Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines

• Muhammad Hasan,
• Anatoly A. Peshkov,
• Syed Anis Ali Shah,
• Andrey Belyaev,
• Chang-Keun Lim,
• Shunyi Wang and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74

• pyrazolodiazepines 16w and 16x, respectively. Such an outcome is notable, as related carbocyclizations often switch to an exo mode when shifting from internal to terminal alkynes [61][62][63]. To demonstrate the robustness of our methodology, we tested a telescope procedure in which, after the Ugi step, the product

Recent advances in controllable/divergent synthesis

• Jilei Cao,
• Leiyang Bai and
• Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

• activation in the divergent synthesis of silacyclic compounds (Scheme 14) [43]. This reaction employs the ODCS reagent to capture a five-membered C,C-palladacycle species, using reaction time as a control switch to enable transformations of three distinct substrates – acrylamides, 2-halo-N

Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion

• Leon M. Friedrich and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57

• ]. Specifically, the reversible E/Z isomerization of the azo group in azobenzene glycosides is suited to control the spatial presentation of glycoligands and, for example, switch carbohydrate-specific bacterial adhesion on and off [20][21][22][23]. Indeed, glycoazobenzene derivatives are excellent tools to

Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction

• Thomas Brandt,
• Pascal Lentes,
• Jeremy Rudtke,
• Michael Hösgen,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36

• designing a photoswitchable drug is to place the switch at a position in the pharmacophore that allows switching of the biological effect by irradiation with light without greatly reducing the overall activity by unselective interference with the inhibitor–receptor interaction. This is a difficult task

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• release [216] and even switch catalysis on and off [196]. MOCs containing peptides in the edge pieces also look promising to direct catalysis [217]. Extended frameworks Metal-organic frameworks (MOFs) [218][219] and covalent organic frameworks (COFs) [220][221][222][223][224] are well-studied as

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• reaction mixture. This step allows the oxidative addition of nickel on the aryl bromide 9 followed by the reductive elimination giving the desired product 11. Besides the innovative synthetic results obtained in this study, the authors underline a major advantage to switch to red light as it enables a

Effect of substitution position of aryl groups on the thermal back reactivity of aza-diarylethene photoswitches and prediction by density functional theory

• Misato Suganuma,
• Daichi Kitagawa,
• Shota Hamatani and
• Seiya Kobatake

Beilstein J. Org. Chem. 2025, 21, 242–252, doi:10.3762/bjoc.21.16

• replacing the rotor pyridyl group of a hydrazone switch with a phenyl group afforded long-lived negative photochromic compounds [49]. In addition, Hecht and co-workers reported that the thermal stability of indigos can be tuned by N-functionalization [50][51]. They revealed that the introduction of electron

Controlled oligomerization of [1.1.1]propellane through radical polarity matching: selective synthesis of SF₅- and CF₃SF₄-containing [2]staffanes

• Jón Atiba Buldt,
• Wang-Yeuk Kong,
• Yannick Kraemer,
• Masiel M. Belsuzarri,
• Ansh Hiten Patel,
• James C. Fettinger,
• Dean J. Tantillo and
• Cody Ross Pitts

Beilstein J. Org. Chem. 2024, 20, 3134–3143, doi:10.3762/bjoc.20.259

• to be more manageable than controlling oligomerization. However, under the right circumstances, alternating radical polarity matching throughout the chain propagation steps could be one way to theoretically "switch off" oligomerization beyond formation of a [2]staffane. Using this logic, our

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• is derived from the hydrophobic-interaction-based inclusion formation; thus they are only low number of reports on their structural control. The photoisomerization-based structural control system is often applied to CD-based rotaxane. Typically, the photo-switch behavior is used, and it is based on

O,S,Se-containing Biginelli products based on cyclic β-ketosulfone and their postfunctionalization

• Kateryna V. Dil and
• Vitalii A. Palchykov

Beilstein J. Org. Chem. 2024, 20, 2143–2151, doi:10.3762/bjoc.20.184

• -alkyl/aryl-substituted analogues, and aldehyde component switch to heteroaromatic (2-pyridinaldehyde) and aliphatic (iPrCHO, cinnamaldehyde). Unfortunately, we failed in both replacements and were unable to obtain any reasonable products. The list of unsuccessful reagents is shown in Figure S7 (see

A fiber-optic spectroscopic setup for isomerization quantum yield determination

• Anouk Volker,
• Jorn D. Steen and
• Stefano Crespi

Beilstein J. Org. Chem. 2024, 20, 1684–1692, doi:10.3762/bjoc.20.150

• molecular switch by UV–vis absorption spectroscopy in operando. We provide all the information necessary to build the setup as well as the scripts and examples to retrieve the quantum yields of forward and backward isomerization of a molecular photoswitch following the evolution of the absorption in the low

• the known absorption spectrum of the pure switch [17]. To retrieve the quantum yield values for forward and backward isomerization, we solved rate equations Equations 5 and 6 (or Equation 6 and Equation 7, when the monochromatic excitation light approximation was not considered) numerically using two

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• on the arene were unsuccessful. Without substituents on the ring, aryl C–H activation and subsequent C–O bond formation occurred along with benzylic fluorination (7) (low efficiency). The presence of a p-methoxy group resulted in a switch in selectivity to acyloxylation 8’ as the major product. The

• is therefore not as concentrated in solution, allows for equilibration between benzylic radicals towards the more stable secondary radical. This switch in selectivity provides an interesting tool for selective fluorination in substrates with multiple benzylic sites. In 2017, Wu and co-workers

A comparison of structure, bonding and non-covalent interactions of aryl halide and diarylhalonium halogen-bond donors

• Nicole Javaly,
• Theresa M. McCormick and
• David R. Stuart

Beilstein J. Org. Chem. 2024, 20, 1428–1435, doi:10.3762/bjoc.20.125

• Information File 1, Table S8) and the electronic energy at the BCPs, E(r) (Scheme 5). On the bonding continuum positive values of E(r) are generally associated non-covalent bonds and negative values of E(r) indicate increasing covalency [42]. We observed a switch from positive E(r) values for the lighter

• (halogen or hypervalent bond) between chloride anion and diarylchloronium cation 9 is non-covalent and likely dominated by electrostatic attraction. A similar switch from non-covalent halogen bond for the lighter (X = Cl and Br) to partially covalent halogen bond for the heavier (X = I and At) was also

Challenge N- versus O-six-membered annulation: FeCl₃-catalyzed synthesis of heterocyclic N,O-aminals

• Giacomo Mari,
• Lucia De Crescentini,
• Gianfranco Favi,
• Fabio Mantellini,
• Diego Olivieri and
• Stefania Santeusanio

Beilstein J. Org. Chem. 2024, 20, 1412–1420, doi:10.3762/bjoc.20.123

• represents an interesting example of auto-tandem catalysis in which FeCl3 promotes two subsequent reactions. For further confirmation to support our mechanistic hypothesis and in an attempt to switch the reaction toward the formation of hemiaminal 6a, we repeated the reaction of thiohydantoin 4j, (chosen as

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• be employed in two variants modulated by light irradiation. This external switch can be used to selectively trigger side-chain or core halogenation. Keywords: aryl halides; benzyl halides; bromination; sustainability; Introduction Activation through halogens has become a key strategy in achieving

Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries

• Akanksha Ashok Sangolkar,
• Rama Krishna Kadiyam and
• Ravinder Pawar

Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93

• an undesired byproduct due to thermal dissociation. Consequently, the type-Id switch does not meet the criteria for reversible photoswitching desired for an ideal MOST system. This leads to the inference that the heteroatom used to extend the unsaturated bridge of the BBD molecules plays a crucial

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• straightforward synthesis of a wide-range of disubstituted BCPs from [1.1.1]propellane allows them to be easily integrated into drug discovery programmes. The case of Darapladib is one well-known example of a productive para-benzene-to-BCP bioisosteric switch [24]. By comparison, the number of bioisosteres of

• potential explanation for these observations is an increase in heterocycle basicity on bioisosteric switch of a neighbouring aromatic group. However, the drug-specific half-maximal rescue concentration (RC50 CFTR, lower indicates higher biological activity), indicative of the biological activity, increased

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

• and drug delivery systems [12]. pH-Responsive molecular tweezers A particular case of coordination-responsive systems is when a proton is used as a stimulus leading to pH-responsive systems with the protonation/deprotonation of the switchable moiety. The conformational switch in these systems is

• attached functional arms. The formation of new hydrogen bonds between -OMe groups and protonated pyridine stabilizes a "W"-shaped open conformation. The conformation switch can be easily followed by NMR spectroscopy in solution. Remarkably, the water-soluble tweezers 1, when functionalized with hydrophobic

• signals in the low-range visible/NIR region. Upon protonation of the pyridine, the conformation switch leads to a spatial separation of the active Pt moieties and a release of the guest (Figure 4). Also, the same group demonstrated the induction of chirality and fluorescence with chiral guest molecules

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• benzonitrile, the formation of an exciplex was not observed and it was considered that the CS state ((F12SubPc–TCBD)•−–aniline•+) was formed from the singlet excited state of F12SubPc before returning to the singlet ground state. The aforementioned phenomenon, characterized by the switch in the exciplex or the

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• were not fruitful, mostly due to poor solubility. Anion–π catalysis on carbon nanotubes With fullerenes confirmed as privileged scaffold for induced anion–π catalysis but higher oligomers inaccessible [12][67][80], the obvious next move was to switch to carbon nanotubes. Compared to the sixty free

Selectivity control towards CO versus H₂ for photo-driven CO₂ reduction with a novel Co(II) catalyst

• Lisa-Lou Gracia,
• Philip Henkel,
• Olaf Fuhr and
• Claudia Bizzarri

Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129

• ) intermediate could be favored concerning the formation of the CO2 adduct with the reduced metal center. Thus, besides the development of novel efficient catalysts, different strategies have been pursued to switch the catalyst selectivity towards carbon products [4][5]. Generally, scientists can interplay by

• was fully earth-abundant, as the complex [Cu(dmp)DPEPhos](BF4) was used as the photosensitizer. Preliminary tests in the solvent mixture of DMA/TEOA showed that the novel catalyst reduces CO2 to CO. However, the evolution of molecular hydrogen was prevailing. Thus, we modified the conditions to switch

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

• solvent-controlled regioselectivity switch of this aza-Friedel–Crafts reaction can be explained by the involvement of the polar solvent (acetonitrile) in the H-bonding with the catalyst thus creating a more hindered environment for a C3 alkylation, rather favoring the reaction through the less congested

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• , and potassium pivalate (KOPiv) as base, linear C–H-alkylated products 40 were obtained from both acrylates and acrylamides in moderate to high yields (Scheme 9, reaction conditions a). However, when K3PO4 was employed as the base under otherwise identical conditions, the authors observed a switch in

• regioselectivity and branched products 41 were obtained with acrylamides as coupling partners (Scheme 9, reaction conditions b). Thus, the authors demonstrated a switch in regioselectivity (linear/branched) which was controlled exclusively by the base used. During further investigations the authors found that the

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• ]. Excimers are formed when pyrene moieties form supramolecular complexes by intermolecular or intramolecular π–π interactions, causing a significant shift of single pyrene bands to longer wavelengths. Pyrenes are often used as a sensor part of receptor molecules, so their excimer bands switch on/off to

• , this result could lead to the development of new probes based on pyrene–phenanthridine chromophores that can switch fluorescence signals on/off upon binding to biomacromolecules. Experimental Synthesis The phenanthridine derivative of alanine amino acid (Phen-AA) has been prepared according to the

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• the IC50 values of three different nanoparticle formulations containing equal amounts of drug may be related to the surface charges of the nanoparticles. For CT26 cells, when 6-O-capro-β-CD and CS-(6-O-capro-β-CD) nanoparticle formulations are compared, it can be interpreted that the switch of NP