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Search for "cascade" in Full Text gives 398 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

  • Stephanie G. E. Amos,
  • Marion Garreau,
  • Luca Buzzetti and
  • Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

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  • possible, such as halogenations, azidations, olefinations, or alkynylations. This activation mode was employed by the same group in a cascade strategy, which allowed a remote functionalization [143]. To extend the scope of such transformations, our group reported novel organic dyes in 2018, such as
  • oxidation of 29.1 was achieved using Mes-Acr-Me+ (OD2) and a cobalt cocatalyst, ensuring an efficient dehydrogenation. Various N-heterocycles 29.3 were accessed via a radical cyclization cascade with the alkyne derivatives 29.2. Amidyl radical generation The oxidation of amides is more difficult compared to
  • previously described approach for iminyl radical formations was employed [140]. The same tunable aryloximes 31.1 were used as electrophores to generate the desired amidyl radicals. This methodology allowed the development of a hydroamination/cyclization cascade to give the heterocycles 31.2 and
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Published 29 May 2020

Palladium-catalyzed regio- and stereoselective synthesis of aryl and 3-indolyl-substituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones

  • Valeria Nori,
  • Antonio Arcadi,
  • Armando Carlone,
  • Fabio Marinelli and
  • Marco Chiarini

Beilstein J. Org. Chem. 2020, 16, 1084–1091, doi:10.3762/bjoc.16.95

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  • (Te), Italy 10.3762/bjoc.16.95 Abstract Cascade cyclocarbopalladation of the readily available aryl/alkyl-substituted propargylic amides containing an aryl iodide moiety, followed by Suzuki–Miyaura coupling with arylboronic acids, allowed an efficient regio- and stereoselective synthesis of
  • tetrasubstituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones. Moreover, cascade cyclocarbopalladation, followed by the reaction with 2-alkynyltrifluoroacetanilides, accomplished a double cyclization to afford challenging 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones bearing a 3-indolyl substituent through
  • stereoselective Pd-catalyzed cascade reactions, consisting of the addition of in situ-generated arylpalladium complexes over a proximate carbon–carbon triple bond, followed by cross-coupling reactions, have been reported [26][27][28][29][30][31]. Our continuing interest in the palladium-catalyzed reactions of
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Published 20 May 2020

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

  • Phil M. Pithan,
  • Sören Steup and
  • Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

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  • + and Fe3+ ions most likely induced a ring opening/ring closing cascade of the spirooxazine unit in 3a and 3b including an electron transfer to the respective metal cations. These reaction steps seemed to have different rates in the presence of Cu2+ or Fe3+, which may even allow the differentiation
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Published 05 May 2020

Recent advances in Cu-catalyzed C(sp3)–Si and C(sp3)–B bond formation

  • Balaram S. Takale,
  • Ruchita R. Thakore,
  • Elham Etemadi-Davan and
  • Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

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  • that a specific geometry of the tethered alkene is required, as no 6-membered ring formation was observed. Interestingly, Cárdenas’ precursor 35 [30] led, after a cascade of reactions, to the formation of compound 36. Computational as well as experimental studies suggested that the ligand and
  • -derived benzylic copper species with an electrophilic source of a cyano residue, Yang and co-workers reported on the Cu-catalyzed borylation of styrenes bearing an allylic group at the 1-position. After the initial addition, a cascade of reactions occurred, including cyanation generating a dearomatized
  • electrophiles, such as N-cyanosulfonamides, leading to 1,2 or 4,3-borocyanation in a regiospecific fashion from borocuprative intermediates, respectively [111]. Extending earlier efforts from the Montgomery group for Cu-catalyzed cascade diborylation/ortho-cyanations of terminal allenes [112] and styrene
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Published 15 Apr 2020

Microwave-assisted efficient and facile synthesis of tetramic acid derivatives via a one-pot post-Ugi cascade reaction

  • Yong Li,
  • Zheng Huang,
  • Jia Xu,
  • Yong Ding,
  • Dian-Yong Tang,
  • Jie Lei,
  • Hong-yu Li,
  • Zhong-Zhu Chen and
  • Zhi-Gang Xu

Beilstein J. Org. Chem. 2020, 16, 663–669, doi:10.3762/bjoc.16.63

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  • ][28][29] of complex heterocyclic compounds. Recent advance has been focused in the area toward the development of one-pot [30][31][32] Ugi cascade protocol [33][34] as the powerful synthetic strategy for the construction of increasingly complex heterocyclic compounds in the absence of metal catalysts
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Published 09 Apr 2020

Cascade trifluoromethylthiolation and cyclization of N-[(3-aryl)propioloyl]indoles

  • Ming-Xi Bi,
  • Shuai Liu,
  • Yangen Huang,
  • Xiu-Hua Xu and
  • Feng-Ling Qing

Beilstein J. Org. Chem. 2020, 16, 657–662, doi:10.3762/bjoc.16.62

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  • Organofluorine Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Science, Chinese Academy of Science, 345 Lingling Lu, Shanghai 200032, China 10.3762/bjoc.16.62 Abstract A cascade oxidative trifluoromethylthiolation and cyclization
  • )propioloyl]indole and N-propargylindoles, respectively. Inspired by these elegant results, we became interested in the preparation of SCF3-substituted pyrrolo[1,2-a]indol-3-ones, which might be potentially useful in medicinal chemistry. Radical cascade reactions constitute highly efficient strategies for the
  • construction of compounds with structural diversity and complexity. In 2014, Wang reported the first radical cascade trifluoromethylthiolation and cyclization of activated alkenes (Scheme 1a) [23]. Afterward, Nevado [24], Hopkinson and Glorius [25], Dagousset and Magnier [26], as well as Fu [27] applied this
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Published 08 Apr 2020

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

  • Svetlana V. Amosova,
  • Andrey A. Filippov,
  • Nataliya A. Makhaeva,
  • Alexander I. Albanov and
  • Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

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  • (Scheme 3). Cascade regio- and stereoselective reactions of thiaselenole 1 with water and ethylene glycol resulted in the formation of the first representatives of the new family of polyfunctional 2,3-dihydro-1,4-thiaselenines [41]. The regioselective nucleophilic substitution reactions in thiaselenole 1
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Published 27 Mar 2020

Controlling alkyne reactivity by means of a copper-catalyzed radical reaction system for the synthesis of functionalized quaternary carbons

  • Goki Hirata,
  • Yu Yamane,
  • Naoya Tsubaki,
  • Reina Hara and
  • Takashi Nishikata

Beilstein J. Org. Chem. 2020, 16, 502–508, doi:10.3762/bjoc.16.45

Graphical Abstract
  • Pd-catalyzed cascade reaction (C–C bond formation/C–H cyclization process) of N-arylpropynamide 4 for the preparation of indolinone derivatives 5 was previously reported by Li’s group [34][35]. In another report on C–H cyclization by Lei’s group, Ni-catalyzed aromatic C–H alkylation occurs via a
  • radical reaction [36]. Both cases were helpful in our development of the current Cu-catalyzed cascade C–H cyclization system. After careful optimization, we found that CuI, 1,10-Phen, Cy2NMe as a base, and 1,4-dioxane were effective for obtaining the best yields of products 5 (Figure 2). In this
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Published 26 Mar 2020

Ultrasonic-assisted unusual four-component synthesis of 7-azolylamino-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines

  • Yana I. Sakhno,
  • Maryna V. Murlykina,
  • Oleksandr I. Zbruyev,
  • Anton V. Kozyryev,
  • Svetlana V. Shishkina,
  • Dmytro Sysoiev,
  • Vladimir I. Musatov,
  • Sergey M. Desenko and
  • Valentyn A. Chebanov

Beilstein J. Org. Chem. 2020, 16, 281–289, doi:10.3762/bjoc.16.27

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  • Republic 10.3762/bjoc.16.27 Abstract Four-component reactions of 3-amino-1,2,4-triazole or 5-amino-1H-pyrazole-4-carbonitrile with aromatic aldehydes and pyruvic acid or its esters under ultrasonication were studied. Unusual for such a reaction type, a cascade of elementary stages led to the formation of
  • ]pyrimidines via a cascade of elementary stages that is unusual for such transformations. Thus, we extended the molecular diversity of the compounds obtained by introducing an additional azolyl substituent to the pyrimidine ring. Alternative structures A and B for the tetrahydroazolopyrimidines 4. Molecular
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Published 27 Feb 2020

Combination of multicomponent KA2 and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

  • Riccardo Innocenti,
  • Elena Lenci,
  • Gloria Menchi and
  • Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

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  • [39][40], consisting of a [2 + 2 + 1] cycloaddition between an olefin, alkyne, and carbon monoxide. This reaction has been also applied in cascade approaches [41], and in combination with RCM [42], Diels–Alder [43] and Staudinger [44] reactions to produce novel structurally complex chemical entities
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Published 12 Feb 2020

Understanding the role of active site residues in CotB2 catalysis using a cluster model

  • Keren Raz,
  • Ronja Driller,
  • Thomas Brück,
  • Bernhard Loll and
  • Dan T. Major

Beilstein J. Org. Chem. 2020, 16, 50–59, doi:10.3762/bjoc.16.7

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  • , Dept. of Chemistry, Technical University of Munich (TUM), Lichtenbergstr. 4, 85748 Garching, Germany 10.3762/bjoc.16.7 Abstract Terpene cyclases are responsible for the initial cyclization cascade in the multistep synthesis of a large number of terpenes. CotB2 is a diterpene cyclase from Streptomyces
  • cascade can provide important information towards a biosynthetic strategy for cyclooctatin and the biomanufacturing of related terpene structures. Keywords: active site; CotB2 cyclase; diterpene; mechanism; quantum mechanics; Introduction Enzymes catalyze numerous complex biochemical reactions in
  • , representing the first committed step in the biosynthesis of the next-generation anti-inflammatory drug cyclooctatin. The intracellular target of cyclooctatin is an as of yet uncharacterized lysophospholipase, which is involved in early steps of the inflammatory signaling cascade [38][39][40]. In the last
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Published 08 Jan 2020

Terpenes

  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2019, 15, 2966–2967, doi:10.3762/bjoc.15.292

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  • generate a highly reactive cationic intermediate that can be subject to a cascade reaction through typical carbocation chemistry, including cyclisation reactions, hydride migrations and Wagner–Meerwein rearrangements [1][2]. The cascade is usually terminated by deprotonation or attack of water. The
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Published 13 Dec 2019

Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering

  • Eric J. N. Helfrich,
  • Geng-Min Lin,
  • Christopher A. Voigt and
  • Jon Clardy

Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283

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  • a result of the inherent differences between these biosynthetic machineries. In modular assembly lines, each individual domain is responsible for one defined biosynthetic transformation, while TCs rather act as chaperones [10] to guide oligoprenyl pyrophosphate precursors through a cascade of
  • the leaving pyrophosphate group and the nucleophilic alkenes in proximity to initiate the C–C-bond forming, carbocation-mediated cascade reactions [10]. The hydrophobic binding pocket stabilizes the reaction intermediates and tames the propagation of carbocations through cation–π and other
  • inverted direction of charge propagation along the oligoisoprene chain in the cyclization cascade [53]. The resulting cyclized product retains the pyrophosphate moiety and can serve as the substrate for a second cyclization catalyzed by type I TCs to generate even more complicated diterpene backbones
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Published 29 Nov 2019

Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

  • Zhen Cao,
  • Aline Lacoudre,
  • Cybille Rossy and
  • Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

Graphical Abstract
  • for gold(III) chloride whose photoreduction to gold(I) was fast and controlled [44][45]. These gold complexes at different oxidation states showed efficient catalytic properties, that were highlighted in a one-pot cascade synthesis of 4H-benzoquinolizin-4-one. Now, we propose to investigate a rigid
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Published 17 Oct 2019

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

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  • 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
  • dogmatic dispute in the TPS community about the respective roles of the protein acting as a scaffold and the “inherent” carbocation reactivity [91] in orchestrating an enzyme specific reaction cascade. With regard to the latter, the “inherent reactivity” of carbocations is no doubt an important ingredient
  • in terpene biosynthesis. The enzyme could be understood as passive catalyst, essentially chaperoning the intermediates during the reaction cascade. It is clear that much of terpene biosynthesis can be understood by this concept. “Inherent reactivity” largely relies on theoretical calculations
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Published 02 Oct 2019

Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

  • Benedikt C. Melzer,
  • Alois Plodek and
  • Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

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  • to a pentacyclic ketone. A similar cyclization reaction was developed by our group some years ago for ester substrates [18], and an analogous cyclization of nitriles was described by Kristensen in ring-closing cascade reactions [34]. The new cyclization method was first tested with ester 20a
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Published 26 Sep 2019

Synthesis of acremines A, B and F and studies on the bisacremines

  • Nils Winter and
  • Dirk Trauner

Beilstein J. Org. Chem. 2019, 15, 2271–2276, doi:10.3762/bjoc.15.219

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  • intramolecular cyclization of 23. Attempted photochemical cyclization of 25. Representative screening conditions for the biomimetic cascade. Supporting Information Experimental procedures, spectroscopic data and copies of NMR spectra (PDF) as well as crystallographic data of compounds 16 and 17. CIF files for
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Published 23 Sep 2019

Characterization of two new degradation products of atorvastatin calcium formed upon treatment with strong acids

  • Jürgen Krauß,
  • Monika Klimt,
  • Markus Luber,
  • Peter Mayer and
  • Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2085–2091, doi:10.3762/bjoc.15.206

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  • , resulting in clean conversion into 6 as well. In the following, this unsaturated lactone (Michael system) most likely performs an acid-mediated intramolecular attack at C-2 of the electron-rich pyrrole ring. In a cascade of subsequent reactions, the carboxanilide moiety at C-3 is eliminated and the
  • concentrated sulfuric acid) is not the initial step in the cascade of reactions leading from intermediate 3 to product 6. In a control experiment, we treated compound 7 with 37% hydrochloric acid under the above mentioned conditions, but only a complex mixture of decomposition products was obtained, with no
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Published 02 Sep 2019

Genome mining in Trichoderma viride J1-030: discovery and identification of novel sesquiterpene synthase and its products

  • Xiang Sun,
  • You-Sheng Cai,
  • Yujie Yuan,
  • Guangkai Bian,
  • Ziling Ye,
  • Zixin Deng and
  • Tiangang Liu

Beilstein J. Org. Chem. 2019, 15, 2052–2058, doi:10.3762/bjoc.15.202

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  • recently reported type III TPSs, UbiA-related TPSs, also catalyse cascade reactions by diphosphate elimination [8]. In addition, each type of TPS is characterised by a unique aspartate-rich motif; most type I TPSs have a DDXXD/E motif and an NSE/DTE motif, whereas type II TPSs have the DXDD motif [9][10
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Published 28 Aug 2019
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  • abstracted, resulting in d8-α-cubebene [M]+• with m/z = 212 as highly labeled isotopologue (Figure 4, lower mass spectrum). Biosynthesis of sesquiterpene hydrocarbons via (R)-(+)-germacrene D Lodewyk, Gutta and Tantillo postulated an α-ylangene-forming carbocation cascade based on computer calculations [34
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Published 14 Aug 2019

Inherent atomic mobility changes in carbocation intermediates during the sesterterpene cyclization cascade

  • Hajime Sato,
  • Takaaki Mitsuhashi,
  • Mami Yamazaki,
  • Ikuro Abe and
  • Masanobu Uchiyama

Beilstein J. Org. Chem. 2019, 15, 1890–1897, doi:10.3762/bjoc.15.184

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  • the first detailed analysis of the inherent atomic mobility in carbocation intermediates during sesterterpene biosynthesis. We identified two methyl groups as the least mobile of all the carbons of the carbocation intermediates in the first half of the cyclization cascade. Our analysis suggests that
  • ) triggering the biosynthetic cyclization cascade by the elimination of pyrophosphate or by protonation; (ii) preorganization of the substrate to generate the reactive conformation; (iii) protection of reactive intermediates from water; and (iv) termination of the reaction by deprotonation or hydration. We
  • previously established the importance of conformation in the carbocation cyclization cascade [1], focusing on two sesterterpenes, i.e., quiannulatene [1][2] and sesterfisherol [3][4][5], as representative examples. These two sesterterpenes are synthesized via a 5/12/5 tricyclic intermediate, which leads to a
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Published 07 Aug 2019

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

  • Shuhei Sumino,
  • Takahide Fukuyama,
  • Mika Sasano,
  • Ilhyong Ryu,
  • Antoine Jacquet,
  • Frédéric Robert and
  • Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

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  • together with 1.5 equivalents of 3a led to a higher conversion (ca. 90%), affording acceptable yield and selectivity (Table 1, entry 5). With optimized reaction conditions in hand (Table 1, entry 5), we then examined the generality of this four-component radical cascade reaction using xanthates 1, olefins
  • functionalized keto-aldehydes [22], aminoalcohols [30], triazoles [31], just to name a few. A reaction mechanism is finally proposed for the four-component cascade reaction, which is depicted in Figure 2 [22][23][24][32][33][34]. Initially, α-carbonyl radical A [8] was generated by the reaction of the
  • radical which sustains the radical chain. Since radical B can also add to sulfonyl oxime ether 3a, we used high CO pressure conditions to encourage the radical carbonylation to form acyl radical C. Conclusion In summary, we demonstrated that a four-component radical cascade reaction, between xanthogenates
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Published 31 Jul 2019

Enantioselective PCCP Brønsted acid-catalyzed aza-Piancatelli rearrangement

  • Gabrielle R. Hammersley,
  • Meghan F. Nichol,
  • Helena C. Steffens,
  • Jose M. Delgado,
  • Gesine K. Veits and
  • Javier Read de Alaniz

Beilstein J. Org. Chem. 2019, 15, 1569–1574, doi:10.3762/bjoc.15.160

Graphical Abstract
  • a trans relationship between the C4 and C5 substituents [13][14][15]. It is believed that the 4π conrotatory electrocyclization step that converts the pentadienyl cation 5 into the corresponding cyclopentenone adduct 6 is responsible for controlling the relative diastereoselectivity in this cascade
  • furan ring required to initiate the cascade sequence. This highlights that a balance between nucleophilicity and hydrogen bond capabilities are required to obtain an efficient and selective reaction. Compared to the rearrangement of furylcarbinol 1a, sterically bulky aryl groups attached to the
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Published 12 Jul 2019

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

  • András György Németh,
  • György Miklós Keserű and
  • Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

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  • been developed between isocyanides, sulfur and alcohols or thiols under mild reaction conditions to afford O-thiocarbamates and dithiocarbamates in moderate to good yields. The one-pot reaction cascade involves the formation of an isothiocyanate intermediate, thus a catalyst-free synthesis of
  • functional group tolerance to halogen, olefin and nitrile groups among others. Moreover, this multicomponent reaction is suitable for a one-pot cascade annulation providing a thioxo dihydroquinazolinone derivative in a metal-free approach. Compared to other reported syntheses of thiocarbamates, this method
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Published 10 Jul 2019

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

  • Piyali Sarkar,
  • Sayan Sarkar and
  • Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

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  • nanoreactor which is a single molecule as catalyst in the earliest steps of the mechanistic pathway (Figure 6). This multicomponent reaction is expected to comprise a series of condensations and subsequent ring-closure cascade reactions (Scheme 3). To demonstrate the mechanistic pathway, dimedone (2), isatin
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Published 08 Jul 2019
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