Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• heterocycle substitute at the sulfur atom [49][50][54]. Non-enzymatic process of the rat (Wistar) liver homogenate lipid peroxidation (LP) in the presence of additives of target compounds 1–9 was studied in vitro. The concentration of the carbonyl compounds forming in the reaction of the lipid peroxidation

• ). The CV curves of 7 at the potential ranges from –0.5 to 1.3 V (curve 1); from –0.5 to 1.8 V (curve 2) (CH3CN, GC electrode, Ag/AgCl/KCl(sat.), 0.15 M n-Bu4NClO4, c = 3 mmol·L−1). The level of TBARS in rat liver homogenates in vitro, in the presence of compounds 1–9, Trolox, and without additives

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

• additions to imines, comprising alcohols, thiols, phosphonates, diazoacetamides, peroxides, benzothiazolines and more as nucleophiles. Apart from reactant classes, the reactions also vary in additives, and solvent among others. Since these reactions all adhere to the same mechanism of enantioinduction, the

Cell-free protein synthesis with technical additives – expanding the parameter space of in vitro gene expression

• Tabea Bartsch,
• Stephan Lütz and
• Katrin Rosenthal

Beilstein J. Org. Chem. 2024, 20, 2242–2253, doi:10.3762/bjoc.20.192

• osmolarity using ten different technical additives including organic solvents, polymers, and salts. It is shown that the synthesis of two model proteins, namely superfolder GFP (sfGFP) and the enzyme truncated human cyclic GMP-AMP synthase fused to sfGFP (thscGAS-sfGFP), is very robust against most of the

• tested additives. Keywords: cell-free protein synthesis; cGAS; Escherichia coli cell-free extract; sfGFP; TX-TL; Introduction In addition to other applications such as biomanufacturing or biosensing, cell-free protein synthesis (CFPS) of enzymes has established itself as a tool for rapid screening of

• encoding for the target protein, amino acids and nucleoside triphosphates as substrates, an energy regeneration system and other additives such as polyethylene glycol (PEG) [9]. Although CFPS has been used and improved since the 1960s, there are challenges in its application such as low production volumes

Factors influencing the performance of organocatalysts immobilised on solid supports: A review

• Zsuzsanna Fehér,
• Dóra Richter,
• Gyula Dargó and
• József Kupai

Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183

• generated by altering the reaction conditions during synthesis [52][53][54][55][56][57] or by using potassium chloride or ammonium fluoride salts as additives [58][59][60]. In a comprehensive study [61], the catalytic properties of three types (rope, rod and fibre) of mesoporous silica Santa Barbara

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• -membered cyclic diboron compounds 18 undergo an insertion reaction of isocyanides into the boron–boron single bond of 18 under mild conditions without the addition of any additives (Scheme 11a) [48]. The reaction is thought to proceed by an ionic mechanism. Recently, several insertion-type reactions of

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• product in the reaction, with a yield of 86% in 20 minutes (Table 1, entry 1). Encouraged by this result, we added additives to the reaction with the aim of further increasing the chemical yield of 2a. When 1.5 equivalents of water were added to the reaction, the yield of 2a dropped to 79% (Table 1, entry

Novel oxidative routes to N-arylpyridoindazolium salts

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

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• . Our experiments with the acid additives (see above) showed that protonation of the pyridyl group suppresses the pyridoindazolium salt formation. Voltammetry testing also showed that 2,6-lutidine addition facilitates oxidation of the amine (Figure 2); the peak potential was of 100 mV shifted toward

• into the reaction mixture (Figure 4a,b). Notably, the effect was more pronounced in the presence of lutidine, especially in the case of TEMPO. The difference between the oxidation potential of A3 and the potential of the TEMPO/TEMPO+ redox couple is rather significant (ca. 0.35 V); the base additives

• useful compounds with multiple functionalities that were poorly available previously. CV curves for salt S2 and corresponding amine A2 (left, Figure 1a) and salt S3 with and without diethyl malonate additives (right, Figure 1b). (Pt, MeCN, 0.1 M Bu4NBF4, 0.1 V/s, vs Ag/AgCl, KCl(sat.). CV curves for

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• iodanes (NHIs) as suitable reagents for the mild oxidation of activated alcohols. Two different protocols, both involving activation by chloride additives, were used to synthesize benzylic ketones and aldehydes without overoxidation in up to 97% yield. Based on MS experiments an activated hydroxy(chloro

• the corresponding carboxylic acids [16]. Additives such as bromide salts or Al2O3 can eliminate this problem and allow selective oxidation to some extent [17][18][19][20]. During the past years, N-heterocycle-stabilized iodanes (NHIs) were demonstrated as suitable tools for various applications among

• ). At this temperature, the reaction time was significantly reduced to 2.5 h. A variety of other additives were tested next, revealing TsOH or NaOTs inhibiting the reaction (Table 1, entries 2 and 3). The addition of tetrabutylammonium halides showed the chloride salt being superior, giving comparable

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

• Pooja Goyal,
• Akhil K. Dubey,
• Raghunath Chowdhury and
• Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

• solvent, as the product 3aa was isolated in reproducible yield (77%) and enantioselectivity 74% ee (Table 1, entry 3). Next, we explored a variety of achiral and/or chiral Brønsted acids A1–6 as additives in order to increase the yield and the enantioselectivity of the reaction (Table 1, entries 4–9). A

Synthesis of 2-benzyl N-substituted anilines via imine condensation–isoaromatization of (E)-2-arylidene-3-cyclohexenones and primary amines

• Lu Li,
• Na Li,
• Xiao-Tian Mo,
• Ming-Wei Yuan,
• Lin Jiang and
• Ming-Long Yuan

Beilstein J. Org. Chem. 2024, 20, 1468–1475, doi:10.3762/bjoc.20.130

• additives in the petrochemical industry [3]. Besides, 2-benzylanilines also serve as valuable building blocks in synthetic chemistry [4]. The classical route to this kind of aniline derivatives usually starts from parent anilines, which undergo Friedel–Crafts reaction with acyl halides followed by carbonyl

• -benzylidenecyclohex-3-en-1-one (2a) and 4-methoxybenzylamine (3a) as starting materials to investigate the feasibility and efficiency of the reaction (Table 1). Initially, the reaction was conducted in the presence of 2.0 equiv of 3a in toluene at 60 °C without any addition of catalysts or additives. To our delight

Hypervalent iodine-catalyzed amide and alkene coupling enabled by lithium salt activation

• Akanksha Chhikara,
• Fan Wu,
• Navdeep Kaur,
• Prabagar Baskaran,
• Alex M. Nguyen,
• Zhichang Yin,
• Anthony H. Pham and
• Wei Li

Beilstein J. Org. Chem. 2024, 20, 1405–1411, doi:10.3762/bjoc.20.122

• loading and longer reaction time did not improve the overall reaction efficiency (Table 1, entries 6–8). Furthermore, we evaluated several salt additives containing different counterions, and found that LiBF4 was the optimal additive (Table 1, entries 7, 9, and 10). The optimal conditions were shown in

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• relevance. In 2022, Yu et al. [29] showcased a very mild procedure for the effective synthesis of α,α′-diarylated ketones (Scheme 2). Compared to previous procedures, this methodology was a significant improvement as it did not require an excessive amount of additives or high temperature. The methodology

• product. The photomediated formation of acyl radicals directly from acids mostly employs DMDC or phosphines (e.g., PPh3, PMe2Ph) as additives and [Ir(III)] as photocatalyst. In 2022, Chu and co-workers [32] developed a protocol to form acyl radicals directly from acids utilizing Ph2S as activator and the

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• solutions. However, these studies might be important for explaining reactivity changes when Aza-H is employed in photoreactions requiring or releasing Brønsted acids. During the 3-CR experiment, we observed a decomposition of the catalyst that occurred faster than in the absence of any additives (see

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

• Manoel T. Rodrigues Jr.,
• Aline S. B. de Oliveira,
• Ralph C. Gomes,
• Amanda Soares Hirata,
• Lucas A. Zeoly,
• Hugo Santos,
• João Arantes,
• Catarina Sofia Mateus Reis-Silva,
• João Agostinho Machado-Neto,
• Leticia Veras Costa-Lotufo and
• Fernando Coelho

Beilstein J. Org. Chem. 2024, 20, 1167–1178, doi:10.3762/bjoc.20.99

• 3-aryl-1-indanones) in good to excellent yield. The reaction did not require additives and was insensitive to both air and moisture. Preliminary biological evaluation of some indanones showed a promising profile against some human cancer line cells. Keywords: bismuth; catalysis; heterocycles

• -indanones. The reactions were catalyzed by bismuth triflate, an environmentally friendly metal. By simply changing the temperature and reaction time, it was possible to modulate the reactivity. In this methodology, no additives were used, and the reaction was insensitive to both air and moisture. To the

Auxiliary strategy for the general and practical synthesis of diaryliodonium(III) salts with diverse organocarboxylate counterions

• Naoki Miyamoto,
• Daichi Koseki,
• Kohei Sumida,
• Elghareeb E. Elboray,
• Naoko Takenaga,
• Ravi Kumar and
• Toshifumi Dohi

Beilstein J. Org. Chem. 2024, 20, 1020–1028, doi:10.3762/bjoc.20.90

• -trimethoxybenzene in the presence of a diverse range of organocarboxylic acids. These reactions were conducted under mild conditions using the trimethoxyphenyl (TMP) group as an auxiliary, without the need for additives, excess reagents, or counterion exchange in further steps. These protocols are compatible with a

A Diels–Alder probe for discovery of natural products containing furan moieties

• Alyssa S. Eggly,
• Namuunzul Otgontseren,
• Carson B. Roberts,
• Amir Y. Alwali,
• Haylie E. Hennigan and
• Elizabeth I. Parkinson

Beilstein J. Org. Chem. 2024, 20, 1001–1010, doi:10.3762/bjoc.20.88

• determined that a ratio of 1:1 MeOH/H2O should be used as this solubilized the chemical probe most efficiently. Additionally, others have previously noted that polar solvents tend to benefit Diels–Alder reactions between furoic acids and maleimides [19][23]. Next, we looked at how different additives would

• affect the conversion. Others have observed that sodium hydroxide or salts can have beneficial effects on a Diels–Alder reaction with furans [18][19]. For this reason, we explored both sodium hydroxide and sodium chloride as additives. When 1 equivalent of a 5 percent solution of sodium hydroxide was

Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• and by adding pyridine and CsF as additives. By this route the products were obtained under mild reaction conditions applying low pressure of CO, temperature of 80 °C for 12 h. A stoichiometric amount of I2 was necessary to restore the catalyst that underwent a possible reduction (Scheme 41). Another

• (indolyl)methane compounds were isolated in moderate and excellent yields after 24 hours in DMSO, Et3N and formic acid as additives and, Pd(PPh3)2Cl2/P(o-tolyl)3 as catalyst system. The reaction conditions and some important BIMs synthesized are shown in Scheme 42. In the second paper they used

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• the corresponding acetate 123 when exposed to hydrochloric acid in the presence of acetic acid. Omission of acetic acid let to alcohol 133. Screening of various additives identified that hydrochloric acid saturated with ZnCl2 or FeCl3 significantly improved the reaction rate. FeCl3-saturated solutions

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• light of lower wavelength, which is expected to cause degradation [47]. Indeed, when the reaction was carried out using 440 nm blue light a lower yield of 10% was obtained and full conversion of the EBX reagent was observed (Table 1, entry 4). Next, we wanted to test different additives in the

• , entry 10). The addition of DABCO [18] or TBAI [50], two additives known to activate azidobenziodoxolone (ABX), afforded complex mixtures with no trace of 4a (Table 1, entry 11). Acids or fluorinated alcohols were tested to activate the different hypervalent iodine reagents. While AcOH, TFA and TFE had

• . Having already modified most of the reaction parameters available we decided to explore the effect of different additives. In most reactions, 10 resulting from water addition was observed to some extent (4–8%), the presence of 4 Å molecular sieves effectively suppressed the formation of 10 (Table 7

A laterally-fused N-heterocyclic carbene framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts

• Andrew D. Gillie,
• Matthew G. Wakeling,
• Bethan L. Greene,
• Louise Male and
• Paul W. Davies

Beilstein J. Org. Chem. 2024, 20, 621–627, doi:10.3762/bjoc.20.54

• type (Scheme 1a, path a). However, attempts to form the desired imidazolium ring from 3 using triethyl orthoformate and different additives were unsuccessful. Similarly, an imine precursor 6, prepared in high yields by synthesising the known acetal-bearing oxazole 5 [21] and reacting it with 2,6

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• carbamate 1b is used with JPhosAu(CH3CN)SbF6 (5), the reaction is 6.3 times faster in CH3OH compared to CD3OD. These results demonstrate very consistently large solvent isotope effects that appear to be independent of both ligand and substrate. Other additives We sought to determine whether the accelerating

• faster the reaction. With a more strongly Bronsted acidic additive (acetic acid), rates are diminished with increasing additive. With a more polar non-protic additive (DMSO) the rate initially increases, then decreases with possible catalyst decomposition observed. Ether additives THF and dioxane have a

• ]. Protic additives are widely accepted to “facilitate proton transfer,” but they can also influence the aggregation of charged intermediates. Most mechanistic discussions incorporate protodeauration of alkylgold intermediates and consider a continuum from rate or enantio-determining nucleophilic attack

Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas

• Alexander S. Hampton,
• David R. W. Hodgson,
• Graham McDougald,
• Linhua Wang and
• Graham Sandford

Beilstein J. Org. Chem. 2024, 20, 460–469, doi:10.3762/bjoc.20.41

• the difluorination of 1a with fluorine gas as a model process to assess how direct fluorination reactions could be achieved using reaction additives. The lack of reactivity of 1a towards one equiv of fluorine gas when compared with strong reactivity towards Selectfluor suggested the use of a cationic

• selective difluorination using fluorine gas. After screening basic additives as mediating agents and subsequent optimization (see Supporting Information File 1), we found that reaction of ethyl benzoylacetate (4a), quinuclidine (1.5 equiv), and fluorine (3 equiv) in acetonitrile gave the desired

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• resulting concentration of radicals. In such instances, opting for a stronger catalytic reductant or utilizing a stoichiometric electron donor can greatly improve the efficiency of radical generation. On the other hand, additional factors such as the ability of Brønsted and Lewis acid additives to promote

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