal phenomenon. The issue of intra- vs intermolecular H-bonding of vicinal fluorohydrins can complicate matters

•  8) that adds to the hyperconjugation and intramolecular H-bonding phenomena [96]. The conformational effects of fluorination in these two derivatives (i.e., esters and protonated alcohols) have been little exploited to date in the design of functional molecules [111]. However, one standout example

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• group properties to obtain 1,2-trans glycosides without compromising the reactivity of the glycosyl donors. The use of chiral and achiral auxiliary groups also participates through various pathways including solvent participation and H-bonding assisted glycosylation protocols enabling the modulation of

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• -derived azadiene by H-bonding. This dual activation promotes a stereoselective addition of 3-chlorooxindole to the azadiene leading to intermediate A. The latter is also activated by the chiral guanidine and undergoes an intramolecular nucleophilic substitution which delivers the product 19b with the

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• proposed by the authors (Scheme 3). Activation of the HVI reagent by H-bonding leads to ligand exchange to give an aminofluoro iodonium intermediate A. Cyclisation occurs via nitrogen attack on the alkene to then give aziridinium intermediate B. Subsequent nucleophilic attack by fluoride on the more

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• -defined binding pockets, offer a preorganized arrangement of functional groups as a suitable microenvironment for organocatalysis. In 2008, Kohnke, Soriente and co-workers first reported [37] the H-bonding organocatalytic activity of calix[4]pyrrole derivatives 3 and 4 and acyclic dipyrromethane 5 for the

Synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose

• Olivier Lessard,
• Mathilde Grosset-Magagne,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2024, 20, 2442–2454, doi:10.3762/bjoc.20.208

• exception being bromine). Dipole moments for the 4C1 structures are 2 Debye larger than for 1C4 structures, making them substantially more stable in chloroform. Both chair structures have multiple C–F bonds in gauche arrangements which are stable due to hyperconjugation: there is donation from C–H bonding

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• 121.6°). In addition, the intermolecular H-bonding is observed between group O2–H2 of molecule A and the thione group C=S of molecule B (the distance H2A···S1B is 2.42(1) Å, the angle O2A–H2A–S1B is 161°). At the same time, for molecule B, there is a hydrogen bond between the O2B–H2B group with the

• intermolecular H-bonding O2–H2···O1 between catechol moieties of two neighbouring molecules leading to pairs was also observed in the crystal of catechol 8 (Figure 5): The H2···O1 distance is 2.06 (1) Å, the O2···O1 distance is 2.87(1) Å, the angle O2–H2–O1 is 151.4°. However, the additional intermolecular

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• , blocking (94) or removing (95) one of the N–H groups responsible for H-bonding resulted in a dramatic loss of enantioselectivity (7% ee in 94 and 26% ee in 95), while removing both of the N–H groups gave the racemate (1% ee for 96). Interestingly, thioamide 97 also showed a low ee. Replacing the 3,5-bis

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• -disubstituted olefins is observed and interpreted as evidence that aziridination proceeds via a carbocation intermediate that subsequently cyclizes. These results demonstrate a simple method for activating iminoiodinane reagents, provide analysis of the extent of activation achieved by H-bonding, and indicate

• described in some group-transfer schemes [23][24][25], and in particular, fluorinated alcohol solvents, such as 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), have been reported to enhance hypervalent iodine reactivity by providing a H-bonding solvent cluster that enhances the electrophilicity of the iodine

• consistent with H-bonding between HFIP and 2c, which results in a more potent oxidant and gives rise to the observed HFIP-promoted olefin aziridination chemistry. A number of observations are relevant to the mechanism by which unactivated olefin aziridination is accomplished by the HFIP-activated

Novel oxidative routes to N-arylpyridoindazolium salts

• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• make oxidation of amines less anodic (due to the H-bonding and facilitation of deprotonation of the radical cations), thus narrowing the potential gap. Preparative experiments were performed under the same conditions as described above: A one-compartment cell, DMF, 0.25 mol equiv of a mediator was

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

• Ana Flávia Candida Silva,
• Francisco A. Martins and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

• -fluoropyrrolidinium cation and 3-fluoropyrrolidine. The conformational space of 2,3-, 2,4-, and 3,4-difluoropyrrolidines is notably dictated, both in the gas phase and implicit polar solution, by the N to C–F bond anomeric effect. Additionally, albeit less significant, electron delocalization from the C–H bonding

Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes

• Zining Li,
• Sana Jindani,
• Volga Kojasoy,
• Teresa Ortega,
• Erin M. Marshall,
• Khalil A. Abboud,
• Sandra Loesgen,
• Dean J. Tantillo and
• Jeffrey D. Rudolf

Beilstein J. Org. Chem. 2024, 20, 1320–1326, doi:10.3762/bjoc.20.115

• rearrangement (27.7 kcal mol−1; Figure S12, Supporting Information File 1) of uncharged 11 compared to that of 2 (Figure 3B). The free energy barrier value for 11 is likely too high to be non-enzymatic at 28 °C and may at least require deprotonation of the hydroxy group or at least H-bonding with solvent [23

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• their profound implications on device performance [1]. Among these interactions, hydrogen bonding (H-bonding, HB) as a highly directional noncovalent interaction can influence the structural, electronic, and optoelectronic properties of bulk materials [2][3]. Hydrogen bonding plays a crucial role in

• and charge injection/extraction processes [7]. The additional merits of H-bonding designs in organic optoelectronic materials include higher thermal stability, synergistic stabilizing effects with π-stacking interactions, etc. [8]. Acenes and N-heteroacenes are two prominent π-conjugated scaffolds for

• perylenebisimide (PBI) components connected laterally through H-bonding and self-assembled orthogonally through π–π interactions [13]. Mixtures of PBI and OPV successfully exhibited ambipolar charge transport depending on processing conditions as a result of the co-assembled morphology. Our group utilized a

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

• -responsive switchable tweezers are based on an H-bonding motif that can establish recognition interactions with the anionic species. One of the first examples was developed by Sessler, Jeppesen, and co-workers with a calix[4]pyrrole switching unit [68]. Calix[4]pyrrole tweezers 33 are functionalized by four

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• mechanism to a <1st-order dependence on catalyst, which could indicate a competing alcohol or H-bonding driven mechanism. In CD3OD, first-order-catalyst dependence is maintained. The entropy of activation reveals an organized transition state (−42.1 cal/mol·K) which would be consistent with the mechanism in

• MeOH within the transition state; rate enhancements with protic co-solvents point to the importance of H-bonding clusters. • Significant slow-down and primary isotope effects observed with MeOH versus MeOD; such KIE’s are typically used to support rate determining protodeauration, but in this case do

• not correspond to alkylgold buildup. In protic solvents perhaps the strength of the H-bonding network controls the rate of reaction [82]. • Stronger donor ligands that would enhance protodeauration do not increase the rate of reaction. • Rates correlate most significantly with nucleophile effects

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• (E1/2red[IrIV/*IrIII] = −0.96 V vs SCE) would not promote the reduction of 44 (−1.25 V vs SCE) [56] (Scheme 10). Interestingly, the role of H-bonding in substrate activation was not considered. To explain the observed transformation, it was suggested that the IrIII-photocatalyst acted as a

• , the authors proposed that (R)-TRIP-Li has the capability to engage enamide 51 through H-bonding and NHPI ester 3 through Li-promoted Lewis acid activation, acting as a pocket that facilitates the formation of charge-transfer complex 52 (Scheme 11B). This complex can be excited either by direct

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• approach to acenaphthylene systems. Suggested amination products 6 and two resonance forms of dianion 7. Targeted dipyridoacenaphthylene 8. Molecular and crystal structure of salt 5·HCl·2H2O is strongly dominated by severe H-bonding (blue dotted lines) and π-stacking (one preorganized layer along the c

• overlap (с). Again, π-stacking and H-bonding (blue dotted lines) strongly dominate in this structure. Fragment of the crystal packing of neutral dipyridoacenaphthene 5 showing self-association via multiple C–H…N contacts (blue dotted lines) between three independent molecules. Structure of

Studying specificity in protein–glycosaminoglycan recognition with umbrella sampling

• Mateusz Marcisz,
• Sebastian Anila,
• Margrethe Gaardløs,
• Martin Zacharias and
• Sergey A. Samsonov

Beilstein J. Org. Chem. 2023, 19, 1933–1946, doi:10.3762/bjoc.19.144

• , particular three positively charged residues, R101, K106, and K116, maintained strong H-bonds that have been also established in the X-ray structure-based MD simulation [51]. Some of these residues are absent as the most contributing to H-bonding in the less stable complexes (both last windows of the pulling

• away and pulling in processes). At the same time, the essential difference between the H-bonding pattern observed in the unrestrained MD simulation of the X-ray structure is that there were several non-charged residues (N8, A17, Y84) among the top residues contributing to H-bonds, while almost

• potential of non-purely electrostatics dominance in the protein–GAG interactions. The more detailed analysis of the GAG recognition in this system in near-native states points out to the complexity of free energy landscape but at the same identifies the key charged H-bonding contributors to the GAG binding

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• studied hydrazones. Crystal, data collection and refinement parameters for hdz-CH3 and hdz-NO2.a H-bonding parameters for hdz-CH3 and hdz-NO2. Supporting Information Supporting Information contains Fourier difference maps (Figure S1), Hirshfeld surface analyses (Figures S2 and S3), optimized calculated

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• and acceptor molecules (N···F and N···H bonding when using the acceptor Y6), as well as an induced dipole moment in the molecule for increased work function tuning of the cathode. The use of benzyl and pentafluorobenzyl substituents was to evaluate the impact of H vs F on the electrochemical

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• stereoselectivity is also explained. Keywords: asymmetric; aza-Friedel–Crafts reaction; H-bonding; organocatalysis; stereoselectivity; Introduction The ease of a chemical transformation depends on the thermodynamic instability of a chemical bond owing to its fast cleavage under mild reaction conditions. A C–H

• the reaction partners in a highly ordered three dimensional transition state through noncovalent interactions (like H-bonding, π–π interactions) thus promoting the stereoselective reaction. Examples of covalent bonding organocatalysts are amines [6][7], N-heterocyclic carbenes [8][9], phosphines [10

• –Crafts reaction has also been explored under the influence of organocatalysis. However, here organocatalysts act as Brønsted acids which form noncovalent interactions (H-bonding) with the imine nitrogen to enhance the electrophilicity of the imine component. In addition, by selecting suitable imine

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• , the authors revealed the product 4a as E-isomer due to the strong intramolecular H-bonding. It was also observed that the labile acetal group in the product 4g remained unaffected during the reaction process under the standard conditions. Imidazole N-oxides reacted with ethyl cyanoacetate to produce

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• , which entailed the quantitative formation of the edge-directed molecular prism 15 (Figure 3). The adequate length of the ditopic clip 13 constrained the urea triangle from intersupramolecular H-bonding. Thus, the urea moieties in this newly assembled 3D architecture were freely available for

• interactions with appropriate guest molecules through H-bonding. Different organic molecules, such as nitroolefins, capable of forming H-bonding with the urea moieties inside the cavity were investigated in water for their ability to encapsulate in the cavity under heterogeneous conditions. Successful binding

• . For this purpose, they have chosen the ditopic bisurea “strut” 12 (Figure 3), which generated a 2D discrete molecular triangle 14 in the presence of an equimolar amount of the cis-(tmen)Pd(NO3)2 acceptor 5 [59]. In order to prevent the urea moieties on the triangle to get engaged in intermolecular H

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

• Tommaso Lorenzetto,
• Fabrizio Fabris and
• Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

• series of control experiments supported in all cases the evidence that the reaction is not just promoted by the acidity of 16 or its H-bonding properties, but that a combination of weak Brønsted acidity together with the presence of an accessible electron-rich cavity that favors the stabilization of the

• recorded after 64 h at room temperature, while A and B were recorder right after sample preparation. Resorcin[4]arene 1 forming the corresponding hexameric capsule 16 and the species used for control experiments like 4-n-hexylresorcinol (2) to mimic the H-bonding properties of the capsule