Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• mechanism. Although an in-depth investigation into the mechanism of iridium-catalyzed hydroacylation reactions has never been carried out, the mechanistic pathways should parallel those of other analogously reactive d7 metals. On the basis of pioneering mechanistic investigations into rhodium-catalyzed

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• fairly high fraction of amino acids present in an anti-parallel β-sheet backbone conformation. aAxWt also shows a small fraction of anti-parallel β-sheet, while P5 trans only shows a marginal percentage of parallel β-structure. The backbone RMSD-based clustering further breaks down the conformational

Electrocatalytic C(sp³)–H/C(sp)–H cross-coupling in continuous flow through TEMPO/copper relay catalysis

• Bin Guo and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2021, 17, 2650–2656, doi:10.3762/bjoc.17.178

• alkyne 22 afforded 1.05 g (61%) of product 14 in 13 h (Scheme 3). The productivity could be increased if multiple reactors were employed in parallel [43]. A mechanism for the electrochemical synthesis was proposed based on reported studies (Scheme 4) [3][10]. Anodic oxidation of TEMPO generates the

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

• . Under optimized conditions, the substrate scope was examined and determined to include activated olefins, unactivated olefins, and arylalkynes. In parallel, Hu and co-workers [51] reported the photoinduced, copper-catalyzed chlorosulfonylation of alkenes and alkynes under irradiation with blue LEDs

• 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

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• , desymmetrization of 86 was achieved under Sharpless epoxidation conditions employing a t-BuOOH/(+)-DIPT/Ti(O-iPr)4 system to give epoxide 85 (63%), which was subsequently protected as PMB ether 84 in 86% yield (Scheme 10). In parallel, the same precursor 86 was subjected to another Sharpless epoxidation using

• Poit., i.e., the brevipolides A–O, parallel with their appealing biological activity, in addition to the fact that they were produced in a small quantity from nature, make these natural products highly relevant when considering total synthesis. Since the first attempt to prepare brevipolide H by

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• focus has also been turned to the development of other catalyst systems that are not based on N–H bonds, such as the chiral silanediol catalysts first reported by Mattson and co-workers in 2013 [19][20]. Furthermore, it is worthy to mention that in parallel to the investigations towards new chiral

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

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• the desired product 137a. In a parallel pathway the product decomposes to selenone 144, 3-(phenylthio)indole (139) and regenerates Se. In a recent effort by Talukdar, the cheap and non-anhydrous solvent ethanol was used to prepare the desired bis(indol-3-yl)selanes 136 in moderate yields [98

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

• orientation of the individual chains and in the number of hydrogen bonds in the crystalline structures [42][43]. In Cellulose I, the chains are oriented parallel, whereas in Cellulose II antiparallel. Natural cellulose is produced by cellulose synthases [44][45][46]. As the chain gets elongated, microfibrils

• geometries were observed with a block wise arrangement of methyl groups. As chemical synthesis offers high flexibility in terms of manipulation, non-carbohydrate moieties can be exploited to guide the geometry of the resulting compounds. β(1–4)-Linked glucose chains were connected parallel via an

• studies revealed that long β(1–3)-glucan structures adopt a parallel, triple helical structures [146]. A glycosynthase derived from Bacillus licheniformis could polymerize glycosyl fluoride donors to prepare artificial mixed linkage β-glucans with an average molecular mass of 10–15 kDa [147]. The better

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• mechanisms occur in parallel, which results in the formation of the Michael adduct as a byproduct and the desired spirocyclopentanes 104. It is noteworthy that the mechanistic studies showed that the product is formed through a concerted mechanism and therefore is not part of an intermediate adduct. A

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

• to dsDNA [1][2]. The parallel PNA-dsDNA triplex, where the N-terminus of PNA aligns with the 5′-terminus of a polypurine strand of DNA (Figure 2A), is a binding mode that is particularly sensitive to electrostatic repulsion as three negatively charged strands are brought in proximity. PNA was also

• Rozners and co-workers showed that PNAs as short as hexamers formed strong and sequence specific triplexes at pH 5.5 [27]. Later studies using nucleobase-modified PNA (vide infra) confirmed that PNA had >10-fold higher affinity for dsRNA than for the same sequence of dsDNA [28][29][30][31]. While parallel

• for antiparallel triplexes. The strand invasion complex contains two PNA molecules binding the purine-rich strand of DNA. While one PNA strand forms an antiparallel Watson–Crick duplex, the other strand forms a parallel Hoogsteen triplex, which brings the N- and C-ends of the two strands in proximity

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

• Feng Xiong,
• Bo Li,
• Chenrui Yang,
• Liang Zou,
• Wenbo Ma,
• Linghui Gu,
• Ruhuai Mei and
• Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

• observed by parallel experiments, again suggesting that the C‒H activation is kinetically relevant (Scheme 4d). Based on our mechanistic findings and previous studies, we propose a tentative plausible reaction pathway in Scheme 5. The transformation commences with substrate coordination and subsequent

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

• Santiago Ramos-Carreño,
• Ivone Giffard-Mena,
• Jose N. Zamudio-Ocadiz,
• Alfredo Nuñez-Rivera,
• Ricardo Valencia-Yañez,
• Jaime Ruiz-Garcia,
• Maria Teresa Viana and
• Ruben D. Cadena-Nava

Beilstein J. Org. Chem. 2021, 17, 1360–1373, doi:10.3762/bjoc.17.95

• ®, Europe) [47]. This inoculum solution is referred to as the 1:10 dilution. The in vivo experiments were immediately initiated after preparing the inoculums. Simultaneously, uninfected shrimp or free WSSV were parallel-used under the same procedure as a negative control (WSSV-negative). Viral inoculum

A new glance at the chemosphere of macroalgal–bacterial interactions: In situ profiling of metabolites in symbiosis by mass spectrometry

• Marine Vallet,
• Filip Kaftan,
• Veit Grabe,
• Fatemeh Ghaderiardakani,
• Simona Fenizia,
• Aleš Svatoš,
• Georg Pohnert and
• Thomas Wichard

Beilstein J. Org. Chem. 2021, 17, 1313–1322, doi:10.3762/bjoc.17.91

• SYBR Gold staining (Figure 3a) as previously described [8][37]. These findings indicated that bacteria are associated with their algal host during symbiosis. In parallel, we visualised the metabolites produced by the biofilm formed around U. mutabilis by imaging analysis with AP-SMALDI-HRMS. Three

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

• system with the steam being recycled back through the reactor. After phase separation, the obtained mixture was enriched to 85% of 83 (equating to a 73% isolated yield). Once the reaction conditions were optimised, the apparatus can merge with other flow systems to develop a parallel continuous multistep

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

• ]. Compound 13 is a recollection of the older sample 13A and is almost identical in structure. Both feature a parallel alignment of porphyrins tied together with the reciprocated Br···H contacts with the pyrrole hydrogens and a second contact between the bromine and the p-methoxy hydrogens (Figure 17A, Figure

•  18A). Both structures also feature the hexyl chain overlapping with the face of the porphyrin ring (Figure 17B, Figure 18B, Supporting Information File 1, Figure S35). Compound 14 forms a similar parallel alignment as the one seen in compounds 13 and 13A (Supporting Information File 1, Figure S36A

• Information File 1 (Figure S43 and Figure S44). The hydrogen···halogen interactions are listed in Table 2. Compounds 16–18 are a series of structures that only differ by the type of metal center in the porphyrin core [34][35]. In compound 16 the stacked porphyrin layers are orientated in a parallel

Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

• Ákos Bajtel,
• Mounir Raji,
• Matti Haukka,
• Ferenc Fülöp and
• Zsolt Szakonyi

Beilstein J. Org. Chem. 2021, 17, 983–990, doi:10.3762/bjoc.17.80

• oxazolidin-2-one 9. NOESY experiments and X-ray structure proofment of the structure of oxazolidine 17. Proposed pathway for the ring–ring tautomerism. Stereoselective synthesis of the pinane-fused oxazolidin-2-one 9. Stereoselective synthesis of the pinane spiro-fused oxazolidin-2-one 12. Parallel synthesis

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

• °C) [99][101]. Moreover, (S)-GNA and (R)-GNA do not cross-pair either in a parallel or antiparallel fashion; thus GNA:GNA duplex formation is limited to homochiral pairing between either (S)-GNA or (R)-GNA strands [103]. With respect to nuclease stability, Nielson et al. showed that a 17mer

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

• , multimode microwave reactors for parallel synthesis and multimode microwave reactors for single-batch scale-up. The reactors vary in capacity and the distribution mode of the electromagnetic wave in the reactor vessel. The introduction of the Si–C (silicon–carbon) vials enables high temperature resistance

• seems to be compromised imposing restrictions on using microwaves at a scale-up level. However, the batch process and continuous flow process seem to provide an entry into scale-up standards with safety. The microwave reactors serving the purpose of batch and parallel approach are designed in various

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• ]. This method with long perfluorinated alkyl chains is attractive in parallel synthesis and also in high-throughput biological screening. However, both the modified LR and the fluorous solvents are rather expensive and not practical for scaling up. Besides, basic aqueous solutions were utilized as well

DNA with zwitterionic and negatively charged phosphate modifications: Formation of DNA triplexes, duplexes and cell uptake studies

• Yongdong Su,
• Maitsetseg Bayarjargal,
• Tracy K. Hale and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2021, 17, 749–761, doi:10.3762/bjoc.17.65

• provide either a zwitterionic phosphoramidate with N+ modification or a negatively charged phosphoramidate for Ts modification in the DNA sequence. The incorporation of these N+ and Ts modifications led to the formation of thermally stable parallel DNA triplexes, regardless of the number of modifications

• parallel triple-helix structure, a polypyrimidine TFO binds to dsDNA through Hoogsteen base-pairing [17], in which the cytosine bases in the TFO are protonated at the N3 atom (Figure 1B). In antisense strategies, antisense ONs (AOs) interact with RNA molecules to interfere with protein expression [18][19

• various positions in the sequence. The thermal stability of a parallel DNA triplex and duplexes of DNA and RNA formed with these ONs where then evaluated. Thermal denaturation experiments, nuclease resistance and cell-uptake assays were also conducted to evaluate these chemically modified ONs. Results

Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

• Ramazan Koçak and
• Arif Daştan

Beilstein J. Org. Chem. 2021, 17, 719–729, doi:10.3762/bjoc.17.61

• reaction conditions. Inverse electron-demand Diels–Alder reactions are cycloadditions between electron-rich dienophiles and electron-poor dienes. EDGs raise the electron density of dienes and, in parallel, raise the LUMOdiene–HOMOdienophile energy gap, and consequently the reactivity decreases. Although

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• diacylation reactions were run in parallel and then combined for oxidative hydrolysis. The quantities for each reaction are separated by a forward slash. To a mixture of 3-aminopyrrolizine hydrochloride 17 (22.3/43.6 mg, 0.118/0.231 mmol) and a solution of distilled pyridine in acetonitrile (1.20/2.30 mL, 0.5

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

• ) and for the incorporation of 5-fluorotryptophan (1) and 6-fluorotryptophan (2) in streptavidin [14]. Parallel to the development of these new strategies for recombinant fluorinated protein production, significant efforts have been made within the last decade to expand the pool of available amino acids

1,2,3-Triazoles as leaving groups in S_NAr–Arbuzov reactions: synthesis of C6-phosphonated purine derivatives

• Kārlis-Ēriks Kriķis,
• Irina Novosjolova,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 193–202, doi:10.3762/bjoc.17.19

• compared the reaction outcome and rates when DMSO-d6 solutions of the starting materials 2a and 2b were treated either with NaN3 or NaCl in parallel experiments. The reaction mixtures were directly analyzed by 1H and 31P NMR spectroscopy using 1,2,3-trimethoxybenzene as an internal standard (Tables S1 and