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

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

• Lewis bases as additive to the bulk CH2Cl2 solvent (Figure 6) and compared them to the baseline rate in the absence of additive. The rates of formation of 3a are mildly sensitive to alcohol structure with MeOH outperforming EtOH and propanol. For the set of linear alcohols, the shorter the chain, the

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

• , wherein the activation of complex 74 takes place through SET under constant current electrolysis [64]. The Glorius and Y. Fu groups have independently proposed the formation of analogous charge-transfer complexes involving NHPI esters, bis(pinacolato)diboron (B2pin2), and Lewis bases (pyridine or

Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates

• Xing Liu,
• Wenjing Shi,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143

• spirooxindoles [36][37][38][39][40][41][42][43]. In the presence of Lewis bases, isatin-derived MBH carbonates usually undergo [3 + 2] and [3 + 3] cycloaddition reactions with a broad range of active C–C and C–N double bonds and 1,3-dipolarpohiles to give various five- or six-membered cyclic spirooxindoles [44

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• Carlee A. Montgomery Graham K. Murphy Department of Chemistry, University of Waterloo, 200 University Ave W., Waterloo, Ontario, N2L3G1, Canada 10.3762/bjoc.19.86 Abstract Halogen bonding is commonly found with iodine-containing molecules, and it arises when Lewis bases interact with iodine’s σ

• -hole bond is the non-covalent inter- or intramolecular interaction between the σ-hole of a group IV–VII atom with the electron-rich site of Lewis bases such as anions, hydrides, or even π electrons [24][30]. Halogen bonding is a subset of this bonding classification, represented by the generic bonding

• leading to an iodocycle that underwent reductive elimination of an iodoarene. 2.3 Halogen bonding-initiated reactions: recent discoveries In recent years, additional processes have emerged that involve halogen bond-based adducts between iodonium ylides and Lewis bases, and with these have also emerged

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

• ]. The well-known and convenient classification of organocatalysts into Lewis bases, Lewis acids, Brønsted bases, and Brønsted acids [1] also leaves the redox-organocatalysts behind. Moreover, in numerous research papers employing redox-active molecules as catalysts the developed processes are not

Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides

• Dharmendra Das,
• Akhil A. Bhosle,
• Amrita Chatterjee and
• Mainak Banerjee

Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100

• with N-bromosuccinimide (NBS) was carried out in toxic polar solvents (e.g., DMF), but no iodinated or chlorinated products were obtained because of the low reactivity of NIS and NCS (Scheme 1a) [24][25][26][27]. In recent time, the use of Lewis or Brønsted acids, Lewis bases, and transition-metal

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• spectral changes [38]. This demonstrates that stronger Lewis acids and Lewis bases will result in stronger charge transfer. Moreover, stronger electron donors or more accessible nitrogen-containing groups would interact easily via Lewis acid coordination. As shown in Figure 13b, the energy levels

Photoredox-catalyzed silyldifluoromethylation of silyl enol ethers

• Vyacheslav I. Supranovich,
• Vitalij V. Levin and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 1550–1553, doi:10.3762/bjoc.16.126

• silane is very sensitive to Lewis bases and accordingly it was used as a precursor of difluorocarbene, which can react with enol ethers [19][20] (Scheme 1). We showed that this silane could be involved in the radical chain hydrofluoroalkylation of electron-deficient alkenes, using a boron hydride as a

Halogen-bonding-induced diverse aggregation of 4,5-diiodo-1,2,3-triazolium salts with different anions

• Xingyu Xu,
• Shiqing Huang,
• Zengyu Zhang,
• Lei Cao and
• Xiaoyu Yan

Beilstein J. Org. Chem. 2020, 16, 78–87, doi:10.3762/bjoc.16.10

• noncovalent interaction between electrophilic halides and Lewis bases or electron-rich regions [1][2]. Computational studies [3][4][5][6][7] and cyrstal architectures including XB-donors (σ-hole) such as perfluorocarbons [8][9][10][11][12], tetraiodoethylene [13], 1,2-diiodo-1,2-difluoroethene [14

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• , boron with sp2 hybridization, such as in triarylboranes, offers the possibility to modulate fluorescence properties by the addition of Lewis bases (e.g., fluoride ions [27][28][29][30][31]) or by exploring the electron-accepting properties of the boron, including charge-transfer and photoinduced

• properties but constitutes also a potential binding motif for Lewis bases. In this context it is well established that the electron-deficient trivalent boron can bind anions, such as fluoride or cyanide, through interaction with the vacant 2pπ orbital [30]. In Figure 4 the fluorescence responses of the dyes

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• happen between Lewis bases and electron-defective heavy chalcogen atoms containing Lewis acidic s-holes which is known under the term chalcogen bonding (ChB) [18]. A mechanically interlocked rotaxane 8 (Figure 8) has been prepared by Beer and co-workers utilizing the 5-(methylchalcogeno)-1,2,3-triazole

DABCO- and DBU-promoted one-pot reaction of N-sulfonyl ketimines with Morita–Baylis–Hillman carbonates: a sequential approach to (2-hydroxyaryl)nicotinate derivatives

• Soumitra Guin,
• Raman Gupta,
• Debashis Majee and
• Sampak Samanta

Beilstein J. Org. Chem. 2018, 14, 2771–2778, doi:10.3762/bjoc.14.254

• ) all led to lower yields (19–68%, entries 5–8, Table 1) as compared to the toluene-mediated reaction (76%, entry 4, Table 1). Next, several N/P-containing Lewis bases such as Et3N, DMAP, DBU and PPh3 were tested for this reaction in toluene and resulted in very poor yields (5–21%, entries 9–12). Based

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst

• Longcheng Hong,
• Sebastian Ahles,
• Andreas H. Heindl,
• Gastelle Tiétcha,
• Andrey Petrov,
• Zhenpin Lu,
• Christian Logemann and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48

• -orbital of the boron atom. This may prevent the boron compound from decomposition as well as hydrolysis and provide a practical Lewis acid catalyst for organic reactions. To test the hypothesis, several Lewis bases were subjected to the coordination reaction with the bidentate bisboron catalyst, 5,10

• -dimethyl-5,10-dihydroboranthrene (A in Scheme 1), developed in our group [13]. A complexation was confirmed by a high field shift of the aromatic protons compared with the non-coordinated catalyst A. As shown in Scheme 2, besides 1,2-diphenylhydrazine (1d), most of the Lewis bases including monodentate 1a

• –1c and bidentate Lewis bases 1e–1j can coordinate with bisboron compound A as determined by NMR spectroscopy (see Supporting Information File 1). The stability was then evaluated exposing the resulting complexes to air. However, most adducts quickly decomposed under ambient conditions except the

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• nitrosoalkene generation employs their stable nitrosoacetals of type 3 (N,N-bis(silyloxy)enamines) [17][18]. The latter eliminate (Alk3Si)2O upon the action of Lewis bases generating the corresponding nitrosoalkenes at low stationary concentrations in a controllable manner. Furthermore, synthetic precursors of

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• form stable adducts with neutral and charged Lewis bases, and to account for this IUPAC provided the following recommendation “A halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• be effected by adding Lewis bases (such as HMPA) or by using Lewis acidic tin hydrides (such as Bu2SnClH) [16][17]. Potential catalysts of hydride reduction such as benzenesulfinic acid (PhSO2H) and tributyltin benzenesulfinate (PhSO2SnBu3) could form under these conditions [11]. The imine reduction

Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• splitting is likely to be caused by Lewis acid–base interactions, arising from electron donation from the lone pair of the oxygen in a carbonyl group to the electron-deficient carbon atom in CO2. On this basis carbon dioxide should also interact favourably with other Lewis bases, another potential reason

• intrinsic properties for both surfactant and polymer solubility in scCO2, which have been highlighted above. These include the inclusion of CO2-philic moieties which show favourable interactions with CO2, such as Lewis bases and fluorocarbons. Effort has been made to move away from the use of fluorocarbons

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• reactions as those reported above, phosphoramidates, prepared by AT reactions, can also act as an organocatalyst. Indeed, with the strongly polarized P–O bond on one hand, and the P–N or P–NH bond on the other hand phosphoramides are good Lewis bases [96][97][98]. Hexamethylphosphoric triamide (HMPA) (or

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• in the presence of 100 mol % of TiCl4 in THF gave a 5:1 (anti/syn) mixture of adducts 20 and 21. Tetrahydrofuran coordinates quite strongly to Lewis acids, which increases the electron density at the metal atom. This lowers the metal atom’s ability to coordinate to other Lewis bases, such as the

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

• allows the formation of an agostic contact. Treatment of A8 with Lewis bases also removes the agostic interaction, generating the adduct complex. Natural Bond Orbital (NBO) and Atoms In Molecules (AIM) calculations on complexes A1, A2b, A5b and A7 classified the Pt···H–C contacts as agostic interactions

Enantioselective reduction of ketoimines promoted by easily available (S)-proline derivatives

• Martina Bonsignore,
• Maurizio Benaglia,
• Laura Raimondi,
• Manuel Orlandi and
• Giuseppe Celentano

Beilstein J. Org. Chem. 2013, 9, 633–640, doi:10.3762/bjoc.9.71

• 10.3762/bjoc.9.71 Abstract The behavior of readily synthesized and even commercially available (S)-proline derivatives, was studied in the trichlorosilane-mediated reduction of ketoimines. A small library of structurally and electronically modified chiral Lewis bases was considered; such compounds were

• studies were also performed in order to elucidate the origin of the stereoselection. Keywords: chiral prolines; imine reduction; Lewis bases; organocatalysis; trichlorosilane; Introduction The reaction with stoichiometric amounts of trichlorosilane in the presence of a chiral catalyst is a well

• -established methodology to perform enantioselective reductions of carbon nitrogen double bonds [1]. In the past decade different classes of enantiomerically pure Lewis bases have been developed, including N-formyl derivatives, oxazolines, imidazole derivatives, sulfonamides and picolinamides [2][3]. Some of

A quantitative approach to nucleophilic organocatalysis

• Herbert Mayr,
• Sami Lakhdar,
• Biplab Maji and
• Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

• –200 kJ mol–1) Lewis bases. While structurally analogous imidazolylidenes and imidazolidinylidenes have comparable nucleophilicities and Lewis basicities, the corresponding deoxy Breslow intermediates differ dramatically in reactivity. The thousand-fold higher nucleophilicity of 2-benzylidene

• NHCs, 41, 42, and 43, react quantitatively with the quinone methide 18k, while none of the other Lewis bases, despite their similar nucleophilicities, gives an adduct. The resulting conclusion, that all NHCs are significantly stronger Lewis bases than PPh3 (10b), DMAP (39), and DABCO (38), is confirmed

• by quantum chemical calculations: The methyl cation affinities (MCAs) of the three carbenes 41–43 are 100–200 kJ mol–1 higher than those of the other Lewis bases in Figure 23 [96]. As the carbenes 41 and 42 have almost identical nucleophilicities and Lewis basicities, the question arose as to why

Cation affinity numbers of Lewis bases

• Christoph Lindner,
• Raman Tandon,
• Boris Maryasin,
• Evgeny Larionov and
• Hendrik Zipse

Beilstein J. Org. Chem. 2012, 8, 1406–1442, doi:10.3762/bjoc.8.163

• Christoph Lindner Raman Tandon Boris Maryasin Evgeny Larionov Hendrik Zipse Department of Chemistry, Ludwigs-Maximilians-Universität München, Butenandstr. 5–13, D-81377 München, Germany 10.3762/bjoc.8.163 Abstract Using selected theoretical methods the affinity of a large range of Lewis bases

• Discussion Methyl cation affinities (MCA) The methyl cation (CH3+) is the smallest carbocation which is useful as a chemical probe for Lewis bases. The respective methyl cation affinity of a given Lewis base (LB) is obtained as the reaction enthalpy at 298.15 K and 1 bar pressure for the reaction shown in

• equation 1a for a neutral Lewis base and in equation 1b for an anionic base (Scheme 1). This definition is in analogy to that for proton affinities (PA) and implies large positive energies for most of the P- and N-based Lewis bases used in catalytic processes. Using pyridine (1) as an example for a weak

On the control of secondary carbanion structure utilising ligand effects during directed metallation

• Andrew E. H. Wheatley,
• Jonathan Clayden,
• Ian H. Hillier,
• Alison Campbell Smith,
• Mark A. Vincent,
• Laurence J. Taylor and
• Joanna Haywood

Beilstein J. Org. Chem. 2012, 8, 50–60, doi:10.3762/bjoc.8.5

• authenticated tertiary carbanions, significant similarities are seen insofar as the connectivity of the alkali metal is concerned when changing tridentate Lewis bases. Thus, whereas 6-Lil·PMDTA fails to show a Li–(α-C) interaction in the solid state, in Lil·DGME the corresponding distance (2.406(6) Å) suggests

• presence of different Lewis bases. In contrast to previous work on carbanion formation in the presence of an aromatic N+O directing group, 6-Lil·L dissolves in hydrocarbon media to reveal two structures in solution. Based on previous work and new DFT studies, we ascribe these as being cis (minor) and trans

• between the identity and structure of the tridentate Lewis base and the propensity of the metal and deprotonated α-C centre to interact. In particular, tandem theoretical and NMR spectroscopic studies will seek to elucidate whether polydentate Lewis bases may exhibit dynamic and variable hapticity with