Copper-promoted C5-selective bromination of 8-aminoquinoline amides with alkyl bromides

• Changdong Shao,
• Chen Ma,
• Li Li,
• Jingyi Liu,
• Yanan Shen,
• Chen Chen,
• Qionglin Yang,
• Tianyi Xu,
• Zhengsong Hu,
• Yuhe Kan and
• Tingting Zhang

Beilstein J. Org. Chem. 2024, 20, 155–161, doi:10.3762/bjoc.20.14

• , employing activated and unactivated alkyl bromides as the halogenation reagents without additional external oxidants. This method features outstanding site selectivity, broad substrate scope, and excellent yields. Keywords: aminoquinolines; C–H bromination; copper catalysis; regioselectivity; Introduction

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• present, the reaction was performed in presence of 1 equiv of BF3·Et2O and a reaction time of 1 h (Table 4, entry 4). In this way, the selectivity was improved and only the hydration product 2d was obtained in 81% yield. For electron-rich terminal alkynes, the corresponding ketones could not be

• 1f decreased the selectivity with respect to formation of the hydration product 2f, favouring the condensation product 3f (Table 4, entry 6). On the other hand, an ortho methyl group in 1g favoured formation of the ketone 2g, with a good yield, probably due to the steric hindrance of the aldol

• hydration product 2i with good yield, reducing its reactivity (Table 4, entry 9). With 1,4-diethynylbenzene (1j) both the products of mono (2j) and bis hydration (2jj) were obtained under all conditions tested (see Table S1, Supporting Information File 1). The highest selectivity for the generation of 2j

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

• achieved using highly reducing metals, molecular reductants can potentially enable more selectivity, as required for the use of such reactions in the synthesis of molecules bearing various functional groups. In particular, Wanzlick dimers (C=C-bonded dimers of N-heterocyclic carbenes, Figure 1a, i) have

• process (given the reduction potentials in Table 2). As shown in Scheme 1, we found 2-iodobenzyl chloride is cleanly converted to benzyl chloride under the standard conditions used in Table 2 (see Supporting Information File 1, Table S4 for more details). This selectivity is not typically achievable using

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• planar π surfaces of anion–π catalysts. The A/D product ratio is thus a convenient measure for anion–π catalysis, the larger the better, with A/D > 1, the intrinsic selectivity for decarboxylation has been inverted [2][3][18]. Applying lessons from simpler anion–π catalysts, trialkylamines were tethered

• derivatives. In fullerene 8, this is an amide with a short ethylene tether for the tertiary amine (Figure 3). Fullerene 8 catalyzed the formation of the addition product 6 with high selectivity over the decarboxylation product 7 [12]. The experimental product ratio A/D8 was divided by the product ratio A/D9

• product 26 and exo product 27 [64][65][66]. With the less powerful fullerene catalyst 14, the increase of the exo/endo selectivity compared to the fullerene-free control 12, i.e., exo/endo14/12 = 1.1, was negligible [12]. With the best fullerene catalyst 21, the presence of the fullerene made 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 of La@C2v-C82 is an easy and effective method for controlling its reactivity and selectivity via ionization for the production of La@C2v-C82 derivatives. Experimental General: All chemicals and solvents were obtained from Wako, TCI, and Aldrich and were used without further purification unless

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• , acetonitrile, with 91–100% efficiency, and the catalyst was reused in five reaction cycles without the loss of activity and selectivity. Keywords: baclofen; catalyst recovery; lipophilic cinchona squaramide; organocatalysis; stereoselective catalysis; Introduction In today’s chemical industry, catalytic

• flow systems. Accordingly, the main recycling methods rely on the immobilization of catalysts on heterogeneous supports, however, this could often lead to the deterioration of activity and/or selectivity [27]. A possible solution to avoid these drawbacks is the heterogenization of the catalyst after a

• addition of trans-β-nitrostyrene (12) and acetylacetone (13). Choosing the best solvent for the reaction is crucial, thus, solubility tests were carried out (Table 1). Since homogeneous catalysts usually exhibit higher activity and selectivity than their heterogeneous counterparts [27], our aim was to

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• specificity in the synthesis of β-alkylated styrenes 5. This study underscored the broad applicability and selectivity of the NaI/PPh3 catalytic system in facilitating the synthesis of β-alkylated styrenes using diverse redox-active esters. It is worth highlighting that triphenylphosphine is not essential for

• of fused ketones 34, eliminating the need for transition-metal catalysts or oxidants. The technique offered a broad substrate scope, remarkable selectivity, and simple reaction conditions. A plausible mechanism had been proposed for the photocatalytic decarboxylative [3 + 2]/[4 + 2] annulation, as

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

• concentration of this greenhouse gas by upcycling. Selectivity towards CO2-reduction products is highly desirable, although it can be challenging to achieve since the metal-hydrides formation is sometimes favored and leads to H2 evolution. In this work, we designed a cobalt-based catalyst, and we present herein

• its physicochemical properties. Moreover, we tailored a fully earth-abundant photocatalytic system to achieve specifically CO2 reduction, optimizing efficiency and selectivity. By changing the conditions, we enhanced the turnover number (TON) of CO production from only 0.5 to more than 60 and the

• selectivity from 6% to 97% after four hours of irradiation at 420 nm. Further efficiency enhancement was achieved by adding 1,1,1,3,3,3-hexafluoropropan-2-ol, producing CO with a TON up to 230, although at the expense of selectivity (54%). Keywords: carbon monoxide selectivity; cobalt(II) complex; copper(I

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

• aprotic solvents (1,4-dioxane or DME), the selectivity of the reaction dramatically decreased and a mixture of 5 and 6 along with significant amounts of various unidentified byproducts was formed. For example, the reaction of 4 with N2H4∙H2O (4.1 equiv) in refluxing 1,4-dioxane for 2 h, followed by

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• enhanced sensitivity, selectivity, and accuracy in biomarker detection, physiological parameter monitoring, and disease diagnosis. Furthermore, their efficient charge transport properties make them valuable in improving energy storage and conversion systems, including batteries and supercapacitors. The

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

• binding towards different cationic species [48][87][113]. Additional efforts have been directed towards designing and synthesising alkali and other cation sensors based on capped crown ether porphyrins, providing enhanced sensitivity and selectivity for specific cations [114][115][116][117][118][119

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• a powerful tool for polymer crosslinking and preparation of materials with enhanced properties. 3.3 Polymer surface modification When modifying the surface of polymers, chemical selectivity typically plays a minor role, while harsh reaction conditions are useful for the modification of chemically

C–H bond functionalization: recent discoveries and future directions

• Indranil Chatterjee

Beilstein J. Org. Chem. 2023, 19, 1568–1569, doi:10.3762/bjoc.19.114

• well as famous Noble-prize-winning cross-couplings, therefore approaching another step up towards sustainability. Likewise, a free-radical process is also a classical way to functionalize nonactivated C−H bonds in which site selectivity arises either from the relative strength of the C−H bonds or from

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• affinity and selectivity of the R[4]A–amine complexes depend on several factors, including the size, shape, and functional groups of both the host and the guest molecules. For example, R[4]A derivatives with different substituents on the aromatic rings [12] have been synthesized to enhance the binding

• affinity and selectivity towards specific amines. In addition to their potential applications in sensing and molecular recognition, R[4]A have also been studied for their potential pharmaceutical [13] and biochemical [14] applications. R[4]A typically exhibit complex structures containing over a hundred

Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials

• Jessica Villegas,
• Bryce C. Ball,
• Katelyn M. Shouse,
• Caleb W. VanArragon,
• Ashley N. Wasserman,
• Hannah E. Bhakta,
• Allen G. Oliver,
• Danielle A. Orozco-Nunnelly and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2023, 19, 1511–1524, doi:10.3762/bjoc.19.108

• this bioactivity screening of the structural variants is to identify unique selectivity in antimicrobial effects, as compared to the original plant-derived compounds. Results and Discussion Prior to evaluating the activity of berberine and chelerythrine variants against the full panel of 12 microbes

• markedly less potent towards fungi. Though antifungal properties are desirable, selectivity for prokaryotic over eukaryotic cells would be beneficial for a selective antibacterial treatment. A two-tailed T-test analysis (with significance set at P ≤ 0.05). revealed that these differences in activity for

• against all Gram-positive strains, with exceptional activity against S. epidermidis. This variant further enhanced the bacterial selectivity, as its heightened antibacterial levels were coupled with notable decreases in antifungal activity as compared to berberine. A graph showing a complete comparison of

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

• , and TMSOTf resulted in good chemical yields. In the transformation, the selectivity of the endo or exo cyclization depended on the atom number of the chain between alkene and arene, leading to the formation of 6-, 7-, or 8-membered rings. In addition to N-(thio)phthalimides, benzenesulfenyl chloride

• exo ratio was either related to the electron density of the alkene or the steric effect of a substituent. The tether lengths could affect the cyclization. For example, the two-carbon-tethered substrate completely showed endo selectivity, while the four-carbon-tethered substrate exclusively led to

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• File 1, Tables S4 and S5, Figures S20–S31) as those of 4, the corresponding homolog of 6, and 5, a homolog of the 2MIBS side product 1-methylcamphene (7) (Scheme 2C). The stereochemical course for the cyclisation of the GPP analogs GA-1 and GA-2 with respect to the face selectivity at C-7 is reflected

α-(Aminomethyl)acrylates as acceptors in radical–polar crossover 1,4-additions of dialkylzincs: insights into enolate formation and trapping

• Angel Palillero-Cisneros,
• Paola G. Gordillo-Guerra,
• Fernando García-Alvarez,
• Olivier Jackowski,
• Franck Ferreira,
• Fabrice Chemla,
• Joel L. Terán and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2023, 19, 1443–1451, doi:10.3762/bjoc.19.103

• , we investigated further the reaction conditions starting with enoate 8a as model substrate (Table 3). Carrying out the reaction at −78 °C instead of −33 °C was deleterious both for the yield and the selectivity (Table 3, entry 2). By contrast, we rapidly learned that leaving diethylzinc in contact

• carbonyl and sulfinyl unit to achieve good levels of selectivity. Hence, to reinforce Lewis pair formation, the reaction was also carried out in apolar solvents such as toluene and hexane (entries 4 and 5 in Table 3). In hexane, an 88% yield with 85:15 dr was obtained, which constituted the best conditions

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

• stable; as a result, the stability of the resulting metal complexes is enhanced [14]. This has led to the development of a variety of NHC-incorporating metal compounds exhibiting increased activity/selectivity in catalysis [15]. Nature of the NHC–metal bond NHCs constitute a well-established class of

• substrates and alkylboranes. Later in 2012, Hoveyda and co-worker [63] used chiral bidentate NHC–Cu complexes bearing sulfonates, which was critical to regioselectivity and resulted in high selectivity for the γ-position. Thus, allenyl-containing products were generated in up to 95% yield and 99:1 er. The

• the A3 reaction is catalyzed by the NHC–Cu complex while the selective hydrogenation is catalyzed by Ru(0) nanoparticles. The versatility of this tandem catalytic approach was established by using a wide range of substrates. Furthermore, the catalytic activity and selectivity remained fairly constant

One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

• Hans-Ulrich Reissig and
• Fei Yu

Beilstein J. Org. Chem. 2023, 19, 1399–1407, doi:10.3762/bjoc.19.101

• other triazolyl-substituted aminopyran derivatives we encountered similar selectivity problems due to the sensitivity of benzylic bonds to the applied hydrogenolysis conditions [59]. Despite of the discouraging results with model compound 23 we nevertheless examined the reductive cleavage of bis(1,2,3

• reaction time and the fairly high amount of catalyst employed. As an alternative method, which should be more chemoselective, we examined the reduction with samarium diiodide [60]. This versatile one-electron transfer reagent is known to cleave N–O bonds with high selectivity [61][62] and was applied

Functional characterisation of twelve terpene synthases from actinobacteria

• Anuj K. Chhalodia,
• Houchao Xu,
• Georges B. Tabekoueng,
• Binbin Gu,
• Kizerbo A. Taizoumbe,
• Lukas Lauterbach and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1386–1398, doi:10.3762/bjoc.19.100

• , while with GGPP an efficient conversion with high selectivity into allokutznerene (28), known as a minor product of bacterial phomopsene synthase [50], was observed (Figure 8A and 8B). It is interesting to note that the low sequence identity between phomopsene synthase and Kutzneria konfuensis

• activity with formation of a product mixture. The 7-epi-α-eudesmol synthase from Streptomyces flavidovirens showed a loss of function and selectivity with formation of hedycaryol and germacrene A. This observation may be interpreted as the starting point towards pseudogenisation within the branch of 7-epi

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

• are numerous and aimed to improve its efficacy and/or the selectivity that could also reduce side effects. In the next section, we report a selection of the molecular modifications that are classified depending on the position of the glycerol moiety (sn-1 lipid chain; sn-2; sn-3 polar head group

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

• significantly different reactivity and chemical selectivity from noble metals (Ru, Rh, Pd). Compared with noble metals, copper catalysts are cheaper and easier to obtain, making Cu more advantageous for industrial applications of C–H functionalization reactions. The Glaser–Hay reaction may be one of the oldest

• through double C(sp3)–H/C(sp3)–H functionalization using 2,2,6,6-tetramethyl-N-oxopiperidin-1-ium tetrafluoroborate (T+BF4−) salt as the oxidant (Scheme 5) [53]. A catalytic amount of Ac2O played a significant role in the reaction, which can significantly improve the yield and selectivity of the reaction

• coordinated with metal catalysts to control the selectivity and improve the reactivity in metal-catalyzed or -mediated reactions. Therefore, controlling the regioselectivity of CDC reactions by directing groups is of great interest [95][96]. Li et al. reported a cobalt-catalyzed CDC between unactivated C(sp2

Acetaldehyde in the Enders triple cascade reaction via acetaldehyde dimethyl acetal

• Alessandro Brusa,
• Debora Iapadre,
• Maria Edith Casacchia,
• Alessio Carioscia,
• Giuliana Giorgianni,
• Giandomenico Magagnano,
• Fabio Pesciaioli and
• Armando Carlone

Beilstein J. Org. Chem. 2023, 19, 1243–1250, doi:10.3762/bjoc.19.92

• proved to yield the desired product, indicating that the catalytic system may indeed be applicable. Lowering the amount of organocatalyst 1 to 10 mol % (Table 1, entry 2) resulted in a decrease of both yield and selectivity. Based on the results obtained (Table 1, entry 2) and the reaction conditions

• selectivity, measured as the ratio between yield and conversion (Table 2, entry 1). This means that the productivity of the reaction using 6 is superior, since far more substrate was converted into the desired product. A solvent screening (see Supporting Information File 1) did not reveal any better

• alternative to toluene. The use of chloroform (Table 2, entry 2), as in our previous report [17], showed an improvement on selectivity, however, toluene was chosen as a more benign solvent. After further optimization of the acidic resin, stoichiometry, concentration, temperature, and reaction time (see

Radical ligand transfer: a general strategy for radical functionalization

• David T. Nemoto Jr,
• Kang-Jie Bian,
• Shih-Chieh Kao and
• Julian G. West

Beilstein J. Org. Chem. 2023, 19, 1225–1233, doi:10.3762/bjoc.19.90

• functionalization of alkyl radicals, with successful synthetic reactions requiring efficiency and selectivity in both of these processes and inherent compatibility between each. Radical generation has benefitted from many general mechanistic approaches, including hydrogen atom transfer (HAT) [5], alkene addition [6

• the power of RLT to install a variety of medicinally relevant groups, largely mirroring the selectivity of CYP450s. Intriguingly, studies by Groves have revealed earth abundant iron and manganese to be particularly privileged for this application of RLT, a major advantage for sustainable method

• , including terminal aliphatic alkenes, internal (cyclic) styrenes, and one example of a nonconjugated diene, suggesting RLT to be compatible with many functionalities. The diastereoselectivity of the reaction varies, with high anti-selectivity being achieved with cyclic styrenes and low diastereoselectivity