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Search for "[3 2]" in Full Text gives 512 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Oxetanes: formation, reactivity and total syntheses of natural products

  • Peter Gabko,
  • Martin Kalník and
  • Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

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  • -, particularly 2-methylideneoxetanes have become valuable intermediates in oxetane chemistry as they readily undergo a variety of chemical transformations, including ring-opening reactions with nucleophiles, epoxidations, cyclopropanations and [3 + 2] cycloadditions with nitrile oxides [51][52]. In addition
  • regioselectivity of the Friedel–Crafts alkylation to the para-position, forming exclusively (or significant amounts of) 3,3-diaryloxetanes. In 2017, Vanderwal and co-workers published a novel, facile synthesis of furans 181 and pyrroles 185 from 3-(2-oxoalkylidene)oxetanes 179, precursors which are readily
  • -catalysed heterocycle synthesis, specifically a [3 + 2] annulation of 3-(4-hydroxyphenyl)oxetan-3-ol (211) with β-naphthylamines or phenols 210 to give benzoindolines and 2,3-dihydrobenzofurans 212, respectively (Scheme 50) [104]. The reaction gave moderate to high yields and control experiments indicated
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Published 27 Jun 2025

Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes

  • Bartłomiej Pigulski

Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99

Graphical Abstract
  • CHCl3, AcOH and o-DCB [44]. The resulting mixture of brominated PAHs 30 and 31 was then subjected to single or double [3 + 2] annulation with various alkynes, leading to the extended structures 32 and 33. Notably, compound 33d can undergo Pd-catalysed dimerization, resulting in the formation of a chiral
  • characteristics to most azulene-embedded PAHs obtained via Scholl oxidation – specifically, the azulene subunit does not exhibit aromaticity, and the surrounding benzenoid rings predominantly determine the electronic structure of 49. [3 + 2] Annulation of alkynes accompanied by a phenyl ring expansion: The
  • and co-workers [55]. A palladium-catalysed variation of [3 + 2] annulation, accompanied by ring expansion [56], was used for the intermolecular reaction between acenes bearing alkyne substituents 55a–d and di-n-butylacetylene (56). The reaction gave a series of azulene-embedded isomers of linear
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Published 26 Jun 2025

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

  • Jiangfei Chen,
  • Yi-Lin Qu,
  • Ming Yuan,
  • Xiang-Mei Wu,
  • Heng-Pei Jiang,
  • Ying Fu and
  • Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

Graphical Abstract
  • -methylpiperidine, proved compatible with the reaction conditions, yielding the corresponding 3-(2-oxoethyl)indolin-2-ones 5a–g in 40–78% yields. Following a detailed investigation, a plausible mechanism was proposed, as illustrated in Scheme 3. Initially, TBHP undergoes cleavage by Fe2+ to generate a tert-butoxy
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Published 24 Jun 2025

A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones

  • Ashutosh Nath,
  • John Mark Awad and
  • Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92

Graphical Abstract
  • reaction followed by the cleavage of the alkyl group to give intermediate II as a free amine. Annulation of II with CDI gave product B which is an HIV reverse transcriptase inhibitor (Scheme 1B) [17]. We have reported a three-component [3 + 2] cycloaddition followed by IMDA reaction for making heterocyclic
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Published 13 Jun 2025

Salen–scandium(III) complex-catalyzed asymmetric (3 + 2) annulation of aziridines and aldehydes

  • Linqiang Wang and
  • Jiaxi Xu

Beilstein J. Org. Chem. 2025, 21, 1087–1094, doi:10.3762/bjoc.21.86

Graphical Abstract
  • moieties of biologically active compounds. A salen–scandium triflate complex-catalyzed asymmetric (3 + 2) annulation of dialkyl 1-sulfonylaziridine-2,2-dicarboxylates and aldehydes generated optically active functionalized oxazolidine derivatives in moderate to good yields and good to excellent
  • method uses readily available salen as chiral ligand, which coordinates with scandium triflate to generate a salen–Sc complex acting as efficient catalyst. The catalytic asymmetric (3 + 2) annulation of dialkyl 3-aryl-1-sulfonylaziridine-2,2-dicarboxylates and aldehydes generated optically active
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Published 28 May 2025

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

  • Betty A. Kustiana,
  • Galuh Widiyarti and
  • Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

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Published 28 May 2025

Recent total synthesis of natural products leveraging a strategy of enamide cyclization

  • Chun-Yu Mi,
  • Jia-Yuan Zhai and
  • Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

Graphical Abstract
  • cyclization modes that provide entries to various N-heterocycles, some of which serve as key structural motifs in natural alkaloids. This review highlights recent advancements in enamide-based cyclization reactions, including enamide–alkyne cycloisomerization, [3 + 2] annulation, and polycyclization, with a
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Published 22 May 2025

Studies on the syntheses of β-carboline alkaloids brevicarine and brevicolline

  • Benedek Batizi,
  • Patrik Pollák,
  • András Dancsó,
  • Péter Keglevich,
  • Gyula Simig,
  • Balázs Volk and
  • Mátyás Milen

Beilstein J. Org. Chem. 2025, 21, 955–963, doi:10.3762/bjoc.21.79

Graphical Abstract
  • hydrogenation of the C=C double bond in the side chain gave brevicarine (2). The first total synthesis of brevicarine is shown in Scheme 3 [2][20][21]. Condensation of indole (11) with 1-methylpiperidone (12) gave compound 13 [22]. N-Alkylation of 13 with benzyl bromide, followed by treatment of the quaternary
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Published 20 May 2025

Recent advances in controllable/divergent synthesis

  • Jilei Cao,
  • Leiyang Bai and
  • Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

Graphical Abstract
  • ) and (3 + 2) cyclization strategies. Two distinct pathways were established: (1) The titanium-catalyzed ring opening of bicyclobutane (BCB) 32 generates a γ-carbonyl radical intermediate Int-42, which undergoes trapping by vinylazide 33. Subsequent dinitrogen extrusion produces an iminyl radical
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Published 07 May 2025

Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones

  • Carola Tortora,
  • Christian A. Fischer,
  • Sascha Kohlbauer,
  • Alexandru Zamfir,
  • Gerd M. Ballmann,
  • Jürgen Pahl,
  • Sjoerd Harder and
  • Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59

Graphical Abstract
  • through calcium catalysis [8][9][10]. Asymmetric synthesis has also been achieved via, e.g., 1,4-addition and [3 + 2] cycloaddition of 3-tetrasubstituted oxindoles with a calcium Pybox catalyst [11][12], or through enantioselective Friedel–Crafts and carbonyl–ene reactions [13]. Since the pioneering
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Published 14 Apr 2025

Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

  • Yurii A. Sayapin,
  • Eugeny A. Gusakov,
  • Inna O. Tupaeva,
  • Alexander D. Dubonosov,
  • Igor V. Dorogan,
  • Valery V. Tkachev,
  • Anna S. Goncharova,
  • Gennady V. Shilov,
  • Natalia S. Kuznetsova,
  • Svetlana Y. Filippova,
  • Tatyana A. Krasnikova,
  • Yanis A. Boumber,
  • Alexey Y. Maksimov,
  • Sergey M. Aldoshin and
  • Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

Graphical Abstract
  • -methylquinazolinones [3], 2-methylbenzoxazinones [4], and 2-methylbenzoxa(thia)zoles [5] the interaction with sterically hindered 1,2-benzoquinones and 3,4,5,6-tetrachloro-1,2-benzoquinone proceeds with the expansion of the o-quinone ring and results in 2-hetaryl-substituted 1,3-tropolones 1 (Scheme 1), which exhibit
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Published 17 Feb 2025

Red light excitation: illuminating photocatalysis in a new spectrum

  • Lucas Fortier,
  • Corentin Lefebvre and
  • Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

Graphical Abstract
  • band. These combined effects can be illustrated in the case of the [M(phen)3]2+ set with iron, ruthenium, and osmium (Figure 1). For a same phenanthroline ligand, these three complexes show an MLCT absorption band at different wavelengths, i.e., 522 nm for [Fe(phen)3]2+ [14], 449 nm for [Ru(phen)3]2
  • + and 660 nm for [Os(phen)3]2+ [15]. In a same way, spin–orbit coupling, stemming from the relativistic effects, can be exploited in photoredox-catalyzed reaction [16]. Spin–orbit coupling promotes intersystem crossing (ISC) between the singlet and triplet excited states, and even allows for direct
  • penetrate all the used materials and can initiate the reaction through the core of the reaction medium as the polymer forms, unlike blue light. This penetrating power of red light was also characterized by comparing the ruthenium complex [Ru(bpy)3]2+ absorbing at 450 nm with the osmium complex [Os(tpy)2]2
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Published 07 Feb 2025

Cu(OTf)2-catalyzed multicomponent reactions

  • Sara Colombo,
  • Camilla Loro,
  • Egle M. Beccalli,
  • Gianluigi Broggini and
  • Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

Graphical Abstract
  • process by using α-diazoketones, nitroalkenes and primary amines, in the presence of air as oxidant. The mechanism involved the formation of α-ketocarbene XXVI from α-diazoketone, able to react with the amine affording imine XXV after copper-catalyzed oxidative dehydrogenation. The subsequent [3 + 2
  • [3 + 2] cycloaddition reaction between azodicarboxylates and nitrile ylides XXXVI as 1,3-dipoles. The latter are generated from diazoalkanes under the coordination of the copper catalyst to form a carbenoid species that undergoes nucleophilic attack of the nitriles. This transformation has
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Published 14 Jan 2025

Recent advances in organocatalytic atroposelective reactions

  • Henrich Szabados and
  • Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

Graphical Abstract
  • followed by lactonization to Int-21 and Int-22 (Scheme 11c). Chi and co-workers showed that desymmetrization of urazoles can lead to axially chiral derivatives [31]. The NHC-catalyzed (3 + 2) annulation between α,β-unsaturated aldehydes 36 and urazoles 37 generates atropoisomers 38 with a C–N stereogenic
  • of products in low to satisfactory yields, but having high enantiomeric purities. An organocatalytic asymmetric (3 + 2) cyclization of 3-arylindoles 154 with either achiral 155 or racemic 157 propargylic alcohols was reported by Wu et al. (Scheme 46) [74]. Utilizing CPA C37 with 3-arylindoles 154 and
  • 161 were constructed by a (3 + 2) cycloaddition of isoindolinone-substitued propargylic alcohols 160 with bisindoles 159 mediated by CPA C39 (Scheme 47) [75]. These axially chiral spirocyclic products were prepared with good to very good yields and excellent enantiomeric purities. The slow
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Published 09 Jan 2025

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

  • Sergio Torres-Oya and
  • Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

Graphical Abstract
  • -workers reported a cinchona alkaloid-derived thiourea-catalyzed regio- and stereoselective cycloaddition of 3-isothiocyanatooxindoles and imines containing two or three electron-deficient unsaturated bonds [25]. Firstly, the (3 + 2) cycloaddition of 3-isothiocyanatooxindoles 4 and aldimines 5 was explored
  • (Scheme 3). The reaction of 3-isothiocyanatooxindoles 4 and ketimines 7 led to the (3 + 2) cycloaddition through the C=C bond of the α,β-unsaturated imine instead of the C=N bond, affording various spirocyclic derivatives 8 with excellent yields (92–98%), diastereoselectivities (15:1–20:1 dr), and
  • -workers reported a dihydroquinine-derived squaramide-catalyzed (3 + 2) cycloaddition reaction of isocyanoacetates 26 and saccharin-derived 1-azadienes 14 [32]. In this work, the azadiene works as a C2 synthon, while the isocyanoacetate, bearing a protected carboxylic acid and a carbene-like divalent
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Published 10 Dec 2024

Germanyl triazoles as a platform for CuAAC diversification and chemoselective orthogonal cross-coupling

  • John M. Halford-McGuff,
  • Thomas M. Richardson,
  • Aidan P. McKay,
  • Frederik Peschke,
  • Glenn A. Burley and
  • Allan J. B. Watson

Beilstein J. Org. Chem. 2024, 20, 3198–3204, doi:10.3762/bjoc.20.265

Graphical Abstract
  • potential as functional handles for downstream elaboration of CuAAC products. To date, the main use of germanyl alkynes in (3 + 2) cycloadditions has been limited to a small number of Huisgen (non-Cu-catalysed) reactions [68][69]. Zaitsev and co-workers reported the synthesis and CuAAC reactions of a
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Published 05 Dec 2024

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

  • Lucía Campos-Prieto,
  • Aitor García-Rey,
  • Eddy Sotelo and
  • Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

Graphical Abstract
  • benzodioxepinones 12 in all cases (Scheme 11). The synthesized compounds demonstrated excellent drug-like features. Parkinson disease (PD) Knoevenagel–Michael addition/cyclization (MCR 3 + 2): Sirtuins, a group of enzymes that rely on NAD+ to function as protein deacetylases, have garnered attention across multiple
  • of the nitrogen in lactams 11 with an oxygen in 12 to influence hydrogen-bond donating properties and synthesis of the benzodioxepinone derivatives via Passerini reaction. MCR 3 + 2 reaction to develop spirooxindole, spiroacenaphthylene, and bisbenzo[b]pyran compounds. Synthesis of ML192 analogs
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Published 03 Dec 2024

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

  • Ritu Mamgain,
  • Kokila Sakthivel and
  • Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

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Published 13 Nov 2024

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

  • Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

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  • showed moderate or low antiproliferative activity against various cancer cell lines. 3-(2-Acetamido-4-oxo-4,5-dihydrothiazol-5-ylidene)indolin-2-one-N-glycosides The reaction of isatin-N-glycosides β-16a and β-16e with pseudo-thiohydantoin (47b) afforded β- and Z-configured 3-(2-acetamido-4-oxo-4,5
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Published 08 Nov 2024

Copper-catalyzed yne-allylic substitutions: concept and recent developments

  • Shuang Yang and
  • Xinqiang Fang

Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232

Graphical Abstract
  • sequence, [4 + 1] and [3 + 2] annulations involving yne-allylic substitutions have been released. These studies have shown the huge potential of this protocol in affording diversified molecular scaffolds, and more studies will be expected to demonstrate the value of this reaction. Copper-catalyzed allylic
  • -ethynylthiophene esters. Proposed mechanism. [4 + 1] annulation of yne-allylic esters and cyclic 1,3-dicarbonyls. Asymmetric [4 + 1] annulation of yne-allylic esters. Proposed mechanism. Asymmetric [3 + 2] annulation of yne-allylic esters. Postulated annulation step. [4 + 1] Annulations of vinyl ethynylethylene
  • consistent with the standard reaction conditions. However, nonlinear effect experiments confirmed that the active catalyst is a mono-copper species, so it is speculated that the dinuclear copper is the precursor of active single copper species (Scheme 33). Fang et al. [67] achieved the first asymmetric [3
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Published 31 Oct 2024

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

  • Ruben Manuel Figueira de Abreu,
  • Peter Ehlers and
  • Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

Graphical Abstract
  • )-dione (4g). Compound 4g was obtained as a brown solid in 58% yield (58.3 mg, 184 µmol, Rf 0.19 (heptane/ethyl acetate 3:2)); mp 152–154 °C; IR (ATR) ν̃: 1695 (s), 1642 (vs), 1582 (s), 1493 (s), 1440 (s), 1421 (s), 1176 (m), 1079 (m), 756 (s) cm−1; 1H NMR (500 MHz, chloroform-d) δ 7.51–7.48 (m, 2H), 7.45
  • acetate 3:2)); mp 187–189 °C; IR (ATR) ν̃: 1708 (s), 1654 (vs), 1574 (s), 1514 (s), 1506 (s), 1446 (s), 1423 (s), 1232 (s), 1158 (s) cm−1; 1H NMR (500 MHz, chloroform-d) δ 7.48–7.44 (m, 2H), 7.26–7.22 (m, 2H), 7.15–7.10 (m, 2H), 7.06–7.02 (m, 2H), 3.70 (s, 3H), 3.44 (s, 3H); 19F NMR (471 MHz, chloroform-d
  • 54% yield (189 mg, 488 µmol, Rf 0.21 (heptane/ethyl acetate 3:2)); mp 162–164 °C; IR (ATR) ν̃: 1695 (s), 1640 (vs), 1582 (s), 1510 (s), 1446 (s), 1428 (s), 1219 (m), 813 (s) cm−1; 1H NMR (300 MHz, chloroform-d) δ 7.94–7.87 (m, 1H), 7.65–7.59 (m, 1H), 7.58 (s, 1H), 7.39–7.31 (m, 2H), 7.06–7.01 (m, 2H
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Published 28 Oct 2024

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

  • Nian Li,
  • Ruzal Sitdikov,
  • Ajit Prabhakar Kale,
  • Joost Steverlynck,
  • Bo Li and
  • Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

Graphical Abstract
  • product (Scheme 30a). In the same year, the Xia group reported an iodide ion and PPh3-induced electrochemical oxidative [3 + 2] cycloaddition of carboxylic acids and isocyanoacetates [41]. The successful LSF of drug molecules such as sulbactam acid and oxaprozin demonstrated the potential applicability of
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Published 09 Oct 2024

Visible-light-mediated flow protocol for Achmatowicz rearrangement

  • Joachyutharayalu Oja,
  • Sanjeev Kumar and
  • Srihari Pabbaraja

Beilstein J. Org. Chem. 2024, 20, 2493–2499, doi:10.3762/bjoc.20.213

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  • , [Ru(bpy)3]2+ undergoes transition to [Ru(bpy)3]2+* which is quenched by persulfate resulting in [Ru(bpy)3]3+ along with the simultaneous generation of sulfate and a sulfate radical. SET from furfuryl alcohol closes the catalytic cycle of the PC and an intermediate A is generated with L (L = SO4−· or
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Published 08 Oct 2024

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

  • Yutaro Miyashita,
  • Sae Someya,
  • Tomoko Kawasaki-Takasuka,
  • Tomohiro Agou and
  • Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

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  • , University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan 10.3762/bjoc.20.206 Abstract We describe herein a facile method to access 2,3-epoxyesters with fluorine-containing substituents at their 3-position starting from the corresponding enoates by utilization of the low-costed and easy
  • by use of Hex/CHCl3 3:2 as a solvent to afford 0.14 g (0.39 mmol) of the title compound 3aa in 78% yield as a sole stereoisomer. Rf 0.30 (Hex/AcOEt 2:1); mp 95–97 °C; 1H NMR (300.40 MHz, CDCl3) δ 3.70 (brs, 1H), 3.76 (s, 3H), 4.31–4.33 (m, 2H), 4.39 (brs, 1H), 5.14 (dd, J = 12.0, 21.3 Hz, 1H), 6.74
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Published 25 Sep 2024

Deuterated reagents in multicomponent reactions to afford deuterium-labeled products

  • Kevin Schofield,
  • Shayna Maddern,
  • Yueteng Zhang,
  • Grace E. Mastin,
  • Rachel Knight,
  • Wei Wang,
  • James Galligan and
  • Christopher Hulme

Beilstein J. Org. Chem. 2024, 20, 2270–2279, doi:10.3762/bjoc.20.195

Graphical Abstract
  • aldehyde [10]. Latterly, Yamamoto utilized a 90% deuterated [D2]-isocyanide in a copper catalyzed [3 + 2] cycloaddition to afford a 60% deuterated [D2]-pyrrole [11]. The utility of the Leuckart–Wallach reaction towards the generation of isocyanides was first explored by Dömling [12], yet the use of such
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Published 06 Sep 2024
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