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

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

• metal exchange reaction of porphyrin 90 with excess CoCl2·6H2O in an acetone/THF (1:1) mixture. The results of the photophysical investigations demonstrated that these dyads exhibit adequate electronic interactions between the sensitizer and catalyst in the excited state. In this study, NiO films were

Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic liquids (TAAILs)

• Swantje Lerch,
• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2023, 19, 212–216, doi:10.3762/bjoc.19.20

• derivatives (see Scheme 1). First, the arylimidazole is obtained through a ring closing reaction using an aniline derivative, glyoxal, formaldehyde and ammonium chloride. The following alkylation with hexyl bromide yields the bromido ionic liquid. TAAILs 1–6 are then formed by an anion exchange reaction using

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

• intermediate A to form a π-complex B, and a ligand exchange reaction from B occurs to produce intermediate D, together with the elimination of selenol C. The selenol C is oxidized to diselenide 2. Finally, the intermediate D undergoes a reductive elimination to form the desired product 4, with the regeneration

Borylated norbornadiene derivatives: Synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions

• Robin Schulte and
• Heiko Ihmels

Beilstein J. Org. Chem. 2022, 18, 368–373, doi:10.3762/bjoc.18.41

• derivatives may be metalated in a Li–halogen exchange reaction [27]. In another versatile approach, arylation and alkenylation reactions of the norbornadiene may be accomplished with a Suzuki–Miyaura coupling reaction. In this case, halogenated norbornadienes react with arylboronic acids or their esters to

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• derivative 7 was generated in 79% yield by treatment of amine 6 with chloroacetyl chloride. Next, the aminoacetyl group in 7 was benzyl-protected to give 8 in 88% yield. Halogen exchange reaction using excess sodium iodide in acetone gave the desired iodo-alkyl derivative 9 in 79% yield. Lastly, our attempt

Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• prepared from carbonyl compounds and chloromethyl p-tolyl sulfoxide and were converted into alkynes via the sulfoxide/magnesium exchange reaction and subsequent Fritsch–Buttenberg–Wiechell (FBW) rearrangement of the resulting magnesium alkylidene carbenoids. The mechanism of the FBW rearrangement of

• p-tolyl sulfoxide, via the sulfoxide/magnesium exchange reaction [11]. During the course of our study on the ambiphilic reactions of magnesium alkylidene carbenoids 3 (Scheme 2b and 2c) [12][13][14][15], we found that the FBW rearrangement of magnesium alkylidene carbenoids 3 occurred to give

• p-tolyl sulfoxide and alkyne 4a were obtained in 97% yield and 99% yield, respectively. This result shows that both the sulfoxide/magnesium exchange reaction and the FBW rearrangement occurred with high efficiency. A similar reaction of sulfoxide 2a with sec-butyllithium also gave alkyne 4a in 97

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• a 2-oxonia-Cope-mediated side-chain exchange reaction and is entirely consistent with Willis and co-workers’ result [29], which leads to the partial racemization observed in the desired product formation. Another Lewis acid, SnBr4, was found to be more efficient than BF3·OEt2/HOAc in terms of

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• that the catalyst efficiency is almost constant even after five cycles, but the rate of the reaction considerably decreased from the first cycle (0.31 min−1) to the fifth cycle (0.15 min−1). Zhang, Lu, et al. prepared β-CD-decorated CdS nanocrystals (CdS–CD, Figure 9) via a ligand-exchange reaction

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• and 2. In our first attempts to perform the exchange reaction, the aqueous solution of NPcit was treated with a solution of (R)-1 and 2 in methanol. Unfortunately it turned out that 2 was insufficiently soluble in the resulting solvent mixture. The ligand thus precipitated and did not react. We tried

• to address this solubility issue by increasing the fraction of the organic solvent during the exchange reaction, but the products thus obtained also did not contain immobilized 2 according to the 1H NMR spectroscopic characterization. For similar reasons, the simultaneous immobilization of (R)-1 and

• another acid and tested citric acid, which was attractive because we expected this acid to produce a buffer together with the citrate present on the nanoparticles, which should reduce the influence of possible pH changes on the exchange reaction. In this case, adjusting the aqueous solution of NPcit to pH

A dynamic combinatorial library for biomimetic recognition of dipeptides in water

• Florian Klepel and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2020, 16, 1588–1595, doi:10.3762/bjoc.16.131

• cysteines are converted quantitively to disulfides by oxidation with oxygen. Until fully oxidized library members can exchange building blocks in a thiol–disulfide exchange reaction. While a closed monomer can be observed in the beginning (Figure S1, Supporting Information File 1), exclusively cyclic

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

• for studying the possibility of an N-alkylation by alkyl bromide, formed during the silylation step. Finally, compound 13 was included to study the possibility of a chlorine for bromine exchange reaction. The phosphonocarboxylates 8 and 9 were used to explore whether the carboxyester group could be

• best of our knowledge, there were no reports on using BTMS for the nucleophilic substitution of alkyl chlorides. A similar exchange reaction was reported only for 2-chloropyridines [51], and required harsh reaction conditions, such as heating at 90–100 °C for 100 h. In this study we investigated the

• , CDCl3 (Table 3, entry 2, 42% conversion after 3 h) as well as lowering the temperature (Table 3, entry 3, rt, CDCl3, after 24 h 50% conversion into 22) slowed down the reaction. When TEA was added to the mixture, the halogen-exchange reaction slightly decreased (Table 3, entries 4 and 5). Remarkably

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

• Tobias Lucas,
• Jule-Philipp Dietz and
• Till Opatz

Beilstein J. Org. Chem. 2020, 16, 445–450, doi:10.3762/bjoc.16.41

• (5). First, a Finkelstein halogen exchange reaction and a dehydration reaction were combined to obtain fluoroacetonitrile (7) in 82% yield [36]. The latter then underwent a Claisen condensation with ethyl formate to obtain 8 in 77% yield with a purity of 90%. The product contained about 10% (1H NMR

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• deprotection then furnished 83b in reasonable yields between 68 and 87%. Bis(diphenylphosphine)-substituted imidazoles were also synthesized by Karthik et al. [87] starting from the diiodoimidazole derivative 84. The lithium chloride mediated magnesium/iodine exchange reaction of 84 followed by the addition of

Formal preparation of regioregular and alternating thiophene–thiophene copolymers bearing different substituents

• Atsunori Mori,
• Keisuke Fujita,
• Chihiro Kubota,
• Toyoko Suzuki,
• Kentaro Okano,
• Takuya Matsumoto,
• Takashi Nishino and
• Masaki Horie

Beilstein J. Org. Chem. 2020, 16, 317–324, doi:10.3762/bjoc.16.31

• to afford the regioregular polythiophene in which 2,5-dihalo-3-substituted thiophene 1 is employed as a monomer precursor, converting to the corresponding organometallic monomer by a halogen−magnesium exchange reaction with a Grignard reagent. The employment of 1 leading to polythiophene has been

Preparation of anthracene-based tetraperimidine hexafluorophosphate and selective recognition of chromium(III) ions

• Qing-Xiang Liu,
• Feng Yang,
• Zhi-Xiang Zhao,
• Shao-Cong Yu and
• Yue Ding

Beilstein J. Org. Chem. 2019, 15, 2847–2855, doi:10.3762/bjoc.15.278

• of 58% [41]. Compound 1 was then treated with SOCl2 to generate 9,10-bis{[N,N-di(2-chloroethyl)amino]methyl}anthracene (2) in 75% yield, which reacted with 1-ethylperimidine in the presence of KI to afford the analogous iodide salt to tetraperimidine 3. Subsequently, an anion exchange reaction with

In search of visible-light photoresponsive peptide nucleic acids (PNAs) for reversible control of DNA hybridization

• Lei Zhang,
• Greta Linden and
• Olalla Vázquez

Beilstein J. Org. Chem. 2019, 15, 2500–2508, doi:10.3762/bjoc.15.243

• quencher (BHQ)-labelled single-strand (ss) DNA template, a complementary fluorescein (FAM)-labelled ssDNA and the PNA of interest. In this framework, the PNA could bind the BHQ-ssDNA; thus, its addition to the quenched BHQ/FAM-DNA duplex would trigger an exchange reaction and the release of the FAM-ssDNA

Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• material could not be recovered, another product 23, which is most likely the debrominated, not cyclized analogue of 20a, was observed in traces. The outcome of this experiment shows that the bromine–magnesium exchange reaction was most likely completed, but the intramolecular trapping of the ester group

• using TMPMgCl∙LiCl and quenching with various electrophiles or cross-coupling reactions. Attempted synthesis of kuanoniamine A (3). Synthesis of pyrido[4,3,2-mn]acridone 22 starting from 20a via bromine–magnesium exchange reaction and subsequent intramolecular trapping of the methyl ester. Supporting

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

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• AuNR are functionalized selectively in a two-step ligand exchange reaction. The ends are capped with per-6-thio-β-cyclodextrin (tCD) and CTAB is removed from the remaining surface by monothiolated tetraethylene glycol (tTEG) enabling reversible host–guest chemistry. The addition of a divalent AAP

• [44]. Furthermore, the ζ-potential is known to be highest in deionized water and highly pH-dependent [45]. The ligand exchange reaction was also analyzed by UV–vis spectroscopy (Figure 1b). The synthesized [CTAB]AuNR show the two expected absorption maxima at λ = 525 nm for the TSPR band and at λ

• divalent AAP linker forms a 1:2 complex with per-6-thiolated β-CD which is selectively located at the ends of the AuNR. This was achieved through a novel two-step ligand exchange reaction including the complete removal of CTAB by the addition of thiolated TEG. The removal of CTAB is crucial due to its

Understanding the unexpected effect of frequency on the kinetics of a covalent reaction under ball-milling conditions

• Ana M. Belenguer,
• Adam A. L. Michalchuk,
• Giulio I. Lampronti and
• Jeremy K. M. Sanders

Beilstein J. Org. Chem. 2019, 15, 1226–1235, doi:10.3762/bjoc.15.120

• Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK 10.3762/bjoc.15.120 Abstract We here explore how ball-mill-grinding frequency affects the kinetics of a disulfide exchange reaction. Our kinetic data show that the reaction progress is similar at all the frequencies studied (15–30 Hz

• ) conditions with 50 μL of acetonitrile added to 200 mg of powder. The kinetic points prepared for this study are all single point experiments. The reaction under study is a base-catalyzed disulfide exchange reaction starting from equimolar amounts of homodimers using DBU as the base catalyst to result in the

• exchange reaction. The results of the milling experiments were plotted as mol % concentration of phase composition versus grinding time (see Figure 1, Figure 4 and Supporting Information File 1). The phase composition is calculated from the Rietveld refinement of the PXRD scans. The estimated accuracy of

Cobalt-catalyzed C–H cyanations: Insights into the reaction mechanism and the role of London dispersion

• Eric Detmar,
• Valentin Müller,
• Daniel Zell,
• Lutz Ackermann and
• Martin Breugst

Beilstein J. Org. Chem. 2018, 14, 1537–1545, doi:10.3762/bjoc.14.130

• structures resulted in barrierless reactions when a proton approaches the amidine substructure (→ 12a). As the cyanated 2-phenylpyridine 3a is less Lewis-basic compared to the starting material 1a, 12a could also react with 1a in a thermodynamically favorable ligand exchange reaction (ΔG = −2.2 kcal mol−1

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• procedure shown in Scheme 2 including: 1) protection of the formyl group in ortho-bromoaldehydes 1 and 2 with 1,3-propanedithiol, 2) the Br/Li exchange reaction in the resulting ortho-bromo-1,3-dithianes 3 and 4 with n-BuLi followed by condensation with a second (hetero)aromatic aldehyde Ar2-CHO. The

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

• and Brückner reported the synthesis of 7-hydroxy-2,3-benzotropones by ring-closing metathesis (Scheme 48) [173]. 7-Hydroxy-2,3-benzotropone (241) was synthesized in four steps starting from a Br/Li exchange reaction of o-bromostyrene (283) followed by the addition of aldehyde 284 to give the benzylic

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• ’-O-acetylthiomethyl-containing RNA, produces various 2’-O-alkyldithiomethyl (RSSM)-modified RNAs bearing lipophilic or polar groups through a thiol disulfide exchange reaction with alkyldisulfanyl-pyridine derivatives (Scheme 3). In a preliminary evaluation, the RSSM modifications were shown to