Nucleophilic functionalization of thianthrenium salts under basic conditions

• Xinting Fan,
• Duo Zhang,
• Xiangchuan Xiu,
• Bin Xu,
• Yu Yuan,
• Feng Chen and
• Pan Gao

Beilstein J. Org. Chem. 2024, 20, 257–263, doi:10.3762/bjoc.20.26

• reaction system, yielding product 3ak in good yield. Furthermore, heteroaromatic rings, such as pyridine (2l), thiophene (2m), benzoxazole (2n), and benzimidazole (2o) all afforded the desired products (3al–ao) in satisfactory yields. Subsequently, we investigated the substrate scope of amines, which is

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• irradiation with orange light in several solvents [40]. However, due to the technical limitations of the spectrometer, Pummerer and Marondel were not able to detect the short-living Z-11a in aromatic solvents such as benzene, bromobenzene and pyridine. Nevertheless, the E–Z isomerization of 11a was observed

Optimizations of lipid II synthesis: an essential glycolipid precursor in bacterial cell wall synthesis and a validated antibiotic target

• Milandip Karak,
• Cian R. Cloonan,
• Brad R. Baker,
• Rachel V. K. Cochrane and
• Stephen A. Cochrane

Beilstein J. Org. Chem. 2024, 20, 220–227, doi:10.3762/bjoc.20.22

• . Finally, the benzyl-protecting groups in compound 7 were cleaved via hydrogenolysis, followed by co-evaporation of the resulting crude product in pyridine. This yielded a monopyridyl salt, setting the stage for the final lipid coupling and deprotection sequence. To establish the vital lipid diphosphate

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• overnight, then quenched by addition of dry ice (solid CO2) and concentrated under reduced pressure. The residue was co-concentrated with toluene (3 mL), dried in vacuo, dissolved in anhydrous pyridine (3 mL per 0.1 mmol of sialyl donor), and acetic anhydride (3 mL per 0.1 mmol of sialyl donor) was added

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• [c]quinolizinium tetrafluoroborate (3g) According to GP, a solution (c = 0.25 mM) of (E)-5-acetylamino-2-(3,4-dimethoxystyryl)pyridine (30.0 mg, 101 µmol) in a mixture of MeCN/H2O (7:3, 400 mL) was irradiated for 33 min and the crude product was washed with n-hexane (3 mL) and redissolved in dest

• : piperidine, MeOH, reflux (2a,c), ii: Ca(OTf)2, Bu4NPF6, 130 °C (2d,f), iii: N2H4·H2O, Pd/C, MeOH, reflux (2b), iv: NaNO2, CuCl, aq HCl (37%), room temp., 2 h, 60 °C, 30 min (2e), v: acetyl chloride, pyridine, THF, room temp. (2g). Photoinduced formation of styrylpyridine derivatives 2b–g to the benzo[c

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

• Kan Tang,
• Megan R. Brown,
• Chad Risko,
• Melissa K. Gish,
• Garry Rumbles,
• Phuc H. Pham,
• Oana R. Luca,
• Stephen Barlow and
• Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

• -containing catalysts [32]. We note that another all-organic reductive dimerization of benzyl halides using 2,3,5,6-tetrakis(tetramethylguanidino)pyridine has recently been reported [37]. The less readily reduced halides examined here (1d,e, and 2) are only sluggishly converted, even when using both (N-DMBI)2

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• Organic Synthesis, Aizkraukles 21, LV-1006, Riga, Latvia 10.3762/bjoc.19.139 Abstract The pyridine-3,5-dicarbonitrile moiety has gained significant attention in the field of materials chemistry, particularly in the development of heavy-metal-free pure organic light-emitting diodes (OLEDs). Extensive

• research on organic compounds exhibiting thermally activated delayed fluorescence (TADF) has led to numerous patents and research articles. This study focuses on the synthesis and investigation of the semiconducting properties of polyaromatic π-systems containing two and three fragments of pyridine-2,6

• compounds. In general, polyaromatic π-systems with pyridine-3,5-dicarbonitrile fragments demonstrate promising potential for use in organic electronic devices, such as OLEDs. Keywords: charge transport; intramolecular charge transfer; photophysical properties; pyridine-3,5-dicarbonitrile; Introduction The

Controlling the reactivity of La@C₈₂ by reduction: reaction of the La@C₈₂ anion with alkyl halide with high regioselectivity

• Yutaka Maeda,
• Saeka Akita,
• Mitsuaki Suzuki,
• Michio Yamada,
• Takeshi Akasaka,
• Kaoru Kobayashi and
• Shigeru Nagase

Beilstein J. Org. Chem. 2023, 19, 1858–1866, doi:10.3762/bjoc.19.138

• reduction [21] using a degassed tetrabutylammonium hexafluorophosphate (TBAF) pyridine solution. After stirring for 3 h, a dark green solution was obtained. CS2 was added to precipitate TBAF, and the solution was filtered to collect the La@C2v-C82 anion solution. The solvent was then removed under reduced

• in the second step. Preparation of the La@C2v-C82 anion As described in [21], La@C2v-C82 (0.34 × 10−6 mol) was dissolved in 10 mL of a pyridine solution containing TBAF (0.54 × 10−3 mol) and then stirred for 2 h under an Ar atmosphere. The resulting green solution was concentrated to 2.0 mL. CS2 was

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• (Figure 2) were designed to be obtained from precursors containing two 1,4-dioxobenzene fragments required to facilitate π–π interactions with the pyridine unit in the axle (compound 6 in Scheme 1) and confer stability to the supramolecular complex necessary for the formation of [2]rotaxanes. For the

• synthesis of the axle unit (compound 6 in Scheme 1) we considered a convergent synthetic approach that consist in preparation of the stopper, functionalized with azide groups, decoration of the central pyridine-based moiety with propargyl groups and their connection by CuAAC click chemistry. Thus, as

• -functonalized stopper 3 after substitution of bromine with azide. The dialkyne-decorated pyridine 5 was prepared starting from 2,6-bis(bromomethyl)pyridine that was reacted with compound 4, under phase transfer catalysis (Scheme 1). Finally, the axle 6, as well as the reference macrocycles M1 and M2 [44], were

Selectivity control towards CO versus H₂ for photo-driven CO₂ reduction with a novel Co(II) catalyst

• Lisa-Lou Gracia,
• Philip Henkel,
• Olaf Fuhr and
• Claudia Bizzarri

Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129

• (BzQuTr) [42] and the cobalt precursor Co(NCS)2(py)4 [43], where py is pyridine. The reaction was performed under an argon atmosphere at room temperature. The resulting complex 1 was obtained after evaporation of the solvent, as a lilac precipitate in good yield (60%). The structure was investigated by

• (NCS)2(NN) complexes, where NN is a chelating diimine compound such as pyridyl-tetrazole [44], or a pyridine-oxazole [45]. The bond lengths are very similar when comparing the polymorphs 1a and 1b. Nevertheless, the bond angles vary significantly (see Table S2 in Supporting Information File 1

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

• ). Next, we tested other protic (iPrOH, MeOH, EtOH/H2O, 1,4-dioxane/H2O) and aprotic (THF, 1,4-dioxane, pyridine, MeCN) solvents for the dimerization of 8 promoted by hydrazine hydrate to improve both yield and purity of 5 (Table 1, entries 4‒17). As can be seen from Table 1 the solvent had a dramatic

• effect on the outcome of the reaction. With THF, pyridine, MeCN, iPrOH, EtOH/H2O, or 1,4-dioxane/H2O either low conversion of 8 (Table 1, entry 4), or poor product yield (entries 9, 10, 12, 16, and 17), or low purity of 5 (entries 11 and 12) were observed. Using 1,4-dioxane with 3 equivalents of N2H4·H2O

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• macrocycles. The formation of (29b)2-Hg was reversible – its reaction with [2.2.2]cryptand resulted in the removal of mercury(II) and the contraction to 29b. Recently, Sessler and co-workers synthesised a new macrocycle 36 exploiting a pyridine-bridged dipyrroledialdehyde 35 (Scheme 10) [131]. The compound

• also demonstrated the crowned fused expanded porphyrinoids incorporating a pyridine moiety [135]. Macrocycles 45 were obtained in 5–10% yield from the condensation of 38 with the corresponding pyridine-based dipyrromethane analogue. Compound 45 exhibited a unique structural arrangement, with the

• pyridine ring and two thiophenes inverted and fused with two pyrrole nitrogen atoms. The macrocycles exhibited facile oxidations, indicating their electron-rich nature, and demonstrated selective sensing of Cu2+ ions. Conclusion and Outlook The construction of new macrocycles has been a driving force for

Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• residue was added a solution of ʟ-cysteine methyl ester hydrochloride (2 mg) in pyridine (200 μL), and the mixture was stirred at 65 °C for 1 h. Then, a solution of o-tolyl isothiocyanate (2.2 μL) in pyridine (200 μL) was added and the resulting mixture was stirred at 65 °C for 1 h. The final mixture was

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• acid organocatalysts were evaluated for sulfenylation on C3, or C2 position of N-heterocycles 115, including indoles, peptides, pyrrole, and 1-methyl-1H-pyrrolo[2,3-b]pyridine. The authors hypothesized a mechanism for the activation of N-sulfanylsuccinimides 1 or 14 by conjugate Lewis base Brønsted

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

• short times and required low catalyst loadings and a single product was obtained in each case. Furthermore, the cycloaddition with an internal alkyne could also be achieved using these catalysts. Interestingly, the catalysts were found effective in the cycloaddition of 2-(prop-1-yn-1-yl)pyridine with

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• challenging, and to the best of our knowledge, only Kawase's group [26] reported the preparation of such compounds starting from α-hydroxy acids or α-amino acids in the presence of trifluoroacetic anhydride and pyridine with very limited substrate scope (Scheme 1c). Therefore, the development of a more

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• oleyl chain. Accordingly, the primary alcohol was protected with p-methoxydiphenylmethyl (MeO-trityl) in pyridine and then, esterified in sn-2 position with benzoyl chloride to produce 9.4. The deprotection of the primary alcohol under acidic conditions gave 9.5. The polar head group was installed by

• protection was not regioselective (a mixture of primary and secondary protected alcohols was formed). The acylation of the secondary alcohol was then achieved with acetic anhydride in the presence of pyridine. Then, the deprotection of the trityl moiety of compound 12.4 by catalytic hydrogenation failed

• pyridine. A stereocontrolled synthesis of 26.4 was reported by Hajdu and Bhatia in 1988. The sequence starts from 27.1 that was prepared from ʟ-glyceric acid (Figure 27) [118]. Then, the free alcohol was converted as an efficient leaving group by reaction with 4-nitrobenzenesulfonyl chloride in the

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• ether α-C–H bond. In the presence of Cu(II), the C(sp2)–C(sp3) coupling of pyridine N-oxides and coumarins with cyclic ethers could be achieved under mild conditions (Scheme 13) [63][64]. These reactions do not all follow the reaction mechanism of the oxidative olefination of simple ethers. The role of

• chemoselective and regioselective CDC between pyridines and ethers, which used Sc(OTf)3 as the catalyst and DTBP as the oxidant (Scheme 36) [101]. This strategy allowed the synthesis of a series of α-substituted pyridine derivatives. The control experiments showed that the mechanism may proceed via a radical

• pathway. Initially, a tert-butoxyl radical is generated by thermal decomposition. Then, the tert-butoxyl radical extracts an α-hydrogen atom from tetrahydrofuran to form tetrahydrofuran radical A. Sc(OTf)3 as a Lewis acid activates pyridine forming the pyridine complex B. Then, radical A adds to the more

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• pyridine was in fact interacting with the LUMO+1 MO of I-7, corresponding to the σ* orbital oriented along the I–C bond axis [87]. Lüthi et al. quantified the symmetry-adapted perturbation theory (SAPT) interaction energies of halogen bonded acetonitrile complexes of HVI molecules [72], and Huber et al

New one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones based on 5-aminopyrazoles and azlactones

• Vladislav Yu. Shuvalov,
• Ekaterina Yu. Vlasova,
• Tatyana Yu. Zheleznova and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2023, 19, 1155–1160, doi:10.3762/bjoc.19.83

• when irradiated with UV light. Keywords: 5-aminopyrazole; azlactone; elimination; fluorescence; one-pot synthesis; pyrazolo[3,4-b]pyridin-6-one; Introduction The pyrazolo[3,4-b]pyridine scaffold is present in many biologically active compounds [1][2][3][4][5][6][7][8][9][10][11][12]. Among them, 4

• formation of the target products with low yields [21]. Therefore, the development of a new effective method for the preparation of 4-arylpyrazolo[3,4-b]pyridin-6-ones is an urgent task. Results and Discussion One of the rational approaches to the synthesis of fused pyridine derivatives is based on the

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• ]pyridines represent an important class of heterocyclic compounds, which skeleton is the key frame of many bioactive and natural compounds. For example, tetrahydrofuro[3,2-c]pyridine A demonstrates excellent in vitro JAK2 inhibitory activity superior to tofacitinib (Figure 1) [1]. Furan B is a potent κ

• relatively selective α2-adrenoceptor antagonist [5]. Despite the simplicity of the tetrahydrofuro[3,2-c]pyridine core, only limited approaches for the synthesis of this subclass of heterocycles using furan derivatives as starting compounds have been described [6][7][8]. The first group of methods is based on

• delight, when 2 equiv of HCl were subsequently added to the solution of imine 3a at 50 °C, the formation of the desired 2-methyl-4-phenyl-4,5,6,7-tetrahydrofuro[3,2-c]pyridine (4a) was observed in 26% yield (Table 1, entry 1). It should be noted that most part of the product 4a was formed as the

The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

• Xiu-Yu Chen,
• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

• ]. The well-known Huisgen 1,4-dipoles have a special kind of zwitterionic intermediates and are usually prepared by a nucleophilic addition of pyridine, quinoline, isoquinoline and other aza-arenes to electron-deficient alkynes [4][5][6][7][8]. The reactive Huisgen 1,4-dipoles have been widely employed

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• , the authors were able to obtain X-ray crystallographic data of the pyridine–catalyst complex which showed two intramolecular H-bonding interactions in the molecular framework of the catalyst where two free OH groups were engaged in interactions with the pyridine. This data clearly indicates the

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• , which provides convenience for studying the host–guest chemistry of TMeQ[6] and constructing fluorescent probes in aqueous solution [37][38]. There is a π–π conjugation effect between the carbon–carbon double bond and the pyridine ring in 1,2-bis(4-pyridyl)ethene (G), which determines its ultraviolet

• absorption [39]. Because the N atom on the pyridine ring of the G molecule has lone-pair electrons, it can form coordination compounds with metal ions. At present, the host–guest fluorescent probes designed by G and Q[n]s have been rarely reported. Therefore, we constructed the host–guest fluorescent probes

• at a wavelength of 350 nm. With the continuous addition of TMeQ[6], the fluorescence intensity of G is continuously enhanced, and the wavelength is redshifted to 391 nm, indicating that TMeQ[6] interacts with the guest molecule G. The TMeQ[6] cavity may limit the rotation of the pyridine ring on the

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• , National Institute of Pharmaceutical Education and Research - Ahmedabad, Gandhinagar, Gujarat, 382355, India 10.3762/bjoc.19.62 Abstract Pyridine is a crucial heterocyclic scaffold that is widely found in organic chemistry, medicines, natural products, and functional materials. In spite of the discovery

• of several methods for the synthesis of functionalized pyridines or their integration into an organic molecule, new methodologies for the direct functionalization of pyridine scaffolds have been developed during the past two decades. In addition, transition-metal-catalyzed C–H functionalization and

• rare earth metal-catalyzed reactions have flourished over the past two decades in the development of functionalized organic molecules of concern. In this review, we discuss recent achievements in the transition-metal and rare earth metal-catalyzed C–H bond functionalization of pyridine and look into