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

• , Cazin and co-workers reported the synthesis of Cu(I) complexes 61, 63, and 65 of the so-called ‘abnormal’ NHCs (Scheme 21) [35]. Thus, the conventional heating method as well as microwave irradiation methods were employed. The structures of the synthesized complexes were confirmed by X-ray analysis

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• to reduce energy consumption and the carbon footprint. The traditional heating techniques used to synthesize compounds are being replaced by contemporary green alternative energy systems, such as photocatalysis, microwave irradiation, ultrasonic irradiation, grinding, and ball milling processes

• -free conditions, and under microwave irradiation. (1) Reactions in water In recent years, organic reactions in aqueous medium have grown in popularity due to their low cost and environmental friendliness. The use of water as a solvent medium for the synthesis of pyrrole derivatives using various

• any catalysts under microwave conditions. In this procedure, various arylsulfonamides or anilines 58 are heated with 2,5-dimethoxytetrahydrofuran (2) in H2O under microwave irradiation conditions to produce the corresponding N-substituted pyrrole derivatives 59 in 81–99% yields (Scheme 28). A variety

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• acrylamide derivatives [140]. Using the same directing group, a panel of α-arylacrylamide derivatives 39a–f was successfully functionalized with a high Z-selectivity (yields up to 98%, Scheme 18). Both, thermal reaction conditions (DMSO at 70 °C for 16 h) and microwave irradiation (100 °C using microwaves in

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

• microwave irradiation conditions. The prepared nanoparticles from free-base PPCs showed colorimetric aqueous pH sensing, which suggests that the PPC nanoparticles could serve as chemical sensing applications. In 2008, the Crossley’s group [59] reported the synthesis of a ‘capped’ porphyrin 142 forming a

Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• esters, lactones, and carbonates with HBpin under microwave irradiation (Scheme 13) [57]. When HBpin and boric acid were reacted together, BH3-coordinated HBpin and O(Bpin)2 were detected by 11B NMR spectroscopy. Supported by computational analysis and single-turnover experiments, the reaction was

Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin

• János Máté Orosz,
• Dóra Ujj,
• Petr Kasal,
• Gábor Benkovics and
• Erika Bálint

Beilstein J. Org. Chem. 2023, 19, 294–302, doi:10.3762/bjoc.19.25

• efficient reaction used so far for the selective monofunctionalization of CDs [1]. Besides traditional synthetic methods, alternative techniques, such as ultrasound and microwave irradiation [21], as well as mechanosynthesis [22][23] for the functionalizations, such as tosylation or azidation of CDs have

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities

• Hongling Shui,
• Yuhong Zhong,
• Renshi Luo,
• Zhanyi Zhang,
• Jiuzhong Huang,
• Ping Yang and
• Nianhua Luo

Beilstein J. Org. Chem. 2022, 18, 1507–1517, doi:10.3762/bjoc.18.159

• . In addition, Aravinda's group [11] prepared 3-(1,3-dioxolan-2-yl)benzo[h]quinolines containing thiol and selenol groups in one pot by microwave irradiation, and tested the antibacterial activity of the compounds. The results showed that the antibacterial effect of some compounds was better than

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

• Péter Kisszékelyi,
• Tibor Peňaška,
• Klára Stankovianska,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124

• 1,3-dicarbonyl compounds using a catalytic amount of hydrazine hydrate without solvent in a short reaction time (10 min) [14]. Reactions of 2-aminothiophenols with β-keto esters and β-diketones under microwave irradiation (MWI) using basic alumina as heterogeneous catalyst without solvent afforded 4H

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

• convection across a surface. Compared to heating under microwave irradiation, the system does not need to be encased for safety reasons. Inductive heating of materials is extremely fast with the best determined power transfer value of all heating technologies [10]. It has therefore found wide industrial

• pressure-stable reactors, which leads to shortened residence times. Inductive heating, in addition to microwave irradiation [44][45][46] heating, can serve as an indirect and rapid heating technology that, when combined with pressure-resistant microstructured flow reactors, enables "flash" heating so that

• even supercritical conditions can be achieved. In this context, Poliakoff and co-workers used supercritical water to perform several industrially relevant and continuously guided conversions, using microwave irradiation as an indirect heating method [47]. Other examples in which the two enabling

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• model reaction without any external ligand and required 20 h for completion. However, the same reaction under microwave irradiation was complete within 2.5 h. The product was obtained with an excellent yield of 95% by the utilization of Fe(III) acetylacetonate and CuI as the catalyst. Among several iron

• systems utilizing an iron catalyst under microwave irradiation has been reported [34]. N-Arylated azaindoles were prepared by Sonogashira coupling followed by cyclization. The Sonogashira coupling of 2-arylamino-3-iodopyridines with terminal acetylenes followed by cyclization afforded the 2-N-arylated 7

• -azaindole derivatives under microwave irradiation that helps to reduce the reaction time and minimizes side product formation. Co-catalyzed Sonogashira cross-coupling reactions Nanoparticle-based protocols The advantages of using immobilized catalysts include the possibility of the catalyst to be easily

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

• can also be used as an oxidant for the oxidation of benzamidine derivatives 2b,c in acetonitrile under microwave irradiation. Along with the cyclization reaction, bromination of the pyrazole ring proved to occur at position C(4) to give the products 3j,k, as evidenced by disappearance of the

• formation of difficult-to-separate reaction mixtures with a low content of the target products 3a,b,g, which could not be isolated in a pure form. Heating of tetrazines 2 with N-bromosuccinimide in refluxing acetonitrile without microwave irradiation made it possible to obtain the product 3j in a low yield

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• Pd source together with the water-soluble Buchwald ligand sulfonated SPhos (sSPhos) and potassium fluoride as a base. The reaction was performed in a solvent mixture of dimethoxyethane, ethanol and water (DME/EtOH/H2O 9:9:2) at 120 °C under microwave irradiation for 30 min (Scheme 1) [78]. The

Efficient N-arylation of 4-chloroquinazolines en route to novel 4-anilinoquinazolines as potential anticancer agents

• Rodolfo H. V. Nishimura,
• Thiago dos Santos,
• Valter E. Murie,
• Luciana C. Furtado,
• Leticia V. Costa-Lotufo and
• Giuliano C. Clososki

Beilstein J. Org. Chem. 2021, 17, 2968–2975, doi:10.3762/bjoc.17.206

• -anilinoquinazoline; anticancer agents; N-arylation; 4-chloroquinazoline; microwave irradiation; Introduction N-Heterocyclic compounds are commonly present in pharmaceuticals, bioactive natural products, agrochemicals, and synthetic drugs [1][2]. Quinazoline, a benzo-fused N-heterocyclic framework (benzo-1,3-diazine

• ]. These limitations can be overcome by using microwave irradiation [12][13][18][19][20], which promotes fast and efficient anilination reactions when a wide range of anilines bearing both electron-donating and electron-withdrawing groups are employed as nucleophiles (Scheme 1b) [12][13]. Moreover, 4

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

• Chuanhua Qu,
• Run Huang,
• Yong Li,
• Tong Liu,
• Yuan Chen and
• Guiting Song

Beilstein J. Org. Chem. 2021, 17, 2822–2831, doi:10.3762/bjoc.17.193

• treated with 20 mol % Ag2CO3 in THF in the presence of Cs2CO3 at 90 °C under microwave irradiation for 10 min, fortunately, the sulfonylated diarylmethane product 3a was isolated in 36% yield (Table 1, entry 2). When ZnI2 or Cu(OAc)2 was used instead of Ag2CO3, we found that the yield of 3a catalyzed by

• the reaction mixture was heated under microwave irradiation at 90 °C for 10 min and monitored by TLC until starting material was consumed. Then, the reaction mixture was concentrated under reduced pressure followed by column chromatography over silica gel using petroleum/EtOAc (0 to 10%) as eluent to

Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction

• Dušan Đ. Škorić,
• Olivera R. Klisurić,
• Dimitar S. Jakimov,
• Marija N. Sakač and
• János J. Csanádi

Beilstein J. Org. Chem. 2021, 17, 2611–2620, doi:10.3762/bjoc.17.174

• acid, reflux, 12 h (74% for 4; 69% for 8); d) SeO2, acetic acid, microwave irradiation, 150 °C, 15 min (74% for 4; 67% for 8); and e) Ac2O, benzene/pyridine, rt, 24 h (74%). Synthesis of 7-oxo intermediate 11 from chenodeoxycholic acid (9). Reagents and conditions: a) EtOAc, pTsOH, reflux, 12 h (66

(Phenylamino)pyrimidine-1,2,3-triazole derivatives as analogs of imatinib: searching for novel compounds against chronic myeloid leukemia

• Luiz Claudio Ferreira Pimentel,
• Lucas Villas Boas Hoelz,
• Henayle Fernandes Canzian,
• Frederico Silva Castelo Branco,
• Andressa Paula de Oliveira,
• Vinicius Rangel Campos,
• Floriano Paes Silva Júnior,
• Rafael Ferreira Dantas,
• Jackson Antônio Lamounier Camargos Resende,
• Anna Claudia Cunha,
• Nubia Boechat and
• Mônica Macedo Bastos

Beilstein J. Org. Chem. 2021, 17, 2260–2269, doi:10.3762/bjoc.17.144

• )pyrimidine-pyridine (PAPP) group as a pharmacophoric fragment, and these compounds were biologically evaluated. The synthesis of twelve new compounds was performed in three steps and assisted by microwave irradiation in a 1,3-dipolar cycloaddition to obtain 1,2,3-triazole derivatives substituted on carbon C

• cycloaddition reactions via the copper-catalyzed 1,3-dipolar cycloaddition reaction (CuAAC) of the azides 5 and 9 with suitably functionalized acetylenes 6a–j, using sodium ascorbate and copper sulfate in ACN/H2O 2:1 under microwave irradiation were carried out to obtain the 1,4-regioisomers of the final

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

• Premansh Dudhe,
• Mena Asha Krishnan,
• Kratika Yadav,
• Diptendu Roy,
• Krishnan Venkatasubbaiah,
• Biswarup Pathak and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

• decomposition of N-pyridylbenzotriazoles. Later, the reaction conditions were modified to make this reaction more versatile and operationally simple such as by the use of microwave irradiation [12]. Meanwhile, the Fischer indole synthesis was successfully extended for the synthesis of significant biologically

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• stimulation by application of variable temperature zones, light or microwave irradiation, electrolysis and even high frequency sonication. The ability to quickly and easily assemble and modify a flow setup allows not only the chemical reaction to be performed as a continuous dynamic flow process but also for

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• was the only effective reagent when performing the reaction at 60 °C in THF [16]. Ketimines were also synthesized with Ti(OEt)4, under microwave irradiation in a solvent-free system [20]. In hindered ketones, Ti(OiPr)4 or Ti(OEt)4 using vacuum or under a nitrogen flow were effective to tert

Synthesis of multiply fluorinated N-acetyl-D-glucosamine and D-galactosamine analogs via the corresponding deoxyfluorinated glucosazide and galactosazide phenyl thioglycosides

• Vojtěch Hamala,
• Lucie Červenková Šťastná,
• Martin Kurfiřt,
• Petra Cuřínová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2021, 17, 1086–1095, doi:10.3762/bjoc.17.85

• reaction with diethylamino sulfurtrifluoride (DAST) [27]. This reaction was greatly improved by microwave irradiation, especially in the GalNAc series [31][32]. The deoxyfluorination of the secondary hydroxy groups at the 3- and 4-positions was accomplished using a treatment of the C3/4 hydroxy groups with

• sulfurtrifluoride (DAST) [51], but our experiments revealed that DAST-mediated C6-deoxyfluorination of thioglycosides 14–17 and 19 proceeded satisfactorily under microwave irradiation, on condition that pure or substantially enriched α-anomers were subjected to reaction with DAST, yielding thioglycosides 22–26

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• the reaction (Scheme 6) [40]. A different approach using microwave irradiation was explored by the group of Toma et al. [41]. After an initial tuning of the reaction conditions of a catalytic system based on Pd(OAc)2/2,2’-bipy several optically pure phosphoramidite and diphosphine ligands in

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• aprotic solvent, which led to moderate to good conversions after less than 30 minutes. Chen et al. were the first to show a significant acceleration of the reaction between cyanoguanidine and variously substituted aniline hydrochlorides under microwave irradiation (Scheme 7A) [22]. The reaction was

• substituted cyanoguanidine as the intermediate. Practically, very little improvement was made over synthetic procedures reported 50 years ago. To the best of our knowledge modern activations such as Lewis acid-promoted additions, catalysis or microwave irradiation have never been tried for this reaction

• . screened various conditions for the addition of TMG to different alkyl- and arylcarbodiimides [80]. In particular, the authors compared different approaches such as classical thermic conditions, microwave irradiation with or without Y(OTf)3, high-speed vibrational milling using stainless steel balls, high