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

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• the presentation [39] (i.e., microenvironment) of glycosyl donor molecules, which are incorporated in supramers, hence their chemical properties [35], thus making possible a shift of a fragile and not well-understood borderline between different reaction pathways at the SN1–SN2 interface [22][24][25

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• stimuli, pH response is of particular interest in the construction of supramolecular systems for intelligent drug delivery because of the presence of pH gradients in the microenvironment of organs, tissues, and cell organelles [5]. In the past years, pH-responsive and other stimuli-responsive

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

• primarily responsible for the anticancer action [8][14][16][17][18]. To avoid CPT inactivation at alkaline medium, the concept that the lactone form can be kept stable by being encapsulated in an acidic microenvironment is also fascinating. Custom synthesized polycationic cyclodextrin amphiphiles have shown

Shift of the reaction equilibrium at high pressure in the continuous synthesis of neuraminic acid

• Jannis A. Reich,
• Miriam Aßmann,
• Kristin Hölting,
• Paul Bubenheim,
• Jürgen Kuballa and
• Andreas Liese

Beilstein J. Org. Chem. 2022, 18, 567–579, doi:10.3762/bjoc.18.59

• methacrylate and aldolase: amino methacrylate). The microenvironment and material surrounding the enzyme have a significant influence on the enzyme activity [30]. For reusability studies, the three most appropriate carriers were selected and analyzed with respect to the activity of the immobilized enzymes

Site-selective reactions mediated by molecular containers

• Rui Wang and
• Yang Yu

Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35

• ; microenvironment; molecular containers; noncovalent protective group; site-selectivity; Introduction To run reactions with discriminate control over product selectivity represents one of the huge challenges in organic synthetic chemistry [1], among which, site-selectivity is always crucial to a reaction when

• more reactive alkynes and allylic alcohols. Both the microenvironment of the supramolecular catalyst and the steric profile of the substrate were responsible for the site-selectivity of hydrogenation. This beautiful work of a supramolecular-mediated catalytic site-selective reaction exhibited the

• containers, which have drawn much attention in the past years and shown broad prospects in the future. The supramolecular cavity and its constrained microenvironment resemble the active site of natural enzymes, where the guest substrate is encapsulated and positioned with a specific fixed orientation and

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• crystallization. Finally, the study revealed a few polar interactions of the fluoropyrrolidine ring within the protein microenvironment. In a study on thioredoxin, four out of five proline residues were mutated to alanine, and the only remaining proline residue was the one adopting a cis-amide-bond conformation

• ) reoccurs in the protein structures, given that a statistically significant number of residues is analyzed. Nonetheless, in some individual cases, the native preference of a fluoroproline residue can be overridden due to the residue microenvironment and the overall packing of the protein structure. 7 The

Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247

• >> ADP > UDP. Nucleobases undergo differential interactions with the tryptophan residues and naphthimide which varies the hydrophobic microenvironment around the fluorophore and results in dissimilar fluorescence enhancement. The addition of monophosphorylated species such as HPO42−, c-AMP, AMP, CMP, GMP

• emission increases due to the increased hydrophobic microenvironment around the pyrenes and the restriction of their intramolecular rotation under bound conditions. The structurally similar two proteins trypsin and chymotrypsin as well as bovine serum albumin does not exhibit any significant changes in

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• microenvironment of a protein binding site could also change the relative energies of the various F–C–C–F and F–C–C=O rotamers, offering the possibility that analog 2 might be an effective conformational mimic of 1 in some environments but not in others. Herein, we describe the optimisation of a synthetic route to

Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions

• Edgar Peris,
• Raúl Porcar,
• María Macia,
• Jesús Alcázar,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2020, 16, 1924–1935, doi:10.3762/bjoc.16.159

• -like phases (SILLPs) [33][34][35][36][37][38]. In these systems, the microenvironment provided by the ionic liquid-like units can have a remarkable influence on the overall process, particularly on the catalytic activity and recyclability of the supported species. Indeed, the appropriate design of the

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

• Xiaodong Zhang,
• Jun Xie,
• Zhiling Xu,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

• benzene ring. In spectrum (d), the peaks at 704, 778 and 898 cm−1 for the guest disappeared due to the inclusion of Q[8] and the molecular microenvironment of BALE being changed. From DTA (Figure 6), we can also see that BALE and Q[8] interacted with each other. Q[8] (Figure 6b) has a broad endothermic

Synthesis of a water-soluble 2,2′-biphen[4]arene and its efficient complexation and sensitive fluorescence enhancement towards palmatine and berberine

• Xiayang Huang,
• Xinghua Zhang,
• Tianxin Qian,
• Junwei Ma,
• Lei Cui and
• Chunju Li

Beilstein J. Org. Chem. 2018, 14, 2236–2241, doi:10.3762/bjoc.14.198

• , compounds P and B alone only displayed fairly feeble fluorescence emission. Upon addition of 2,2’-CBP4, the fluorescence intensity was remarkably improved more than 600 times (Figure 2 and Supporting Information File 1, Figure S10). This was due to the effect of lowering polar microenvironment when P or B

• was included by 2,2’-CBP4; the guest emits stronger fluorescence in a more hydrophobic microenvironment [48]. Combined with NMR results, we can unambiguously conclude the alkaloid molecules must insert into the hydrophobic cavity of 2,2’-CBP4 to form inclusion complexes. Interestingly, the emission

Natural and redesigned wasp venom peptides with selective antitumoral activity

• Marcelo D. T. Torres,
• Gislaine P. Andrade,
• Roseli H. Sato,
• Cibele N. Pedron,
• Tania M. Manieri,
• Giselle Cerchiaro,
• Anderson O. Ribeiro,
• Cesar de la Fuente-Nunez and
• Vani X. Oliveira Jr.

Beilstein J. Org. Chem. 2018, 14, 1693–1703, doi:10.3762/bjoc.14.144

• cancer cells versus normal cells is likely due to the acidic microenvironment that accompanies cancer cells, and the increased net negative charge of cancer cells versus normal cells, which display a net neutral charge [12][20]. The mechanism of peptide-mediated cell death was further analyzed using flow

On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site

• Eirinaios I. Vrettos,
• Gábor Mező and
• Andreas G. Tzakos

Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80

• tumor microenvironment In order to selectively deliver cytotoxic drugs to malignant tumor sites, scientists can take advantage and map first the differential microenvironment between cancer and normal cells. The first one to report a fundamental difference between malignant and normal cells was Otto

• ]. Overwhelming production of stimulus agents and enzymes [21]. For instance, many types of cancer show enhanced levels of reactive oxygen species (ROS) which are reactive molecules and play a crucial role in cell proliferation [22]. The slightly acidic pH of the tumor microenvironment [23] (Warburg effect

• vehicles and formulates like nanoparticles [24] and calixarenes or cyclodextrins [25][26], where the cytotoxic drug is loaded and can be released at the malignant tumor site; b) installation of labile chemical groups to the tumor microenvironment (i.e., low pH) able to mask the cytotoxic drug and form a

Regulation of integrin and growth factor signaling in biomaterials for osteodifferentiation

• Qiang Wei,
• Theresa L. M. Pohl,
• Anja Seckinger,
• Joachim P. Spatz and
• Elisabetta A. Cavalcanti-Adam

Beilstein J. Org. Chem. 2015, 11, 773–783, doi:10.3762/bjoc.11.87

• Intelligent Systems, Stuttgart, Germany Department of Internal Medicine V, Oncology, Hematology, and Rheumatology, Heidelberg University Hospital, 69120 Heidelberg, Germany 10.3762/bjoc.11.87 Abstract Stem cells respond to the microenvironment (niche) they are located in. Under natural conditions, the

• , chondrocytes, adipocytes, and reticular cells (Figure 1) [3]. Osteogenic differentiation is especially valuable in regenerative medicine approaches [4]. It has been proven that stem cell fate can be regulated from the specific microenvironment known as stem cell niche. The extracellular matrix (ECM), which

• -bound cells and their cytoskeleton. Second, the signals resulting from these interactions enable cells to sense the chemical and mechanical properties of the microenvironment (niche) and to respond by activating signaling systems for regulating the cell fate [19]. Conversely, the contraction of the

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• supported catalyst has proven beneficial with regard to rate acceleration and increased selectivity due to formation of an aqueous microenvironment favored by the swelling properties of polymeric materials [43]. Particularly, in the case of dendritic proline derivatives [44][45][46] and N-alkylimidazole

Synthesis of a hexasaccharide partial sequence of hyaluronan for click chemistry and more

• Marina Bantzi,
• Stephan Rigol and
• Athanassios Giannis

Beilstein J. Org. Chem. 2015, 11, 604–607, doi:10.3762/bjoc.11.67

• the cells, nowadays it is well known that the ECM composes the ideal microenvironment for cells in order to interact with each other and also for supporting signaling between ECM macromolecules and intracellular components [2]. Besides water, the ECM consists of electrolytes, amino acids

Natural phenolic metabolites with anti-angiogenic properties – a review from the chemical point of view

• Qiu Sun,
• Jörg Heilmann and
• Burkhard König

Beilstein J. Org. Chem. 2015, 11, 249–264, doi:10.3762/bjoc.11.28

• secretion of pro-angiogenic factors either by the tumor cells themselves or by cells of the tumor microenvironment. After the tumor reaches a diameter of 1–2 mm, the tumor cells located far away from blood vessels undergo apoptosis or necrosis resulting from the lack of oxygen and nutrients. At that point

TEMPO-derived spin labels linked to the nucleobases adenine and cytosine for probing local structural perturbations in DNA by EPR spectroscopy

• Dnyaneshwar B. Gophane and
• Snorri Th. Sigurdsson

Beilstein J. Org. Chem. 2015, 11, 219–227, doi:10.3762/bjoc.11.24

• three labels, in particular TA, can report minor changes in their microenvironment, such as protonation, when placed in structured regions of nucleic acids. Base pairing of TC with G (A), TA with T (B), UC with G (C) and UA with T (D). EPR spectra of 14-mer DNA duplexes 5′-d(GACCTCGTAATCGTG)•5′-d

Effects of RAMEA-complexed polyunsaturated fatty acids on the response of human dendritic cells to inflammatory signals

• Éva Rajnavölgyi,
• Renáta Laczik,
• Viktor Kun,
• Lajos Szente and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2014, 10, 3152–3160, doi:10.3762/bjoc.10.332

• heterogeneity of these cells depending on the actual tissue microenvironment that is able to drive monocyte differentiation either to inflammatory or to tolerogenic directions [31]. In the past decade it was also discovered that phylogenetically ancient Toll-like receptors (TLR) play essential roles in the

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• the optimal catalyst. Based on the X-ray crystal structure of the catalyst, they proposed that the chiral microenvironment of the binaphthyl-based phosphepine was amplified by its 3,3´-diphenyl substituents. In the presence of the chiral phosphepine B4, the reactions of allenes with electron-deficient

Pyrene-modified PNAs: Stacking interactions and selective excimer emission in PNA₂DNA triplexes

• Alex Manicardi,
• Lucia Guidi,
• Alice Ghidini and
• Roberto Corradini

Beilstein J. Org. Chem. 2014, 10, 1495–1503, doi:10.3762/bjoc.10.154

• [9][10]. Among the possible reporter groups, pyrene has been proposed in several in vitro detection systems, due to the sensitivity of its fluorescence properties to microenvironment and due to its ability to produce stabilizing stacking interactions and to show excimer fluorescence [11][12][13][14

Design of a novel tryptophan-rich membrane-active antimicrobial peptide from the membrane-proximal region of the HIV glycoprotein, gp41

• Evan F. Haney,
• Leonard T. Nguyen,
• David J. Schibli and
• Hans J. Vogel

Beilstein J. Org. Chem. 2012, 8, 1172–1184, doi:10.3762/bjoc.8.130

• concentration was substantially higher than the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values (Table 1). Tryptophan fluorescence spectroscopy Tryptophan emission fluorescence of all the gp41w derivatives was performed to examine the microenvironment surrounding the