Synthesis of imidazo[4,5-e][1,3]thiazino[2,3-c][1,2,4]triazines via a base-induced rearrangement of functionalized imidazo[4,5-e]thiazolo[2,3-c][1,2,4]triazines

• Dmitry B. Vinogradov,
• Alexei N. Izmest’ev,
• Angelina N. Kravchenko,
• Yuri A. Strelenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2023, 19, 1047–1054, doi:10.3762/bjoc.19.80

• derivatives undergo rearrangement into the corresponding isomeric derivatives of imidazo[4,5-e]thiazolo[2,3-c]-1,2,4-triazine [18][21] (Scheme 1A). In the present study, we report a new base-induced recyclization of functionalized imidazothiazolotriazines 1 and 2 resulting in derivatives of the new

Synthesis of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines and investigation of their fungistatic activity

• Anna V. Korotina,
• Svetlana G. Tolshchina,
• Rashida I. Ishmetova,
• Natalya P. Evstigneeva,
• Natalya A. Gerasimova,
• Natalya V. Zilberberg,
• Nikolay V. Kungurov,
• Gennady L. Rusinov,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2022, 18, 243–250, doi:10.3762/bjoc.18.29

• 8 (which is characteristic for the behavior of [4,3-b]-annulated systems) triazolopyrimidine 9 has been obtained (Scheme 4). Product 9, like products 6a,b, appears to be derived from double addition of the reagent, accompanied by opening of the tetrazine ring and recyclization (Scheme 4). In the

Synthesis of functionalized imidazo[4,5-e]thiazolo[3,2-b]triazines by condensation of imidazo[4,5-e]triazinethiones with DMAD or DEAD and rearrangement to imidazo[4,5-e]thiazolo[2,3-c]triazines

• Alexei N. Izmest’ev,
• Dmitry B. Vinogradov,
• Natalya G. Kolotyrkina,
• Angelina N. Kravchenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2021, 17, 1141–1148, doi:10.3762/bjoc.17.87

• is, probably, a result of a transamidation reaction upon the treatment with a base, for example, alkoxide anion. The nucleophilic attack of the alkoxide anion leads to the cleavage of the C(7)–N(8) bond to form intermediates B and C followed by the recyclization of the thiazolidine ring involving the

Hydrazides in the reaction with hydroxypyrrolines: less nucleophilicity – more diversity

• Dmitrii A. Shabalin,
• Evgeniya E. Ivanova,
• Igor A. Ushakov,
• Elena Yu. Schmidt and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2021, 17, 319–324, doi:10.3762/bjoc.17.29

• , namely a Brønsted acid-activated hydroxypyrroline, depend on the reaction conditions and the structure of the hydrazides. Keywords: hydrazides; pyridazines; pyrrolines; recyclization; ring expansion; Introduction Di- and tetrahydropyridazines are valuable heterocyclic motifs which are utilized as key

• saturated pyridazine scaffolds is both highly topical and necessary. Recently, we have developed a convenient approach to the 1,4-dihydropyridazine core based on the Brønsted acid-catalyzed regioselective recyclization of 5-hydroxypyrrolines (assembled in a one-pot manner from ketoximes and acetylene gas [8

• nucleophilicity of the hydrazides diversifies the recyclization of 5-hydroxypyrrolines and results in the chemoselective formation of highly functionalized azaheterocyclic scaffolds. Such a short-cut to partially saturated azaheterocyclic scaffolds meets the interests of modern medicinal chemistry which today

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• opposite to the CF2 moiety, which was followed by the recyclization of the intermediate diradical (Scheme 42). The activation energy for the rearrangement of 90 was lower by 9.4 kcal/mol than for the parent hydrocarbon system 92. The activation energy of the trans-isomer 91 was greater than that of cis

One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines

• Valeriya G. Melekhina,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Vitaly S. Mityanov,
• Artem N. Fakhrutdinov,
• Arkady A. Dudinov,
• Vasily A. Migulin,
• Yulia V. Nelyubina,
• Elizaveta K. Melnikova and
• Michail M. Krayushkin

Beilstein J. Org. Chem. 2019, 15, 2840–2846, doi:10.3762/bjoc.15.277

• Federation Lomonosov Moscow State University, Moscow 119991, Russian Federation 10.3762/bjoc.15.277 Abstract The condensation of primary amines with N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamides was explored. Thus, a previously unknown recyclization of the starting material was

• : condensation; dihydropyrrolone derivative; one-pot synthesis; pyrrolo[3,4-b]pyridine-4,5-diones; recyclization; Introduction Derivatives of pyrrolo[3,4-b]pyridin-5-one are known for their broad-spectrum biological activity [1][2][3]. One example includes a family of compounds based on this fragment that was

• this reaction to proceed, furnishing target materials 2 in good yields (Scheme 2). The established straightforward synthesis of acetamides 2 provides further access to target materials with diverse substituent patterns. It is known that in the presence of amines, pyranones undergo recyclization under

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

• and recyclization, rather than species C. Quenching of species Ba with water (high nucleophilicity) affords alcohol Z-4a. The formation of compound 4a in exclusively Z-configuration may indicate that cation Ba reacts with H2O in SN2 manner, keeping in mind that carbon C5 in Ba possesses a large

A novel synthetic approach to hydroimidazo[1,5-b]pyridazines by the recyclization of itaconimides and HPLC–HRMS monitoring of the reaction pathway

• Dmitry Yu. Vandyshev,
• Khidmet S. Shikhaliev,
• Andrey Yu. Potapov,
• Michael Yu. Krysin,
• Fedor I. Zubkov and
• Lyudmila V. Sapronova

Beilstein J. Org. Chem. 2017, 13, 2561–2568, doi:10.3762/bjoc.13.252

• -addition by the activated C=C double bond and subsequent intramolecular recyclization of the intermediate with the amino group involved. Keywords: cascade reaction; diaminoimidazoles; HPLC–HRESIMS; imidazo[1,5-b]pyridazines; itaconimides; Introduction Among the numerous bicyclic fused imidazole

• the exocyclic activated C=C double bond allows itaconimides to react with heteroaromatic dinucleophiles as dielectrophilic reagents with the possibility of recyclization. Recently, our group reported the first example of this recyclization with N-arylitaconimides 1 and 1,2-diaminobenzimidazole (2) as

• ]. Mechanistically, further intramolecular recyclization of the succinimide fragments in intermediates 5–8 could proceed by any of the two imide C atoms (Scheme 5). Thus, for products 5 of the reaction of diaminoimidazole 4 as a 1,3-C,N-dinucleophile in the routes A and B, imidazo[1,5-b]pyridazines 9 and imidazo[1,5

Regiodivergent condensation of 5-alkoxycarbonyl-1H-pyrrol-2,3-diones with cyclic ketazinones en route to spirocyclic scaffolds

• Alexey Yu. Dubovtsev,
• Maksim V. Dmitriev,
• Аndrey N. Maslivets and
• Michael Rubin

Beilstein J. Org. Chem. 2017, 13, 2179–2185, doi:10.3762/bjoc.13.218

• , recyclization into the thermodynamically more favorable “normal” spirocyclic products 3a occurs. It should be further noted that in contrast to reactions of enamines, which readily provide the corresponding adducts with pyrrolediones in the absence of catalysts, the similar transformation involving enols 6

Synthesis of oligonucleotides on a soluble support

• Harri Lönnberg

Beilstein J. Org. Chem. 2017, 13, 1368–1387, doi:10.3762/bjoc.13.134

• recyclization of the large solvent amounts. All the other approaches discussed above allow lab-scale syntheses of oligonucleotides used for research purposes in gram scale. The advantage of the proposed soluble support strategies is that no special equipment is needed, and hence, they evidently are of interest

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• [2,3,4-kl]acridines (the core structure of plakinidine C) from enaminones and 3-indolyl-3-hydroxyoxindoles through a cascade ring-opening/recyclization/methyl migration sequence (Scheme 61) [78]. The reactions proceeded well in MeCN in the presence of catalytic I2 (30 mol %) under an O2 atmosphere

A new and convenient synthetic way to 2-substituted thieno[2,3-b]indoles

• Roman A. Irgashev,
• Arseny A. Karmatsky,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2015, 11, 1000–1007, doi:10.3762/bjoc.11.112

• , including oxidative cyclization of indolin-2-thiones 1 [20], radical or palladium catalyzed cyclization of 3-(2-bromoindol-3-yl)acrylonitriles 2 [21][22], intramolecular CH/NH-coupling in benzo[b]thiophenes 3 [23], AlCl3 catalyzed recyclization of 2-(2-isothiocyanatophenyl)furanes 4 [24], reductive

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

• , desilylation, and recyclization accompanied by a ring opening of oxirane or oxetane (Scheme 62 and Scheme 63). Cobalt(II) acetylacetonate (acac) or bis-2,2,6,6-tetramethylheptane-3,5-dienoate (thd) were used as the catalyst for the peroxidation of 219. The cyclization of the intermediate peroxide 220 was

• materials for the synthesis of cyclic peroxides [250][251][252][332]. For example, the ozonolysis of the double bond in the oxetane-containing compound, 2-methyl-2-(3-methylbut-3-enyl)oxetane (244) afforded 2-(3-hydroperoxy-3-methoxybutyl)-2-methyloxetane (245), which underwent recyclization in the presence

3-Pyridylnitrene, 2- and 4-pyrimidinylcarbenes, 3-quinolylnitrenes, and 4-quinazolinylcarbenes. Interconversion, ring expansion to diazacycloheptatetraenes, ring opening to nitrile ylides, and ring contraction to cyanopyrroles and cyanoindoles

• Curt Wentrup,
• Nguyen Mong Lan,
• Adelheid Lukosch,
• Pawel Bednarek and
• David Kvaskoff

Beilstein J. Org. Chem. 2013, 9, 743–753, doi:10.3762/bjoc.9.84

• nitrene 10 and the ketenimine 16 may undergo ring opening with rather low activation barriers, the ring opening of the ketenimine has the lowest barrier. Both of these reactions can take place with ease under conditions of FVT. With a low barrier for ring opening, recyclization of the nitrile ylide 11 now

• -pyridylnitrene 41, which undergoes cyclization to afford the pyridoindole (4-azacarbazole) 42 (Scheme 10) [29]. The alternative ring expansion/ring contraction/recyclization to the pyrimidoisoindole 43 also takes place [29]. The formation of 42 is important, as it demonstrates that 2-pyrimidinylcarbenes can

Efficient synthesis of 5-substituted 2-aryl- 6-cyanoindolizines via nucleophilic substitution reactions

• Eugene V. Babaev,
• Natalya I. Vasilevich and
• Anna S. Ivushkina

Beilstein J. Org. Chem. 2005, 1, No. 9, doi:10.1186/1860-5397-1-9

• products in good yields.[3] An interesting method for preparing 5-substitutied indolizines by recyclization of oxazolo[3,2-a]pyridinium salts was developed in our laboratory.[4][5] Using this strategy a series of 5-substituted indolizines have been prepared in good yields, but (although the method seems to