Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

• Pamarthi Gangadhar,
• Sayini Ramakrishna,
• Ponneri Venkateswarlu and
• Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

• concentrations [11]. There have been few contributions on the total synthesis of strongylodiols [12][13] employing alkynylation of an unsaturated aliphatic aldehyde catalyzed by Trost’s pro-phenol ligand [12][14], β-elimination of epoxy chloride [15], Noyori’s asymmetric reduction of ynones [16], diyne addition

Selective formation of a zwitterion adduct and bicarbonate salt in the efficient CO₂ fixation by N-benzyl cyclic guanidine under dry and wet conditions

• Yoshiaki Yoshida,
• Naoto Aoyagi and
• Takeshi Endo

Beilstein J. Org. Chem. 2018, 14, 2204–2211, doi:10.3762/bjoc.14.194

• carbon dioxide without a water molecule. It is expected that the zwitterion adducts of guanidine derivatives and CO2 are not only efficient catalysts for cycloaddition of CO2 to epoxides but also a thermal latent curing agent for epoxy resin. Herein, we achieved selective formation of the zwitterionic

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• amine component has with the epoxy groups of GO, as divergent notes are included in this study’s results. The reaction of GO with diamines is a well-documented process (i.e., a nucleophilic attack on GO’s epoxides) [16][27], so the unexpected presence of an amide bond in the material, obtained via the

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• the presence of acetic anhydride [46]. As the peroxy compounds can react with alkenes, leading to the anti-products via epoxy intermediates, substrates must be added slowly by a syringe pump to provide reasonable yields and diastereoselectivity. The diastereoselectivity of the reaction can be

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• moderate enantioselectivity (Scheme 8 upper part). By this method naphthol 39 could be oxidized to chiral o-quinol 40 with 50% ee [41]. Varying the catalyst loading could alter the reaction outcome to afford either o-quinol 40 or epoxy o-quinol 41. Recently, Pouységu and Quideau et al. modified their

A stereoselective and flexible synthesis to access both enantiomers of N-acetylgalactosamine and peracetylated N-acetylidosamine

• Bettina Riedl and
• Walther Schmid

Beilstein J. Org. Chem. 2018, 14, 856–860, doi:10.3762/bjoc.14.71

• pivotal role in cell–cell interaction and receptor induced cell signaling. Herein, we present a synthetic route in which two of the four stereogenic centers present in the target compound are derived from enantiopure tartaric acid being selectively converted to epoxy alcohols. The key step is the Pd

Preparation and isolation of isobenzofuran

• Morten K. Peters and
• Rainer Herges

Beilstein J. Org. Chem. 2017, 13, 2659–2662, doi:10.3762/bjoc.13.263

• ) δ 8.32 (s, 2H), 7.45 (dd, 3J = 6.8 Hz, 4J = 2.8 Hz, 2H), 6.86 (dd, 3J = 6.8 Hz, 4J = 2.8 Hz, 2H) ppm; 13C NMR (150 MHz, 300 K, DMSO-d6) δ 136.1, 124.2, 123.5, 119.0 ppm; HRMS (EI) m/z: [M]+ calcd. for C8H6O, 118.04173; found, 118.04186. Dimethyl 1,4-epoxy-1,4-dihydronaphthalene-2,3-dicarboxylate (10

Synthesis of ergostane-type brassinosteroids with modifications in ring A

• Vladimir N. Zhabinskii,
• Darya A. Osiyuk,
• Yuri V. Ermolovich,
• Natalia M. Chaschina,
• Tatsiana S. Dalidovich,
• Miroslav Strnad and
• Vladimir A. Khripach

Beilstein J. Org. Chem. 2017, 13, 2326–2331, doi:10.3762/bjoc.13.229

• biosynthetic precursors/metabolites differing by the ring A fragment. The protocol is based on the use of readily available phytohormones of this class bearing a 2α,3α-diol moiety (epibrassinolide or epicastasterone) as starting materials. The required functionalities (Δ2-, 2α,3α- and 2β,3β-epoxy-, 2α,3β-, 2β

• developed a new strategy for synthesizing minor constituents of the class of BS phytohormones which is based on the use of readily available brassinosteroids of this class. Its advantage is that it allows preparing a full set of A-ring units (Δ2-, 2α,3α- and 2β,3β-epoxy-, 2α,3β-, 2β,3α-, and 2β,3β-dihydroxy

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

• have previously reported a concise method for synthesising compounds that contain three vicinal C–F bonds [34]; their method commences with an epoxy alcohol, which undergoes three successive nucleophilic substitutions with fluoride (i.e., deoxyfluorination of the alcohol, epoxide ring opening with

• afforded the syn,anti-epoxy alcohol 28b with good stereoselectivity, albeit in poor yield. One reason for the low yield of 28b was the difficulty in its chromatographic separation from the byproducts of the epoxidation reaction. Nevertheless, a sufficient quantity of 28b was obtained to proceed some way

• epoxy alcohol 28b was troublesome; third, the fluorination of 28b proceeded with poor stereoselectivity; and fourth, the final fluorination reaction suffered from an undesired rearrangement side-reaction. We subsequently found that all four of these problems could be solved by making a single change to

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• total synthesis of erythronolide B (an aglycone of erythromycin B) from intermediate 52, Corey and co-workers suggested the ring opening of α,β-epoxy oximes 53 with Gilman’s reagents as a plausible way to introduce a methyl group at the C-10 position [40] (Scheme 18). Since the addition occurs in α

• (+/−)-perhydrohistrionicotoxin. Addition of Gilman’s reagents to α,β-epoxy oximes 53. Addition of Gilman’s reagents to α-chlorooximes. Reaction of silyl nitronate 58 with organolithium reagents via nitrosoalkene NSA12. Reaction of β-ketoxime sulfones 61 and 63 with lithium acetylides. Electrophilic addition of nitrosoalkenes

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Detection of therapeutic radiation in three-dimensions

• John A. Adamovics

Beilstein J. Org. Chem. 2017, 13, 1325–1331, doi:10.3762/bjoc.13.129

• equivalent [43][44][45]. Polyurethane Acrylic, epoxy, polycarbonate, polyester, polystyrene, polyurethane, polyvinyl chloride and silicone were the common transparent plastics that were evaluated as potential 3D dosimeter matrices [17]. Polyvinyl chlorides and silicones were not further considered since

• high background color. Epoxy resins, which use basic curatives, oxidize leuco dyes making them inappropriate for use as dosimetric matrices. This left the polyurethanes as the most viable option. Transparent polyurethane starting materials are commercially available in two parts where part A is

Secondary metabolome and its defensive role in the aeolidoidean Phyllodesmium longicirrum, (Gastropoda, Heterobranchia, Nudibranchia)

• Alexander Bogdanov,
• Cora Hertzer,
• Stefan Kehraus,
• Samuel Nietzer,
• Sven Rohde,
• Peter J. Schupp,
• Heike Wägele and
• Gabriele M. König

Beilstein J. Org. Chem. 2017, 13, 502–519, doi:10.3762/bjoc.13.50

• correlations from H3-28 to C-23 and from H3-29 to C-22, C-23, C-24 and C-30 (see Figure 3). The NMR data (Supporting Information File 1, Table S1) of compound 1 resembled most closely those of epoxy-secosterols isolated from the gorgonian Pseudopterogorgia americana [22] and from the soft coral Pachyclavularia

• violacea (now Briareum violaceum [23]) by Anta et al. ([24], Figure 4). However, the 13C NMR chemical shifts of C-5 and C-6 in compound 1 (δC 80.7 and δC 75.7, respectively) differ from shifts for the equivalent carbons in epoxy-secogorgosterol reported by Naz et al. (δC 61.0 and δC 60.4, respectively; [22

• ]) and from those of the epoxy-secosterol reported by Anta et al. (δC 65.5 and δC 58.1, respectively; [24]). The downfield shift, observed for these carbons in 1, results from the cleavage of the epoxide ring, and 13C values around δC 70–80 as observed for 1 are characteristic for hydroxylated carbons

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• in 98% yield for both THP and MOM ethers (Scheme 62). Irradiation of aromatic γ,δ-epoxy ketones 226 with a medium-pressure UV mercury lamp (450 W) led to the formation of 1-indanones 227 via a photochemical epoxy rearrangement and 1,5-biradical cyclization tandem reaction (Scheme 63) [92]. The best

cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

• Dimpee Gogoi,
• Runjun Devi,
• Pallab Pahari,
• Bipul Sarma and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

• Abstract We have synthesized a series of cis-6a,7,8,12b-tetrahydro-6H-naphtho[2,1-c]chromen-6a-ols as B-ring-modified analogues of (±)-brazilin. A completely regio- and cis-diastereoselective intramolecular Friedel–Crafts epoxy–arene cyclization of 1-tetralone-derived glycidyl ethers catalyzed by Brønsted

• been reductively removed by a diastereoselective method which should be useful in future for preparing libraries of chroman-fused tetralins with trans-stereochemistry at the ring junction. Keywords: brazilin; chroman; epoxy-arene cyclization; natural-product-like molecules; tetralin; Findings The

• studied during the past 15 years [19]. Moreover, on many occasions natural product-like molecules exhibit more potent biological activities than the parent natural products [20]. Meanwhile, the intramolecular Friedel–Crafts epoxy–arene (IFCEA) cyclization has been well-established as a powerful tool for

Synthesis of the C8’-epimeric thymine pyranosyl amino acid core of amipurimycin

• Pramod R. Markad,
• Navanath Kumbhar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2016, 12, 1765–1771, doi:10.3762/bjoc.12.165

• Sharpless asymmetric epoxidation (SAE) [16][17]. Thus, allyl alcohol 7 was subjected for SAE first using (+)-DET that afforded a diastereomeric mixture of epoxy alcohols 8 and 9 in the ratio of 88:12 (based on the 1H NMR analysis) in 85% yield. Similarly, use of (–)-DET in SAE afforded epoxide 8 and 9 in

• the ratio of 18:82 in 83% yield. With the understanding of SAE mnemonic, we assigned the absolute configuration in epoxide 8 as 7S,8S and in epoxide 9 as 7R,8R. Subsequently, major isomers of epoxy alcohols 8 and 9 were individually subjected to regioselective epoxide ring opening using trimethyl

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• (Scheme 6). The acid-catalyzed Baeyer–Villiger oxidation of cyclic epoxy ketones 22 produces lactones of type 23, which convert into carbenium ions 24 in the presence of the acid. Subsequently, these ions can be transformed with participation of H2O2 through three different pathways into dihydroperoxides

• synthesis of various heterocyclic systems, such as furan, thiophene, and pyrrole derivatives. The reaction of unsymmetrical epoxy dioxanes 290a–d with triethylamine is accompanied by the 1,2-dioxane-ring opening to form 4-hydroxy-2,3-epoxy ketones 291a–d in high yields. The base catalysis involves the

• abstraction of the most acidic α-proton in the vicinity of the O–O bond followed by the rearrangement accompanied by the O–O-bond cleavage to form 4-hydroxy-2,3-epoxy ketones (Scheme 86) [364]. The Kornblum–DeLaMare rearrangement is of special synthetic value in view of the synthesis of biologically active

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

• haliangicin stereoisomers, which differed in the configuration of the three terminal double bonds in the tetraene moiety. Each of the isomers haliangicin, haliangicin B, haliangicin C and haliangicin D happened to be present with two different configurations around the epoxy group. The NOESY spectra showed

Highly stable and reusable immobilized formate dehydrogenases: Promising biocatalysts for in situ regeneration of NADH

• Barış Binay,
• Dilek Alagöz,
• Deniz Yildirim,
• Ayhan Çelik and
• S. Seyhan Tükel

Beilstein J. Org. Chem. 2016, 12, 271–277, doi:10.3762/bjoc.12.29

• boidinii as cross-linked enzyme aggregate (CLEA) and demonstrated that the residual activity and thermal stability of CLEA were strictly dependent on the type of cross-linker. Epoxy group containing supports are widely used in enzyme immobilization studies to obtain highly stable enzyme preparations by

• conditions. Hence, the use of a proper immobilization technique and support could stabilize its dimeric form. In this study, NAD+-dependent FDH from Candida methylica was covalently immobilized onto Immobead 150, an epoxy group containing commercial support, and Immobead 150 support modified with

• immobilized enzyme is the type of binding groups on the support which provides higher loading of enzyme and higher retention of activity [28]. Epoxy group containing supports are widely used in the immobilization of many enzymes through multi-point covalent attachments since epoxy groups can easily react with

Amino-functionalized (meth)acryl polymers by use of a solvent-polarity sensitive protecting group (Br-t-BOC)

• Helmut Ritter,
• Monir Tabatabai and
• Markus Herrmann

Beilstein J. Org. Chem. 2016, 12, 245–252, doi:10.3762/bjoc.12.26

• polymerization; (meth)acryl polymers; neighboring group effects; solvent polarity; Introduction Amino groups are important functionalities in polymer chemistry, e.g., for hardening various epoxy resins [1]. However, they easily react in an undesired side reaction with electron-poor double bonds of (meth

Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions

• Shawna L. Balof,
• K. Owen Nix,
• Matthew S. Olliff,
• Sarah E. Roessler,
• Arpita Saha,
• Kevin B. Müller,
• Ulrich Behrens,
• Edward J. Valente and
• Hans-Jörg Schanz

Beilstein J. Org. Chem. 2015, 11, 1960–1972, doi:10.3762/bjoc.11.212

• was truncated to isolate the sample, sealed with epoxy, and mounted on a pin; the pin was placed on a goniometer head. The crystallographic properties and data were collected using Mo Kα radiation and the charge-coupled area detector (CCD) detector on an Oxford Diffraction Systems Gemini S

Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks

• Meriem K. Abderrezak,
• Kristýna Šichová,
• Nancy Dominguez-Boblett,
• Antoine Dupé,
• Zahia Kabouche,
• Christian Bruneau and
• Cédric Fischmeister

Beilstein J. Org. Chem. 2015, 11, 1876–1880, doi:10.3762/bjoc.11.201

• Chemistry, Hlavova 2030, CZ-128 40 Prague, Czech Republic Faculty of Chemistry, University of Seville, E-41012 Seville, Spain 10.3762/bjoc.11.201 Abstract The cross metathesis of 1,2-epoxy-5-hexene (1) with methyl acrylate and acrylonitrile was investigated as an entry to the synthesis of polyfunctional

• are much more demanding transformations [13][14][24]. We have investigated the reactivity of 1,2-epoxy-5-hexene (1) with methyl acrylate and acrylonitrile and further exploited the versatility of the epoxide ring to prepare trifunctional molecules by ring opening of the epoxide. To date, 1 has been

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• . Polyesters containing epoxy moieties. Biocatalyzed synthesis of polyesters containing glycerol. Iataconic (34) and malic (35) acid. Oxidized poly(hexanediol-2-mercaptosuccinate) polymer. C-5-substituted isophthalates. Curcumin-based polyesters. Silylated polyesters. Polyesters containing reactive ether

Design and synthesis of polycyclic sulfones via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1373–1378, doi:10.3762/bjoc.11.148

• , commercially available as Oxone®) in aqueous methanol. Equipped with this information, oxidation of compound 5 was attempted under similar reaction conditions to get the desired sulfone 6 [33] (Scheme 1, Table 1). Initially, when the reaction was carried out at 0 °C, the epoxy sulfone 7 was the major product

• (Table 1, entry 1). However, after a considerable amount of experimentation (Table 1), the desired sulfone 6 has been produced in 89% yield (Table 1, entry 2) but it was not possible to eliminate the formation of the epoxy sulfone 7. Next, our efforts were directed towards the synthesis of various

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

• Stephan Schmidt,
• Hanqing Wang,
• Daniel Pussak,
• Simone Mosca and
• Laura Hartmann

Beilstein J. Org. Chem. 2015, 11, 720–729, doi:10.3762/bjoc.11.82

• Equation 1). AFM force spectroscopy with a NanoWizard 3 system (JPK instruments AG, Berlin, Germany) was performed to determine the elastic modulus of the microparticles. As AFM probe a glass bead with a diameter of 5.1 µm was glued with an epoxy glue onto a tipless, non-coated cantilever (spring constant