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Search for "Lewis base" in Full Text gives 71 result(s) in Beilstein Journal of Organic Chemistry.
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- tetrahedral value which results in a large ring strain of 25.5 kcal/mol, comparable to oxirane (27.3 kcal/mol) and much greater than tetrahydrofuran (5.6 kcal/mol) [4]. Moreover, the strained C–O–C bond angle effectively exposes the oxygen lone pairs, making oxetane a strong hydrogen-bond acceptor and Lewis
- base [5]. In fact, its hydrogen-bond-accepting ability is even stronger than that of the other 3-, 5- and 6-membered cyclic ethers, as well as the carbonyls of aldehydes, ketones, esters and carbonates [6][7][8]. The only better carbonyl-based hydrogen-bond acceptors are amides, carbamates and ureas [9
New advances in asymmetric organocatalysis II
Beilstein J. Org. Chem. 2025, 21, 766–769, doi:10.3762/bjoc.21.60
- ]. The enantioselective addition of propargyltrichlorosilane to aldehydes was studied by Prabhakar, Takenaka, and co-workers. This transformation was catalyzed by a biisoquinoline N,N’-dioxide catalyst, which acted as a chiral Lewis base [26]. Torres-Oya and Zurro reviewed the recent developments in
Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones
Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59
- studies by the groups of Akiyama and Terada in 2004 [14][15], many excellent results have been achieved by applying BINOL-derived phosphoric acids, which can act as proton donor and acceptor [16][17][18][19], possessing both Brønsted acid and Lewis base character [20]. Substantial effort has been invested
Molecular diversity of the reactions of MBH carbonates of isatins and various nucleophiles
Beilstein J. Org. Chem. 2025, 21, 286–295, doi:10.3762/bjoc.21.21
- ]. In the presence of a Lewis base, MBH carbonates of isatins can be easily converted to activated allylic ylides, which in turn can undergo allylic substitution and annulation reactions to give diverse 3-substituted and spirooxindole derivatives [36][37][38][39][40][41]. Inspired by these elegant
- derivatives. At first, a Lewis base attack at the α-position of the MBH nitrile of isatin resulted in the intermediate A with elimination of carbon dioxide and tert-butoxide ion. Secondly, the product 3 was produced by the SN2 substitution of the Lewis base by the arylamine. When MBH maleimides of isatin were
- addition of Lewis base is needed. When triphenylphosphine or tri(n-butyl)phosphine were involved in the reaction, the similar SN2’ substitution of tri(n-butyl)phosphine with the elimination of carbon dioxide and tert-butoxide anion gives the phosphonium salt C. Then, the deprotonation of phosphonium salt C
Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines
Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268
- organocatalyst acts as a Lewis base forming an enamine which raises the HOMO energy of the dienophile, while the thiourea moiety acts as a Lewis acid, lowering the LUMO level of the diene (Scheme 1). A confined transition state is formed providing a high enantiocontrol of the reaction. In 2016, Shi and co
- concerted mechanism which could be explained by the transition state depicted in Scheme 16: the chiral phosphoric acid could act as a bifunctional catalyst; the OH group acts as a Brønsted acid activating the 1-azadiene, while the phosphoryl oxygen atom activates the enecarbamates as a Lewis base. In order
- authors proposed a possible mechanism for the reaction which is depicted in Scheme 20. The chiral phosphoric acid activates both the azoalkene acting as a Brønsted acid and the indole acting as a Lewis base promoting a Friedel–Crafts-type 1,4-addition of the indole to the azoalkene. In this manner, a
Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts
Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257
- -alkyloxazolidinones, eliminating the need for any Lewis base or additives [74]. This represented a significant advancement over their previously reported work. They used six different protonated porphyrins as catalysts: TPPH4X2 (18a, X = Cl; 18b, X = Br; 18c, X = I), and TPPH4(RCOO)2 (18d, R = CF3; 18e, R = ClCH2
Enantioselective regiospecific addition of propargyltrichlorosilane to aldehydes catalyzed by biisoquinoline N,N’-dioxide
Beilstein J. Org. Chem. 2024, 20, 3069–3076, doi:10.3762/bjoc.20.255
- % yield with 61:39–92:8 enantiomeric ratios. Furthermore, possible mechanisms of propargyl–allenyl isomerization of propargyltrichlorosilane were computationally investigated. Keywords: α-allenic alcohol; computational chemistry; Lewis base catalysis; organocatalysis; propargyltrichlorosilane
- ][34]. In sharp contrast, propargyltrichlorosilane is configurationally stable and only reacts through the SE2’ mechanism under Lewis base-catalyzed conditions [43][44][45], although it was reported that distillation of propargyltrichlorosilane substantially isomerizes it to the thermodynamically more
Computational design for enantioselective CO2 capture: asymmetric frustrated Lewis pairs in epoxide transformations
Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224
- colleagues [1]. These compounds, which feature a Lewis acid (LA) and a Lewis base (LB), whose interaction is hindered by bulky substituents or chain strain, have garnered significant attention. Initially explored for their ability to trap small molecules [2][3], such as H2 [4], CO2 [5][6][7], N2O [8][9], and
- , depicted by the purple points in Figure 1B. Results and Discussion The following nomenclature will be used during the volcano plot analysis: FX_LBLA_S1_S2 where X is the label of the family (1, 2, 3, 5, or 6), LB is the Lewis base considered (N or P), LA is the Lewis acid (in this particular study only B
- intermediate undergoes reorganization, leading to Min2. Surprisingly, family 5, having phosphorus as the Lewis base, presents a different reactivity from the other families (Figure S3, Supporting Information File 1). Compounds F5_PB_H and F5_PB_CF3 react following mechanism 3 (Figure 5C), but the reaction
Transition-metal-free synthesis of arylboronates via thermal generation of aryl radicals from triarylbismuthines in air
Beilstein J. Org. Chem. 2024, 20, 2577–2584, doi:10.3762/bjoc.20.216
- generating a boron radical (pinB•) by photoirradiation of (Bpin)2 and found that the addition of (PhS)2 was effective in generating the boron radical [30]. We therefore investigated this reaction by adding (PhS)2 as a Lewis base, but the yield of 3a was not improved and (PhS)2 was recovered almost
Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt
Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204
- in a Mannich reaction [4]. In 2018, our group showed in a proof-of-principle study [5] that the Lewis acid catalysis by DAI salts is based on halogen bonding (XB), an interaction between a Lewis base (XB acceptor) and an electrophilic halogen atom in the Lewis acid (XB donor) [6][7][8][9][10]. In
Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis
Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196
Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis
Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182
- -covalent electron pair, making it impossible to generate boron radicals by homolysis via the n–σ* transition. In addition, since boron has an empty orbital, it forms ate complexes when Lewis base compounds coexist. As the result, the boryl groups of the ate complexes are bulky and often cause steric
Synthesis of indano[60]fullerene thioketone and its application in organic solar cells
Beilstein J. Org. Chem. 2024, 20, 1270–1277, doi:10.3762/bjoc.20.109
- . Additionally, the ketone structure acts as a Lewis base, resulting in a passivation effect on Pb2+ [19]. In this study, we designed and synthesized indano[60]fullerene thioketones (FIDSs) with various para-substituents. The vacuum-deposition performance and thermal stability of FIDS were assessed by both
Carbonylative synthesis and functionalization of indoles
Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87
- protocol the use of a Lewis base such as SnCl2 was not required and the reaction took place under milder conditions using Pd(OAc)2 as catalyst and PPh3 as ligand. The reaction was performed at 70 °C for 15–48 hours, under 4 bar of CO in a DMF/MeOH 2:1 mixture giving the indole derivatives without obvious
Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination
Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43
- effect of MeOH co-solvent on the 1a → 3a transformation was due to its role as a hydrogen bonding donor (proton source), or due to its role as a hydrogen bonding acceptor (Lewis base) [44]. To this end, we examined the impact of different alcohols (varied acidity and polarity) and different non-protic
- nitrogen. Thus, the rate of intramolecular hydroamination is enhanced by a more nucleophilic nitrogen. Another qualitative interpretation is that rates are enhanced by carbonyl basicity. Gas-phase basicity measurements indicate that ureas are more basic than amides [47][50], and here the most Lewis base
Using the phospha-Michael reaction for making phosphonium phenolate zwitterions
Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6
- reactive in chloroform solution, while in methanol the corresponding phosphonium phenolate is formed. Keywords: Lewis-base catalysis; Michael acceptor reactivity; phospha-Michael reaction; phosphonium phenolate zwitterion; Introduction Organocatalysis has emerged in recent years as a valuable and
- powerful tool for performing organic reactions [1] and polymerizations [2]. In this context phosphines have proven to be potent Lewis-base catalysts [3][4] for a variety of reactions [5], including but not limited to Rauhut–Currier [6], Morita–Baylis–Hillman [7], and Michael reactions [8][9][10]. In all
- -carbonyl-based Michael acceptors. Results and Discussion Synthesis During our endeavors to identify potent Lewis-base catalysts for the oxa-Michael reaction [13][14], the triarylphosphine 1 was tested in a model reaction (2 equiv allyl alcohol, 1 equiv acrylonitrile, 0.05 equiv 1). However, no conversion
Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates
Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143
- depicted in Scheme 5. At first, MBH carbonates of isatin 2 is attacked at the α-position by the Lewis base to give the ammonium salt A with elimination of carbon dioxide and a tert-butoxide ion. Secondly, the ammonium salt A is deprotonated by the in situ generated tert-butoxide ion to give the allylic
- elimination of a proton and the Lewis base. Obviously, the spiro compounds 5 and 7 are formed by a similar reaction mechanism. Additionally, the method was applied to a gram-scale reaction of α-halogenated p-toluenesulfonylhydrazone 6c and MBH nitrile of isatin 2c under the standard conditions (Scheme 6). The
Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks
Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127
- pairs and provides a good basis and scope for further extensions and explorations [39] (Scheme 3). Based on the work by Wu et al. and extending their previous work, Rueping and co-workers explored the effects of fluorine in organocatalytic reactions. They developed an asymmetric Brønsted acid–Lewis base
- Brønsted acid-assisted Lewis base catalysis. Synthesis of CF3-pyrazoles and CF3-1,6-dihydropyridazines. Asymmetric reactions of trifluoromethylimines with organometallic reagents. Mannich-type reaction of trifluoroacetaldehyde hydrazones. Synthesis of trifluoromethylated hydrazonoyl halides. Early work of
N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations
Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106
- azepane. A possible mechanism was suggested for this Lewis base catalysis system. Methanesulfonic acid (MsOH) activated reagent 14, which coordinated with the Lewis base (S)-E, to form complex I. Then, the transfer of the sulfenium ion to the alkene resulted in chiral thiiranium ion II. Capture of the
- enantioselectivity and the product yield were reduced. Although, the authors did not further explain the catalytic pathway. The use of organocatalysts in sulfenylation of N-heterocyclic compounds was investigated by Gustafson′s group in 2017 (Scheme 48) [81]. In their work, a series of conjugate Lewis base Brønsted
- acid organocatalysts were evaluated for sulfenylation on C3, or C2 position of N-heterocycles 115, including indoles, peptides, pyrrole, and 1-methyl-1H-pyrrolo[2,3-b]pyridine. The authors hypothesized a mechanism for the activation of N-sulfanylsuccinimides 1 or 14 by conjugate Lewis base Brønsted
Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control
Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86
- reactions in processes that are typically metal-mediated, as well as the reactions observed between iodonium ylide-Lewis base pairs, including single electron transfers and proton transfers. As iodonium ylides exhibit two σ-holes, they offer two potential sites for halogen bonding to occur, potentially
- pattern shown in Figure 1, where R is the host atom or functional group to which the halogen is covalently bound, where X is the halogen atom possessing the σ-hole (halogen bond donor), and where Y is the Lewis base (halogen bond acceptor) [31]. σ-Holes arise from anisotropic covalent bonds between the
- such that they can undergo intramolecular reactions within the iodine’s ligand sphere. These EDA complexes have been proposed to then undergo single electron transfers from the Lewis base to the ylide, under both thermal or blue LED irradiation conditions, leading to C–H insertion products. Irradiating
Group 13 exchange and transborylation in catalysis
Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28
- loses dihydrogen to give a neutral borane 12, followed by B–C(sp2)/B–H transborylation with HBpin (ΔG‡ = 14.7 kcal mol−1) to give the borylated arene 13 and regenerate the catalyst (Scheme 4a). Fontaine showed that the steric bulk of the Lewis base had a significant effect on the rate of the reaction
A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH4I
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
Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons
Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83
- ; fluorescence; Lewis acid; Lewis base; post-synthesis; Introduction Organic light emitting diodes (OLEDs) show great potential to dominate the next generation of flat-panel displays and efficient light sources attributed to the advantages of self-illumination, high efficiency, wide color gamut, and flexibility
Bioinspired tetraamino-bisthiourea chiral macrocycles in catalyzing decarboxylative Mannich reactions
Beilstein J. Org. Chem. 2022, 18, 486–496, doi:10.3762/bjoc.18.51
- anion binding property and potent electrophilic activation ability [31][32][33][34][35][36]. To incorporate extra functionality, tertiary amine groups can be also embedded as Lewis base sites for realizing electrophilic/nucleophilic cooperative catalysis [37][38][39]. For this purpose, one kind of
- linking components to afford Lewis base sites and also for introduction of chirality. Different alkyl substituents including methyl, n-propyl, isopropyl, and 3-pentyl were incorporated in order to tune the size and steric effect of the macrocyclic cavity and thus to enable diverse cavity environments
New advances in asymmetric organocatalysis
Beilstein J. Org. Chem. 2022, 18, 240–242, doi:10.3762/bjoc.18.28
- many reactions and a variety of organocatalysts can engage with them [18]. Nine excellent research articles within this special issue demonstrate the current state of the art in asymmetric organocatalysis. Chiral isothioureas became useful Lewis base catalysts for various transformations. Weinzierl and
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