Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• . In this regard a higher release efficiency would equally undoubtedly be required than that shown by prototype 1 described herein. To this end, shortening/rigidification of the hydrocarbon azobenzene-BAPTA linkages in 1 may be anticipated to lead to an exalted difference in trans/cis-binding affinity

Current understanding and biotechnological application of the bacterial diterpene synthase CotB2

• Ronja Driller,
• Daniel Garbe,
• Norbert Mehlmer,
• Monika Fuchs,
• Keren Raz,
• Dan Thomas Major,
• Thomas Brück and
• Bernhard Loll

Beilstein J. Org. Chem. 2019, 15, 2355–2368, doi:10.3762/bjoc.15.228

• generate a vast number of (poly)cyclic hydrocarbon scaffolds. Remarkably, this complex chemical reaction, comprising changes in bonding, hybridization as well as the introduction of specific stereochemistry, is performed in a single reaction cascade without consumption of a cofactor [11]. In this review we

• result of heterolytic cleavage of the pyrophosphate–hydrocarbon bond or protonation of a double bond, (2) propagation of the carbocation along the forming terpene skeleton as a result of ring formations, hydride and/or methyl shifts, de- and reprotonation of intermediates, the creation of a terminal

Harnessing enzyme plasticity for the synthesis of oxygenated sesquiterpenoids

• Melodi Demiray,
• David J. Miller and
• Rudolf K. Allemann

Beilstein J. Org. Chem. 2019, 15, 2184–2190, doi:10.3762/bjoc.15.215

• -derived sesquiterpenes β-sesquiphellandrene [38][39][40] and zingiberene [40], a hydrocarbon with antifertility, antiviral and anticancer activity [41], suggested that the major compound was 12-methoxy-β-sesquiphellandrene (26), while the minor product was identified as 12-methoxyzingiberene (27). The two

Analysis of sesquiterpene hydrocarbons in grape berry exocarp (Vitis vinifera L.) using in vivo-labeling and comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC–MS)

• Philipp P. Könen and
• Matthias Wüst

Beilstein J. Org. Chem. 2019, 15, 1945–1961, doi:10.3762/bjoc.15.190

• corresponding synthase as a final proof is yet missing. In the following, the sesquiterpene hydrocarbon α-cubebene is used as an example to illustrate our interpretations in more detail (Figure 4). Genuine (d0) α-cubebene has a molecular ion peak [M]+• at m/z = 204 (Figure 4, upper mass spectrum, marked red

• isopropyl group leads to the fragment with m/z = 166. At this point it becomes obvious why it can be assumed that the tricyclic sesquiterpene hydrocarbon α-cubebene is synthesized via (S)-(−)-germacrene D and not via (R)-(+)-germacrene D. Assuming the biosynthesis of α-cubebene takes place via (R

• ]. Tantillo and co-workers showed that germacrene D does not have to be involved in the formation of α-ylangene due to carbocation energetics. However, according to our results the formation of this tricyclic sesquiterpene hydrocarbon and its isomer β-ylangene occurs via the intermediate (R)-(+)-germacrene D

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• of [KA'] and alkali metal iodides, extracting the ground mixtures with hydrocarbon solvents, and then attempting crystallization of the extracts. This is necessarily an imperfect route to sampling the product space, as definitive characterization of any product(s) depended critically on the

Cyclobutane dication, (CH₂)₄²⁺: a model for a two-electron four-center (2e-4c) Woodward–Hoffmann frozen transition state

• G. K. Surya Prakash and
• Golam Rasul

Beilstein J. Org. Chem. 2019, 15, 1475–1479, doi:10.3762/bjoc.15.148

• G. K. Surya Prakash Golam Rasul Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA 90089-1661, USA 10.3762/bjoc.15.148 Abstract The structures of the elusive cyclobutane dication, (CH2)42+, were investigated at the

• CCSD(T)/cc-pVTZ optimized Cartesian coordinates of 1–4, energies, ZPE and relative energies of 1–4 (Table S9) and calculated frequencies and IR intensities of 1 (Table S10). Acknowledgements Support of our work by Loker Hydrocarbon Research Institute is gratefully acknowledged.

Formation of an unexpected 3,3-diphenyl-3H-indazole through a facile intramolecular [2 + 3] cycloaddition of the diazo intermediate

• Andrew T. King,
• Hugh G. Hiscocks,
• Lidia Matesic,
• Mohan Bhadbhade,
• Roger Bishop and
• Alison T. Ung

Beilstein J. Org. Chem. 2019, 15, 1347–1354, doi:10.3762/bjoc.15.134

• (H···H = 2.48 Å) there is also a linear C6D–H6D···H6D–C6D close contact (H···H = 2.37 Å) around a further inversion centre. These two motifs alternate along the a axis to produce infinite hydrocarbon tapes with inversion centres separated by a/2 (Figure 6). The molecular structure of 8 precludes

• stepladder association of eight molecules (5b, lower). Crystallographic colour code: C–H···N purple), C–H···H–C (light blue), inversion centre (orange sphere), and incomplete contacts (red). Part of a hydrocarbon tape along a formed by a combination of alternating linear and cyclic C–H···H–C close contacts

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• install C–O functionality with high selectivity into a C–H bond is a challenge to synthetic organic chemists. Importantly, this transformation allows for the creation of value-added products from hydrocarbon feedstocks. Benzylic positions are a prevalent example of a functionality whose relatively weak C

Thiol-free chemoenzymatic synthesis of β-ketosulfides

• Adrián A. Heredia,
• Martín G. López-Vidal,
• Marcela Kurina-Sanz,
• Fabricio R. Bisogno and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2019, 15, 378–387, doi:10.3762/bjoc.15.34

• Table 2, entries 1–6) [46]. For aliphatic substituents at the α-position, a methyl group was perfectly accepted (Table 2, entries 22–24). Longer unbranched hydrocarbon was tolerated, although moderate conversion was achieved, even with higher lipase loading (Table 2, entry 12, 1l). For the latter, it

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• substrate range, shorter reaction times and higher yields of products than previously reported methods. Keywords: C–H activation; norbornadiene; palladium; phenanthrene derivatives; Introduction Phenanthrene is a polycyclic aromatic hydrocarbon which contains three benzene rings. The phenanthrenes can be

Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum

• Jan Rinkel,
• Alexander Babczyk,
• Tao Wang,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 2974–2990, doi:10.3762/bjoc.14.277

• mycotoxins [2], a class of highly bioactive secondary metabolites that belong to the strongest known inhibitors of protein biosynthesis in eukaryotes [3]. Similarly, the sesquiterpene aristolochene (2) is the parent hydrocarbon of PR toxin [4][5] and has been used as a marker to differentiate between toxin

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

• USA 10.3762/bjoc.14.225 Abstract Some of the least studied calixarenes are those that consist of azulene rings bridged by -CH2- groups. Since Lash and Colby’s discovery of a simple and convenient method for producing the parent all-hydrocarbon calix[4]azulene, there have been two other all

• -hydrocarbon calix[4]azulenes which have been synthesized in good yields by their method. This allowed studying their supramolecular properties. This report is of our latest work on the solution-state supramolecular complexation of one of these calix[4]azulenes, namely tetrakis(5,7-diphenyl)calix[4]azulene or

• reported to date. In 2002 Lash and Colby’s reported a convenient one-step Florisil®-mediated cyclocondensation of azulene with paraformaldehyde to produce an all-hydrocarbon “calix[4]azulene” 3 [15]. Later, Lash et al. reported their synthesis of a second all-hydrocarbon tetra-6-tert-butylcalix[4]azulene

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• Tetsuaki Fujihara Yasushi Tsuji Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan 10.3762/bjoc.14.221 Abstract Carbon dioxide (CO2) is one of the most important materials as renewable chemical feedstock. In this

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• are better suited to be included in the late stage functionalisation (LSF) section. 2.4 Reactions manipulating hydrocarbon backbones The reactions of hydrocarbons are central to building the scaffolds of molecules. This is also true in medicinal chemistry. There are countless C–C bond-forming

• . Examples of heterocyclic (e.g., pyridinyl) anilines would be more relevant to the pharmaceutical industry. Medicinal chemistry often requires particularly furnished hydrocarbon backbones as bioisosteric replacements. One such interesting group is the difluoromethyl group. Akita et al. have described a

Cobalt-catalyzed nucleophilic addition of the allylic C(sp³)–H bond of simple alkenes to ketones

• Tsuyoshi Mita,
• Masashi Uchiyama,
• Kenichi Michigami and
• Yoshihiro Sato

Beilstein J. Org. Chem. 2018, 14, 2012–2017, doi:10.3762/bjoc.14.176

• bonds; cobalt; ketones; Introduction The cleavage of C–H bonds of unreactive hydrocarbon followed by functionalization should be an ideal method for constructing complex molecules without introduction of reactive functionality in advance [1][2][3][4][5][6][7][8][9]. Since terminal alkenes including α

Steric “attraction”: not by dispersion alone

• Ganna Gryn’ova and
• Clémence Corminboeuf

Beilstein J. Org. Chem. 2018, 14, 1482–1490, doi:10.3762/bjoc.14.125

• recognized in aliphatic systems compared to London dispersion, and are therefore likely to have implications for the development of force fields and methods for crystal structure prediction. Keywords: charge penetration; dispersion; hydrocarbon; non-covalent interactions; steric attraction; Introduction In

• model based on a promolecule augmented with point charges [53] and a screened charge model with a molecular mechanics outer density screening algorithm [54]. In the context of hydrocarbon chemistry, the need to include charge penetration in FFs when modeling π–π and CH···π interactions in unsaturated

• ], is far less – if at all – recognized. In the present work, we quantify the penetration energy in a diverse range of hydrocarbon dimers, including π-conjugated moieties and bulky aliphatic substituents. A direct one-to-one quantitative comparison between the fairly polarizable sp2-rich (π-conjugated

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• -yn-1,4-diones) [13][17][38][39], diphenylacetylene [1][2][9][13][15][32] or even acetylene itself [1][2] have also been successfully reacted with sydnones. The most typical procedure involves heating both components in boiling hydrocarbon solvent (benzene, toluene or xylene) for several hours (up to

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• small molecules comprise various heterocyclic and/or aromatic hydrocarbon rings with limited rotational freedom and torsion, allowing these drugs to fit into major/minor grooves of DNA by displacing water molecules from the spine of hydration as shown in the Figure 2 [25][26][27]. These molecules bind

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

Development of novel cyclic NGR peptide–daunomycin conjugates with dual targeting property

• Andrea Angelo Pierluigi Tripodi,
• Szilárd Tóth,
• Kata Nóra Enyedi,
• Gitta Schlosser,
• Gergely Szakács and
• Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 911–918, doi:10.3762/bjoc.14.78

• is worth mentioning that Nle has a linear hydrocarbon side chain with the same length as Lys, the amino functional group missing. To further characterize the biological activity of the conjugates, their lysosomal degradation and cellular uptake were studied. In this study our goal was to compare the

Volatiles from three genome sequenced fungi from the genus Aspergillus

• Jeroen S. Dickschat,
• Ersin Celik and
• Nelson L. Brock

Beilstein J. Org. Chem. 2018, 14, 900–910, doi:10.3762/bjoc.14.77

• spore distribution [11]. Furthermore, volatiles can be used as taxonomic markers [12] and can serve as indicators for fungal toxin production, e.g., the fungal emission of the sesquiterpene hydrocarbon trichodiene points to the production of trichothecene mycotoxins [13]. Aspergillus is a well-described

Volatiles from the tropical ascomycete Daldinia clavata (Hypoxylaceae, Xylariales)

• Tao Wang,
• Kathrin I. Mohr,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 135–147, doi:10.3762/bjoc.14.9

• roqueforti [7][8][9], trichodiene (4) is the parent hydrocarbon of the trichothecene family of mycotoxins in various Trichothecium and Fusarium strains [10], and the diterpene ent-kaurene (5) is the precursor of gibberellins, a class of plant hormones that are produced in large amounts by the rice pathogen

Position-dependent impact of hexafluoroleucine and trifluoroisoleucine on protease digestion

• Susanne Huhmann,
• Anne-Katrin Stegemann,
• Kristin Folmert,
• Damian Klemczak,
• Johann Moschner,
• Michelle Kube and
• Beate Koksch

Beilstein J. Org. Chem. 2017, 13, 2869–2882, doi:10.3762/bjoc.13.279

• hydrophobic than their hydrocarbon analogues [44][45]. Furthermore, fluorine substitution has been shown to polarize neighboring C–H bonds (here the γ-hydrogens) that could affect noncovalent interactions [9][11]. Since the amino acids used here (Figure 1a) differ in their degree of fluorination, spatial

• [59][61]. We observed that the fluorinated P2 variants show a smaller amount of digestion after 120 min compared to their hydrocarbon analogues, while all variants are more stable than the control FA (Figure 2). After 24 h, all P2 peptides except for P2-LeuFA are still more stable than FA

• peptide FA, while all other sequences are digested faster. Here, the introduction of fluorine into Leu seems to stabilize the peptide by about 20%. Interestingly, after 24 h this trend is reversed, and the P1’-HfLeuFA peptide is destabilized to an amount of 17% compared to the hydrocarbon analogue, but

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• . Confocal microscopy confirmed that 5 predominantly stains mitochondria but it also accumulates in the nucleoli of the cells. Keywords: confocal microscopy; luminescence; nucleobases; oligonucleotide binding; pyrene; X-ray; Introduction Pyrene is a planar, polycyclic aromatic hydrocarbon which shows well