Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• cells. When TPP was conjugated to the pMPC PISA particles more cellular uptake as well as better spheroid penetration were observed, while TPP on PEG-based PISA had only little effect. It was hypothesized that TPP on the micelle surface may not be accessible enough to allow mitochondria targeting, but

• result in more bioactive PISA nanoparticles [28]. Therefore, the relative short MPC block (p(MPC17-co-PENAO4), MP2 ) was selected, which was reacted with MMA in water–methanol to yield nanoparticles of around 76 nm (Table 1). In order to identify a matching nanoparticle of similar size with a PEG surface

• attachment of TPP-COOH to the micelle variants resulted in an increase in hydrodynamic diameter from approximately 85 nm to 136 nm for the PEG micelles and from 75 nm to 138 nm for the zwitterionic counterparts. However, no major change in dispersities was detected and well-defined nanoparticles (PdI < 0.078

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

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• synthesis of fully decorated 1,2,3-triazoles 162, 164, and 166 was reported by Ackermann et al. via intramolecular oxidative C–H arylation of 1,2,3-triazoles 161, 163, and 165 using a reusable palladium catalyst in PEG, Pd@PEG, under O2 atmosphere. The main advantages of this strategy include i) a versatile

• methodology for aerobic C–H activation; ii) PEG as green and recyclable reaction medium; and iii) a reusable palladium catalyst complex [65]. Fully functionalized 1,2,3-triazolo-fused chromenes 162, 164, and 166 were regioselectively prepared in moderate yield. The isoindoline-fused triazoles 164 were

• ]triazoles 166 were also prepared through the cyclodehydrogenative arylation of 165. It was demonstrated that the Pd and PEG mixture could be reused for further cycles, and only a catalytic amount of the copper source, pivalic acid, and the substrates needed to be added [65]. As shown in Scheme 44, this

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• −1 to 3710 cm−1 relying on pendant hydroxy groups of the PEG structure, the signal at 1719 cm−1 is corresponding to the C=O group stretching and the more pronounced intensities from 980 cm−1 to 1202 cm−1 are attributed to C–H bending and C–O stretching vibrations. Consequently, all FTIR spectra

• overall interpretation is that the condition variety did not drastically affect ESR results of each sample. HGCM-PEGMEMA has the highest ESR in every condition that is in good agreement with the nonionic and highly flexible structure of PEG that can resist electrolytes and pH stimuli. On the other hand

Enhanced target cell specificity and uptake of lipid nanoparticles using RNA aptamers and peptides

• Roslyn M. Ray,
• Anders Højgaard Hansen,
• Maria Taskova,
• Bernhard Jandl,
• Jonas Hansen,
• Citra Soemardy,
• Kevin V. Morris and
• Kira Astakhova

Beilstein J. Org. Chem. 2021, 17, 891–907, doi:10.3762/bjoc.17.75

• challenging. In an effort to target LNPs composed of an ionizable cationic lipid (DLin-MC3-DMA), cholesterol, the phospholipid 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), and 1,2-dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000 (DMG-PEG 2000) to particular cell types, as well as to generate

• lipid, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol, and PEG-lipid, each with an essential role in the design (Figure 1). These lipids promote the effective distribution of the LNP in vivo as well as aid in effective cargo release from the endosome [1][37]. To this end, we herein

• mixture of DLin-MC3-DMA, DSPC, cholesterol, and 1,2-dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000 (DMG-PEG 2000). Lipids were first extruded and then complexed with negatively charged aptamers annealed with fluorescently tagged complementary DNA oligonucleotides (GP160:A-1 or CCR5:G-3) to

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

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

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

• Masayori Hagimori,
• Estefanía E. Mendoza-Ortega and
• Marie Pierre Krafft

Beilstein J. Org. Chem. 2021, 17, 511–518, doi:10.3762/bjoc.17.45

• penetrating properties, such as the transactivator of the transcription (TAT) peptide. Moreover, peptides being smaller than the antibodies generally induce a lower immunogenicity [15][16][17]. Micro- and nanocarriers are often covered by poly(ethylene glycol) (PEG) stealth coatings that significantly enhance

• occurrence of side reactions due to reactive groups introduced during PEG to lipids (or peptides) connecting reactions [23][24][25]. In particular, the PEG layer grafted on the surface of certain nanocarriers restricts the exposure of functional peptides [26][27]. Novel ligand-grafted lipids have been

• proposed for the preparation of functional drug carriers for clinical applications [25][28][29]. In order to alleviate the steric hindrance effect of PEG chains, a novel spacer consisting of alternating serine–glycine sequences (SG)n was introduced between the ligand and lipid within the molecular

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• trimethylsilyl cyanide (TMSCN) in poly(ethylene glycol) (PEG) solution. The advantages of the sonochemical versus the conventional α-(arylamino)acetonitrile synthesis are the significantly shorter reaction time (30 min instead of 72 hours), the higher purity and the easier separation of the product that

• , ferrocene or benzene units was screened by the Salmonella mutagenicity assay (Ames test) [28] using S. typhimurium TA98 and TA100 strains. Results and Discussions Ultrasound-assisted synthesis The Strecker reaction between (hetero)aromatic aldimines and TMSCN in poly(ethylene glycol) (PEG)–water medium [18

• TMSCN (1 equiv) to a solution containing the aldimine (1 equiv) dissolved in PEG (5 mL) and water (1 mL). After completion of the reaction, the product was collected by filtration directly from the reaction mixture, or after being poured into water. The crystalline product was dried and if necessary

Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

• María C. Mollo,
• Natalia B. Kilimciler,
• Juan A. Bisceglia and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2020, 16, 32–38, doi:10.3762/bjoc.16.5

• reactions in either case. The synthesis of 2-phenyl-4,5,6,7-tetrahydro-1,3-thiazepine by cyclodehydration of N-(4-hydroxybutyl)thiobenzamide was attempted with different condensing agents: PPA (100 °C, 15 h), Burgess (25 °C, 48 h) and PEG-Burgess (80 °C, 2 h) reagents, and under Mitsunobu conditions. In the

• first case, the 1H NMR spectrum of the resulting product contained no signals in the aromatic region [31]. The Burgess reagent led to 58% of the desired product, while the modified PEG-Burgess reagent yielded a mixture of the thiazepine (17%) and the isomeric N-thiobenzoylpyrrolidine (40%). The use of

• -thiobenzoylaminobutanol with PEG-linked Burgess reagent and under Mitsunobu conditions led to significant amounts of N-thiobenzoylpyrrolidine [32]. In fact, this kinetically favoured competitive reaction also occurs in the closely related cyclization of N-benzoylaminobutanol with PPSE, which leads exclusively to N

Targeted photoswitchable imaging of intracellular glutathione by a photochromic glycosheet sensor

• Xianzhi Chai,
• Hai-Hao Han,
• Yi Zang,
• Jia Li,
• Xiao-Peng He,
• Junji Zhang and
• He Tian

Beilstein J. Org. Chem. 2019, 15, 2380–2389, doi:10.3762/bjoc.15.230

• control reporter 8o with a PEG chain instead of the galactoside targeting group was also prepared. The detailed synthetic procedures and characterizations are given in Supporting Information File 1. Photochromic performances of Glyco-DTE The photoswitching performances of Glyco-DTE (1 × 10−5 mol/L) were

Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses

• Anne-Marie Caminade,
• Artem Zibarov,
• Eduardo Cueto Diaz,
• Aurélien Hameau,
• Maxime Klausen,
• Kathleen Moineau-Chane Ching,
• Jean-Pierre Majoral,
• Jean-Baptiste Verlhac,
• Olivier Mongin and
• Mireille Blanchard-Desce

Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221

• one case, phenol PEG (poly(ethylene glycol) was grafted together with pyridine imine phenol, affording dendrimers stochastically functionalized on the surface, but all having precisely 12 fluorophores in the internal structure [59]. Another way to induce solubility in water consists in having

• the synthesis was carried out up to the second generation, then 24 phenol-PEG were grafted. In the second case, the synthesis was carried out up to the third generation, which was functionalized with 48 ammonium groups (Figure 6). Photo-physical studies of both compounds indicated that the

• fluorophores are more protected by the PEG groups of the second generation G2 than by the ammonium groups of the third generation G3 as indicated by the quantum yields Φf = 0.24 (G3 ammonium) and 0.39 (G2 PEG). However, the TPA cross-section measurements gave σ2max = 13,600 GM for G3 ammonium, and 8,400 GM for

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• functionalised fulvene as the polydiene. Initially, a fulvene derivative (4-(cyclopenta-2,4-dien-1-ylidene)pentanoic acid) was conjugated to dextran, and employed in DAC at 37 °C with a dichloromaleic acid-modified PEG derivative (Scheme 20) [191]. The formed hydrogels exhibited self-healing at physiological

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• the product was detected when the reaction was carried out in ethanol/water 1:1 (Table 1, entry 12). Even when repeating the reaction in the presence of the phase-transfer catalyst, poly(ethylene glycol) (PEG) no mentionable yield of product was observed (Table 1, entries 13 and 14). The subsequent

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• conjugation at the N-terminus required microwave irradiation due to the bulkier character of the amino component. Besides steroids, the method worked well with varied boronic acids, including those bearing fluorescent labels, lipids and PEG chains, thus providing a new class of biomolecular conjugates showing

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• (33) is replaced by bromoisobenzofuranone 61, also leading to isoindoloquinazoline derivatives 57 (Scheme 18) [99]. After optimization of the reaction conditions, a 4:1 combination of water and PEG-400 was chosen as the best solvent and an array of nineteen isoindoloquinazolinones 57 with yields

Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts

• Rodrigo Abonia,
• Luisa F. Gutiérrez,
• Braulio Insuasty,
• Jairo Quiroga,
• Kenneth K. Laali,
• Chunqing Zhao,
• Gabriela L. Borosky,
• Samantha M. Horwitz and
• Scott D. Bunge

Beilstein J. Org. Chem. 2019, 15, 642–654, doi:10.3762/bjoc.15.60

• ]. Furthermore, it is highly desirable to perform these reactions in environmentally friendly solvents such as water, ethanol, and PEG [6][7]. Motifs bearing triarylmethane (Ar3CH) [8][9][10] and their heterocyclic variants (Het-Ar)3CH [8][9][10][11][12], constitute an integral part of a number of bioactive

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

• Jessica Hassenrück and
• Valentin Wittmann

Beilstein J. Org. Chem. 2019, 15, 584–601, doi:10.3762/bjoc.15.54

• allowed the determination of rate constants in aqueous solution. As reported for ManNCyoc, an excess of ManNCyc and ManNCp, respectively, was reacted with water-soluble tetrazine Tz-PEG-OH in acetate buffer (pH 4.7, Figure 2A). The decrease of absorption of Tz-PEG-OH at λmax = 522 nm was measured and

• peracetylation step. Stock solutions of Tz-PEG-OH and sugar were prepared in acetate buffer (pH 4.8) and mixed in a quartz cuvette to give final concentrations of 1 mM Tz-PEG-OH and 10 mM, 13.3 mM and 16.6 mM, respectively, of ManCyc or ManCp. The reaction was monitored by measuring the absorption of the

• tetrazine at 522 nm. Pseudo-first-order rate constants were determined for every concentration of ManNCyc and ManNCp, respectively, by plotting ln(A0/At) versus time. For the determination of A0, a 1 mM solution of Tz-PEG-OH was used. At is the absorption of the reaction at time point t. Analysis by linear

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• metathesis to proceed efficiently “in water” [36]. Lipshutz and co-workers generalized the application of a three-component non-ionic surfactant for numerous reactions in water, including olefin metathesis [37][38][39]. The surfactant, PTS, incorporates α-tocopherol, sebacic acid and PEG moieties as part of

• analogues (Scheme 8). However, catalysts 1 and 2 are unstable in water and their use is limited to ROMP. Polyethylene glycol (PEG)-tagged catalysts (10 and 11, Figure 1c) showed significantly improved RCM activities in water, but they tend to form aggregates in water due to their high molecular weight (ca

• (Figure 1c) through host–guest interactions [61]. Chung and co-workers used a PEG-tethered adamantyl ligand for various metathesis reactions in water and DCM [62]. The authors showed that the catalyst can be easily removed by generating a host–guest complex between silica-grafted β-cyclodextrin and the

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• -substituted NB with poly(ethylene glycol) (PEG) [69]. Ring-opening metathesis copolymerization of the rather strained cyclooctene (COE) and a strainless 27-membered macrocyclic olefin (MCO) led to the multiblock copolymer consisting of octenylene blocks linked with ring-opened MCO segments (Scheme 6) [70

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

• Daniel F. Sauer,
• Johannes Schiffels,
• Takashi Hayashi,
• Ulrich Schwaneberg and
• Jun Okuda

Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265

• catalyst and carbohydrate or small polyethylene glycol (PEG) groups were attached [11]. As another strategy to modify a protein surface with olefin metathesis, Isarov and Pokorski introduced a Grubbs 3rd generation catalyst on the surface of lysozyme and performed ring-opening metathesis polymerization

• (ROMP) on the protein surface employing a PEGylated norbornene derivative as substrate [13]. This led to proteins modified with PEG chains. These two examples illustrate the potential applications of olefin metathesis in protein modification. Further applications would be the implementation of olefin

The design and synthesis of an antibacterial phenothiazine–siderophore conjugate

• Abed Tarapdar,
• James K. S. Norris,
• Oliver Sampson,
• Galina Mukamolova and
• James T. Hodgkinson

Beilstein J. Org. Chem. 2018, 14, 2646–2650, doi:10.3762/bjoc.14.242

• -cleavable linker. A polyethylene glycol (PEG) linker was selected as PEG linkers demonstrate enhanced water solubility in comparison to alkyl chain linkers. We then had to make a decision on the position of attachment for the PEG linker to compound 1. For siderophore conjugates, it is crucial that the

• suitable position for PEG linker attachment [13]. From commercially available 2-(2-aminoethoxy)ethanol the amine functionality was Boc-protected under standard conditions to give compound 2 (Scheme 1). Under basic conditions 2 underwent an SN2 reaction with commercially available p-xylylene dichloride to

• suitable to progress to the next steps. Initially, the reaction of 3 with chlorpromazine (free base) was attempted at room temperature; however, it was found refluxing was required to drive the reaction to completion to generate compound 4 in excellent yield. The final PEG-amine-functionalised

Calixazulenes: azulene-based calixarene analogues – an overview and recent supramolecular complexation studies

• Paris E. Georghiou,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Hidetaka Nishimura,
• Jaehyun Lee,
• Atsushi Wakamiya and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2018, 14, 2488–2494, doi:10.3762/bjoc.14.225

• Stueker of Compute/Calcul Canada via the Westgrid and Acenet facilities. The late Prof. R. Marceau, Vice-President Research, M.U.N. is gratefully acknowledged for research support to PEG.