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Search for "C–O bond" in Full Text gives 152 result(s) in Beilstein Journal of Organic Chemistry.

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

  • Rodrigo Costa e Silva,
  • Luely Oliveira da Silva,
  • Aloisio de Andrade Bartolomeu,
  • Timothy John Brocksom and
  • Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

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  • platform for dual catalysis due to their ability to promote both metallocatalysis and photocatalysis in a one-pot system [36][37][38][39]. Martin and co-workers carried out the CO bond cleavage of alcohols using a cobalt porphyrin under visible light irradiation and a carbon monoxide atmosphere (Scheme 11
  • ) [36]. The authors hypothesized that the CO bond cleavage could be achieved via cobalt-mediated alcohol carbonylation followed by radical decarboxylation of the alkoxycarbonyl intermediate. In a proof-of-concept study, they proceeded with the carbonylation of 1-phenylethanol using Co(II) tetrakis(4
  • tetrahydroquinolines by reductive quenching. Selenylation and thiolation of anilines. NiTPP as photoredox catalyst in oxidative and reductive quenching, in comparison with other photocatalysts. CO bond cleavage of 1-phenylethanol using a cobalt porphyrin (CoTMPP) under visible light. Hydration of terminal alkynes by
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Published 06 May 2020

Copper catalysis with redox-active ligands

  • Agnideep Das,
  • Yufeng Ren,
  • Cheriehan Hessin and
  • Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

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  • -active ligands is itself a much broader area, we shall limit our discussion to copper catalysis with redox-active ligands and the present review aims at providing an overview of the relevant literature on this topic over the last three decades. Review Oxidation: CO bond formation The central role of
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Published 24 Apr 2020

Synthesis of organic liquid crystals containing selectively fluorinated cyclopropanes

  • Zeguo Fang,
  • Nawaf Al-Maharik,
  • Peer Kirsch,
  • Matthias Bremer,
  • Alexandra M. Z. Slawin and
  • David O’Hagan

Beilstein J. Org. Chem. 2020, 16, 674–680, doi:10.3762/bjoc.16.65

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  • ether was used as the linkage in compound 10, the compound becomes more flexible and, perhaps surprisingly, the overall Δε parameter became more positive. Clearly the effect of introducing a CO bond renders this molecule dissimilar from the others in this series. However, changing the core aliphatic
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Published 14 Apr 2020

Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

  • Seiya Terai,
  • Yuki Sato,
  • Takuya Kochi and
  • Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

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  • alkyl and alkoxy substituents at the 3, 6, 13, and 16-positions was achieved based on the ruthenium-catalyzed coupling reactions of anthraquinone derivatives with arylboronates via C–H and CO bond cleavage. The reaction sequence involving the arylation, carbonyl methylenation, and oxidative cyclization
  • class of tetrabenzo[a,d,j,m]coronene derivatives having alkyl and alkoxy-substituents at the 3, 6, 13, and 16-positions was achieved based on a ruthenium-catalyzed coupling reaction of anthraquinone derivatives with arylboronates via a C–H or/and CO bond cleavage. The reaction sequence involving the
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Published 31 Mar 2020

[1,3]/[1,4]-Sulfur atom migration in β-hydroxyalkylphosphine sulfides

  • Katarzyna Włodarczyk,
  • Piotr Borowski and
  • Marek Stankevič

Beilstein J. Org. Chem. 2020, 16, 88–105, doi:10.3762/bjoc.16.11

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  • signals were found at 41.2 ppm/11.0 Hz and 41.6 ppm/10.7 Hz, respectively. The shifts indicated the presence of a C–S and not a CO bond in the carbon skeleton [64][65], and the coupling constant value was typical for an γ-carbon atom present in a phosphine derivative [67][68][69]. In this regard, 31P NMR
  • 2 and 3). The difference must therefore have arisen from the different CO bond dissociation energies of the alcohols and mesylates. Assuming that the Lewis acid coordinated to either hydroxy oxygen atom or to one of the oxygen atoms of the mesyl group, the activation energies for CO bond
  • mesylate 61, with a tert-butyl group at the β-carbon atom, the initial dissociation of the CO bond must have been followed by CH3 group migration before the observed sulfur transfer took place. Analogous attempts were made for compounds 62–65 (Scheme 8). A mixture of alkenylphosphine sulfides 62 and 63
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Published 21 Jan 2020

Why do thioureas and squaramides slow down the Ireland–Claisen rearrangement?

  • Dominika Krištofíková,
  • Juraj Filo,
  • Mária Mečiarová and
  • Radovan Šebesta

Beilstein J. Org. Chem. 2019, 15, 2948–2957, doi:10.3762/bjoc.15.290

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  • h. ωB97X-D/6-31G* calculated uncatalyzed Ireland–Claisen rearrangement of 1c. Charges on allylic oxygen (blue); CO bond-breaking and C–C bond-forming distances in TS (black). ωB97X-D/6-31G* calculated Schreiner thiourea (12)-catalyzed Ireland–Claisen rearrangement of 1c. Charges on allylic oxygen
  • (blue); CO bond-breaking and C–C bond-forming distances in TS (black); hydrogen-bond distances (black). ωB97X-D/6-31G* calculated Ph-thiourea (top) and squaramide-catalyzed (bottom) Ireland–Claisen rearrangement of 1c. Charges on allylic oxygen (blue); CO bond-breaking and C–C bond-forming distances
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Published 10 Dec 2019

Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

  • Sachin S. Burade,
  • Sushil V. Pawar,
  • Tanmoy Saha,
  • Navanath Kumbhar,
  • Amol S. Kotmale,
  • Manzoor Ahmad,
  • Pinaki Talukdar and
  • Dilip D. Dhavale

Beilstein J. Org. Chem. 2019, 15, 2419–2427, doi:10.3762/bjoc.15.234

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  • . The molecular modeling study of N-acetylated compound 2b also indicated the presence of a seven-membered hydrogen bonding between NH(II) and –C=O [bond distance (d) = 2.74 Å and bond angle (NH···O) = 112.98°] suggesting the presence of a γ-turn conformation (Figure 5B). Ion transport activity The
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Published 14 Oct 2019

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

  • Xiaowei Li,
  • Xiaolin Shi,
  • Xiangqian Li and
  • Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

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  • , promoting the C–F over CO bond formation via an inner-sphere pathway. Fluorination of arenes, aryl bromides, -alcohols, -triflates, and -boronic acid derivatives: In 2013, Larhed and co-workers [51] established a one-pot, two-step fluorination of aryl alcohols via aryl nonafluorobutylsulfonates. This
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Published 23 Sep 2019

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

  • Kesari Lakshmi Manasa,
  • Yellaiah Tangella,
  • Namballa Hari Krishna and
  • Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

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  • of a C–C bond followed by formation of a new C–N/CO bond in the presence of K2CO3. Various pyridinium salts of phenacyl bromides can be readily transformed into a variety of amides and esters which is an alternative method for the conventional amidation and esterification in organic synthesis. High
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Published 05 Aug 2019

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

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Published 19 Jul 2019

Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings

  • Manuel Pedrón,
  • Laura Legnani,
  • Maria-Assunta Chiacchio,
  • Pierluigi Caramella,
  • Tomás Tejero and
  • Pedro Merino

Beilstein J. Org. Chem. 2019, 15, 1552–1562, doi:10.3762/bjoc.15.158

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  • –O distance increased to 3.00 Å in TS2 and to 3.15 Å in TS3 (similar data were found in acetonitrile, see Supporting Information File 1) clearly indicating a delay in the formation of the CO bond. This situation is compatible with the stabilization of a developing positive charge at the carbon atom
  • , showing a substantial delay in the formation of the CO bond with respect to the H transfer from the C atom to the O atom, and following the sequence TS1 < TS2 < TS3 (Figure 1, red arrows). Even though the above data clearly point out to a typical one-step-two-stage process [69][70][71] in which the bonds
  • with the transition state at point 77 (29% of IRC). Breaking of the C1–H bond is immediately followed by H transfer (point 78) and O3–H bond formation (point 81). The formation of the second CO bond takes place at point 128 (48% of IRC). The gap between H transfer and C1–O6 bond formation (from point
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Published 11 Jul 2019

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

  • Ruben Pomar Fuentespina,
  • José Angel Garcia de la Cruz,
  • Gabriel Durin,
  • Victor Mamane,
  • Jean-Marc Weibel and
  • Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

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  • species. Applied to oxiranyllithium derived from cis or trans-alkynyloxiranes, such dimer may easily form from the cis-oxirane (Scheme 2, entry 4), but not from the trans-isomer, or at least the large steric constrain present in it may hamper its stability. Indeed, the long oxirane CO bond adjacent to
  • B could be envisaged with the large pinacol substituent facing the small oxirane ring and thus placing the migrating group antiparallel to the adjacent oxiranyl CO bond. This may explain the role of the diol substituent on the reaction efficacy (see Table 1). Upon migration and oxirane ring opening
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Published 27 Jun 2019

Mechanochemical Friedel–Crafts acylations

  • Mateja Đud,
  • Anamarija Briš,
  • Iva Jušinski,
  • Davor Gracin and
  • Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

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  • transient reactive intermediates were predicted by density functional theory method B3LYP/6-31G* (Supporting Information File 1) [61]. The stretching of the +CO bond of the acylium ion was predicted to be at about 2300 cm−1. Raman spectroscopy revealed that the complexation of phthalic anhydride with AlCl3
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Published 17 Jun 2019

Alkylation of lithiated dimethyl tartrate acetonide with unactivated alkyl halides and application to an asymmetric synthesis of the 2,8-dioxabicyclo[3.2.1]octane core of squalestatins/zaragozic acids

  • Herman O. Sintim,
  • Hamad H. Al Mamari,
  • Hasanain A. A. Almohseni,
  • Younes Fegheh-Hassanpour and
  • David M. Hodgson

Beilstein J. Org. Chem. 2019, 15, 1194–1202, doi:10.3762/bjoc.15.116

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  • rationalised due to the enolate π-system and potentially cleavable beta σ-CO bond lying mutually orthogonal, while the latter was subsequently ascribed to alkylation occurring from an envelope conformation wherein the unenolised ester resided pseudoequatorial to avoid 1,3-steric interactions with a
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Published 31 May 2019

Switchable selectivity in Pd-catalyzed [3 + 2] annulations of γ-oxy-2-cycloalkenones with 3-oxoglutarates: C–C/C–C vs C–C/O–C bond formation

  • Yang Liu,
  • Julie Oble and
  • Giovanni Poli

Beilstein J. Org. Chem. 2019, 15, 1107–1115, doi:10.3762/bjoc.15.107

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  • -forming annulations with dimethyl 3-oxoglutarate (1a). C–C/CO bond-forming annulations with various bis-nucleophiles. Decarboxylative rearrangement of 4a into 5a. Proposed mechanism for the Pd-catalyzed part of the [3 + 2] annulation reaction. Proposed mechanism for the temperature dependent cyclization
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Published 16 May 2019

Novel (2-amino-4-arylimidazolyl)propanoic acids and pyrrolo[1,2-c]imidazoles via the domino reactions of 2-amino-4-arylimidazoles with carbonyl and methylene active compounds

  • Victoria V. Lipson,
  • Tetiana L. Pavlovska,
  • Nataliya V. Svetlichnaya,
  • Anna A. Poryvai,
  • Nikolay Yu. Gorobets,
  • Erik V. Van der Eycken,
  • Irina S. Konovalova,
  • Svetlana V. Shiskina,
  • Alexander V. Borisov,
  • Vladimir I. Musatov and
  • Alexander V. Mazepa

Beilstein J. Org. Chem. 2019, 15, 1032–1045, doi:10.3762/bjoc.15.101

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  • of the trifluoroacetic molecule as anion is confirmed by close values of the CO bond lengths (1.229(2) Å and 1.238(2) Å, respectively) and the absence of the hydrogen atom at the carboxylic group. The analysis of the bond lengths in the imidazole ring has revealed that the C1–N1 and C1–N3 bonds are
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Published 06 May 2019

Nucleofugal behavior of a β-shielded α-cyanovinyl carbanion

  • Rudolf Knorr and
  • Barbara Schmidt

Beilstein J. Org. Chem. 2018, 14, 3018–3024, doi:10.3762/bjoc.14.281

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  • -tetramethylindan-2-ylidene)acetonitriles added reversibly to three small aldehydes and two bulky ketones at room temperature. Experimental conditions were determined for transfer of the nucleofugal title carbanion unit between different carbonyl compounds. These readily occurring retro-additions via C–C(O) bond
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Published 11 Dec 2018

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

  • Tetsuaki Fujihara and
  • Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

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  • first generated by the reduction of Co(II) with Mn. Secondly, the oxidative addition of the CO bond in 1 occurs, affording Co(III) intermediate B (step a) [30]. Next, the propargyl Co(III) species B is reduced by Mn, producing the corresponding propargyl Co(II) intermediate C (step b). Subsequently
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Published 19 Sep 2018

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

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  • geometrical structures of 2 and 3 were computed with DFT calculation (Figure 5). In the calculated geometry for 2, the bond length between CO2 and imine nitrogen was 1.548 Å and the bent angle of O–CO bond was 135.76°. These bond length and angle were fairly similar to that of the zwitterion adduct between
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Published 23 Aug 2018

Cobalt-catalyzed nucleophilic addition of the allylic C(sp3)–H bond of simple alkenes to ketones

  • Tsuyoshi Mita,
  • Masashi Uchiyama,
  • Kenichi Michigami and
  • Yoshihiro Sato

Beilstein J. Org. Chem. 2018, 14, 2012–2017, doi:10.3762/bjoc.14.176

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  • remained underdeveloped even though CO bond formation of allylic C(sp3)–H bonds was firmly established by using SeO2 [14] or CrO3/3,5-dimethylpyrazole [15] (ene-type allylic oxidation). Although the most prominent work on catalytic allylic functionalization studied thus far is considered to be a palladium
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Published 02 Aug 2018

Cationic cobalt-catalyzed [1,3]-rearrangement of N-alkoxycarbonyloxyanilines

  • Itaru Nakamura,
  • Mao Owada,
  • Takeru Jo and
  • Masahiro Terada

Beilstein J. Org. Chem. 2018, 14, 1972–1979, doi:10.3762/bjoc.14.172

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  • suggest that the CO bond would form prior to cleavage of the C–H bond in the [1,3]-rearrangement reaction. Due to the fact that the reaction of 1a in the presence of tri- and tetravalent cationic metal catalysts afforded the para-isomer 3a as a major product (Table 1, entries 14–18), the reaction of
  • furnished through direct CO bond formation at the para-position through ionic cleavage of the N–O bond by cationic Ru(III) as a much stronger Lewis acid, while it is also possible that the second migration of the alkoxycarbonyloxy group from ortho to para occurs prior to proton transfer (Scheme 5b) [25
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Published 31 Jul 2018

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

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  • attack of acetates to the exposed re-face establishes the S-configured benzylic CO bond. Without the hydrogen bonding effect, the same reaction with a diester-containing iodoarene catalyst was explored [55]. The sterically hindered adamantyl-substituted catalysts 17 were demonstrated to be efficient to
  • -olefin functionalization via C–C and CO bond formation, in which electron-rich aromatic groups and vinylogous esters acting as independent nucleophiles to provide oxabicyclo[3.2.1]octanes (Scheme 17) [71]. Mechanistically, the olefin is activated by iodine(III) to form species 57 which is followed by
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Published 18 Jul 2018

DFT calculations on the mechanism of copper-catalysed tandem arylation–cyclisation reactions of alkynes and diaryliodonium salts

  • Tamás Károly Stenczel,
  • Ádám Sinai,
  • Zoltán Novák and
  • András Stirling

Beilstein J. Org. Chem. 2018, 14, 1743–1749, doi:10.3762/bjoc.14.148

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  • before the CO bond formation in the ring closing step (see Scheme 1). As an example of the catalytic arylation–cyclisation strategy, an efficient procedure to form substituted oxazoline derivatives from alkyl and aryl propargylamides has been developed. The process involves a 5-exo-dig cyclisation and
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Published 12 Jul 2018

The phenyl vinyl ether–methanol complex: a model system for quantum chemistry benchmarking

  • Dominic Bernhard,
  • Fabian Dietrich,
  • Mariyam Fatima,
  • Cristóbal Pérez,
  • Hannes C. Gottschalk,
  • Axel Wuttke,
  • Ricardo A. Mata,
  • Martin A. Suhm,
  • Melanie Schnell and
  • Markus Gerhards

Beilstein J. Org. Chem. 2018, 14, 1642–1654, doi:10.3762/bjoc.14.140

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  • methanol (373 cm−1) and also lower than the calculated barrier height of 341 cm−1 (cf. Table S9, Supporting Information File 1). This somewhat lower methyl group internal rotation barrier for the OH–O’ isomer could point to a softening of the CO bond of methanol due to the hydrogen bond. The DID plots in
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Published 02 Jul 2018

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

  • Kimihiro Komeyama,
  • Shunsuke Sakiyama,
  • Kento Iwashita,
  • Itaru Osaka and
  • Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

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  • converted to vinylchromium, which would be inactive in the oligomerization, but is a highly nucleophilic species. According to these findings, the reversed diastereoselectivity in Scheme 9 might be due to stereoelectronic effects [21][22]. Thus, the σ*(CO) bond stabilizes the forming σ(Co–C) bond in the
  • by the stereoelectronic interaction between the forming σ(C–Co) bond and a neighboring σ*(CO) bond. Further mechanistic studies and expansion of the substrate scope, including synthetic applications of this three-component coupling, are currently in progress. Nucleophilic and π-electrophilic
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Published 11 Jun 2018
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