The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• scope of 8 GBB adducts was obtained (Scheme 6). Yamajala et al., in the last article discussed in the previous sub-chapter, also described the use of sodium dodecyl sulfate (SDS) as surfactant in GBB reactions performed in water, synthesizing 27 distinct imidazopyridines in 72–98% yield employing very

• work described below, KTGS was applied to multicomponent reactions in limited cases [25]. Van der Veken et al. selected as template the protein urokinase plasminogen activator, a serine protease targeted in oncology and inhibited by imidazopyridines [26]. The main challenges of this project were the

Synthesis of 4-functionalized pyrazoles via oxidative thio- or selenocyanation mediated by PhICl₂ and NH₄SCN/KSeCN

• Jialiang Wu,
• Haofeng Shi,
• Xuemin Li,
• Jiaxin He,
• Chen Zhang,
• Fengxia Sun and
• Yunfei Du

Beilstein J. Org. Chem. 2024, 20, 1453–1461, doi:10.3762/bjoc.20.128

• of efforts to developing efficient thio/selenocyanation approaches [33][34][35][36][37][38][39][40][41]. Specifically, a plethora of synthetic strategies have been reported for the thiocyanation of heteroaromatic compounds including arenes, indoles, carbazoles, pyrroles, and imidazopyridines [42][43

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• functionalization is still challenging for chemists to combine a C(sp3) carbon of incoming functionalities and C(sp2) carbon of the IP core. The direct C-3 alkylation of imidazopyridines using active malonates and related moieties has been achieved by different routes [17][18][19][20]. However, these reactions rely

A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• Raphael Bereiter Marco Oberlechner Ronald Micura Institute of Organic Chemistry, Center for Molecular Biosciences, Innsbruck (CMBI), Innrain 80-82, 6020 Innsbruck, Austria 10.3762/bjoc.18.172 Abstract Imidazopyridines and pyrrolopyrimidines are an important class of compounds in medicinal

• nitration. A further strength of our route is divergency, additionally enabling the synthesis of 1-deazahypoxanthine (c1I base). Keywords: deazapurine; heterocycles; imidazopyridines; nucleoside; nucleotides; pyrrolopyrimidines; RNA atomic mutagenesis; Introduction Deazapurines (imidazopyridines and

On drug discovery against infectious diseases and academic medicinal chemistry contributions

• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 1355–1378, doi:10.3762/bjoc.18.141

• ]. The initial hits came from a phenotypic screening which, out of more than 120,000 molecules, found the antimycobacterial effects of imidazopyridines 23 and 24 [159]. It would be of interest to retrace the reason for the presence of these two compounds in the chemicals screened, random luck seems the

Synthesis of novel alkynyl imidazopyridinyl selenides: copper-catalyzed tandem selenation of selenium with 2-arylimidazo[1,2-a]pyridines and terminal alkynes

• Mio Matsumura,
• Kaho Tsukada,
• Kiwa Sugimoto,
• Yuki Murata and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 863–871, doi:10.3762/bjoc.18.87

• or dialkyl diselenides, followed by C–H selenation with imidazopyridines to form the corresponding compounds. We also reported the one-pot two-step reaction of Se powder with imidazopyridine and triarylbismuthines using the CuI/1,10-phenanthroline catalytic system without bases, which formed similar

• limited to C(sp2)–Se–C(sp2) or C(sp2)–Se–C(sp3) bond-formation reactions. However, C(sp2)–Se–C(sp) bond formation reactions using the imidazopyridines and alkyne derivatives have not been reported to date. Based on previous reports and our ongoing investigation of the synthesis of unsymmetrical selenides

Synthesis and anticancer activity of bis(2-arylimidazo[1,2-a]pyridin-3-yl) selenides and diselenides: the copper-catalyzed tandem C–H selenation of 2-arylimidazo[1,2-a]pyridine with selenium

• Mio Matsumura,
• Tsutomu Takahashi,
• Hikari Yamauchi,
• Shunsuke Sakuma,
• Yukako Hayashi,
• Tadashi Hyodo,
• Tohru Obata,
• Kentaro Yamaguchi,
• Yasuyuki Fujiwara and
• Shuji Yasuike

Beilstein J. Org. Chem. 2020, 16, 1075–1083, doi:10.3762/bjoc.16.94

• successive use of imidazopyridine, Se powder, and aryl donors were developed in 2018 as more convenient methods for the synthesis of 3-selanylimidazopyridines. Guo, Li, et al. reacted imidazopyridines, Se powder, and arylboronic acids in the presence of Ag2CO3 (2 equiv) and Cs2CO3 (2 equiv) using a CuI/1,10

• -phenanthroline catalytic system [28]. Guo, Han, et al. reported a method that used a Cu(OAc)2/1,10-phenanthroline catalyst in the presence of KOH (2 equiv); this method replaced the aryl source from an arylboronic acid with an aryl iodide [30]. Zhou et al. reported the reactions of imidazopyridines, Se powder

• , and aryl halides in the presence of Na2CO3 (2 equiv) using a NiBr2/2,2-bipyridine system [31]. We also developed reactions of imidazopyridines, Se powder, and triarylbismuthanes using a CuI/1,10-phenanthroline catalytic system that did not require a base or an additive [32]. On the other hand, the

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

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

• Gagandeep Kour Reen Ashok Kumar Pratibha Sharma School of Chemical Sciences, Devi Ahilya University, Indore, (M. P.), India 10.3762/bjoc.15.165 Abstract A comprehensive account of recent advances in the synthesis of imidazopyridines, assisted through transition-metal-catalyzed multicomponent

• development and (ii) for the modifications needed thereof in the R&D sector. Keywords: C–H activation/functionalization; coupling reactions; imidazopyridines; multicomponent reactions; transition metal catalysis; Introduction The structural diversity and biological importance of nitrogen-containing

• methods to functionalize these systems [1][2]. In one such context, imidazopyridines are one of the fascinating classes of fused N-heterocyclic scaffolds of versatile concern. Their chemistry has drawn substantial attention in last few years owing to their involvement in various medicinal applications viz

Mn-mediated sequential three-component domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction towards annulated imidazo[1,2-a]pyridines

• Olga A. Storozhenko,
• Alexey A. Festa,
• Delphine R. Bella Ndoutoume,
• Alexander V. Aksenov,
• Alexey V. Varlamov and
• Leonid G. Voskressensky

Beilstein J. Org. Chem. 2018, 14, 3078–3087, doi:10.3762/bjoc.14.287

• medicinal chemistry and biology [19][20], illustrated by the marketed drugs, e.g., alpidem, minodronic acid, olprinone, zolimidine (Figure 1) and some recent examples of the imidazopyridines inhibiting tubulin polymerization [21], NF-κB [22], aldosterone synthase [23], or autotaxin [24]. Whereas many

• interesting approaches towards the imidazo[1,2-a]pyridine core are being published nowadays [25][26][27][28][29][30], this molecular entity is still a pursued synthetic target and novel routes to diverse imidazopyridines are of value. Another privileged scaffold for drug discovery is 2-aminochromene, which

• annulation patterns. Biologically relevant imidazo[1,2-a]pyridines and chromenes. General view of the molecule 7b in the crystal state (CCDC 1849215). Anisotropic displacement parameters are drawn at 50% probability. Domino formation of imidazopyridines and current work. Scope of the reaction between N

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

• Camila S. Pires,
• Daniela H. de Oliveira,
• Maria R. B. Pontel,
• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Diego Alves,
• Raquel G. Jacob and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256

• imidazopyridines, for example, is widely found in literature [6][7]. However, the preparation of 4-arylselanyl-1H-pyrazoles is quite scarce. Tiecco and co-workers described the preparation of phenylseleno substituted pyrazolidines by reacting allylhydrazines with phenylselanenyl sulfate generated in situ (Scheme 1

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• the formation of aromatic thioethers by functionalising C–H bonds of imidazo[1,2-α]pyridines and benzo[d]imidazo[1,2-b]thiophenes using Eosin B and sulfinic acids (Scheme 8) [51]. The manipulated heterocycles, particularly the imidazopyridines, are motifs which are commonly encountered in medicinal

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• ]thiazoles and imidazopyridines, were compatible with this reaction conditions affording the corresponding analogues in moderate to good yields. The proposed reaction mechanism is shown in Scheme 38. Initially, the trifluoromethyl radical is generated in situ by the reaction of TBHP with CF3SO2Na in the

Reactivity of bromoselenophenes in palladium-catalyzed direct arylations

• Aymen Skhiri,
• Ridha Ben Salem,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2017, 13, 2862–2868, doi:10.3762/bjoc.13.278

• -heteroarylated selenophene with regeneration of the Pd(0) species. Conclusion In summary, the reactivity of 2-bromoselenophenes was investigated and revealed that the C2-heteroarylation of 2-bromoselenophene in high yields is only possible with specific heteroarenes such as thiazoles and imidazopyridines

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

• small amounts in most cases. A radical mechanism was proposed as described in Scheme 41. Imidazopyridines have demonstrated many interesting features toward biological activities and the incorporation of a trifluoromethyl group into such architectures was expected to alter their properties. Therefore

• , Hajra and co-workers reported a direct and regioselective method for the trifluoromethylation of imidazopyridines 67 and other imidazoheterocycles 68 [65]. The combination CF3SO2Na/t-BuOOH/cat. AgNO3 at room temperature under air was applied to 17 imidazopyridines and 3 imidazoheterocycles (Scheme 42

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

• could be of interest for bioorganic and medicinal chemistry studies. Several synthetic approaches for imidazopyridines are available, but only a few examples have been reported to date for the construction of this scaffold with introduction of fluorine [22], trifluoromethyl [23] or trifluoroethyl groups

• [1,2-a]pyrimidines 7d and imidazo[1,2-b]pyridazines 7e, have been synthesized by the same method albeit in slightly decreased yields (Table 2, entries 4 and 5). The structures of molecules 7 are in full agreement with their spectroscopical (NMR) and analytical data (HRMS). For the imidazopyridines, the

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

• reported for [125I]-labeled N,N-dimethylamino chalcones and aurones. Imidazopyridines The imidazopyridine core has also been used in developing novel Aβ imaging agents such as 140–142 (Scheme 10A). Initial SAR studies were based on derivatives 140a–j. One of the most successful imidazopyridines studied to

• imidazopyridine scaffold, but the benzimidazole ring has reduced lipophilicity when compared to imidazopyridines. This has the potential to reduce nonspecific binding and enhance signal-to-noise ratio. The [125I]-labeled benzimidazole analogue of 140e, compound 146, was prepared through cyclization of 4

Tandem aldehyde–alkyne–amine coupling/cycloisomerization: A new synthesis of coumarins

• Maddi Sridhar Reddy,
• Nuligonda Thirupathi and
• Madala Haribabu

Beilstein J. Org. Chem. 2013, 9, 180–184, doi:10.3762/bjoc.9.21

• aminoindolizines, 2-(aminomethyl)indoles, imidazopyridines, butenolides and 1,2-dihydroisoquinoline derivatives, respectively, combining these two approaches successfully. Along the same lines, we investigated a reaction between ethoxyacetylene, pyrrolidine and salicylaldehyde in the presence of a transition-metal

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• introduced via a Friedel–Crafts/Mannich-type alkylation starting either from formaldehyde and dimethylamine or 2,2-dimethoxy-N,N-dimethylacetamide (Scheme 45). In a recent study a more straightforward and general copper-catalysed three component coupling leading to imidazopyridines has been reported [69