Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process

• Kazuhiro Okamoto,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2024, 20, 264–271, doi:10.3762/bjoc.20.27

• cyclic voltammogram of 1. (B) Cyclic voltammograms of 1 in the presence of additives (AcOH or HFIP). (C) Comparison of oxidation potentials of 1 using Bu4NOAc or Bu4NCl. (D) Cyclic voltammograms for the cathodic side. All cyclic voltammograms were recorded in CH2Cl2/Bu4NPF6 (0.1 M). Sample concentration

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• rearrangement. Since the Hock rearrangement results in the formation of a molecule of water, we attempted to add a water scavenger to the reaction solution. Additives like molecular sieves 4 Å or Na2SO4 (2 equiv) did not show any improvement (Table 1, entry 3), while MgSO4 (2 equiv) had a stunning effect

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• usually occur under mild conditions, they typically require expensive metal-based photocatalysts or structurally complex organic dyes [18]. Therefore, the development of a photoinduced cascade reaction without the need of additional catalysts or additives remains highly desirable [19]. The introduction of

• room temperature without additives. Mechanistic investigations support a photochemical process initiated by the homolysis of Umemoto's reagent under visible light irradiation. This method provides rapid access to a diverse range of trifluoromethylated dihydropyrido[1,2-a]indolone derivatives in

Synthesis of N-acyl carbazoles, phenoxazines and acridines from cyclic diaryliodonium salts

• Nils Clamor,
• Mattis Damrath,
• Thomas J. Kuczmera,
• Daniel Duvinage and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 12–16, doi:10.3762/bjoc.20.2

• fluorophors, previously shown to exhibit strong organic phosphorescence when mixed with specific additives [1][2][3][4][5]. Carbazole units are also found in drugs and natural products. They are also used in electrochemistry and as reagents in transamidation reactions [6][7][8][9][10][11][12]. The traditional

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

• developing the major components of a photocatalytic system for CO2 reduction, such as the photosensitizer (PS), the catalyst, and the sacrificial electron donor (SeD). Nevertheless, the solvent and eventual additives play an important role too [6], as they can influence the (photo)redox properties of the

Synthesis of 7-azabicyclo[4.3.1]decane ring systems from tricarbonyl(tropone)iron via intramolecular Heck reactions

• Aaron H. Shoemaker,
• Elizabeth A. Foker,
• Elena P. Uttaro,
• Sarah K. Beitel and
• Daniel R. Griffith

Beilstein J. Org. Chem. 2023, 19, 1615–1619, doi:10.3762/bjoc.19.118

• vast body of knowledge built from many synthetic campaigns towards the Strychnos alkaloids [15]. Several combinations of palladium catalyst, base, and other additives were applied to our system (see Table 1, entries 1–4). Reaction conditions such as those deployed to great effect by Rawal [16] (Table 1

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

• crosslinking of polymers. Polymeric materials may become brittle or colored after being exposed to sunlight for a long time, which was called 'photo-ageing' [134]. In fact, the light sensitivity of many polymers results from some impurities or additives remaining in polymer materials, which can form radical

• crosslinking of photosensitized elastomers. Samples of an EPDM (ethylene-propenebutadiene) terpolymer were prepared with different additives. Observable crosslinking products were obtained through irradiation of different wavelengths. Besides the side reactions induced during photoageing, rational

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• decomposition of azides at higher temperatures required the use of 2a or 2b in excess. No significant difference in yields between 1.5 equiv and 2 equiv of the aryl azide was observed. Adding fluorophilic additives (TMSCl, Table 1, entry 5) or using copper as other transition metal (CuCl or Cu(OAc)2, Table 1

• % yields. It has to be noted, that CuSO4 (1 equiv) was used as an additive for the synthesis of product 4e containing a p-fluoro substituent which improved the yield to 56%. Under regular optimized conditions without CuSO4, product 4e was formed in only 22% yield. However, CuSO4 or any other Cu additives

Metal catalyst-free N-allylation/alkylation of imidazole and benzimidazole with Morita–Baylis–Hillman (MBH) alcohols and acetates

• Olfa Mhasni,
• Jalloul Bouajila and
• Farhat Rezgui

Beilstein J. Org. Chem. 2023, 19, 1251–1258, doi:10.3762/bjoc.19.93

• reflux with an azeotropic distillation, was successfully carried out with no catalysts or additives, affording the corresponding N-substituted imidazole derivatives in good yields. On the other hand, in refluxing toluene or methanol, the aza-Michael addition of imidazole onto acyclic MBH alcohols was

• these substrates and the formation of water as the sole non-toxic byproduct in the reaction [11]. In general, the previous methods for the amination of MBH alcohols needed catalysts or additives such as FeCl3 [12][13], In(OTf)3 [14], MoCl5 [15], AuCl3 [16], and I2 [17] as Lewis acids. Alternatively

• (Table 2, entry 1). Moreover, the addition of additives to the previous reaction mixture, such as DMAP [24][25][26][31] or molecular sieves 4 Å, commonly used to mediate nucleophilic allylic substitutions, did not lead to a notable improvement of the reaction outcome (Table 2, entries 2 and 3). However

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

• additional reaction pathway is proposed in which the incorporated oxygen on the heteroatoms originates from water. Furthermore, the addition of certain additives enhances productivity by affecting kinetics. The industrial potential is demonstrated by conveniently transferring the batch protocol to continuous

• separate” additives, a significant rate enhancement could be obtained with a positive impact on productivity rates. Results and Discussion There are a lot of similarities between electrochemistry and photoredox chemistry [33] as both rely on single-electron transfer processes to initiate reactions. In

• of water (Table 1, entries 1 and 2), the addition of oxygen (entries 1, 5, and 6) and light in the UV-A region (entries 8 and 9) turned out to be crucial (see Supporting Information File 1, Table S2). Additives With the ultimate goal in mind to develop a safe and scalable protocol in continuous flow

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

• terms generating one photon is cheaper than two (or more). Electrons (/holes, in the form of applied potential) are cheaper than photons as well. Regarding the additives necessary for the processes, even if electrolytes needed to reduce the Ohmic drop in PEC reactions are more expensive or more abundant

Copper-catalyzed N-arylation of amines with aryliodonium ylides in water

• Kasturi U. Nabar,
• Bhalchandra M. Bhanage and
• Sudam G. Dawande

Beilstein J. Org. Chem. 2023, 19, 1008–1014, doi:10.3762/bjoc.19.76

• types of hypervalent iodine reagents, diaryliodonium salts are commonly used reagents for the N-arylation of nitrogen-containing compounds, particularly for N-arylation of amines under catalyst-free conditions either in the presence of additives or at higher temperatures [26][27][28][29][30][31][32

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

• the presence of 5 mol % p-TsOH∙H2O. In contrast, method 2 involves a greener protocol in which amides 68 and 2 are reacted under microwave condition at 150 °C for 30–60 min without the use of additives or solvents. Furthermore, these sulfonylpyrroles were converted to the corresponding sulfonic acid

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

• at 120 °C, Cu(OAc)2 was found crucial for the transformation in comparison to other additives and showed good substrate scope while unactivated alkenes like styrene resulted in no reaction. Also, the authors successfully applied the developed protocol to a multigram-scale synthesis of compound 101, a

• of pyridine at the C2 and C3 position (Scheme 35a). Further, during optimization when silver additives like Ag2CO3, Ag2O, and AgOAc were used the reaction resulted in the formation of isoquinoline derivative 181. In addition, the reaction showed high regioselectivity in the presence of unsymmetrical

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

• investigate the influence of various fluoride scavengers as additives in the three-component process [25][26]. An extensive study (not shown), revealed that most common scavengers either led to a decreased yield, a decreased stereoselectivity or a combination of both. Yet a combination of CaCO3, tartaric acid

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry

• Eric Gayon,
• Guillaume Lefèvre,
• Olivier Guerret,
• Adrien Tintar and
• Pablo Chourreu

Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15

• sustainable synthetic procedures involving cheap, non-toxic and efficient additives is also discussed, as well as the mechanistic features guiding the reactivity of such catalytic systems. Keywords: catalysis; cross-coupling; insect pheromones; iron; Introduction Public health issues related to

• cross-coupling field. Discussion The quest for non-toxic and efficient additives for iron-mediated cross-coupling reactions Co-solvents used as NMP surrogates In spite of the very good yields and soft conditions provided by Cahiez’ method (Scheme 2b), a major drawback of the latter is the requirement of

• quest for suitable additives as surrogates of NMP. Szostak and Bisz reported in 2019 that N-methyl-ε-caprolactame (NMCPL) could be used as an alternative solvent, and sp3–sp2 cross-coupling reactions proceeding with good to excellent yields were reported. Alkyl Grignard reagents could thus be used in

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• that no standard set of conditions will suffice to achieve the desired transformations [42][58][59]. This is certainly our own experience in our lab. The optimal reaction times, additives, pH, solvents, and reagents (including reagent grades) can be surprisingly substrate dependent. Nevertheless, given

Practical synthesis of isocoumarins via Rh(III)-catalyzed C–H activation/annulation cascade

• Qian-Ci Gao,
• Yi-Fei Li,
• Jun Xuan and
• Xiao-Qiang Hu

Beilstein J. Org. Chem. 2023, 19, 100–106, doi:10.3762/bjoc.19.10

• %) as the catalyst, AgSbF6 (10 mol %) and KOAc (50 mol %) as additives in 1,2-dichloroethane (DCE) at 100 °C for 16 hours. To our delight, the desired isocoumarin 3aa was obtained in 42% yield (Table 1, entry 1). Then, the influence of solvents has been subsequently investigated. As a result, DCE proved

NaI/PPh₃-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

• Dan Liu,
• Yue Zhao and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2023, 19, 57–65, doi:10.3762/bjoc.19.5

• disclosed a visible light-mediated radical tandem cyclization of N-arylacrylamides with N-(acyloxy)phthalimides to access 3,3-dialkylated oxindoles in the presence of [Ru(bpy)3Cl2]·6H2O [46]. However, these seminal methods remain limited by the need of noble-metal-based photocatalysts, excess additives and

• advantage of circumventing the need for external redox additives and/or noble metals, using readily available and cost-effective NaI and PPh3 under mild reaction conditions. In a broader context, phosphine organocatalysis is probably still underappreciated in organic synthesis, and could lead to important

Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation

• Julian Spils,
• Thomas Wirth and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2

• anodic oxidation [37][38][39][40]. Due to the apparent advantages of electrochemical processes, their implementation in flow is simple and straightforward since further dilution or additives are unnecessary [41][42]. One early example of this combination in the field of HVI chemistry is the anodic

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• presence of appropriate additives (Scheme 18). According to the postulated mechanism, the reaction is initiated by an SET of the dicinnamyl ether substrate to Fukuzumi’s salt 233, leading to radical cation 216. Earlier findings of the same group [107] revealed that substitution on the aryl groups is the

• determinant factor for either 8,8’-cis- or 8,8’-trans-cyclization to furan heterocycle cation 218, which serves as the hypothetical common scaffold of the plan. Diverting this mechanistic route to different lignans is possible by introducing nucleophilic additives (e.g., MeOH), oxidants (e.g., Cu(OTFA)2), or

Preparation of an advanced intermediate for the synthesis of leustroducsins and phoslactomycins by heterocycloaddition

• Anaïs Rousseau,
• Guillaume Vincent and
• Cyrille Kouklovsky

Beilstein J. Org. Chem. 2022, 18, 1385–1395, doi:10.3762/bjoc.18.143

• considered the use of additives in order to make the organolithium intermediate more nucleophilic. However, no reaction was observed when ZnMe2 (which was used in the synthesis of leustroducsin B by Trost and co-workers [17]) was added; trimethylaluminum and cerium chloride also failed to promote the

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies

• Attila Palágyi,
• Jindřich Jindřich,
• Juraj Dian and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2022, 18, 1346–1354, doi:10.3762/bjoc.18.140

• , we describe the synthesis of ten pro-fragrances – Schiff bases prepared from amino-β-cyclodextrin and common volatile aldehydes. Aldehydes constitute a prominent class of molecules broadly used as food product additives and are also key components of perfumes [24]. They were therefore chosen as an

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• -cyclopropanated amino acids in the form of Ni(II)–Schiff base complexes were suggested [16][17][18][19], including electrochemical ones [15]. Cyclopropane-containing amino acids are important components of various pharmaceuticals [20][21] and bio-additives [22]. Meanwhile, the cyclopropane fragment not only