Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

• Ramazan Koçak and
• Arif Daştan

Beilstein J. Org. Chem. 2021, 17, 719–729, doi:10.3762/bjoc.17.61

• unsubstituted pyrrole 10ac was synthesized by the reaction of pyrrole 10ab with 4 equivalents of KOH under microwave irradiation (Scheme 6). The reaction of 2-pyridylpyridazine 4b with Zn did not work at room temperature. Under reflux conditions compound 10ba was obtained, which contained the corresponding

α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• α-(aminoxy)amides 9. Thermal radical cyclization of compounds 9 and further deprotection (general procedure) The α-(aminoxy)amide 9 (0.65 mmol) was heated in t-BuOH (6 mL) in a microwave reactor at 150 °C for 1 h. The reaction mixture was diluted with diethyl ether (5 mL), transferred into a round

Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

• Maryna O. Mazur,
• Oleksii S. Zhelavskyi,
• Eugene M. Zviagin,
• Svitlana V. Shishkina,
• Vladimir I. Musatov,
• Maksim A. Kolosov,
• Elena H. Shvets,
• Anna Yu. Andryushchenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2021, 17, 678–687, doi:10.3762/bjoc.17.57

• followed by microwave-assisted intramolecular azide–alkyne cycloaddition (IAAC) gave a series of target heterocyclic compounds in moderate to excellent yields. Surprisingly, the normally required ruthenium-based catalysts were found to not affect the IAAC, only making isolation of the target compounds

• harder while the microwave-assisted catalyst-free conditions were effective for both terminal and non-terminal alkynes. Keywords: click chemistry; microwave chemistry; multicomponent reactions; triazolobenzodiazepines; Ugi reaction; Introduction Benzannulated heterocycles are among the most important

• temperature conditions for the cyclization, performing a reaction under microwave irradiation in a sealed vial, and changed the solvent to less toxic (than benzene) toluene. That led to a decreasing reaction time to 1–1.5 hours (the reaction progress was monitored by TLC) with no impact on the product purity

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• , glycolysis of PET was performed under microwave heating in the presence of Zn(OAc)2, yielding BHET with an 80% selectivity at 97% conversion due to formation of dimers (Table 2, entry 7) [203][204]. Soluble metal chlorides (zinc, magnesium, iron, zirconium, cobalt, nickel) were also explored as catalysts in

• metal (complex) catalysts, methanolysis of PLA was recently described using alkali metal halides [271]. In an optimised experiment, PLA from various goods (cups, fork, spoons, containers, Mw 120000–260000 g⋅mol−1) was converted into Me-La in up to 97% yield using 2.5 mol % KF, 180 °C microwave heating

Designed whole-cell-catalysis-assisted synthesis of 9,11-secosterols

• Marek Kõllo,
• Marje Kasari,
• Villu Kasari,
• Tõnis Pehk,
• Ivar Järving,
• Margus Lopp,
• Arvi Jõers and
• Tõnis Kanger

Beilstein J. Org. Chem. 2021, 17, 581–588, doi:10.3762/bjoc.17.52

• microwave irradiation, a mixture of monoacylated and diacylated products 3 and 4 in 52% and 33% yield, respectively, was isolated [28]. Enzymatic hydroxylation 3-Ketosteroid 9α-hydroxylase (KSH) from R. rhodochrous has been shown to oxidize C9 in several steroids [29]. This enzyme consists of two

• p-toluenesulfonic acid monohydrate (2.8 mg, 0,008 mmol, 0,01 equiv) in a beaker was subjected to continuous mode of microwave irradiation (800 W) at high power setting in a domestic microwave oven for 6 min. After this, the mixture was cooled to room temperature, and saturated aqueous NaHCO3 (5 mL

Synthesis of N-perfluoroalkyl-3,4-disubstituted pyrroles by rhodium-catalyzed transannulation of N-fluoroalkyl-1,2,3-triazoles with terminal alkynes

• Olga Bakhanovich,
• Viktor Khutorianskyi,
• Vladimir Motornov and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 504–510, doi:10.3762/bjoc.17.44

• Prague, Czech Republic 10.3762/bjoc.17.44 Abstract The rhodium-catalyzed transannulation of N-perfluoroalkyl-1,2,3-triazoles with aromatic and aliphatic terminal alkynes under microwave heating conditions afforded N-perfluoroalkyl-3,4-disubstituted pyrroles (major products) and N-fluoroalkyl-2,4

Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

• Savva A. Ponomarev,
• Roman V. Larkovich,
• Alexander S. Aldoshin,
• Andrey A. Tabolin,
• Sema L. Ioffe,
• Jonathan Groß,
• Till Opatz and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2021, 17, 283–292, doi:10.3762/bjoc.17.27

• = 56:44) was observed for the product 2m. Next, the reaction with 1,3-cyclohexadiene (CHD) was investigated. It was found that the reaction is very sensitive to the structure of starting diene and in the case of CHD proceeds much more slowly. Both thermal and microwave (MW) activation (Scheme 3) was

• °C) and CHD at 110 °C. Scope of the nitrostyrenes 1 in the Diels–Alder reaction with CPD (dr = exo:endo). The Diels–Alder reaction of nitrostyrene 1h with spiro[2.4]hepta-4,6-diene. Diels–Alder reaction of nitrostyrenes 1 with CHD (dr = exo:endo). (а) Reaction under microwave activation. Kinetic

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

• addition, another modification was made in order to increase the speed of the reaction of sodium halodifluoroacetate and alkenes. This was achieved by the use of microwave irradiation in THF solution, which allowed the reactions to be completed within 5 minutes [31]. An application of this method to

1,2,3-Triazoles as leaving groups in S_NAr–Arbuzov reactions: synthesis of C6-phosphonated purine derivatives

• Kārlis-Ēriks Kriķis,
• Irina Novosjolova,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 193–202, doi:10.3762/bjoc.17.19

• development of this topic [8][9][10][11]. On the contrary, only a few examples can be found in the literature where a phosphorus-containing substituent is directly attached to the purine ring [12][13]. In 2008, an SNAr–Arbuzov reaction was developed for 6-chloropurine derivatives under microwave irradiation

• : DMSO-d6, 90 °C. Single-crystal X-ray analysis of diethyl (9-heptyl-2-(4-phenyl-1H-1,2,3-triazol-1-yl)-9H-purin-6-yl)phosphonate (4d). CCDC-2044976. Structural diversity and synthetic methods of purinylphosphonates. MWI = microwave irradiation; LG = leaving group. Synthetic routes for the formation of

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp³)–H bond functionalization under solvent- and catalyst-free conditions

• Divya Rohini Yennamaneni,
• Vasu Amrutham,
• Krishna Sai Gajula,
• Rammurthy Banothu,
• Murali Boosa and
• Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

• times [30]. Rao et al. performed similar reactions without catalyst under microwave irradiation in the presence of water as a solvent [31], but when considering an industrial scale, there are numerous factors that serves as obstacles for the usage of microwave reactors, such as escalated heat loss

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• -unsaturated enone to afford conidiogenone B (171) in 32% yield upon treatment with RhCl3 in microwave. The reaction mechanism of Danheiser’s [3 + 2] annulation is shown according to the Danheiser’s proposal [74] (Scheme 13C, inset). Initial complexation of the α,β-unsaturated ketone 167 and titanium

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• , ring-closing, metathesis, cycloadditions, radical reactions and microwave-assisted reactions [38][39][40]. In this work, we attempt to develop a greener, simpler, more efficient and recyclable system to synthesize arylpyridine derivatives. Initially, the reaction of acetophenone (5a) and 1,3

Fluorine effect in nucleophilic fluorination at C4 of 1,6-anhydro-2,3-dideoxy-2,3-difluoro-β-D-hexopyranose

• Danny Lainé,
• Vincent Denavit,
• Olivier Lessard,
• Laurie Carrier,
• Charles-Émile Fecteau,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2020, 16, 2880–2887, doi:10.3762/bjoc.16.237

• . Nevertheless, we investigated the preparation of 1,6-anhydro-2,3,4-trideoxy-2,3,4-trifluoro-β-ᴅ-hexopyranose analogues from previously described 1,6-anhydro-2,3-dideoxy-2,3-difluoro-β-ᴅ-hexopyranoses 2–5 using DAST (Table 1). We thus used 2 equivalents of DAST at 100 °C under microwave heating for 1 h and

Selective and reversible 1,3-dipolar cycloaddition of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes with 1,3-diphenylprop-2-en-1-ones under microwave irradiation

• Alexander P. Molchanov,
• Mariia M. Efremova,
• Mariya A. Kryukova and
• Mikhail A. Kuznetsov

Beilstein J. Org. Chem. 2020, 16, 2679–2686, doi:10.3762/bjoc.16.218

• cycloaddition of in situ-generated azomethine imine under microwave conditions is described. The reaction of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes with 1,3-diphenylprop-2-en-1-ones proceeds regio- and stereoselectively giving mostly good yields of the corresponding perhydropyrazolopyrazoles. The products of the

• that the Lewis acid-catalyzed reaction of diaziridines with donor–acceptor cyclopropanes and aziridines affords the perhydropyridazine or triazine derivatives, respectively, in good yields [31][32][33]. The use of microwave irradiation in organic synthesis complies with the principles of green

• chemistry and has attracted much interest. For 1,3-dipolar cycloaddition reactions microwave irradiation not only allows to reduce the reaction time and to increase yields, but in some cases also can affect the selectivity of the reaction [34][35][36]. The efficiency of microwave irradiation has been shown

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• 3-nitro-2,2’-bithiophene with triethyl phosphite under microwave irradiation and surprisingly obtained targeted heterotriacene H-DTP (vide supra) with only 11% yield [45]. This result prompted us to have a closer look on the applicability of the Cadogan reaction/cyclization in order to provide S,N

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• was performed using a Thermo Scientific Flash 2000 analyzer at the Gazi University Department of Chemistry. The microwave syntheses were carried out in a Milestone Start microwave reaction system. The melting points were measured using an Electrothermal IA9200 apparatus. Absorption spectra were

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• accurately weighted amount of each sample was treated with a microwave-assisted digestion (CEM MARS Xpress) using 1 mL of suprapure HNO3 obtained by sub-boiling distillation and 1 mL of suprapure H2O2. Each sample was thus diluted to 10 mL with Ultrapure water (UHQ), spiked with 0.5 ppm of Ge used as an

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• crystal of sumanene derivative 82 by means of time-resolved microwave conductivity technique. On the other hand, four years later, Sakurai and his teammates have reported the selective synthesis of diverse monosubstituted sumanene derivatives by employing electrophilic aromatic substitution reactions as

• using trifluoroacetyl nitrate which was in situ generated from conc. HNO3 and trifluoroacetic anhydride. On the other hand, formylation and acetylation were performed under microwave conditions at 130 °C using triflic anhydride and DMF or dimethylacetamide (DMA) to deliver the corresponding

• Suzuki–Miyaura cross-coupling reaction of bromosumanene 82 under microwave reaction conditions. Whereas another route involves the Ni-catalyzed aryl–aryl homo-coupling between the two molecules of iodosumanene 79 [51][52]. Moreover, the bissumanenyl 92, which is thought to be chiral because of the two

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• . Microwave-assisted SPPS was carried out using a CEM Discover system. 1H and 13C NMR spectra were recorded on a DRX 500 MHz Bruker spectrometer at ambient temperature. Chemical shifts (δ) are expressed in parts per million and J values in hertz. The following abbreviations were used for peak multiplicities

Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions

• Edgar Peris,
• Raúl Porcar,
• María Macia,
• Jesús Alcázar,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2020, 16, 1924–1935, doi:10.3762/bjoc.16.159

• of methylimidazolium units leading to a Pd(II)-SILLP system 11 with 0.56 mequiv of Pd/g of SILLP and 3.79 mequiv of IL-like units/g of SILLP (Scheme 4). This system was treated with either NaBH4 or EtOH under microwave irradiation to produce the corresponding PdNPs immobilized onto SILLPs (12a,b

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

• Dalel El-Marrouki,
• Sabrina Touchet,
• Abderrahmen Abdelli,
• Hédi M’Rabet,
• Mohamed Lotfi Efrit and
• Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

• as the main product, with the best yield being obtained in butanol (43%, Table 1, entry 11), however, with the formation of 6b occurring only in 10% yield. Switching to microwave irradiation formed exclusively 7b in 60% yield after 3 h (Table 1, entry 13). Note, that to check the effect of a shorter

• achieve the conformation of the proposed intermediate. We next examined the preparation of a set of indolones under the microwave conditions determined in Table 1, entry 13. These conditions were applied to several amines, producing exclusively the corresponding substituted indolones 7d and 7g–k in 48–56

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

• developed by reacting 5-amino-1,2,3,4-tetrazole with aromatic aldehydes and cyanamide in pyridine under controlled microwave heating with high yields. X-ray crystallography confirmed the structure of the obtained products. Keywords: microwave irradiation; N2-(tetrazol-5-yl)-6-aryl/heteroaryl-1,3,5-triazine

• green methodologies in synthetic heterocyclic chemistry. The utilization of microwave heating as an energy source has several advantages including operational simplicity, high reaction yields, enhanced rates, and increased energy efficiency [34][35][36][37][38][39][40]. In continuation of our efforts in

• 5-aminotetrazole (3) in pyridine under controlled microwave heating (Scheme 2). Results and Discussion With the initial aim of optimizing the reaction conditions, we began our study by reacting equimolar amounts of cyanamide 1, aromatic aldehydes 2, and 5-aminotetrazole (3) in pyridine and the

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• endotermic process is the rate-limiting step and long reaction times are generally associated to this. However, the reaction can be accelerated in conditions that facilitate the dissociation of CO ligands such as heating, microwave irradiation [37][38], visible light, or ultrasonication [39]. Alternatively

• cyclohexene, maleic anhydride, ethylene carbonate, and 1-octene, the desired products were not formed under the reaction conditions. In the same year, Helaja and co-workers examined the electronic effects of the alkyne substituent on the regioselectivity of the microwave-assisted PKR with norbornene [80]. The

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• be performed either at room temperature, in refluxing CH2Cl2 [19][28][29], at higher temperatures [1][30][31], and also under microwave conditions [32][33][34]. At lower temperatures or shorter reaction times an incomplete transesterification was reported [35]. The use of the low-boiling CH2Cl2 at

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116