Search results

Search for "deprotonation" in Full Text gives 551 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Selectfluor and alcohol-mediated synthesis of bicyclic oxyfluorination compounds by Wagner–Meerwein rearrangement

  • Ziya Dağalan,
  • Muhammed Hanifi Çelikoğlu,
  • Saffet Çelik,
  • Ramazan Koçak and
  • Bilal Nişancı

Beilstein J. Org. Chem. 2024, 20, 1462–1467, doi:10.3762/bjoc.20.129

Graphical Abstract
  • selectfluor and a carbocation is formed by bonding with fluorine. Subsequently, fluoroalkoxy compound 4 is formed by Wagner–Meerwein rearrangement followed by alcohol addition and deprotonation. Conclusion New bicyclic fluoroalkoxy compounds were synthesized by a molecular fluorine and metal-free methodology
PDF
Album
Supp Info
Full Research Paper
Published 01 Jul 2024

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

  • Mithu Roy,
  • Bitan Sardar,
  • Itu Mallick and
  • Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

Graphical Abstract
  • iridium photocatalyst [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 leads to excited-state *[Ir(III)], Ered (*[Ir(III)]/[Ir(II)]) = +1.21 V, possessing sufficient energy to oxidize PPh3, forming the triphenylphosphine radical cation. Subsequently, benzoic acid undergoes deprotonation facilitated by a base, producing
  • converted rather selectively in the order tertiary alcohol< secondary alcohol < primary alcohol. They also proposed a mechanism, which is outlined in Scheme 16. The first step involves deprotonation of alcohol in the presence of base and nucleophilic attack of CS2 to generate a xanthate salt intermediate
  • -state *[Ir(III)] complex can effectively oxidize the nitrogen atom of activated NHC–alcohol adduct 66 via SET. The resulting nitrogen radical cation intermediate 67 weakens the adjacent C–H bond, making it more acidic and susceptible to deprotonation by a suitable base, ultimately yielding an α-amino
PDF
Album
Review
Published 14 Jun 2024

Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes

  • Zining Li,
  • Sana Jindani,
  • Volga Kojasoy,
  • Teresa Ortega,
  • Erin M. Marshall,
  • Khalil A. Abboud,
  • Sandra Loesgen,
  • Dean J. Tantillo and
  • Jeffrey D. Rudolf

Beilstein J. Org. Chem. 2024, 20, 1320–1326, doi:10.3762/bjoc.20.115

Graphical Abstract
  • rearrangement (27.7 kcal mol−1; Figure S12, Supporting Information File 1) of uncharged 11 compared to that of 2 (Figure 3B). The free energy barrier value for 11 is likely too high to be non-enzymatic at 28 °C and may at least require deprotonation of the hydroxy group or at least H-bonding with solvent [23
PDF
Album
Supp Info
Full Research Paper
Published 07 Jun 2024

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

  • Jinmin Gao,
  • Liyuan Li,
  • Shijie Shen,
  • Guomin Ai,
  • Bin Wang,
  • Fang Guo,
  • Tongjian Yang,
  • Hui Han,
  • Zhengren Xu,
  • Guohui Pan and
  • Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

Graphical Abstract
  • deprotonation of 8 to form a substrate anion, which activated molecular oxygen to generate a substrate radical and the superoxide anion O2•−. The ensuing radical rebound reaction led to the formation of a peroxide intermediate, which in turn underwent a ring opening reaction to generate the hydroquinone
PDF
Album
Supp Info
Full Research Paper
Published 23 May 2024

Stability trends in carbocation intermediates stemming from germacrene A and hedycaryol

  • Naziha Tarannam,
  • Prashant Kumar Gupta,
  • Shani Zev and
  • Dan Thomas Major

Beilstein J. Org. Chem. 2024, 20, 1189–1197, doi:10.3762/bjoc.20.101

Graphical Abstract
  • isoprenoid allylic carbocation has the capability to engage in standard carbocation reactions, including cyclization via intramolecular olefin attack at the positively charged center, Wagner–Meerwein rearrangements, and hydride or proton shifts. This sequence concludes either through deprotonation, resulting
  • germacradienyl cation, and 1,11-cyclization resulting in the humulyl cation [14][15]. Deprotonation of the intermediate germacradienyl cation yields germacrene A, a doorway towards the synthesis of many eudesmane and guaiane sesquiterpene hydrocarbons through its reprotonation-induced transannular reactions
  • (Scheme 1) [16]. As an alternative to deprotonation, the germacradienyl cation can be captured by water to yield the sesquiterpene alcohol hedycaryol, which is an important intermediate towards the synthesis of sesquiterpene alcohols [17]. The reprotonation of (R)-(+)-1 germacrene A or hedycaryol at the
PDF
Album
Supp Info
Full Research Paper
Published 23 May 2024

Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles

  • Jun Kikuchi,
  • Roi Nakajima and
  • Naohiko Yoshikai

Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79

Graphical Abstract
  • this conjecture, the present reaction is proposed to involve reversible complexation between the alkyne and the cationic iodine(III) electrophile and subsequent trans-addition of the azole nucleophile, the latter step being coupled with concomitant deprotonation of the N–H bond by the triflate anion
PDF
Album
Supp Info
Full Research Paper
Published 22 Apr 2024

Confirmation of the stereochemistry of spiroviolene

  • Yao Kong,
  • Yuanning Liu,
  • Kaibiao Wang,
  • Tao Wang,
  • Chen Wang,
  • Ben Ai,
  • Hongli Jia,
  • Guohui Pan,
  • Min Yin and
  • Zhengren Xu

Beilstein J. Org. Chem. 2024, 20, 852–858, doi:10.3762/bjoc.20.77

Graphical Abstract
  • isotope labeling experiments [6], followed by a 2,7-cyclization, afforded C6 cationic intermediate IM-3 with cyclopiane skeleton. Quench of the cation IM-3 with water would give 4, while upon two 1,2-alkyl shifts of IM-3, followed by deprotonation of cation IM-4, would give spiroviolene (1). On the other
  • IM-7. A key 1,3-hydride shift of IM-7 from the β-face, followed by deprotonation of the formed C2-cation IM-8, would deliver the originally proposed structure 1' [6]. However, no related natural products that would be derived from the intermediates of this pathway have been found so far. A third
  • ][20], and fusaterpenol (8, GJ1012E) [17]. A similar 1,2-alkyl shift of IM-10, followed by deprotonation of the formed spirocyclic cation IM-12, afforded 3. Although previous isotope labeling experiments did not support this pathway for spiroviolene cyclization, it should be noted that a subtle
PDF
Album
Supp Info
Letter
Published 18 Apr 2024

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

  • Kara A. Strickland,
  • Brenda Martinez Rodriguez,
  • Ashley A. Holland,
  • Shelby Wagner,
  • Michelle Luna-Alva,
  • David E. Graham and
  • Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

Graphical Abstract
  • metabolic enzymes. In addition, it has been shown to irreversibly inhibit isocitrate lyase 1 (ICL1) from Mycobacterium tuberculosis [40], and key metabolic protein for these pathogens [41]. Isocitrate lyases convert isocitrate to glyoxylate and succinate. Deprotonation of 3NP (pKa = 9.0) results in the
  • transition analog of carboxylate groups, resulting in nitro compounds also acting as tight-binding reversible inhibitors [42]. Deprotonation of NNG also results in formation of the corresponding nitronate, albeit with a pKa of 6.6 [24], far lower than that for 3-NP (Scheme 2). Therefore, a much larger
PDF
Album
Supp Info
Full Research Paper
Published 17 Apr 2024

Recent developments in the engineered biosynthesis of fungal meroterpenoids

  • Zhiyang Quan and
  • Takayoshi Awakawa

Beilstein J. Org. Chem. 2024, 20, 578–588, doi:10.3762/bjoc.20.50

Graphical Abstract
  • led to the production of preterretonin A (7) (Figure 2) [9]. These data indicated that Trt1 protonates the epoxide of (10'R)-epoxyfarnesyl-DMOA-3,5-methyl ester (6), leading to the cyclization of the terpenoid moiety in the chair–chair conformation, and catalyzes the deprotonation of H-9' of the
  • meroterpenoids: insuetusin A1 (12) and insuetusin B1 (10), respectively (Figure 2) [9]. Like other Trt1-type enzymes, InsB2 catalyzes the protonation of the epoxide, the formation of two six-membered rings in a chair–chair conformation, but the reaction finishes with the deprotonation of the hydroxy group at C-3
  • to produce compound 10. In contrast, InsA7 commonly initiates and terminates the reaction with the protonation of the epoxide and the deprotonation of OH-3, respectively, but it produces product 12 via a boat–chair conformation. Since all of the other Trt1-like cyclases catalyze the reaction with
PDF
Album
Review
Published 13 Mar 2024

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

  • Alexander Yanovich,
  • Anastasia Vepreva,
  • Ksenia Malkova,
  • Grigory Kantin and
  • Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48

Graphical Abstract
  • -membered cycle in the latter case. The main direction of the reaction in these examples becomes isomerization (migration of a proton when it is captured by an intermediate anion) or other side processes. In the conjugated anion formed as a result of deprotonation (Scheme 8), one would also expect
PDF
Album
Supp Info
Full Research Paper
Published 11 Mar 2024

Switchable molecular tweezers: design and applications

  • Pablo Msellem,
  • Maksym Dekthiarenko,
  • Nihal Hadj Seyd and
  • Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

Graphical Abstract
  • and drug delivery systems [12]. pH-Responsive molecular tweezers A particular case of coordination-responsive systems is when a proton is used as a stimulus leading to pH-responsive systems with the protonation/deprotonation of the switchable moiety. The conformational switch in these systems is
PDF
Album
Review
Published 01 Mar 2024

Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas

  • Alexander S. Hampton,
  • David R. W. Hodgson,
  • Graham McDougald,
  • Linhua Wang and
  • Graham Sandford

Beilstein J. Org. Chem. 2024, 20, 460–469, doi:10.3762/bjoc.20.41

Graphical Abstract
  • fluorination of 1a–i affords monofluoro products 2a–i in their keto tautomeric forms. For difluorodiketones 3a–i to be formed, enolization of 2a–i-keto must occur through deprotonation at the 2-position, and this process is a key limiting factor [17]. The challenge posed by enolization of 2a–i-keto may be
  • pKa(MeCN) of 1a-keto is ≈26.3, and we expect a pKa(MeCN) of 2a-keto to be similar in value [51][52], we suggest fluoride ion may be sufficiently basic to cause significant acceleration of the deprotonation of 2a–i-keto and allow formation of 2a–i-enolates, which then react rapidly with fluorine gas
  • as an effective base for the formation of enolates of 1a and 2a, and this is reflected in the modest levels of formation of 3a (Scheme 4). Chloride ion, on the other hand, is less basic (pKa(MeCN) of HCl is 10.30 [60]), however, its greater solubility seemingly allows some level of deprotonation of
PDF
Album
Supp Info
Full Research Paper
Published 28 Feb 2024

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

  • Nahed Ketata,
  • Linhao Liu,
  • Ridha Ben Salem and
  • Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

Graphical Abstract
  • (Table 1, entries 14–16). The decisive influence of the base for this reaction is probably due to a concerted metalation–deprotonation mechanism [27][28][29][30]. Then, the scope of the Pd-catalyzed direct arylation for access to fluoranthenes was investigated (Scheme 2). The first step of the catalytic
  • cycle involves the oxidative addition of 1,8-dibromonaphthalene. Then, a concerted metalation–deprotonation of the arene, which usually occurs at the ortho-position of an activating group such as a fluorine or a chlorine atom, followed by reductive elimination, gives the corresponding intermediate 1
PDF
Album
Supp Info
Full Research Paper
Published 23 Feb 2024

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

  • Carlos R. Azpilcueta-Nicolas and
  • Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

Graphical Abstract
  • deprotonation of 21 to provide radical intermediate 22 [45]. Finally, the iridium excited state (*IrIII) formed under blue light irradiation oxidizes 22 to form product 23 and the corresponding reduced IrII complex, beginning a new photocatalytic cycle. Photocatalytic oxidative quenching mechanism The
  • . Decarboxylative fragmentation of 86 forms radical 9, which upon radical addition to 84 and deprotonation yields radical 87. Finally, oxidation of 87 mediated by 85 delivers the Minisci addition product 84 while regenerating PPh3 and NaI (Scheme 16B). The Ohmiya group has developed a series of light-mediated
PDF
Album
Perspective
Published 21 Feb 2024

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

  • Chuan Yang,
  • Wei Shi,
  • Jian Tian,
  • Lin Guo,
  • Yating Zhao and
  • Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

Graphical Abstract
  • that omitting the photocatalyst led to an even higher yield (Table 1, entry 2), but light irradiation was essential to the reaction (Table 1, entries 3 and 4). Initially, some bases were added into the reaction system considering a deprotonation process, but subsequent investigations indicated that
  • formed radical 7 can be oxidized by 2a or 4 giving a cation 8, which undergoes a deprotonation process and formation of the desired product. Conclusion In conclusion, we have developed a visible-light-promoted protocol for the synthesis of dihydropyrido[1,2-a]indolones bearing a trifluoromethyl group at
PDF
Album
Supp Info
Full Research Paper
Published 19 Jan 2024

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

  • Christina Schøttler,
  • Kasper Lund-Rasmussen,
  • Line Broløs,
  • Philip Vinterberg,
  • Ema Bazikova,
  • Viktor B. R. Pedersen and
  • Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

Graphical Abstract
  • could potentially after deprotonation be reacted with electrophiles as previously established [29] for the parent structure [30] without tert-butyl substituents. UV–vis absorption spectroscopy UV–vis absorption spectra of the known compound 4 [14] and new compounds 9–12 and 15 are depicted in Figure 3
PDF
Album
Supp Info
Full Research Paper
Published 15 Jan 2024

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

  • Matthias R. Steiner,
  • Max Schmallegger,
  • Larissa Donner,
  • Johann A. Hlina,
  • Christoph Marschner,
  • Judith Baumgartner and
  • Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

Graphical Abstract
  • , deprotonation of the phenol moiety by the methoxide gives the final product E (2a when acrylonitrile is used as the Michael acceptor). In this case, the proton at the α-position to the electron-withdrawing group is stemming from the protic solvent. Performing the reaction with methanol-d4 leads to incorporation
PDF
Album
Supp Info
Full Research Paper
Published 10 Jan 2024

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

  • Lorenzo Catti,
  • Shinji Aoyama and
  • Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

Graphical Abstract
  • through the template effect of the hydrophobic nanocarbon guests (Table 2). Moreover, aromatic micelle (PA-Im)n and its host–guest composite (PA-Im)n·(C60)m were anticipated to provide pH-dependent ZPs via imidazole-based protonation/deprotonation. Micelle (PA-Im)n showed a significantly higher ZP (41.7
PDF
Album
Supp Info
Full Research Paper
Published 08 Jan 2024

Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

  • Pavel S. Silaichev,
  • Tetyana V. Beryozkina,
  • Vsevolod V. Melekhin,
  • Valeriy O. Filimonov,
  • Andrey N. Maslivets,
  • Vladimir G. Ilkin,
  • Wim Dehaen and
  • Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

Graphical Abstract
  • deprotonation of acrylonitriles 1 to form anion 1′. The subsequent formal cycloaddition of anion 1′ with azides 2 then affords triazolines 5, which aromatize through a 1,3-H-shift to afford the triazoles 6. Two pathways towards the isomeric triazoles 3 can be proposed: the first involving the electrocyclic ring
PDF
Album
Supp Info
Full Research Paper
Published 05 Jan 2024

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF3: the case of alkyne hydration. Chemistry vs electrochemistry

  • Marta David,
  • Elisa Galli,
  • Richard C. D. Brown,
  • Marta Feroci,
  • Fabrizio Vetica and
  • Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

Graphical Abstract
  • presence of the NHC derived from the IL deprotonation. Conclusion In conclusion, in this work we demonstrated the possibility to carry out the hydration of alkynes in imidazolium ILs, as alternative solvents until now still little explored for this reaction, employing the Lewis acid BF3 as catalyst. The
PDF
Album
Supp Info
Full Research Paper
Published 28 Dec 2023

Aldiminium and 1,2,3-triazolium dithiocarboxylate zwitterions derived from cyclic (alkyl)(amino) and mesoionic carbenes

  • Nedra Touj,
  • François Mazars,
  • Guillermo Zaragoza and
  • Lionel Delaude

Beilstein J. Org. Chem. 2023, 19, 1947–1956, doi:10.3762/bjoc.19.145

Graphical Abstract
  • NHC·CS2 zwitterions relies on the deprotonation of an azolium salt with a strong base, typically potassium tert-butoxide or potassium bis(trimethylsilyl)amide (also known as potassium hexamethyldisilazide, KHMDS) followed by the addition of carbon disulfide either in one pot or after the isolation of the
  • excess to compensate for the possible formation of sodium O-tert-butyl xanthate [72][73][74]. We reasoned that these conditions should favor a quantitative deprotonation of the starting triazolium salts and the concomitant trapping of the free carbenes by CS2 prior to their potential decomposition
  • vanishing signal was always the most deshielded singlet in the spectra of the reagents, it was a very convenient probe to monitor the success of the deprotonation step. Concomitantly, the incorporation of CS2 in products 4a–c and 6a–f led to the emergence of an equally characteristic resonance in the 13C
PDF
Album
Supp Info
Full Research Paper
Published 20 Dec 2023

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

  • Kan Tang,
  • Megan R. Brown,
  • Chad Risko,
  • Melissa K. Gish,
  • Garry Rumbles,
  • Phuc H. Pham,
  • Oana R. Luca,
  • Stephen Barlow and
  • Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

Graphical Abstract
  • concert with sacrificial weak reductants (Figure 1b) [8][9][10][11]. Another approach is to add ambient-stable precursors to reaction mixtures: for example, reducing Wanzlick dimers and related species (Figure 1a, ii) have been formed from precursors through in situ decarboxylation [12] or deprotonation
PDF
Album
Supp Info
Full Research Paper
Published 14 Dec 2023

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

  • Tinglan Liu,
  • Yu Zhou,
  • Junhong Tang and
  • Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

Graphical Abstract
  • the Ph3P−I• species III, forming the cationic intermediate F. Finally, deprotonation of intermediate F yielded the product 34g. Functional polycyclic compounds, such as indene-containing polycyclic motifs and N-containing polyheterocycles are commonly found in many natural products and pharmaceuticals
PDF
Album
Review
Published 22 Nov 2023

Selectivity control towards CO versus H2 for photo-driven CO2 reduction with a novel Co(II) catalyst

  • Lisa-Lou Gracia,
  • Philip Henkel,
  • Olaf Fuhr and
  • Claudia Bizzarri

Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129

Graphical Abstract
  • (helping in the deprotonation of the radical cation BIH•+ formed after the reductive quenching of the PS), but also can actively assist the catalysis, by capturing CO2 [50][51][52]. On the other hand, having three hydroxy groups, TEOA is also considered a proton donor and the formation of metal hydrides is
PDF
Album
Supp Info
Full Research Paper
Published 17 Nov 2023

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

  • Dayanne Martins,
  • Roberta Lamosa,
  • Talis Uelisson da Silva,
  • Carolina B. P. Ligiero,
  • Sérgio de Paula Machado,
  • Daphne S. Cukierman and
  • Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

Graphical Abstract
  • of the resulting hydrazone: a considerable amount of hdz-NO2 deprotonates immediately upon dilution in the aqueous-rich medium at pH 7.4, affording a deep yellow solution due to phenolate-based absorptions centered at around 440 nm. For this reason, we decided to investigate this deprotonation by
  • a hydrazone-involving process, meaning, once again, that it probably involves a transition delocalized throughout the molecule. At pH 8.2, the scenario is very different: due to phenol deprotonation, the spectrum now displays three well-defined bands centered at 281, 331 and 440 nm that can be
  • (moving from 307 to 332) and 108 (from 331 to 439) nm in the phenolate form of hdz-NO2, being the higher energy component quite unsusceptible to deprotonation and therefore confirming our assignment as a TMP-involving transition. From the pKa determined for the phenol group of the nitro-substituted
PDF
Album
Supp Info
Full Research Paper
Published 10 Nov 2023
Other Beilstein-Institut Open Science Activities