Synthesis of 1,2,3-triazoles containing an allomaltol moiety from substituted pyrano[2,3-d]isoxazolones via base-promoted Boulton–Katritzky rearrangement

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 1334–1340, doi:10.3762/bjoc.20.117

• to Boulton–Katritzky rearrangement are furazanes and furoxanes. In the case of furazanes the recyclization leads to 1,2,3-triazoles with an oxime moiety in the side chain [13][14]. At the same time 1,2,3-triazole N-oxides are formed from similar furoxanes [15]. Furthermore, special attention is paid

• be noted that based on NMR spectroscopy data the synthesized product 3b exists as a mixture of E/Z isomers. Having in hands hydrazone 3 we tried to perform the Boulton–Katritzky rearrangement into corresponding 1,2,3-triazole 4. In order to achieve the best yields of product 4b we varied the used

• , intramolecular recyclization accompanied by opening of the isoxazole ring and formation of the N–N bond leads to intermediate B. Finally, target 1,2,3-triazole 4 is produced via acidification of anion B. Next, we tried to expand the presented rearrangement to hydrazones derived from aliphatic hydrazines (MeNHNH2

The Ugi4CR as effective tool to access promising anticancer isatin-based α-acetamide carboxamide oxindole hybrids

• Carolina S. Marques,
• Aday González-Bakker and
• José M. Padrón

Beilstein J. Org. Chem. 2024, 20, 1213–1220, doi:10.3762/bjoc.20.104

• and Figure 2). Like the oxindole scaffold, 1,2,3-triazole is also considered a privileged unit in drug discovery since compounds having this structure have a broad spectrum of biological activities, and have been widely used to create anticancer drug candidates [24][25]. The copper-catalyzed azide

• –alkyne cycloaddition (CuAAC) reaction, or commonly entitled “click” reaction, is a widely and straightforward tool to access the 1,2,3-triazole ring [26][27]. Due to the presence of an alkyne group on the Ugi-adduct 5bb (Scheme 2) we decided to use the CuAAC reaction to introduce a 1,2,3-triazole unit

• into the scaffold. Benzyl azide (6), obtained using a previously reported procedure [27], was used in the CuAAC reaction. The α-acetamide carboxamide 1,2,3-triazole oxindole hybrid 7 was easily obtained in 61% yield using Cu(OAc)2 as catalyst, ascorbic acid, DMF as solvent, and microwave reaction

Mild and efficient synthesis and base-promoted rearrangement of novel isoxazolo[4,5-b]pyridines

• Vladislav V. Nikol’skiy,
• Mikhail E. Minyaev,
• Maxim A. Bastrakov and
• Alexey M. Starosotnikov

Beilstein J. Org. Chem. 2024, 20, 1069–1075, doi:10.3762/bjoc.20.94

• isoxazolo[4,5-b]pyridines 12 were obtained in pure form, however, cyclization of hydrazone 11a provided an inseparable mixture of two compounds which could be attributed to the target isoxazolo[4,5-b]pyridine 12a and triazole 13a formed as a result of Boulton–Katritzky rearrangement (Scheme 5). When this

• ). All other compounds 12 bearing no electron-withdrawing groups in the aryl moiety readily afforded the corresponding triazole derivatives in high yields under relatively mild conditions (K2CO3, DMF, 60 °C, Scheme 5). Substituents in the pyridine ring did not affect this transformation thus indicating

• that they do not participate in the stabilization of the pyridine-3-olate anion. It should be noted that the 4-(2-pyridyl)[1,2,3]triazole fragment is part of some pharmaceutically oriented molecules such as tradipitant, an experimental neurokinin-1 receptor antagonist [31], MU1787, a highly selective

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

• between various azoles and internal alkynes is mediated by benziodoxole triflate as the electrophile in a trans-fashion, affording azole-bearing vinylbenziodoxoles in moderate to good yields. The tolerable azole nuclei include pyrazole, indazole, 1,2,3-triazole, benzotriazole, and tetrazole. The iodanyl

• catalysis encompassed various azoles such as pyrazole, indazole, and (benzo)triazole, exhibiting high Z-selectivity. In addition, Cao et al. reported a gold-catalyzed addition of 5-substituted tetrazoles to terminal alkynes [11]. Analogous hydroazolation reactions of alkynes have also been achieved under

• reaction of azoles with alkynes and iodine(III) electrophile, benziodoxole triflate (BXT, 1; Scheme 1c). Displaying exclusive trans-selectivity, the reaction tolerates a broad range of azoles, including pyrazole, 1,2,3-triazole, tetrazole, indazole, and benzotriazole, with internal alkynes as coupling

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

• constant is higher for the second complexation than the first. The authors later reported a similar system with triazole linkages between the porphyrin and the indoles that act as binding sites for the metal (square planar complex) [76]. These tweezers present a fluorescence quenching upon copper(I

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• -5-mercapto-1,2,4-triazole (AMTA)-functionalized Fe3O4 nanoparticles coated on silica, based on Khalafi-Nezhad’s approach. Optimum catalytic activity was attained when adding 10 mg of the nanocomplex to the reaction mixture, in solvent-free conditions at 80 °C and after a time period of 1.5–8 hours

Catalytic multi-step domino and one-pot reactions

• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2024, 20, 254–256, doi:10.3762/bjoc.20.25

• trisubstituted 3-iodoindoles, which are valuable substrates for the synthesis of, e.g., blue emitters in good yield [16]. The power of double click reactions toward functionalized bis(1,2,3-triazole) derivatives has been demonstrated in the Full Research Paper by Reissig and Yu. The authors successfully combined

Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• dibenzodiazepinones in good yields (up to 45%; 2 steps) and much milder conditions using copper as the catalyst. The synthetic utility of this novel strategy was showcased by demonstrating a formal synthesis for the antipsychotic drug clozapine and to an anticancer triazole–DBDAP hybrid. Keywords: Buchwald–Hartwig

• good yield (this represented a formal synthesis to clozapine [26], if the procedure of Rao [27] is used, which entails heating 4e with 1-methylpiperidine and Ti(IV)Cl4, Scheme 4). Also compound 4a can be transformed to Hügel's 1,2,3-triazole-DBDAP using the methodology described in their report (Scheme

• than the one-pot method. The most important of which was the chloro-containing DBDAP 4e that can be used to synthesize the antipsychotic drug clozapine (see above), a triazole-hybrid with anticancer properties, and can easily be used as the key part in the synthesis of other drugs like dibenzepine and

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

• 1,2,3-triazole ring, either an additional pyrimidinedione, 4-nitroimidazole, isoxazole, 1,3,4-triazole, 2-oxochromone or thiazole ring, has been developed. The process was facilitated by a strong base and includes the cycloaddition reaction of 3,3-diaminoacrylonitriles (2-cyanoacetamidines) to

• -triazole-4-carbimidamides with alkyl, allyl, propargyl, benzyl, cycloalkyl, and indolyl substituents at the N1 position . Keywords: Cornforth rearrangement; cycloaddition reactions; 3,3-diaminoacrylonitriles; heterocyclic azides; 1,2,3-triazole; Introduction Heteroaryl amidines are widely used in the

• synthesis of various nitrogen-containing heterocyclic compounds and have a variety of biological activities [1][2][3][4]. After the discovery of click chemistry [5][6] involving the CuAAC method of 1,2,3-triazole synthesis [7][8], there has been great interest of studing the chemical and biological

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

• ][19]. These mesoionic carbenes (MICs), together with their pyrazolin-4-ylidene [20] and 1,2-isoxazol-4-ylidene cousins [21], are the strongest donors among the various types of carbene ligands known thus far [22]. A distinct class of mesoionic or abnormal carbenes based on the 1,2,3-triazole ring

• -disubstituted-1,2,3-triazole derivatives is readily achieved via the copper(I)-catalyzed [3 + 2] cycloaddition of an azide and a terminal alkyne (CuAAC) [63][64][65]. A further alkylation of the N3 position with an alkyl halide is an equally straightforward procedure that ultimately affords a large assortment

• of MIC precursors [24][25][26][27][28]. By analogy with the archetypical NHCs bearing mesityl (Mes) or 2,6-diisopropylphenyl (Dipp) substituents on their nitrogen atoms, we have prepared three triazole derivatives with mixed Mes/Ph, Mes/Bu, or Dipp/Ph substituents on N1 and C4, respectively (Scheme 3

N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction

• Grigory Kantin,
• Pavel Golubev,
• Alexander Sapegin,
• Alexander Bunev and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136

• pyrazole derivatives (including indazole), benzimidazole, 1,2,3-triazole, indole, carbazole, indoline, quinazoline, and isoquinoline. Nevertheless, many heterocyclic motifs still remain beyond the attention of researchers. For example, glutarimides that incorporate tetrazole and 1,2,4-triazole substituents

• varying characteristics were selected as substrates for the studied insertion reaction, encompassing both aromatic and non-aromatic compounds differing in the number and arrangement of nitrogen atoms (Scheme 3). Notably, several of these heterocycles, including tetrahydroquinoline, 1,2,4-triazole, and

• literature [30]. Despite the low reactivity (the reaction was carried out for 5 days with triple portion of the catalyst), the yield of the N–H insertion product involving 1,2,4-triazole was unexpectedly high (80%). Compound 6l was obtained as a single regioisomer. The reaction with tetrazoles is also

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• macrocycles are more shifted, with the triazole proton presenting an upfield shift from δ = 7.95 ppm to δ = 7.65 ppm and the hydroquinone protons are upfield shifted from δ = 6.77/6.67 ppm to δ = 6.60/6.58 ppm. In order to validate formation of R1 we also recorded a room-temperature H,H-ROESY NMR spectrum

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

• complex obtainable via a straightforward synthesis, with improved solubility, concerning our previous Co(II) complexes [21]. Thus, the new Co(II) complex bears two 1-benzyl-4-(quinolin-2-yl)-1H-1,2,3-triazole (BzQuTr) units, that were obtained through a copper-catalyzed alkyne–azide cycloaddition (CuAAC

• maintaining high selectivity for carbon products. Results and Discussion Synthesis and characterization of the new Co(II)-based catalyst The novel cobalt(II) complex 1 was synthesized in dry methanol (MeOH) by mixing in a 2:1 ratio, the chelating diimine ligand, 1-benzyl-4-(quinolin-2-yl)-1H-1,2,3-triazole

• coordinating nitrogen of the 1,2,3-triazole units. The nitrogen atoms of the two quinoline moieties are therefore trans to each other. This conformation might be induced by the cobalt precursor Co(NCS)2(py)4, which has already the NCS monodentate ligands cis to each other, as it was not the case for other Co

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• trifluoromethylated hydrazonoyl halides. [3 + 2]/[3 + 3] Cycloadditions of trifluoromethylated hydrazonoyl halides. Substrate scope for [3 + 2] cycloadditions with trifluoroacetonitrile imines reported by Jasiński’s team and other groups. Synthesis of trifluoromethylated 1,2,4-triazole and 1,2,4-triazine derivatives

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• of N2H4·H2O (2.9–3.0 equiv) with a catalytic amount of TsOH·H2O (0.05 equiv) in refluxing EtOH or 1,4-dioxane resulted in the formation of mixtures of macrocycle 5, pyrazolyl-1,2,4-triazole 10, and a very small amount of bis-pyrazole 6 according to NMR data (Table 1, entries 22 and 23). It is

• noteworthy that triazole 10 was the major product in dioxane (10/5/6 = 86.5:13:0.5, Table 1, entry 23). Again, macrocycle 5 was separated from this mixture by crystallization from DMF, and pyrazolyl-1,2,4-triazole 10 was isolated from the mother liquor. The structure of compound 10 was established based on

• calculated by the GIAO method at the PBE1PBE/6-311+G(2d,p) level of theory using the DFT B3LYP/6-311++G(d,p) optimized geometries (DMSO solution) and applying a multi-standard approach [44]. It is noteworthy that, in the most stable conformer of 10, the NH2 group of the triazole ring is located between the

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• ][12], inflammation [13], bacterial [14][15], and viral infections [16]. Hence, new ways to rapidly and efficiently access 1,2,3-triazole heterocyclic motifs are still in demand. However, methods for the direct synthesis of 1,4,5-trisubstituted-1,2,3-triazoles are limited [17]. This is highly desirable

• since the selective introduction of substituents at three different positions on the 1,2,3-triazole ring can augment the features of the molecule. Triazoles are also found in many biologically important molecules and functionalized materials [11][12][13][14][15][16]. 1,4,5-Trisubstituted-1,2,3-triazoles

• azides and gem-difluoroalkenes in the presence of morpholine generates 1,5-disubstituted-1,2,3-triazoles with a pendant C-4 morpholine moiety. The regioselectivity of the triazole formation is dictated by morpholine preferentially making the first nucleophilic attack over azide at the α-position of gem

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• copper(I) bromide in CH2Cl2 (Scheme 24) [31]. Nakamura et al. synthesized for the first time a copper complex with a 1,2,3-triazole carbene ligand in 2011. Complexes of copper with 1,4-diphenyl-, 1,4-dimesityl-, and 1-(2,6-diisopropylphenyl)-4-(3,5-xylyl)-1,2,3-triazol-5-ylidene were prepared through

• bulky azide 134 to afford 1-(2,6-dimesityl)phenyl-4-(2-pyridyl)-1,2,3-triazole (135), which is otherwise difficult to achieve (Scheme 51). Oro and co-workers employed complexes 78a and 78a-MCH-41 (Scheme 27) as homogeneous and heterogeneous catalysts, respectively, for the [3 + 2] cycloaddition of

One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

• Hans-Ulrich Reissig and
• Fei Yu

Beilstein J. Org. Chem. 2023, 19, 1399–1407, doi:10.3762/bjoc.19.101

• (bromomethyl)benzene furnished geometrically differing bis(1,2,3-triazole) derivatives. The use of tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine (TBTA) as ligand for the click step turned out to be very advantageous. The compounds with 1,2-oxazinyl end groups can potentially serve as precursors of divalent

• -catalyzed version can generally be executed at room temperature and it affords exclusively 1,4-disubstituted 1,2,3-triazole derivatives, thus allowing a controlled and highly efficient connection of a variety of molecular building blocks. This “Lego-approach” found countless applications and the bestowal of

• converted into several multivalent compounds B by amine or amide bond formations [44][45][46][47]. The transformation of the corresponding azidopyrans and azidooxepanes C or E into multivalent 1,2,3-triazole derivatives D and F by Meldal–Sharpless cycloadditions with suitable alkynes proceeded generally in

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• -tetraarylporphyrins 1 were synthesized from the corresponding 2-nitro-meso-tetraarylporphyrins in two steps by following the literature procedure [42]. The first step involved an amination of copper(II) 2-nitro-meso-tetraarylporphyrins by using 4-amino-4H-1,2,4-triazole in the presence of NaOH in refluxing ethanol

Synthesis of imidazo[1,2-a]pyridine-containing peptidomimetics by tandem of Groebke–Blackburn–Bienaymé and Ugi reactions

• Oleksandr V. Kolomiiets,
• Alexander V. Tsygankov,
• Maryna N. Kornet,
• Aleksander A. Brazhko,
• Vladimir I. Musatov and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2023, 19, 727–735, doi:10.3762/bjoc.19.53

• target compounds, which contained two pharmacophores – [1,2-a]pyridine (1H-imidazo[1,2-b][1,2,4]triazole) and peptidomimetic moieties – were evaluated for their antibacterial activity and exhibited a weak effect. Drugs possessing imidazo[1,2-a]pyridine unit. Drugs possessing peptide unit. Diversity of

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• -methyltribenzotriquinacene-2,3,6,7,10,11-hexayl)hexakis(oxy))hexaacetate (TBTQ-C6) and 2,2',2'',2''',2'''',2'''''-((((12d-methyltribenzotriquinacene-2,3,6,7,10,11-hexayl)hexakis(oxy))hexakis(methylene))hexakis(1H-1,2,3-triazole-4,1-diyl))hexaacetate (TBTQ-CB6), which act as host molecules to bind to guest molecules to

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• fluorescence response. Compounds that consisted of pyrrole-guanidine attached to larger aryl moieties (pyrene and phenanthridine) bind to the human DPP III enzyme [17]. Pyrene–cyanine conjugates connected with a rigid triazole-peptide linker were designed and synthesized in our group and showed a strong pyrene

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• connect two diverse moieties in a single framework. Therefore, this review focuses on the synthesis and photophysical studies of β- and meso-substituted and 1,2,3-triazole-fused porphyrin conjugates. All of the porphyrin conjugates discussed here are synthesized via a copper(I)-catalyzed Huisgen 1,3

• -dipolar cycloaddition reaction between an azide and a terminal alkyne, also popular as "click reaction" or CuAAC reaction. Moreover, the 1,2,3-triazole ring also serves as a spacer and an electron transfer bridge between the porphyrin and the attached chromophores. In order to provide a critical overview

• of the synthesis and properties of various porphyrin-triazole hybrids, this review will discuss some of the key reactions involved in the preparation of triazole-linked porphyrin conjugates. Keywords: azide–alkyne; click chemistry; CuAAC; 1,3-dipolar cycloaddition; porphyrin; 1,2,3-triazole

Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds

• Kah Yean Lum,
• Jonathan M. White,
• Daniel J. G. Johnson,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11

• , cyano, nitro, or halogenated groups at the para-position were crucial for activity [5][16][20]. Thus, compounds 1–3 with a para-phenyl-OCHF2, -Cl or -CN substituent at the C3 position of the triazole were selected as scaffolds in this study. In addition, the reported SAR data also indicated that the use