Methodology for awakening the potential secondary metabolic capacity in actinomycetes

• Shun Saito and
• Midori A. Arai

Beilstein J. Org. Chem. 2024, 20, 753–766, doi:10.3762/bjoc.20.69

• in the genetically programmed death of the producing organism. In addition, Nishiyama et al. suggested that actinorhodin (8) produced by Streptomyces coelicolor A3(2) functions as an organocatalyst to kill bacteria by catalyzing the production of toxic levels of H2O2 [99]. They also suggested that

Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

• Jan Bartáček,
• Karel Chlumský,
• Jan Mrkvička,
• Lucie Paloušová,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

• chiral metal complex catalyst but also as an enantioselective organocatalyst [17]. Accordingly, its application in enantioselective organocatalysis, particularly in asymmetric reactions through “enamine activation”, warrants further investigation. Results and Discussion The corresponding copper(II

• , the configuration of a ligand at position 2 determines the type of enantiomer of nitroaldol in excess and the environment around the stereogenic centre at position 5 affects the resulting value of ee. The structure of compound IV is similar to the well-known organocatalyst 5-(S)-pyrrolidin-2-yl-1H

• acids producing chiral isotetronic acids. However, the application of compound IV as the organocatalyst in these reactions proceeded sluggishly, and the corresponding products were obtained in only moderate ees [24]. Herein, the aldol reaction was chosen as a standard asymmetric reaction to explore the

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

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

• organocatalyst (Scheme 13) [95]. Haloalkynes have the ability to form strong, directional and selective halogen bonds, which makes them a good choice for the synthesis of BIMs [95]. Several substituted carbonyl compounds, as well as indoles, were screened in the optimum reaction conditions as seen in Scheme 13

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• substituents in the isatin ring showed pronounced negative photochromism upon irradiation with red light (625−650 nm). Supramolecular complexation with Schreiner’s thiourea organocatalyst (STC) allowed to reach better conversion with the isomeric ratio in PSS increased from 46% to 84%. The backward switching

• organocatalyst (STC). Photoisomerization of the protonated isoindigo. Absorption maxima of indigo and its derivatives in C2Cl4 at 20 °C [23][24]. Photophysical and photochemical characteristics of N-aryl- N'-alkylindigos [42][66].

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

• , application, and recycling of a new lipophilic cinchona squaramide organocatalyst. The synthesized lipophilic organocatalyst was applied in Michael additions. The catalyst was utilized to promote the Michael addition of cyclohexyl Meldrum’s acid to 4-chloro-trans-β-nitrostyrene (quantitative yield, up to 96

• homogeneous reaction. For example, by incorporating a lipophilic side chain [28] on the organocatalyst that does not interfere with its catalytic activity thanks to a linker between the catalyst and lipophilic units. In this way, a significant difference in polarity can be achieved between the catalyst and

• the other components of the reaction mixture. The lipophilic O-alkylated gallic acid unit increases the solubility of the organocatalyst in less polar solvents, such as DCM or toluene but leads to the precipitation of the organocatalyst in polar solvents, including MeOH or MeCN. As a result, the

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• Knoevenagel condensation of rhodanine with different aldehydes [3]. The reactions were performed in ChCl/urea (1:2) at 90 °C, without needing a catalyst and the products were obtained in low to good yields (10–78%). On another hand, ʟ-proline is well known as an organocatalyst and its use in aldol and

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

• catalytic amount of Et3N. Moreover, mono-sulfenylation of α-methyl-γ-phenyl-substituted butenolide at α-position was carried out in the presence of Et3N as well as quinine organocatalyst and products were obtained in high yields. In addition to the use of N-(alkyl/arylthio)succinimides in the sulfenylation

• ) by using an organocatalyst was reported by Wang and co-workers (Scheme 35) [67]. Several orgnocatalysts, such as piperidine, and pyrrolidine derivatives were evaluated for the coupling reaction, in which pyrrolidine trifluoromethanesulfonamide A was selected as the best catalyst for this purpose. It

• sulfur reagents resulted in thiolated products 92 up to 99% ee, in the presence of quinidine as the organocatalyst (Scheme 38) [72]. For the study of enantioselectivity of products, different N-substituted oxindoles with H, Me, phenyl, and benzyl groups were investigated. As the size of N-protecting

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

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• categorized into two major divisions: 1) covalent bonding and 2) noncovalent bonding catalysts. A covalent bonding organocatalyst reacts with a substrate to form an activated chiral intermediate which undergoes a stereoselective reaction with another reagent. A noncovalent bonding catalyst usually assembles

• -bonding interactions to facilitate a highly face-selective nucleophilic attack by π-nucleophile to the cyclic imine (see transition state 22’ in Scheme 7a). The BINOL-derived chiral phosphoric acid P8 was employed as the asymmetric organocatalyst for this transformation to construct the heterodimerized

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

• conditions by lowering the temperature from 170 °C to 120 °C. Varma and co-workers [80][81] reported the synthesis of various N-substituted pyrrole derivatives 57 in good yields using a nano-ferric-supported glutathione organocatalyst (Scheme 27, Figure 6). This organoccatalyst was prepared by a post

• -functionalization method using a benign and naturally occurring glutathione and magnetic ferrite nanoparticles by sonication in water at room temperature. Furthermore, using this organocatalyst, various N-substituted pyrroles were prepared by reacting various amines 56 with 2,5-DMTHF (2) in water at 140 °C under

• -substituted pyrroles catalyzed by nano-sulfated TiO2 catalyst. Nano-ferric supported glutathione organocatalyst. Various synthestic protocols for the synthesis of pyrroles. A general reaction of Clauson–Kaas pyrrole synthesis and proposed mechanism. AcOH-catalyzed synthesis of pyrroles 5 and 7. Synthesis of N

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• groups the global charge transfer is not so high to be considered a polar process. The reaction, as previously reported by the classical intermolecular reaction takes place smoothly by the action of the organocatalyst that renders a protonated hydrazone as the reacting functional group. However, in

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

• plausible mechanism. The amino acid acts as an organocatalyst and first reacts with the benzaldehyde 47 to generate the transient directing group (47’). Then, formation of the palladacycle (species R) followed by its oxidation to a Pd(IV) intermediate and a ligand exchange with 2,2,2-trifluoroethanol leads

• to the formation of the species S. The latter complex S undergoes a reductive elimination leading to the compound 48’ along with the regeneration of the palladium catalyst. Finally, after hydrolysis of 48’, the expected product 48 is afforded together with the organocatalyst. Then, the group of Sun

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• configuration. Controlling the stereogenic center C-4 of 4 would allow access to the respective enantiomers. Unfortunately, enantiomerically pure 4 is not easily available, in contrast to ketone 17. This compound can be obtained in high optical purity using Jørgensen’s organocatalyst 16 [20][21]. In addition

• , such a synthetic approach would shorten the synthesis from eight to four steps and allow access to both enantiomers of the compounds 12–14. The synthesis started with an enantioselective Michael addition of aldehyde 1 to methyl vinyl ketone (15) catalyzed by (S)-Jørgensen’s organocatalyst S-16, to

• organocatalyst S-16. Conditions: a) S-16 (5 mol %), ethyl 3,4-dihydroxybenzoate (0.2 equiv), 4 °C, 36 h; b) i) diethyl (2-methylallyl)phosphonate (1.5 equiv), THF, −78 °C, 10 min, ii) n-BuLi (1.5 equiv), THF, −78 °C, 1 h, iii) S-17 (1.0 equiv), −78 °C, 10 min, rt, 8 h; c) i) formaldehyde (0.4 equiv

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

• -organocatalyzed”. Within this section, two process types can be distinguished. In one an organocatalyst molecule is not reduced or oxidized itself but facilitates a reaction by activating the redox properties of reactants (Scheme 1, type II). In such processes the basic principles and organocatalyst structures

• organocatalyst does not undergo oxidation or reduction but facilitates interaction between oxidant and substrate (Scheme 1, type II organocatalysis) are fluently discussed below to show the fundamental difference between type II and type III redox-organocatalysis. Organocatalysis by activation of redox

• properties of reagents In this section we demonstrate examples of the main types of oxidative processes, in which an organocatalyst does not behave as a redox-active molecule itself but interacts with substrates and thus modulates their redox properties (Scheme 1, type II organocatalysis). Secondary amines

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

• can act as a bi-functional organocatalyst due to the existence of both Lewis base (NH2) and Brønsted acidic (COOH) sites. In the suggested mechanism, the carboxy group may polarize the carbonyl group of the active methylene ketone and the amino group as a Lewis base serves the formation of enolate to

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• used as organocatalyst in two classical umpolung reactions of cinnamaldehyde: its cyclodimerization and its oxidative esterification. Keywords: Breslow intermediate; cathodic reduction; flow electrochemistry; N-heterocyclic carbene; oxidative esterification; Introduction Ionic liquids (ILs) are well

• oxidation/degradation. In this paper we describe the cathodic generation and accumulation of NHC in a divided flow cell and its subsequent use as organocatalyst in the self-annulation of cinnamaldehyde and in the esterification of cinnamaldehyde. Results and Discussion Cathodic NHC generation and

• cathodic reduction in a divided cell using flow electrochemistry technique, and to compare the results with the corresponding batch process. Once established, the flow electrochemistry NHC synthesis would be combined with applications as an organocatalyst in some organic transformations of cinnamaldehyde

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• (25), formaldehyde (26), and aniline (27) and 10 mol % of the organocatalyst to yield β-aminoketone 28 in 85% yield (88% ee), in less than 1 h. Although a significantly higher yield was achieved compared to the batch experiment, a slight reduction in enantioselectivity was observed. The Petasis or

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• device. It is based on the increasing liberation of a bound organocatalyst with rising speed of the catalytic machinery. This concept was first realized in the slider-on-deck systems (82•X) (X = 83, 84, or 85) (Figure 18) that were simply generated by mixing the tris-ZnPor deck 82 with one of the bipeds

• one of the three ZnPor units being available for the attachment (immobilization) of an organocatalyst, we wondered about the catalytic activity of the dynamic three-component ensembles 89•(82•X) using N-methylpyrrolidine (89) as organocatalyst. For assessment, the conjugate addition of 86 and 87 was

• catalytic machinery was due to kinetic and not thermodynamic reasons (Figure 19). While the concept of increased liberation of an organocatalyst (ILC) has been demonstrated in other dynamic nanomechanical systems as well [99], a particular highlight was recently realized with a catalytic nanorotor that was

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

• Tommaso Lorenzetto,
• Fabrizio Fabris and
• Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

• Tommaso Lorenzetto Fabrizio Fabris Alessandro Scarso Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari di Venezia, via Torino 155, 30172, Mestre-Venezia, Italy 10.3762/bjoc.18.38 Abstract The hexameric resorcin[4]arene capsule as a self-assembled organocatalyst promotes a

• and efficient organocatalyst. Recent promoted reactions by the resorcin[4]arene capsule include the intramolecular ether cyclization [34], the synthesis of bis(heteroaryl)methanes [35], the imine formation [36], the Michael addition reactions of N-methylpyrrole on methyl vinyl ketone [37], the

• synthesis of sesquiterpene natural product derivatives [38][39] and the carbonyl olefin metathesis leading to 2,5-dihydropyrroles [40]. Herein we present our investigation on the ability of the hexameric capsule 16 to act as a supramolecular self-assembled organocatalyst for a series of unimolecular

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• of chiral compounds 3 To a dried small bottle were added 1 (0.12 mmol), 2 (0.10 mmol), chiral organocatalyst C4 (2.7 mg, 0.005 mmol, 5 mol %), and DCM (1.0 mL). The mixture was stirred at room temperature for 12‒40 h, then the reaction mixture was concentrated and directly purified by silica gel

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• ring [36]. Experiments showed that chiral phosphoric acid CPA 2 acted as a bifunctional organocatalyst, that activates 2-naphthols and quinone derivatives via multiple H-bonds and promotes the first step of the enantioselective conjugative addition to generate intermediate I-1 and transfers the its

Solvent-free synthesis of enantioenriched β-silyl nitroalkanes under organocatalytic conditions

• Akhil K. Dubey and
• Raghunath Chowdhury

Beilstein J. Org. Chem. 2021, 17, 2642–2649, doi:10.3762/bjoc.17.177

• nitromethane under the optimized reaction conditions. Pleasingly, using 9-amino-9-deoxyepihydroquinidine (IX)–benzoic acid as organocatalyst system (see Supporting Information File 1 for details) promoted the addition reaction and product 3l was formed in good yield (79%) and excellent enantioselectivity (99

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• has proven to be a successful concept in asymmetric organocatalysis [2][3][4][5][6][7][8]. An amine unit with a hydrogen-bond donating skeleton is highly efficient from among various possible combinations of catalytic moieties within an organocatalyst. This idea has been inspired by proline catalysis

• -sulfinylurea as bifunctional organocatalyst [23]. The enantio- and diastereoselective addition of Meldrum’s acids to nitroalkenes via N-sulfinylurea catalysis gave products that were readily converted to pharmaceutically relevant compounds [24][25]. A sulfinylurea organocatalyst catalyzed a highly selective

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• different approach for the use of cinchona-based organocatalysts. Instead of using the cinchona derivative alone, they employed a mixture of cinchona derivative and amino acid such as ᴅ-proline, termed as the modularly designed organocatalyst (MDO) for the synthesis of bridged tetrahydroisoquinoline

• yields ranged 57–89% with ee 70–97% [52]. A similar chiral multifunctional thiourea/boronic acid was used as an organocatalyst by Michigami et al. for the enantioselective synthesis of N-hydroxyaspartic acid derivatives 76 with perfect regioselectivity and high enantioselectivity (Table 17) [53

• alkaloids, (+)-deethylibophyllidine (88) and (+)-limaspermidine (89) from the reaction of para-dienone imide 84 with benzylamine (85) in the presence of bifunctional thiourea organocatalyst (Scheme 4) [56]. 1.6 Reactions catalyzed by chiral binol-derived phosphoric acids Binol-derived chiral phosphoric