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

• the substrate achieved the activation of the C(sp2)–H bond. Other non-noble metal-catalyzed reactions In 2013, Liu et al. reported that MnO2 could catalyze the CDC of the benzylic C(sp3)–H bond in benzyl ethers with α-carbonyl C(sp3)–H bonds in the presence of air at room temperature (Scheme 33) [98

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• byproducts, and increased efficiency in industrial processes. As such, this field of research is of great importance and interest to both academia and industry. This work showcases a sustainable and catalyst-free oxidation method for heteroatoms (e.g., S, P, and Se) using only air, water and light. An

• selectivity and safety. Traditional oxidants, such as Oxone, CrO3, NaIO4, or KMnO4, produce significant amounts of toxic waste, exacerbating these issues (Scheme 1A) [1]. As environmental concerns and economic factors increasingly affect chemical processes, hydrogen peroxide and oxygen (or air) are becoming

• ) [2][3][4]. Additionally, practical implementation of hydrogen peroxide can be challenging due to requirements for precise dosing to avoid issues such as dismutation, overoxidation, and catalyst degradation [5]. In this respect, oxygen, or preferably air, represents a better alternative to traditional

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• fluorescence under nitrogen atmosphere and a substantial quenching under air or oxygen atmosphere [22], the fluorescence spectra of the dyads containing native PTZ unit under different atmospheres were studied (Figure 3a–d and Figure S32a in Supporting Information File 1). The results show that the

• fluorescence intensity of the dyads is stronger under a N2 atmosphere, but is significantly quenched under air atmosphere. The fluorescence intensity under N2 atmosphere is 2–4 times higher than that under an air atmosphere. However, for the dyads with an oxidized PTZ unit (Figure 3e and 3f and Figure S32b in

• Supporting Information File 1), the fluorescence intensity is less dependent on the atmosphere. Moreover, we suggest that the reduced luminescence of the oxidized molecules in air may be caused by the quenching effect of oxygen to the S1 state. According to this experimental phenomenon, we preliminarily

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• 2013, Zhang and co-workers [67] reported the preparation of a new recyclable magnetic nanoparticle-supported antimony catalyst (γ-Fe2O3@SiO2-Sb-IL) and its application in the filtration-free, Clauson–Kaas synthesis of N-substituted pyrroles. This catalyst is fairly easy to make, air stable, and

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

• mol·L−1 hydrochloric acid solution, heated at 70 °C, cooled and filtered. The filtrate was slowly evaporated in air (about 10 days) to obtain colorless crystals. Ultraviolet–visible absorption and fluorescence spectroscopy An aqueous solution of TMeQ[6] and G@TMeQ[6] at 3.0 × 10−5 mol L−1 was prepared

Honeycomb reactor: a promising device for streamlining aerobic oxidation under continuous-flow conditions

• Masahiro Hosoya,
• Yusuke Saito and
• Yousuke Horiuchi

Beilstein J. Org. Chem. 2023, 19, 752–763, doi:10.3762/bjoc.19.55

• , which diminishes the atom economy [2]. To overcome this limitation, the use of molecular oxygen (O2) present in air as an oxidant is one of the ideal solutions [10][11]. The reduction of O2 generates only water as a byproduct, leading to high atom-economy processes. However, the use of O2 as an oxidant

• air was switched to an O2 balloon to increase the partial pressure of O2 (Table 2, entry 1 vs 2 and 3 vs 4). At room temperature, the reaction rate did not increase although the partial pressure of O2 increased approximately five times with this change. In contrast, at 60 °C, the reaction rate

• the solubility of O2, is not the rate-determining step. Therefore, the reaction rates under open air and O2 balloon did not differ. On the other hand, increasing the temperature decreased the solubility of O2, which converted the catalytic cycle A to the rate-determining step at 60 °C. When the

Palladium-catalyzed enantioselective three-component synthesis of α-arylglycine derivatives from glyoxylic acid, sulfonamides and aryltrifluoroborates

• Bastian Jakob,
• Nico Schneider,
• Luca Gengenbach and
• Georg Manolikakes

Beilstein J. Org. Chem. 2023, 19, 719–726, doi:10.3762/bjoc.19.52

• to the formation of the arylgylcine in trace amounts (Table 1, entries 2–5). Contrary to our previous report with arylboronic acids, the presence of air is highly detrimental to the reaction outcome (Table 1, entry 6). Therefore, inert conditions were employed throughout all subsequent studies

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

• using air as the sole oxygen source. Keeping in mind the progress in photochemical relay catalysis [24] and the attention paid to photocatalytic carbon-bond functionalization in the past several years [25], here we developed an organophotoredox-catalyzed C–H functionalization of imidazo[1,2-a]pyridines

• functionalizations of IPs and present work. Substrate scope. Conditions: unless otherwise noted, all reactions were carried out with 1 (0.2 mmol), 2 (0.4 mmol), PTH (5 mol %), Zn(OAc)2 (0.6 mmol), dry 1,2-DCE (2 mL), irradiation with LEDs (λmax = 390 nm), under air for 10 h. Mechanistic investigations. Plausible

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• at the liquid–air interface, testing solutions with a 2 mL volume were used. Fluorescence and CD spectra were recorded using appropriate 1 cm path quartz cuvettes; UV–vis spectra were recorded in 1 cm path quartz cuvettes or using an immersion probe with 5 cm light path length. Isothermal titration

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• air or moisture sensitive). Under these mild reaction conditions, a panel of α-(hetero)arylacrylamides were trifluoromethylthiolated in good to high yields. Acrylamides substituted at the α-position by an aryl bearing an electron-donating group (OMe) or halogen (Cl) at the para-position were readily

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• milling the ligand precursor 1 with metallic copper powder in air [45]. Another mechanochemical pathway was published using K2CO3 as a base and copper(I) chloride [46][47]. This latter procedure is practical, avoids the use of solvents, and relies on an abundant and cheap base. We have recently disclosed

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• and the isomeric corniculatolides. The isolation of the compounds was achieved from 5 kg of air-dried bark of the aforementioned tree, which was grounded and then extracted with CHCl3 using a Soxhlet apparatus, furnishing 32.0 g of the crude extract. This extract was subjected to a vacuum liquid

• Indian Ocean coastline. The air-dried stems of X. granatum (5 kg) were powdered and extracted successively within hexane, CHCl3, and acetone in a Soxhlet apparatus. The crude CHCl3 extract (21 g) was chromatographed on silica gel (230–400 mesh) vacuum liquid chromatography (VLC) in different gradients of

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

• , rt, 24 h, aq PF6−, (iii) CoCl2∙6H2O, THF/acetone, rt, air bubbling, overnight, (iv) KBr, THF/acetone, rt, 5 d. Synthesis of triazole-linked porphyrin-bearing N-doped graphene hybrid 96. Synthesis of meso-triazole-linked porphyrin-fullerene dyads 100a–d and 104a,b. Synthesis of meso-triazole-bridged

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• ][9]. Metathesis reactions take place by the means of a metallic catalyst. Firstly, olefin metathesis was achieved with an air-sensitive tungsten complex [8]. An important focus on air-stable catalyst design was undertaken and contributed to the popularization of the reaction. Thus, Grubbs catalysts

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

• presented by Wilke and colleagues in 1986 [17]. At that time, chloroaluminate ionic liquids were used both as a solvent and catalyst [18][19], but these systems proved to be unstable under ambient air conditions and prone to decompose in the presence of water [20]. In the following years, ionic liquids

• cost-efficient metal salts in a water and air stable ionic liquid is still hard to find [50][51]. In this contribution, we present the use of imidazolium-based tunable aryl alkyl ionic liquids (TAAILs) in a catalytic Friedel–Crafts acylation. This relatively new class of ionic liquids [52] previously

• robust system for a catalytic Friedel–Crafts acylation. The reaction was carried out at moderate temperatures of 40 °C to 60 °C under air, was scalable to gram-scale and tolerated different electron-rich benzene derivatives as well as anhydrides. The catalytic performance depends on the choice of ionic

Nostochopcerol, a new antibacterial monoacylglycerol from the edible cyanobacterium Nostochopsis lobatus

• Naoya Oku,
• Saki Hayashi,
• Yuji Yamaguchi,
• Hiroyuki Takenaka and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2023, 19, 133–138, doi:10.3762/bjoc.19.13

• ), or Dok Hin (stone flower) [11]. It is consumed as an ingredient of salad and as a folk medicine to treat pain from stomach ulcers or fever [9]. In fact, an ethanolic extract of the air-dried alga was found to inhibit the development of gastric ulcers, suppress ethyl phenylpropiolate-induced edema on

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• . The second process (45spFoam*) consists of introducing 20 mL of the stock solution into a large crystallizer, where the liquid height reaches around 1 cm. The liquid is stirred during 5 min at high speed to make an air/water emulsion. The resulting foam is quickly frozen at −40 °C, lyophilized

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• synthesis of tridachiapyrone B was not investigated, even though it seems conceivable that the compound’s stability to light, air or cytochrome would be higher than its 1,3-cyclohexadiene counterpart. As the molecule combines electron acceptor functions such as α’-methoxy-γ-pyrone and 2,5-cyclohexadienone

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• crude product is mixed with a carrier solvent and an air flow to generate a gas–liquid flow pattern. This is then directed into three different coils held at different temperatures where the solid product precipitates in a controlled manner prior to isolation by filtration. As the same solvent is used

• crystallization procedure regardless of the manufacturing scale [117]. An air-segmented flow crystallizer was developed by Cooks and co-workers for the synthesis and purification of diphenhydramine [118]. In this study ethyl acetate was used as antisolvent and careful control of nitrogen flow (used to obtain

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• include their synthetic availability, wide opportunities for rational structure design, generally lower toxicity, air and water stability, metal-free nature, and the scalability of their production and use. These features have made organocatalysis a prospering area and an even more promising methodology

An alternative C–P cross-coupling route for the synthesis of novel V-shaped aryldiphosphonic acids

• Stephen J. I. Shearan,
• Enrico Andreoli and
• Marco Taddei

Beilstein J. Org. Chem. 2022, 18, 1518–1523, doi:10.3762/bjoc.18.160

• note here that the system is kept under a constant flow of either argon or nitrogen, mainly to avoid side reactions with components in the air (humidity, oxygen), but also to prevent the solid in the addition funnel from contacting any vapour and turning soggy before it is added to the round-bottomed

Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities

• Hongling Shui,
• Yuhong Zhong,
• Renshi Luo,
• Zhanyi Zhang,
• Jiuzhong Huang,
• Ping Yang and
• Nianhua Luo

Beilstein J. Org. Chem. 2022, 18, 1507–1517, doi:10.3762/bjoc.18.159

• synthesize and stable to air [36], and have good operability and reproducibility [37][38]. In recent years, our research group has carried out relevant research on ADC reactions catalyzed by cyclometalated iridium complexes and obtained some interesting research results [39]. In previous studies [39][40][41

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• S26). As a preliminary study to assess the existence of TADF for the dyads and the triad, the fluorescence spectra of the compounds in N2-saturated and air-saturated solution were recorded (Figure 3 and Figure S27 in Supporting Information File 1). For both NI-PTZ and NI-PTZ2, the fluorescence

• . Fluorescence spectra of (a) NI-PTZ, (b) NI-PTZ-O, (c) NI-PTZ2, and (d) NI-Ph-PTZ in HEX under different atmospheres (N2, air). Optically matched solutions were used, A = 0.100, λex = 330 nm, c = 1.0 × 10−5 M, 20 °C. Fluorescence lifetime of NI-PTZ under (a) N2 atmosphere and (d) air atmosphere (λem = 610 nm, c

• = 5.0 × 10−5 M). Fluorescence lifetime of NI-PTZ2 under (b) N2 atmosphere and (e) air atmosphere (λem = 610 nm, c = 5.0 × 10−5 M). Fluorescence lifetime of (c) NI-PTZ-O (λem = 472 nm, c = 1.0 × 10−5 M) and (f) NI-Ph-PTZ (λem = 482 nm, c = 1.0 × 10−5 M). Excited with a picoseconds pulsed laser (λex = 340