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

• (1 h instead of 5 h). The precipitated compound 8 was isolated by filtration in a 96% yield (Scheme 4). Previously, the structure of 8 was assigned based on 1H and 13C NMR spectroscopic data [40]. However, these data are insufficient to distinguish compound 8 and its isomer 9 resulting from a Dimroth

• rearrangement that is known to proceed in 3-substituted 4-iminopyrimidine systems [40][45][46][47]. Our analysis of 1H, 13C NMR, and 2D NMR spectra (DMSO-d6 solution) of the prepared product confirmed its structure as compound 8. For example, the 1H,13C-HMBC spectrum showed correlation of the NH2 protons with

Facile and diastereoselective arylation of the privileged 1,4-dihydroisoquinolin-3(2H)-one scaffold

• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1070–1078, doi:10.3762/bjoc.18.109

• homophthalimides 8 [10][11][12]. We reasoned that a similar strategy could be adopted for the preparation of 1,2,4-trisubstituted 1,4-DHIQs 9 if access to their diazo precursors 10 was gained. N-Sulfonyl analogs of compounds 10 have recently been synthesized via an innovative Dimroth rearrangement of 4

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• technologies microwave and flow were combined are the Dimroth rearrangement exemplified for the conversion of 1,3-thiazine 3 to the corresponding 3-substituted hydropyrimidine 4 (Scheme 7, reaction 1) [48]. A noteworthy example was recently published by Organ and co-workers [49]. A three-component reaction of

• (reaction 1) and steam (reaction 2) methane reforming. Calcination and RF heating. The continuously operated “Sabatier” process. Biofuel production from biomass using inductive heating for pyrolysis. Water electrolysis using an inductively heated electrolysis cell. Dimroth rearrangement (reaction 1) and

Novel library synthesis of 3,4-disubstituted pyridin-2(1H)-ones via cleavage of pyridine-2-oxy-7-azabenzotriazole ethers under ionic hydrogenation conditions at room temperature

• Romain Pierre,
• Anne Brethon,
• Sylvain A. Jacques,
• Aurélie Blond,
• Sandrine Chambon,
• Sandrine Talano,
• Catherine Raffin,
• Branislav Musicki,
• Claire Bouix-Peter,
• Loic Tomas,
• Gilles Ouvry,
• Rémy Morgentin,
• Laurent F. Hennequin and
• Craig S. Harris

Beilstein J. Org. Chem. 2021, 17, 156–165, doi:10.3762/bjoc.17.16

• -opening of the triazole moiety through a Dimroth rearrangement process affording 20 (reaction becomes instantly bright red); c) reduction of diazonium species to afford intermediate 21, observed by UV-LC–MS; and finally d) reductive cleavage of the -O–NH- bond, usually carried out under catalytic

Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides

• Vladimir Ilkin,
• Vera Berseneva,
• Tetyana Beryozkina,
• Tatiana Glukhareva,
• Lidia Dianova,
• Wim Dehaen,
• Eugenia Seliverstova and
• Vasiliy Bakulev

Beilstein J. Org. Chem. 2020, 16, 2937–2947, doi:10.3762/bjoc.16.243

• thioamides with alkyl- and arylsulfonyl azides. For each type of thioamides a reliable procedure to prepare N-sulfonyl amidines in good yields was found. Reactions of 1-aryl-1,2,3-triazole-4-carbothioamides with azides were shown to be accompanied with a Dimroth rearrangement to form 1-unsubstituted 5

• -arylamino-1,2,3-triazole-4-N-sulfonylcarbimidamides. 2,5-Dithiocarbamoylpyridine reacts with sulfonyl azides to form a pyridine bearing two sulfonyl amidine groups. Keywords: amidines; Dimroth rearrangement; isoxazoles; sulfonyl thiazoles; thioamides; 1,2,3-triazoles; Introduction The biological activity

Microwave-assisted efficient one-pot synthesis of N²-(tetrazol-5-yl)-6-aryl/heteroaryl-5,6-dihydro-1,3,5-triazine-2,4-diamines

• Moustafa Sherief Moustafa,
• Ramadan Ahmed Mekheimer,
• Saleh Mohammed Al-Mousawi,
• Mohamed Abd-Elmonem,
• Hesham El-Zorba,
• Afaf Mohamed Abdel Hameed,
• Tahany Mahmoud Mohamed and
• Kamal Usef Sadek

Beilstein J. Org. Chem. 2020, 16, 1706–1712, doi:10.3762/bjoc.16.142

• the synthesis of 6-substituted-N2-aryl-1,6-dihydro-1,3,5-triazine-2,4-diamines via the reaction of aromatic amines, cyanoguanidine, and ketones which afforded the corresponding 1-aryl-1,6-dihydro-6-substituted-1,3,5-triazine-2,4-diamines in 21–56% yields followed by Dimroth rearrangement utilizing

• cyanoguanidine 5 to the formed Schiff’s base (route c). Product 4 was the sole isolable product as under reflux in pyridine as base, compound 8 well undergoes a Dimroth rearrangement forming the more thermodynamically stable product 4 [33]. We established route c, as the formation of the Schiff base is more

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• -promoted Dimroth rearrangement has been previously reported by Potts et al. [19]. In contrast, the reaction of 2-hydrazinyl-5-nitropyridine (1j) with chloroethynylphosphonates at a temperature of 60 °C for 50 hours led to the formation of a mixture of isomers 10 and 12 in a ratio of ≈1:1. Boiling the

• ]triazolo[1,5-a]pyridines. Conditions: a1 (1 mmol), 2 (1 mmol), CH3CN (5 mL), 60 °C. b1 (1 mmol), 2 (1 mmol), CH3CN (5 mL), reflux. cThe product was not isolated. dThe yield was determined by 31P NMR spectroscopy. Acid-promoted Dimroth rearrangement pathway. Synthesis of phosphonylated [1,2,4]triazolo[4,3-a

Revisiting ring-degenerate rearrangements of 1-substituted-4-imino-1,2,3-triazoles

• James T. Fletcher,
• Matthew D. Hanson,
• Joseph A. Christensen and
• Eric M. Villa

Beilstein J. Org. Chem. 2018, 14, 2098–2105, doi:10.3762/bjoc.14.184

• investigation regarding the substituent effects of 4-imino-1,2,3-triazoles on this Dimroth rearrangement is therefore warranted, exemplary results of which are described herein. Results and Discussion The original study of L’abbé regarding this ring-degenerate rearrangement focused on the condensation of 1

• condensation reaction between formyltriazole and amine leads to iminotriazole formation (step a). This iminotriazole is then vulnerable to ring-degenerate Dimroth rearrangement (step b). This rearranged iminotriazole can then undergo hydrolysis to yield a new formyltriazole and a new amine byproduct (step c

• elevated temperature conditions. Surprisingly, triazole analogs with electron-withdrawing substituents underwent significant rearrangement even at room temperature. The spontaneous reactivity of 1-(4-nitrophenyl)-1H-1,2,3-triazole-4-carbaldehyde towards Dimroth rearrangement and its generation of a

A convenient four-component one-pot strategy toward the synthesis of pyrazolo[3,4-d]pyrimidines

• Mingxing Liu,
• Jiarong Li,
• Hongxin Chai,
• Kai Zhang,
• Deli Yang,
• Qi Zhang and
• Daxin Shi

Beilstein J. Org. Chem. 2015, 11, 2125–2131, doi:10.3762/bjoc.11.229

• intramolecular cyclization. Finally, 10 is oxidized to give pyrazolo[3,4-d]pyrimidine 5. Another route is that 7 undergoes an intramolecular Pinner reaction to form 11. Then 11 rearranges to dihydropyrazolo[3,4-d]pyrimidin-4-ones 13 via Dimroth rearrangement and 13 is oxidized to provide 14 [49]. Finally, 14

IBD-mediated oxidative cyclization of pyrimidinylhydrazones and concurrent Dimroth rearrangement: Synthesis of [1,2,4]triazolo[1,5-c]pyrimidine derivatives

• Caifei Tang,
• Zhiming Li and
• Quanrui Wang

Beilstein J. Org. Chem. 2013, 9, 2629–2634, doi:10.3762/bjoc.9.298

• derivatives 5a–o. These incipient products undergo feasible Dimroth rearrangement to furnish the isolated [1,2,4]triazolo[1,5-c]pyrimidines 6a–o in moderate to high yields. Keywords: cyclization; hydrazones; hypervalent iodine; oxidation; rearrangement; [1,2,4]triazolo[1,5-c]pyrimidines; Introduction The

• for the efficient preparation of novel triazolopyrimidines is needed. Recently, we have reported the synthesis of 8-bromo-7-chloro-[1,2,4]triazolo[1,5-c]pyrimidines from the reaction of pyrimidinylhydrazones with bromine followed by Dimroth rearrangement [15]. In the present paper, we wish to report

• an efficient synthesis of new [1,2,4]triazolo[1,5-c]pyrimidine derivatives from hypervalent iodine (IBD)-mediated oxidative cyclisation of aldehyde pyrimidinylhydrazones and consecutive Dimroth rearrangement in relatively good yields under very mild conditions. Results and Discussion The

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• Biginelli reaction and for the preparation of N3-substituted dihydropyrimidinone 10 by Dimroth rearrangement of 1,3-thiazine 9 [46]. In these studies, the 10 mL flow cell was loaded with glass beads and irradiated at 120 or 200 °C, respectively, to give the target heterocycle in yields that compared very