Azidophosphonium salt-directed chemoselective synthesis of (E)/(Z)-cinnamyl-1H-triazoles and regiospecific access to bromomethylcoumarins from Morita–Baylis–Hillman adducts

• Soundararajan Karthikeyan,
• Radha Krishnan Shobana,
• Kamarajapurathu Raju Subimol,
• J. Helen Ratna Monica and
• Ayyanoth Karthik Krishna Kumar

Beilstein J. Org. Chem. 2020, 16, 1579–1587, doi:10.3762/bjoc.16.130

• derivatives 3a–d/g–k/m–q in a yield of 70–88%. Distinctively, the cyano acrylate-substituted MBH adduct stereoselectively afforded the (Z)-cinnamyl-1,4-disubstituted 1,2,3-triazole derivatives 3e/f/l in a yield of 82–92%. Irrespective of the acetylene moiety, the MBH adducts derived from acrylonitrile

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• displays a Cethynyl–H···π interaction (2.530 Å) between the acetylene proton of 8j and the N-phenyl ring of the N-phenylmaleimide (7c) (Table 7, and Figure 4d and Figure 5c). Such an interaction may explain the greater stabilization of the endo approach to give 9p as the major isomer. Due to the scarce X

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• released. Alkali salts of acetylene dicarboxylic acid can also be used as precursor for the preparation of carbon spheres. The structure and morphology of the carbon spheres can be influenced by the used alkali salts [80]. Activated carbon preparation The following chapter summarizes the different

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• complexity, by essentially using a Ru-catalyzed alkene–alkyne (Ru-AA) coupling reaction and a macrolactonization step (Scheme 8). In this carefully designed total synthesis, after applying a Marshall coupling reaction aimed at installing a propargyl group into the initial acetylene component, an enyne

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• two-component or three-component “click” reactions. In the two-component reaction, acetylene compounds and organic azides were stirred in dimethylformamide or in a mixture of t-BuOH/H2O, 3:1, v/v as the solvent using diethylisopropylamine and SiO2–Cu. In the three-component example, acetylene species

• “click” reactions of alkyl halide, NaN3, and acetylene were performed successfully in the presence of 100 (1.0 mol %) as the catalyst and 10 mol % of sodium ascorbate as a reducing agent in water at 50 °C (Scheme 22). Further, the nanocatalyst 100 was durable and could be recycled eight times without any

Palladium-catalyzed Sonogashira coupling reactions in γ-valerolactone-based ionic liquids

• László Orha,
• József M. Tukacs,
• László Kollár and
• László T. Mika

Beilstein J. Org. Chem. 2019, 15, 2907–2913, doi:10.3762/bjoc.15.284

• iodide (Table 3, entries 2–7). Under identical conditions, 2-iodothiophene, and iodopyridine derivatives could also easily be converted to the corresponding acetylene with good or even excellent isolated yields (3i–n). When 2-amino-3-iodopyridine (1i) was converted no C–N bond formation was detected

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• solid. The metathesis reactions were performed in the presence of molecular sieves with a pore size of 5 Å (MS 5 Å) to absorb acetylene which is formed during the reaction. The products of the metathesis reactions could be obtained as orange solids. The RCAM of the butynyl system 1a afforded the desired

Combining the Ugi-azide multicomponent reaction and rhodium(III)-catalyzed annulation for the synthesis of tetrazole-isoquinolone/pyridone hybrids

• Gerardo M. Ojeda,
• Prabhat Ranjan,
• Pavel Fedoseev,
• Lisandra Amable,
• Upendra K. Sharma,
• Daniel G. Rivera and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 2447–2457, doi:10.3762/bjoc.15.237

• peptides and the formation of isoquinolones; so it is expected that in intermediate B the substrate behaves as a tridentate ligand for the Rh(III) center [37][62][63][64][65]. However, such a complexation must be reversible to allow a further ligand exchange with the acetylene to form intermediate C. The

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• ][150][159][164][175][211] derivatives [174][183][200][229] are often used as the complementary dienophiles (Scheme 14, reaction pathways (i), (ii) and (iii), respectively), as well as mono- and disubstituted acetylene derivatives, such as methyl propiolate [229] and dibenzoylacetylene [150]. Conversely

Nanopatterns of arylene–alkynylene squares on graphite: self-sorting and intercalation

• Tristan J. Keller,
• Joshua Bahr,
• Kristin Gratzfeld,
• Nina Schönfelder,
• Marcin A. Majewski,
• Marcin Stępień,
• Sigurd Höger and
• Stefan-S. Jester

Beilstein J. Org. Chem. 2019, 15, 1848–1855, doi:10.3762/bjoc.15.180

• other sides of the square is based on the Glaser coupling of acetylene-terminated precursor structures. These side chains give macrocycles with reduced symmetry. They cannot be obtained by the cyclization of small building blocks, but require the stepwise formation of more complex precursors, where the

• protective groups [28]. Subsequently, 1a/b were prepared by Pd-catalyzed oxidative cyclodimerization of the respective acetylene-terminated precursors under high-dilution conditions [29][30]. The separation of the crude products by recycling gel permeation chromatography (recGPC) yielded the monodisperse

Norbornadiene-functionalized triazatriangulenium and trioxatriangulenium platforms

• Roland Löw,
• Talina Rusch,
• Tobias Moje,
• Fynn Röhricht,
• Olaf M. Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1815–1821, doi:10.3762/bjoc.15.175

• the mechanisms of bulk metal catalysis and open new ways to design new catalytic systems. Towards this end, and following the “platform concept”, we designed a cyano-substituted norbornadiene, which is functionalized with an acetylene spacer on a TATA platform to investigate an eventual “spin

• triazatriangulenium ion 6 was synthesized according to a procedure of Laursen and Krebs [13]. The platform 6 was functionalized with norbornadiene 5 by deprotection of the acetylene with potassium hydroxide and in situ formation of the C–C bond between the acetylene and the central C atom of the platform 6 to yield

• ) crossection along the white line in (a). Syntheses of the norbornadiene TATA platform 1 and TOTA platform 3. a) TMS-acetylene, Pd(PPh3)4, Cu(I)I, Et3N, toluene, N2, 60 °C, 1.3 h; b) KOH, THF, N2, reflux, 5 h; c) sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF4), DCM, rt, 2 h; d) n-BuLi, THF, N2

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• dyes. Synthetic scheme of the selected materials. a) hydroxylamine hydrochloride, NaHCO3, DMSO, 60 °C then acetylene, KOH, DMSO, 110 °C, 24% over the two steps; b) 4-iodobenzoyl chloride, DCM, rt then DDQ, DCM, rt then NEt3, BF3·OEt2, 0 °C to rt, 35%; c) piperidine, cat. PTSA, toluene, 130 °C, 5: 35

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• groups (EDGs) at different positions on the phenyl ring. However, the use of aliphatic aldehydes such as 3-methylbutanal and cyclohexanecarbaldehyde and aliphatic acetylene viz., hex-1-yne resulted in a comparatively lower yield of 66, 70 and 60%, respectively. Heteroaromatic aldehydes such as thiophene

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• , hypervalent iodine reagents, etc. The synthetic methods towards diverse [1,2,4]triazolo[3,4-a]pyridines have been reviewed in detail [12][13]. It should be noted that the use of acetylene species to create this heterocycle (including triazole ring) is presented only by few examples. There has been reported

• one method for the formation of a [1,2,4]triazolo[4,3-a]pyridine ring with participation of an acetylene triple bond; an oxidative cyclization during the reaction of terminal phenylacetylenes with 2-hydrazinylpyridines [14]. However, data on phosphorus-containing triazolopyridines are scarce, although

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• considered (Scheme 10). The required catalytic amount of such superacid may be formed due to the presence of traces of HCl (byproduct in acetylene–allene rearrangement step) in the reaction mixture. Next, the protonaton of complex 13 occurs, leading to allylic cation 22. As analogue of cation 16 (Scheme 9

Diazocine-functionalized TATA platforms

• Roland Löw,
• Talina Rusch,
• Fynn Röhricht,
• Olaf Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1485–1490, doi:10.3762/bjoc.15.150

• platform (triazatriangulenium (TATA)) which adsorbs on the gold surface, with an acetylene spacer standing upright, like a post in the middle of the platform and the azobenzene unit mounted on top. The rate acceleration is due to a very peculiar thermal singlet–triplet–singlet mechanism mediated by bulk

• to the trans-form, which slowly returns back to the stable cis-isomer. To investigate the thermal trans→cis isomerization as a function of the conjugation to the metal surface, we connected the acetylene spacer in meta (weak conjugation) and in para (strong conjugation) position. Both isomers form

• a function of electronic coupling (conjugation) of the azo unit to gold. The para-diazocine-TATA 1 was synthesized in a 5-step synthesis route (Scheme 1). Bromotoluene 3 was synthesized as described [26]. In a Sonogashira cross-coupling reaction acetylene-substituted toluene 5 was prepared from

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• Sonogashira reactions [53]. In the reported procedure, a bulky substituted acetylene derivative was used, probably supressing the formation of the phthalocyanine byproduct to some extent. Indeed, 5,6-dicyano-4,7-bis-(2-trimethylsilylethynyl)-2,1,3-benzothiadiazole (12a) could be synthesized by Sonogashira

• polymerisation of the acetylides. No deprotected terminal acetylene was observed. To avoid polymerization, the solvent was changed to acetonitrile and the temperature was lowered to 0 °C. Additionally, carbon dioxide was not just used as the reaction atmosphere, but directly bubbled through the solution

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• followed by acetylene–allene rearrangement was used to prepare (arylsulfinyl)allenes 1 according to the literature procedure [24][25]. The latter were in situ oxidized to (arylsulfonyl)allenes 2 (see X-ray structure of 2h in Figure 1). Allenes 1a,b were specially isolated to compare their reactivity with

Domino ring-opening–ring-closing enyne metathesis vs enyne metathesis of norbornene derivatives with alkynyl side chains. Construction of condensed polycarbocycles

• Ritabrata Datta and
• Subrata Ghosh

Beilstein J. Org. Chem. 2018, 14, 2708–2714, doi:10.3762/bjoc.14.248

• polycycles from metathesis of norbornene derivatives with alkynyl side-chain. This investigation demonstrated that domino metathesis of norbornene derivatives with alkynyl side-chain requires metathesis initiation at the acetylene unit. Further, the nature of functional groups as well as the substrate

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• a CM in an efficient manner. Biaryl derivatives In view of the interesting properties of biaryl derivatives, we have identified a three-step sequence, which involve cross-enyne metathesis (CEM), DA reaction followed by SM coupling [46]. To this end, acetylene derivatives 96a,b were subjected to CEM

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• ditungsten catalyst W2F3 was also employed in alkyne cross-metathesis (ACM), a reaction which is of large interest for the application of alkyne metathesis, but often leads to product mixtures. Therefore, (trimethylsilyl)propyne and (trimethylsilyl)acetylene were chosen as reaction partners in ACM, since

Synthesis of indolo[1,2-c]quinazolines from 2-alkynylaniline derivatives through Pd-catalyzed indole formation/cyclization with N,N-dimethylformamide dimethyl acetal

• Antonio Arcadi,
• Sandro Cacchi,
• Giancarlo Fabrizi,
• Francesca Ghirga,
• Antonella Goggiamani,
• Antonia Iazzetti and
• Fabio Marinelli

Beilstein J. Org. Chem. 2018, 14, 2411–2417, doi:10.3762/bjoc.14.218

• )acetylene (1) with aryl or vinyl halides and triflates followed by cyclization reactions (Scheme 1) [19]. The reaction, which tolerates a variety of important functional groups, likely involves the formation of the indole intermediates 2 (through aminopalladation/reductive elimination) [20][21] followed by

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• further purified. In the second approach, the copper acetylide was formed in situ by the reaction of the acetylene derivative with triethylamine in the presence of Cu+ salts. Hence, the reaction of iodobenzo[b]quinolizinium 5 with arylacetylenes 7b–d in the presence of one equivalent of triethylamine and

[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

• corresponding rather to type II or even type I cycloadditions. The most reactive were electron-poor alkynes (acetylene(di)carboxylates, benzoyl phenylacetylene) while electron-rich alkynes (tetradec-1-yne, 1-phenylpropyne) were much less reactive. Unfortunately, the reaction rate constant was not measured for

• the reaction with acetylene itself. However, on the basis of the published [1][2] synthetic protocol (acetone, 170 °C, 25 h) it appears that this cycloaddition is very slow and requires a higher temperature. Recently [42][43][44], a kinetic investigation was performed for the cycloaddition of various

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• . Radical addition to the alkyne leads to the anti-Markovnikov adduct via the more stable secondary radical intermediate. As alkyne 2-methyl-3-butyn-2-ol was selected, which is easily prepared from acetylene and acetone on large scale and the respective thiol–yne adducts can be converted into valuable

• (Scheme 35) [70]. o-Methylthioaryl diazonium salts and phenylacetylene are starting materials, and photoexcited Eosin Y transfers an electron to the diazonium salt, which decomposes into a reactive aryl radical and N2. Addition to the acetylene yields a vinylic radical intermediate, which cyclizes to the

• combination of KOH/DMSO and 2-halothioanisole forms an orange adduct, which absorbs visible-light. They propose that KOH/DMSO as a superbase can photoreduce the aryl halide, which subsequently generates an aryl radical by expelling the halide anion. Radical addition to the acetylene derivative yields a vinyl