Selective bromochlorination of a homoallylic alcohol for the total synthesis of (−)-anverene

• Frederick J. Seidl and
• Noah Z. Burns

Beilstein J. Org. Chem. 2016, 12, 1361–1365, doi:10.3762/bjoc.12.129

• stirring rates are critical for obtaining optimal results in these heterogeneous bromochlorination reactions of both allylic and homoallylic alcohols. The origin of this stirring dependence is not definitively known, but we suspect that it facilitates the dissolution of N-bromosuccinimide (NBS) into

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• pyrroloquinoline quinone (PQQ, Figure 2) has a ribosomal origin [17] but has been modified so that no peptide bonds remain. This demonstrates that a huge amount of structural diversity can be introduced into RiPPs, despite an intrinsic requirement to be assembled from the 20 regular proteinogenic amino acids

• (possibly 21, as RiPPs containing selenocysteine were proposed in a recent bioinformatic study [18]). Excitingly, the ribosomal origin of RiPPs means that significant chemical changes to complex natural products can be achieved by simple site-directed mutagenesis. This requires the associated tailoring

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• tolerate many sensitive functional groups, such as free alcohols, silyl enol ethers, and ketones, which makes it an attractive metal for late stage functionalization and elaboration of complex molecules. It is thought that the origin of ruthenium’s divergent behavior stems from a difference in reaction

• reaction of 1,6-enynes is due to acetone’s ability to override any impact the propargylic stereocenter has on the course of the reaction. Considering the data presented in Table 8, we now propose a working mechanism for the origin of enantioselectivity in the redox bicycloisomerization reaction. There are

Synthesis of a deuterated probe for the confocal Raman microscopy imaging of squalenoyl nanomedicines

• Eric Buchy,
• Branko Vukosavljevic,
• Maike Windbergs,
• Dunja Sobot,
• Camille Dejean,
• Simona Mura,
• Patrick Couvreur and
• Didier Desmaële

Beilstein J. Org. Chem. 2016, 12, 1127–1135, doi:10.3762/bjoc.12.109

• the dialdehyde 5 this procedure failed to give the expected Wittig adduct. Whatever the origin of this problem, we decided to explore a new strategy based on a more nucleophilic deuterated synthon. In this regard we targeted prop-1-en-2-yllithium-d5 (15) which is easily accessible through the Shapiro

Modular synthesis of the pyrimidine core of the manzacidins by divergent Tsuji–Trost coupling

• Sebastian Bretzke,
• Stephan Scheeff,
• Felicitas Vollmeyer,
• Friederike Eberhagen,
• Frank Rominger and
• Dirk Menche

Beilstein J. Org. Chem. 2016, 12, 1111–1121, doi:10.3762/bjoc.12.107

• alkaloids of marine origin. Additional features of this route include the stereoselective generation of the central amine core with an appending quaternary center by an asymmetric addition of a Grignard reagent to a chiral tert-butanesulfinyl ketimine following an optimized Ellman protocol and a cross

• highly concise access to the authentic heterocyclic cores of the manzacidins, structurally unique natural products of marine origin. Additional notable features of our modular route also include the generation of an amine appending quaternary center by an optimized Ellman protocol for the asymmetric

Marine-derived myxobacteria of the suborder Nannocystineae: An underexplored source of structurally intriguing and biologically active metabolites

• Antonio Dávila-Céspedes,
• Peter Hufendiek,
• Max Crüsemann,
• Till F. Schäberle and
• Gabriele M. König

Beilstein J. Org. Chem. 2016, 12, 969–984, doi:10.3762/bjoc.12.96

• strains are capable to grow with or without NaCl; and (II) halophilic bacteria are unable to grow without sea salt. Bacteria of group (I) may be derived from terrestrial organisms, which have adapted to saline conditions, whereas those of group (II) may be of truly marine origin. A typical halotolerant

• dwelling in sea habitats are considered as halophilic, that is, of true marine origin. Indeed, early isolates from marine environments were thought to be halotolerant terrestrial myxobacteria whose myxospores had been washed into the ocean [11]. This opinion prevailed until Fudou and Iizuka [12][13][14][15

• designed to tackle the sometimes cumbersome task of finding bioactive secondary metabolites of bacterial origin, i.e., mainly bioactivity- or chemistry-guided methods. An additional approach, complementary to the latter, arose in the late 1990s, when the first microbial genomes were sequenced, allowing

Nucleic acids through condensation of nucleosides and phosphorous acid in the presence of sulfur

• Tuomas Lönnberg

Beilstein J. Org. Chem. 2016, 12, 670–673, doi:10.3762/bjoc.12.67

• crucial step in the origin of life was the prebiotic formation of information carrying polymers. For the polymers playing this role in contemporary biochemistry, i.e., DNA and RNA, such a process appears difficult owing to the low reactivity and solubility of phosphate. Indeed, all of the enzyme-free

Creating molecular macrocycles for anion recognition

• Amar H. Flood

Beilstein J. Org. Chem. 2016, 12, 611–627, doi:10.3762/bjoc.12.60

• for the group’s initial and ongoing activities in anion recognition. Triazolophanes [6] (Figure 1) were the first of these macrocycles and the origin of their design warrants description because it represents the first time we made something new. Triazolophanes were inspired by an overarching

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• ]. Several dibenzo-α-pyrones have been isolated from plant parts. Purified from roots, bulbi, heartwood, or whole plant material, the origin of some plant-derived pyrones is not finally clarified, since the production by endophytic fungi cannot be excluded. Djalonensone was isolated from Anthocleista

• following polymerization to fatty acids [34]. Now, it is generally accepted that most α-pyrones are synthesized via the polyketide pathway. Solely for plant-derived ellagitannins another biosynthetic origin was described. Via the shikimate pathway gallic acid is generated, which represents the precursor in

• ellagitannin biosynthesis [73]. The ellagitannins can then be hydrolyzed to ellagic acid (22), and subsequently converted to urolithins (23–27). In microorganisms the PKS-derived origin was independently postulated for numerous compounds. The polyketide biosynthesis has much in common with fatty acid

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• origin of the asymmetric induction was proposed. In the plausible transition state TS12, acidic hydrogen atoms from both hydroxy and thiourea moieties would activate and fix the nitroalkene. Simultaneously, the tertiary amine of the cinchona framework would deprotonate the acidic proton of acetylacetone

Art, auto-mechanics, and supramolecular chemistry. A merging of hobbies and career

• Eric V. Anslyn

Beilstein J. Org. Chem. 2016, 12, 362–376, doi:10.3762/bjoc.12.40

• , except that the “art” of my group is visualized on the nanoscopic scale rather than on a macroscopic scale of my dad and friend. Thus, my childhood exposure to the combination of art and function has clearly led me to the field of supramolecular chemistry. Origin of a love of organic chemistry, orbitals

• emanating at that time from David Walt [78][79] and Ken Suslick [80][81], who were pursuing similar goals. The field of electronic noses and tongues has a biomimetic origin. Having worked with Breslow as a post-doctoral fellow, who coined the word biomimetic [82], the idea of mimicking the mammalian senses

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• hydrolyzed faster than parathion and methyl parathion. Indeed the two latter can form deeply included complexes (high αin parameter) compared to fenitrothion which is therefore less shielded from hydroxide ions, leading to the highest hydrolysis rate observed in this series (Table 3) [42]. The origin of this

• appears that the size of the cavity is not the only parameter to take into account. Indeed, the ability of CDs to relay radicals towards the phosphorus atom might be tuned by the geometrical disposition of the hydroxy groups of CDs. The origin of the higher efficiency of β-CD on the photodegradation might

• binding constants of β-CD/soman and β-CD/pinacolyl alcohol complexes were then investigated. The similar data obtained proved that the pinacolyloxy group was at the origin of the strong complexation of soman into the β-CD cavity. They then focused their work on the interaction between soman and β-CD due

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• for the stabilized β-CD/ASO complexes confirm the formation of the inclusion compound. Experimental Materials Atlantic salmon (Salmo salar L.) was obtained from the local market (Timişoara, Romania) as a raw product in the spring of 2014. It was an aquaculture product of Norwegian origin. Only the

Simple activation by acid of latent Ru-NHC-based metathesis initiators bearing 8-quinolinolate co-ligands

• Julia Wappel,
• Roland C. Fischer,
• Luigi Cavallo,
• Christian Slugovc and
• Albert Poater

Beilstein J. Org. Chem. 2016, 12, 154–165, doi:10.3762/bjoc.12.17

• prepared polymers [13][14][15]. Focusing on the origin of organic synthesis, basically based on reactions that drive to the formation of carbon–carbon bonds [16], olefin metathesis turns out to be one potential route to get unsaturated molecules bearing C–C double bonds [17][18][19][20][21], thus by

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• 3·TM-βCD compared to the reference 3. Obviously, the LUMO energy value is responsible for the low value of ΔEg in the case of 3·TM-βCD polyrotaxane. Note that the redox behaviors of the investigated polyrotaxanes have a similar origin with those of the reference copolymer 3. Close inspection of the

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• . Evidence for this proposed biogenetic origin of crenulatanes has been provided by Guella and Pietra who showed that irradiation of 4-hydroxydictyolactone (137) with ultraviolet light (254 nm) led to the formation of 4-hydroxycrenulide (138) (Scheme 15) [68]. Although this transformation remains

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• ’ and C-7’ of 27. Moreover, also [2,3-13C2]-4-hydroxybutyrate was incorporated with appearance of labeling in the same positions. The proposed origin of the pyrrothine unit from two cysteins was confirmed by feeding of [2,2’-13C2]cystine and detection of the label at C-2’’ and C-4’’. As deduced from

Diversity-oriented synthesis of analogues of the novel macrocyclic peptide FR-225497 through late stage functionalization

• Jyotiprasad Mukherjee,
• Suman Sil and
• Shital Kumar Chattopadhyay

Beilstein J. Org. Chem. 2015, 11, 2487–2492, doi:10.3762/bjoc.11.270

• peptides of the general structure 1 (Figure 1) displays important histone deacetylase inhibition property relevant to drug design against a number of diseases ranging from antifungal, antimicrobial to arrest of proliferation of several cell types of epithelial and hematological origin [13]. The compounds

Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

• Thibault E. Schmid,
• Sammy Drissi-Amraoui,
• Christophe Crévisy,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 2418–2434, doi:10.3762/bjoc.11.263

• Michael acceptors with regards to copper-based nucleophiles in stoichiometric reactions will be presented. Based on these results, research groups gained better understanding of the origin of the regioselectivity in such processes, and started to develop modern enantioselective catalytic systems. These

• origin of this particular reactivity. The addition of other linear Grignard reagents on the substrates of the type 50 showed a near-perfect 1,4-regioselectivity, while the amount of 1,4-adduct dropped when branched nucleophiles were used. Despite this decrease in regioselectivity, the reaction remained

Evidencing an inner-sphere mechanism for NHC-Au(I)-catalyzed carbene-transfer reactions from ethyl diazoacetate

• Manuel R. Fructos,
• Juan Urbano,
• M. Mar Díaz-Requejo and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2015, 11, 2254–2260, doi:10.3762/bjoc.11.245

• obtained from experimental curves upon fitting to an exponential growth equation using ORIGIN software. Plot of evolved nitrogen with time for the reactions of EDA with styrene or methanol. Top: Plots of evolved nitrogen with time for the reactions of EDA with styrene (left) or methanol (right) varying the

Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

• Kazuaki Kato,
• Daisuke Matsui,
• Koichi Mayumi and
• Kohzo Ito

Beilstein J. Org. Chem. 2015, 11, 2194–2201, doi:10.3762/bjoc.11.238

• the significantly low modulus. Recent research in polyrotaxane gels, which were obtained by the simple cross-linking of polyrotaxanes via intermolecular covalent bonds between CDs, indicated a new origin of the elasticity experimentally and theoretically [12][14][16][18]. Since the polymer chains can

• polymer, their inhomogeneous distribution can generate entropic stress. Thus, the origin of elasticity is not the entropy of polymer chains but that of the CDs, and the abnormally small modulus of polyrotaxane gels can be explained by the characteristic elasticity. Similarly, the extremely low modulus of

Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

• Hynek Balcar,
• Naděžda Žilková,
• Martin Kubů,
• Michal Mazur,
• Zdeněk Bastl and
• Jiří Čejka

Beilstein J. Org. Chem. 2015, 11, 2087–2096, doi:10.3762/bjoc.11.225

• origin of the above mentioned difference in activity of HGIIN+Cl−/SBA-15 and HGIIN+Cl−/MCM-22, we performed a study of cross-metathesis (CM) of methyl oleate and cis-3-hexenyl acetate (Scheme 2) over these two catalysts. cis-3-Hexenyl acetate can be considered as a short-chain analogue of methyl oleate

The marine sponge Agelas citrina as a source of the new pyrrole–imidazole alkaloids citrinamines A–D and N-methylagelongine

• Christine Cychon,
• Ellen Lichte and
• Matthias Köck

Beilstein J. Org. Chem. 2015, 11, 2029–2037, doi:10.3762/bjoc.11.220

• which could be an alternative origin of these metabolites. The molecular formula of citrinamine B (2) was established by HR–ESIMS (m/z 740.0337, [M + H]+, monoisotopic) and the pseudomolecular ion peaks at m/z = 740/742/744 (1:2:1) to be C24H28Br2N11O5S. The 1D 1H and 13C NMR spectra of 2 were similar

A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

• Albert Poater and
• Luigi Cavallo

Beilstein J. Org. Chem. 2015, 11, 1767–1780, doi:10.3762/bjoc.11.192

• the case. This fact suggests that the origin of the remarkably different catalytic activity shown by these systems lays somewhere else. Metallacycle. The energy of the various metallacycles with respect to the uncoordinated C=C double bond are reported in the 5th column of Table 2, while in the 6th

• an NHC ligand. The origin of this difference is in the better ability of the NHC ligand to donate electron density to the Ru center, which formally is in the high formal oxidation state of +4 in the metallacycle. Conclusion After discussing a wide range of representative systems of second generation

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183