Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• substituents were formed. Polycyclic products 35 were prepared through a concerted [4 + 2]-cycloaddition of E-1a with thiophene-functionalized fulvenes 36 [42] (Scheme 12). These cycloadducts are reported to undergo reversible intramolecular photocyclization to give products of type 37. The formation of the

• radical intermediate 46 governs the formal [4 + 2]-cycloaddition reaction of E-1b with 3,4-di(α-styryl)furan (47, Scheme 15). The photoinduced reaction occurs via an electron-transfer (PET) process and led to the formation of the polycyclic product 48 in a stereospecific manner [52]. Similar products were

18-Hydroxydolabella-3,7-diene synthase – a diterpene synthase from Chitinophaga pinensis

• Jeroen S. Dickschat,
• Jan Rinkel,
• Patrick Rabe,
• Arman Beyraghdar Kashkooli and
• Harro J. Bouwmeester

Beilstein J. Org. Chem. 2017, 13, 1770–1780, doi:10.3762/bjoc.13.171

• and achiral oligoprenyl diphosphates in just one enzymatic step into a remarkable diversity of usually polycyclic structurally complex lipophilic terpenes with multiple stereogenic centres. In their active sites type I terpene synthases contain the highly conserved aspartate-rich motif DDXX(X)(D,E

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• annulation of dihydroquinazolinones 77 with diphenylacetylene to generate polycyclic heteroarenes 78 under oxygen atmosphere (Scheme 25) [87]. Diversely substituted quinazolinones were reacted with diphenylacetylene to generate the target compounds in excellent yields. A plausible mechanistic rational

• dehydrogenation of tetrahydroisoquinolines. Ruthenium-catalyzed polycyclic heteroarenes. Plausible mechanism of the ruthenium-catalyzed dehydrogenation. Bi-metallic platinum/iridium alloyed nanoclusters and 5,5’,6,6’-tetrahydroxy-3,3,3’,3’-tetramethyl-1,1’-spiro-bisindane (TTSBI) for the synthesis of quinazolines

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• our recent work on the synthesis of polycyclic aromatic alkaloids like pyridoacridine, benzylisoquinoline-type and oxoaporphine alkaloids using direct ring metalations of heterocycles as vital step [13][21] we intended to develop a novel and more flexible access to oxoisoaporphine alkaloids. Again we

• type of intramolecular Friedel–Crafts-type acylations, and trifluoromethanesulfonic acid [25] is superior to polyphosphoric acid [26][27] for the synthesis of polycyclic ketones. Unfortunately, direct cyclization of esters 10a–c using this reagent failed completely, despite numerous variations of the

Chemical systems, chemical contiguity and the emergence of life

• Terrence P. Kee and
• Pierre-Alain Monnard

Beilstein J. Org. Chem. 2017, 13, 1551–1563, doi:10.3762/bjoc.13.155

• alternative approaches in relation to the emergence of specific biomolecules and biochemical assemblies. The pursuance of such, normally parallel, approaches has led to the development of hypotheses either called by their chemical embodiment, such the lipid- [5], PAH- (polycyclic aromatic hydrocarbons) [6

• . However, recent studies [16][61][74] have substantiated their potential early existence. Indeed, a class of photosensitive chemicals, the polycyclic aromatic hydrocarbons, PAHs (Figure 2), are capable of spontaneously inserting into amphiphile structures, even medium-length fatty acid vesicles (fatty

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• platinum(II). The formed product structures depend not only on the reagents used but also on the substituents attached to the triple bonds. Cycloisomerisations with perfect atom economy lead to polycyclic heterocycles that resemble to some extent the AB ring system of paclitaxel. Herein, we present

• /13C NMR experiments, and by comparison with relatively similar compounds obtained in the reaction of the bis(phenylalkynyl)-derivative of 4a with triflic acid [26], or with K[ReO4] [27]. The polycyclic carbon skeleton in these is identical, but the latter compounds are protonated at the sulfonimide

• cycloisomerisations and help to clarify the role of the substituents, but also yields a novel type of taxoid compounds of complex polycyclic structures with potential biological effects. Synthesis of 3-oxo-camphorsulfonylimine (3) [13][15] and its bis-alkynyl derivatives 4 from camphor-10-sulfonic acid (1). Reactions

Opportunities and challenges for the sustainable production of structurally complex diterpenoids in recombinant microbial systems

• Katarina Kemper,
• Max Hirte,
• Markus Reinbold,
• Monika Fuchs and
• Thomas Brück

Beilstein J. Org. Chem. 2017, 13, 845–854, doi:10.3762/bjoc.13.85

• prevent accumulation of the desired lead structures [33]. Isoprenyl diphosphate formation Downstream of precursor formation condensation of IPP and DMAPP to longer-chain polyprenyls precedes subsequent metabolization to linear or mono- and polycyclic products, respectively, by the terpene synthases [24

A practical and efficient approach to imidazo[1,2-a]pyridine-fused isoquinolines through the post-GBB transformation strategy

• Taofeng Shao,
• Zhiming Gong,
• Tianyi Su,
• Wei Hao and
• Chao Che

Beilstein J. Org. Chem. 2017, 13, 817–824, doi:10.3762/bjoc.13.82

• to structurally complex polycyclic ring systems [33]; an Ugi/aza-Wittig process allowed for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles [34]; the Ugi/Pictet–Spengler sequence provided a rapid and efficient approach to polycyclic natural product-like alkaloids [35]. Accordingly, the

• synthesis of biologically interesting heterocycles [43][44][45][46][47], we were interested in a practical synthetic strategy towards imidazo[1,2-a]pyridine-fused isoquinoline systems. We believe that this type of polycyclic systems may have interesting biological profiles [48]. Herein, we report our recent

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

• of the new metabolites 1, 5, 9, 14, 15 and stereochemical assignment of 12 Repeated fractionation of VLC fractions 5–8 resulted in the isolation of a range of secondary metabolites, i.e., four steroids 1–4, nine cembranoid diterpenes 5–13 and two biscembranoids 14 and 15, as well as four polycyclic

3D printed fluidics with embedded analytic functionality for automated reaction optimisation

• Andrew J. Capel,
• Andrew Wright,
• Matthew J. Harding,
• George W. Weaver,
• Yuqi Li,
• Russell A. Harris,
• Steve Edmondson,
• Ruth D. Goodridge and
• Steven D. R. Christie

Beilstein J. Org. Chem. 2017, 13, 111–119, doi:10.3762/bjoc.13.14

• equipment, allowing automated online and inline optimisation of the reaction medium. This set-up allowed the optimisation of two reactions, a ketone functional group interconversion and a fused polycyclic heterocycle formation, via spectroscopic and chromatographic analysis. Keywords: 3D printing; inline

• allow a much larger chemical space to be analysed (<200 °C). The formation of a fused polycyclic heterocycle 5 (Scheme 2), from pentafluoropyridine (3) and 2-(methylamino)phenol (4), was chosen as this would generate a more complex optimisation set with two starting materials, the reaction product as

• well as any potential reaction intermediates and unwanted side products. The reaction would also require elevated temperatures as well as a solvent system which would have proved destructive to the Accura resin used to manufacture RD1. These types of fused polycyclic heterocycles are of significant

Multicomponent synthesis of spiropyrrolidine analogues derived from vinylindole/indazole by a 1,3-dipolar cycloaddition reaction

• Manjunatha Narayanarao,
• Lokesh Koodlur,
• Vijayakumar G. Revanasiddappa,
• Subramanya Gopal and
• Susmita Kamila

Beilstein J. Org. Chem. 2016, 12, 2893–2897, doi:10.3762/bjoc.12.288

• , antitubercular, anticonvulsant and cardiovascular activities [11][12][13][14][15][16]. As part of our interest in the exploration of 1,3-dipolar cycloaddition reactions [17] for the synthesis of polycyclic molecules, N-alkylated vinylindoles are applied as dipolarophiles in view of the challenges that still pose

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• oligosaccharides consisting of 6–8 glucose units (α-, β- and γ-CD) primarily used in the pharmaceutical, cosmetic and household chemical industry [8]. They form non-covalent inclusion complexes with a great number of the organic contaminants in soil (petroleum hydrocarbons, polycyclic aromatic hydrocarbons, etc

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

• of two or more privileged scaffolds leads to geometrically well-defined rigid polycyclic structures with enhanced receptor-binding selectivity. Thus, the design and synthesis of structurally diverse, privileged structure-based polycyclic molecules with multiple chiral centers has been intensely

Facile synthesis of indolo[3,2-a]carbazoles via Pd-catalyzed twofold oxidative cyclization

• Chao Yang,
• Kai Lin,
• Lan Huang,
• Wei-dong Pan and
• Sheng Liu

Beilstein J. Org. Chem. 2016, 12, 2490–2494, doi:10.3762/bjoc.12.243

• substituents to aromatic rings was also inconvenient. It could still be necessary to exploit more practical methods and economic procedures to assemble these polycyclic molecules. In this paper, we describe a concise, 3 to 4 steps procedure for the synthesis of indolo[3,2-a]carbazoles via palladium-catalyzed

Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides

• Shuai Qiu,
• Choon-Hong Tan and
• Zhiyong Jiang

Beilstein J. Org. Chem. 2016, 12, 2293–2297, doi:10.3762/bjoc.12.222

• three kinds of biologically important chiral 1,4-sulfur-bridged piperidinones and their related derivatives [10]. In order to develop novel chiral S-containing polycyclic scaffolds, the development of [4 + 2] annulations of 5H-thiazol-4-ones with unusual activated alkenes still remains highly desirable

Stereoselective synthesis of fused tetrahydroquinazolines through one-pot double [3 + 2] dipolar cycloadditions followed by [5 + 1] annulation

• Xiaofeng Zhang,
• Kenny Pham,
• Shuai Liu,
• Marc Legris,
• Alex Muthengi,
• Jerry P. Jasinski and
• Wei Zhang

Beilstein J. Org. Chem. 2016, 12, 2204–2210, doi:10.3762/bjoc.12.211

• formaldehyde through [5 + 1] annulation to afford a novel polycyclic scaffold bearing tetrahydroquinazoline, pyrrolidine, pyrrolidinedione, and N-substituted maleimide in stereoselective fashion. Keywords: [5 + 1] annulation; [3 + 2] cycloaddition; one-pot reactions; stereoselective synthesis

• using one-pot intermolecular or intramolecular [3 + 2] azomethine ylide cycloadditions [22][23][24][25][26][27] as the initial step followed by cyclization or cycloaddition reactions to form polycyclic scaffolds with skeleton, substitution, and stereochemistry diversities. Introduced in this paper is a

• new sequence initiated with a three-component [3 + 2] cycloaddition for preparing polycyclic scaffold 1 bearing tetrahydroquinazoline, pyrrolidine, pyrrolidinedione, and N-substituted maleimide rings. Those heterocyclic fragments could be found in bioactive compounds such as bromodomain, thrombin

Application of heterocyclic aldehydes as components in Ugi–Smiles couplings

• Katelynn M. Mason,
• Michael S. Meyers,
• Abbie M. Fox and
• Sarah B. Luesse

Beilstein J. Org. Chem. 2016, 12, 2032–2037, doi:10.3762/bjoc.12.191

• couplings in combination with post-condensation processes to efficiently increase structural complexity [8][9][10]. One of the most effective routes to polycyclic core structures uses intramolecular Diels–Alder reactions (IMDA) of tethered, substituted furans to provide stereoselective construction of

Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• Abstract In this study, a polymer, prepared by crosslinking cyclodextrin (CD) by means of a polycarboxylic acid, was used for the removal of pollutants from spiked solutions and discharge waters from the surface treatment industry. In spiked solutions containing five metals, sixteen polycyclic aromatic

• calcium at high concentrations, which competed with other pollutants for the adsorption sites of the adsorbent. Keywords: alkylphenols; adsorption; cyclodextrin; metals; polycyclic aromatic hydrocarbons; Introduction Although considerable efforts have been made by the industrial sector over the last 30

• polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs) at concentrations varying from hundreds of nanograms per liter to some micrograms per liter [1]. However, it is extremely difficult to remove pollutants present at low concentrations (a few hundreds of micrograms per liter for some organic

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• 1.1.3. 1.3 Polycyclic systems During the biosynthesis of ionophoric terrestrial and marine polyethers, polyolefinic PKS products are first polyepoxidised and these epoxides are then opened in a so-called zipper mechanism that installs furan and/or pyran rings as well as cyclic acetals, if carbonyl

One-pot synthesis of tetracyclic fused imidazo[1,2-a]pyridines via a three-component reaction

• Bo Yang,
• Chuanye Tao,
• Taofeng Shao,
• Jianxian Gong and
• Chao Che

Beilstein J. Org. Chem. 2016, 12, 1487–1492, doi:10.3762/bjoc.12.145

• and peptic ulcers, respectively) [22]. As such, the imidazo[1,2-a]pyridine structure represents an intriguing synthetic target, and its further functionalization is leading to polycyclic fused heterocycles that may have interesting biological profiles [23]. Impressively, the imidazo[1,2-a]pyridine

• development of new GBB-based methods for the efficient synthesis of novel polycyclic fused imidazo[1,2-a]pyridines is highly desirable. In an earlier study, we have developed a GBB/lactamization MCR strategy, which provided the rapid access to isoquinolinone-fused imidazo[1,2-a]pyridines with potent and

• . Mechanistic rationale for the MCR [36]. MCR to polycyclic fused imidazo[1,2-a]pyridine derivatives. Synthesis of imidazo[1,2-a]pyridine derivatives in indicated conditions [36].a Supporting Information Supporting Information File 576: Experimental procedures, characterization and spectral data for

Ring-whizzing in polyene-PtL₂ complexes revisited

• Oluwakemi A. Oloba-Whenu,
• Thomas A. Albright and
• Chirine Soubra-Ghaoui

Beilstein J. Org. Chem. 2016, 12, 1410–1420, doi:10.3762/bjoc.12.135

• from 35, as well as, η1, 36, and η3, 37. Unfortunately none of these produced new stationary points. We will return to this Ni versus Pt issue later. C. Polycyclic examples Pentalene metal complexes have been the subject of a number of investigations [61], as well as, theoretical explorations of

The EIMS fragmentation mechanisms of the sesquiterpenes corvol ethers A and B, epi-cubebol and isodauc-8-en-11-ol

• Patrick Rabe and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1380–1394, doi:10.3762/bjoc.12.132

• substrates to polycyclic terpenes with usually several stereocentres [24][25][26][27][28]. We have demonstrated here, how isotopic labelling experiments can be used to investigate the EIMS fragmentation mechanisms of structurally complex sesquiterpenes. This field was initiated in the 1960s with main

Synthesis, fluorescence properties and the promising cytotoxicity of pyrene–derived aminophosphonates

• Jarosław Lewkowski,
• Maria Rodriguez Moya,
• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Renata Kontek and
• Gabriela Gajek

Beilstein J. Org. Chem. 2016, 12, 1229–1235, doi:10.3762/bjoc.12.117

• [2] or anticancer properties [3]. Various C-aryl substituted derivatives of phosphonoglycine have been synthesized including those of benzene and several polycyclic aromatic hydrocarbons [4], five- [5] and six-membered [6] heteroaromatic compounds and even ferrocene [7]. In contrast, pyrene-based

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

• rings 40, alkenes 42, and alkynes 44 are all tolerated and remain intact under the reaction conditions. The reaction can also tolerate branching at the internal position of the pendant olefin, as polycyclic 46 and 48 displayed excellent enantiomeric ratios. It is also important to point out that no ring

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• reactions for constructing structurally novel and complex polycyclic scaffolds (Scheme 53). A pioneering work has been done on the 3-indolylmethanol-involved cycloaddtion reactions by the Shi group. In 2014, Shi et al. developed a CPA-catalyzed asymmetric [3 + 3] cycloaddition of 3-indolylmethanols with

• entry to polycyclic scaffolds for further biological screening. Similarly, Shi et al. established CPA-catalyzed highly enantioselective aza-ene reactions of cyclic enaminones with 3-indolyl-3-hydroxyoxindoles, incorporating enaminones and 3-indolyl-3-hydroxyoxindoles into C3-functionlized chiral indoles