On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• high levels of selectivity, reactivity, and functional group tolerance, providing a large number of complex nitrogen heterocycles like azaindolines, pyrrolo-quinolines and -quinolones in excellent yields. Amongst the synthesized scaffolds, especially azaindolines are known to be present in M4

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• ] systematically surveyed simple nitrogen heterocycles and found that the 3-pyridazinyl nucleobase formed significantly more stable triplets with C–G than other heterocycles, including P. Several groups have explored extended PNA nucleobases for recognition of C–G base pairs [121][122]. Chen and co-workers

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• irradiation with sunlight, which facilitates the transport of electrons through the system (Scheme 4). Certain nitrogen heterocycles can be inserted into the substituent chain as an acceptor structural unit (Scheme 5). For example, an OSC based on a symmetrically substituted isoindigo derivative 4 containing

• best efficiency. Monoisoindigos with preferred 6,6'-substitution. Possibility of aromatic–quinoid structural transition. Isoindigo structures with incorporated acceptor nitrogen heterocycles. Monoisoindigos bearing pyrenyl substituents. p-Alkoxyphenylene-embedded thienylisoindigo with different

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

• ; electron transfer; γ-lactams; tandem reactions; Introduction Nitrogen-containing heterocycles are widely distributed in biologically active compounds [1][2][3][4]. Saturated nitrogen heterocycles such as pyrrolidines [5][6][7][8][9], piperidines, pyrrolizidines or indolizidines [10][11][12][13][14][15][16

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

• electrophilic metal-bound iminocarbenes form. These iminocarbenes undergo a variety of intriguing reactions, such as a cycloaddition and a C–H functionalization, among others, leading mostly to nitrogen heterocycles [8][9][10]. Using this chemistry, a variety of pyrroles have been prepared starting from N

• -sulfonyl-1,2,3-triazoles (Scheme 1) [11][12][13][14][15][16][17]. We have recently reported that N-perfluoroalkyl-1,2,3-triazoles [18] undergo rhodium-catalyzed transannulation reactions leading to various nitrogen heterocycles, such as imidazoles, pyrrolones, imidazolones, oxazoles, azepines [19][20][21

• trifluorometylated compounds is essential for future progress in areas that eventually improve the quality of life. In this context, N-trifluoromethylated compounds (amines, amides and nitrogen heterocycles) are a relatively underexplored group of molecules with a high potential in medicinal chemistry [29][30

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

• Mysore Bhyrappa Harisha,
• Pandi Dhanalakshmi,
• Rajendran Suresh,
• Raju Ranjith Kumar and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

• precursor for nitrogen heterocycles. As a part of our synthetic design towards the construction of five-membered heterocycles, we have previously reported the synthesis of highly substituted imidazoles [6], indoles [7] and pyrroles [8] starting from different azidochalcones. In continuation, employing α

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• : benzimidazoles; dihydropyrimidinones; highly substituted pyridines; natural dolomitic limestone; ultrasound irradiation; Introduction Nitrogen heterocycles are recognized as “privileged medicinal scaffolds” because these compounds are found in a wide variety of bioactive natural products and pharmaceuticals [1

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

• Gui-Feng Kang and
• Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

• structures of 1,3,5-triazine-2,4-dithione derivatives were characterized by spectroscopic techniques as well as by single crystal X-ray diffraction. Keywords: aldehydes; multicomponent reactions; nitrogen heterocycles; thiourea; triazinethiones; Introduction The construction of nitrogen-containing

Microwave-assisted efficient and facile synthesis of tetramic acid derivatives via a one-pot post-Ugi cascade reaction

• Yong Li,
• Zheng Huang,
• Jia Xu,
• Yong Ding,
• Dian-Yong Tang,
• Jie Lei,
• Hong-yu Li,
• Zhong-Zhu Chen and
• Zhi-Gang Xu

Beilstein J. Org. Chem. 2020, 16, 663–669, doi:10.3762/bjoc.16.63

• has the potential to produce a large number of tetramic acid analogues, which cannot be easily accessed by the classic synthetic methods. Keywords: Dieckmann cyclization; multicomponent reactions; nitrogen heterocycles; one-pot reaction; Ugi reaction; Introduction Nitrogen-containing heterocycles

Rapid, two-pot procedure for the synthesis of dihydropyridinones; total synthesis of aza-goniothalamin

• Thomas J. Cogswell,
• Craig S. Donald and
• Rodolfo Marquez

Beilstein J. Org. Chem. 2020, 16, 135–139, doi:10.3762/bjoc.16.15

• produce the target dihydropyridinones efficiently and in high yields. Keywords: amidoallylation; aza-goniothalamin; dihydropyridinones; protecting-group-free; ring-closing metathesis; two-pot procedure; Introduction Six-membered nitrogen heterocycles are prevalent in many naturally occurring and

• precursor in a single step. This general strategy towards nitrogen heterocycles has been utilized in several reports [20][21][22][23], including asymmetric variants [24][25], but in these cases the ring-closing metathesis precursor was always generated in multiple steps. In order to test this hypothesis

Facile regiodivergent synthesis of spiro pyrrole-substituted pseudothiohydantoins and thiohydantoins via reaction of [e]-fused 1H-pyrrole-2,3-diones with thiourea

• Aleksandr I. Kobelev,
• Nikita A. Tretyakov,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev,
• Michael Rubin and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 2864–2871, doi:10.3762/bjoc.15.280

• good yields, and the products were isolated without applying preparative chromatography methods. Keywords: diversity-oriented synthesis; hydantoin; nitrogen heterocycles; rearrangement; thiourea; Introduction Hydantoin (imidazolidine-2,4-dione) derivatives are omnipresent among biologically active

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

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

• synthesized in a similar manner. The presence of a NO2 group in the starting hydrazinylpyridine induces a Dimroth-type rearrangement leading to 2-methylphosphonylated [1,2,4]triazolo[1,5-a]pyridines. Keywords: cyclization; fused-ring systems; nitrogen heterocycles; phosphorylation; rearrangement

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• the steroidal nucleus, the assembly of nitrogen-heterocycles fused to the steroid-ring system, the steroid conjugation and macrocyclization, all relying on MCRs. 2 Modification of the steroidal nucleus and the side chain 2.1 Isocyanide-based MCRs 2.1.1 Steroids as carbonyl component: One of the first

• , Boruah’s group has been very active in the synthesis of nitrogen heterocycles such as pyrimidines, pyrazolopyrimidines and disubstituted pyridines fused to rings A and D of steroids [47][48][49]. Thus far, most applications of MCRs in steroid derivatization aimed at producing derivatives for screening

Annulation of 1H-pyrrole-2,3-diones by thioacetamide: an approach to 5-azaisatins

• Aleksandr I. Kobelev,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 364–370, doi:10.3762/bjoc.15.32

• developed via an unprecedented annulation of pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones by thioacetamide. A new way of C–H functionalization of thioacetamide has been discovered. The reaction proceeds under green catalyst-free conditions. Keywords: annulation; domino reactions; isatin; nitrogen

• heterocycles; thioamides; Introduction Omnipresent among natural compounds and drugs, the indole core is a privileged scaffold for library design and drug discovery [1]. Its dioxo derivative, isatin (1H-indole-2,3-dione), is an important building block for the construction of diverse indole-based compounds

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• product via double bonds (Scheme 17). Azocine derivatives, eight-membered nitrogen heterocycles, exist as the core structure in many natural and non-natural products [84]. Nevertheless, 2-methyoxyazocine (96) reduces related aromatic 10π-electron dianion 97 (Scheme 18). Paquette’s group investigated benzo

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• 27, which was reduced into 28 prior to be converted into nitrogen heterocycles via [1,3]-hydride shift and cyclisation steps (Scheme 12). The reaction was regioselective and had a broad scope. This application of alkene trifluoromethylation provided a convenient entry to trifluoromethylated nitrogen

• heterocycles. Subsequently, a photoredox-catalysed azotrifluoromethylation of unactivated alkenes was developed by Chen, Xiao and co-workers [32]. The scope was broad for a variety of unactivated alkenes, functionalised or not, and aryldiazonium salts (Scheme 13). Interestingly, the method did not require

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• phosphinyl nitrosoalkenes NSA15 (derived from the corresponding α-bromooximes) with electron-rich nitrogen heterocycles to give adducts 69 is described and the comparison of electrophilic aromatic substitution (1) and cycloaddition (2) routes is discussed [59] (Scheme 24). Quantum-chemical calculations

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

• between two alternative directions affording derivatives of partially hydrogenated indole or benzofurane. The control of this regioselectivity is efficiently governed by steric effects at the hydrazone moiety of the ketazinone reagent. Keywords: nitrogen heterocycles; oxygen heterocycles; pyrrolediones

Preparation of imidazo[1,2-a]-N-heterocyclic derivatives with gem-difluorinated side chains

• Layal Hariss,
• Kamal Bou Hadir,
• Mirvat El-Masri,
• Thierry Roisnel,
• René Grée and
• Ali Hachem

Beilstein J. Org. Chem. 2017, 13, 2115–2121, doi:10.3762/bjoc.13.208

• propargylic derivatives 4 [28] with aromatic aldehydes. Then, the DBU-mediated isomerization afforded the desired enones 6a–e in 21–66% yields (Scheme 2 and Table 1). For the synthesis of the desired nitrogen heterocycles, we started our study by reacting 6a with 2-aminopyridine in the presence of AlCl3 and

High-speed vibration-milling-promoted synthesis of symmetrical frameworks containing two or three pyrrole units

• Marco Leonardi,
• Mercedes Villacampa and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2017, 13, 1957–1962, doi:10.3762/bjoc.13.190

• relevance of nitrogen heterocycles in the generation of bioactive molecules, medicinal chemists would greatly benefit from the ability to build two heterocyclic systems at both ends of the spacer chain in a single maneuver. Further advantages in terms of synthetic efficiency would be gained if the key

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• /bjoc.13.162 Abstract Nitrogen heteroarenes form an important class of compounds which can be found in natural products, synthetic drugs, building blocks etc. Among the diverse strategies that were developed for the synthesis of nitrogen heterocycles, oxidative dehydrogenation is extremely effective

• nitrogen heteroarenes. Keywords: aerobic oxidation; bioinspired Flavin mimics; nitrogen heteroarenes; organo catalytic; oxidative dehydrogenation; Introduction By virtue of their presence in bioactive natural products and active pharmaceutical ingredients, nitrogen heterocycles and heteroaromatics form

• reactions are one of the key synthetic strategies that are applied to generate various nitrogen heterocycles and subsequent aromatization of these heterocycles afforded the corresponding heteroaromatic derivatives [19]. The aromatization of nitrogen heterocycles is facilitated mainly by dehydrogenation of

Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

• Jimena E. Díaz,
• Silvia Ranieri,
• Nadia Gruber and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145

• -assisted ring closure of the corresponding aminoamides promoted by ethyl polyphosphate (PPE). Keywords: dihydroquinazolines; microwaves; N-acylations; N-alkylations; PPE; Introduction Nitrogen heterocycles are part of many drugs and represent structures with wide therapeutic potential. Therefore, much

N-Propargylamines: versatile building blocks in the construction of thiazole cores

• S. Arshadi,
• E. Vessally,
• L. Edjlali,
• R. Hosseinzadeh-Khanmiri and
• E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

• synthesis of various nitrogen heterocycles and complex natural products. In this regard, recently an impressive increase in the number of publications on the preparation of thiazoles and their hydrogenated analogues through inter- and intramolecular cyclization of N-propargylamine derivatives appeared in

An effective one-pot access to polynuclear dispiroheterocyclic structures comprising pyrrolidinyloxindole and imidazothiazolotriazine moieties via a 1,3-dipolar cycloaddition strategy

• Alexei N. Izmest’ev,
• Galina A. Gazieva,
• Natalya V. Sigay,
• Sergei A. Serkov,
• Valentina A. Karnoukhova,
• Vadim V. Kachala,
• Alexander S. Shashkov,
• Igor E. Zanin,
• Angelina N. Kravchenko and
• Nina N. Makhova

Beilstein J. Org. Chem. 2016, 12, 2240–2249, doi:10.3762/bjoc.12.216

• ; nitrogen heterocycles; spiro compounds; Introduction A global trend in modern organic chemistry is the design of molecular systems with various degrees of complexity to maximize the incorporation of useful properties while optimizing cost and efficiency [1]. A very extended and powerful approach for