Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• only when aliphatic disulfides are used because of the higher Lewis basicity of the alkylated sulfur atom, which poisons the copper catalyst. When the reaction was carried out with paraformaldehyde and other solvents (such as DMF, 1,4- dioxane, toluene, and DCE) the yield was very low (between 0–34

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• active groups for a variety of substrates, making their use as supramolecular organocatalysts based on bifunctional activation mechanism (hydrogen-bonding/Lewis basicity) highly promising. At the same time, additional functional groups that are required for the catalysis can be easily installed on the

• affect the optical and electronic properties, as well as the reactivity of porphyrins, mainly introducing non-planarity with easier access to the inner pyrrolic –NHs and –N-lone pairs. Additionally, these alterations potentially increase Lewis basicity that further improves interactions with substrates

Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles

• Jun Kikuchi,
• Roi Nakajima and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79

• lowest-acidic pyrazole being the most competitive. However, we rather surmise that the Lewis basicity of the proton-free nitrogen atom of the azole would have more direct relevance to the results of the competition experiments, where the least Lewis basic tetrazole was the least competitive. Along with

• attributed to its much greater Lewis basicity compared to other azoles, likely killing the reactivity of the iodine(III) electrophile by direct coordination. The present reaction could be performed on a preparative scale. Thus, 1 mmol-scale synthesis of the vinylazoles 4aa and 4ba could be successfully

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

• sulfide molecules 137 (Scheme 58) [90]. The Lewis basicity nature of PhSePh as a catalyst and the presence of Lewis acid TMSOTf improved the chemical yields. It is interesting to note that the reaction carried out at a lower temperature because of the high reactivity of allene 136. When the reaction was

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

• negative electrostatic potential (VS,min) of the acceptor [46][48][51][52], but also by other factors [53][54][55][56][57] including hydrogen bonding [31][48], solvent polarity [47][58], the Lewis basicity of the acceptor [46][50] and by sterics [46]. As with any interatomic interaction, the energy of a

• acidity and the Lewis basicity of the X–H molecule were important. This led the authors to propose an initial halogen-bonded complex 52 (consistent with the rate acceleration seen for more Lewis basic reactants), which would weaken the X–H bond and simultaneously strengthen the basicity of the ylidic

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

• –base interaction mechanisms Chemical essence of Lewis acid–base interaction All the above discussed fluorescent materials share the common characteristics of Lewis basicity. Therefore, the changes in band gaps and colors of the donor materials is essentially attributed to a Lewis acid–base complexation

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• derivative 42f, due to the Lewis basicity of the nitro group. These stereochemical outcomes were also observed in the reaction of acrylamides by means of anchimeric assistance. Preliminary studies to identify asymmetric variants indicated that, in the presence of lactate-based chiral iodoarene catalyst 43

Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds: the role of iodine Lewis basicity

• Tathagata Mukherjee,
• Soumik Biswas,
• Andreas Ehnbom,
• Subrata K. Ghosh,
• Ibrahim El-Zoghbi,
• Nattamai Bhuvanesh,
• Hassan S. Bazzi and
• John A. Gladysz

Beilstein J. Org. Chem. 2017, 13, 2486–2501, doi:10.3762/bjoc.13.246

• and a lower Lewis basicity of the iodine atom as compared to RfnCH2I. After these experiments were carried out, we became aware of the isolation of CF3ICl2 (Rf1ICl2) from the reaction of CF3IClF and TMSCl at −40 °C [43]. This route is conceptually similar to that shown in Scheme 4, and a crystal

• possess sufficient Lewis basicity (Figure 4), but there appears to be a kinetic barrier. In contrast, fluorous aromatic iodine(III) dichlorides bearing a single perfluoroalkyl group, RfnC6H4ICl2, are easily isolated in analytically pure form (Scheme 5), although they are still subject to slow Cl2 loss in

• established a strong correlation between iodine atom Lewis basicity and the feasibility of oxidizing fluorous and non-fluorous aliphatic and aromatic iodides to the corresponding iodine(III) dichlorides. Although a few surprises are noted, these are attributed to special phenomena that can drive equilibria

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• entries 2 and 3 (Table 5). Surprisingly, 2-biphenyl sulfonamide 26 gave an unimproved 26.0:74.0 er, despite the increased steric bulk on the substrate (Table 5, entry 4). Further increasing the Lewis basicity of the nitrogen completely shuts down catalyst activity, as can be seen in the case of the

Asymmetric desymmetrization of meso-diols by C₂-symmetric chiral 4-pyrrolidinopyridines

• Hartmut Schedel,
• Keizo Kan,
• Yoshihiro Ueda,
• Kenji Mishiro,
• Keisuke Yoshida,
• Takumi Furuta and
• Takeo Kawabata

Beilstein J. Org. Chem. 2012, 8, 1778–1787, doi:10.3762/bjoc.8.203

• of the asymmetric acylation. The superior property of 11 compared to 16 as an asymmetric acylation catalyst could be ascribed to the stronger Lewis basicity of the amide carbonyl group than that of the ester carbonyl group (donor number of amides > donor number of esters). However, the reasons for

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

• ]. Quantitative aspects of N-heterocyclic carbene (NHC) catalysis As the following discussion will focus on the difference between the kinetic term “nucleophilicity” and the thermodynamic term “Lewis basicity”, let us first illustrate this aspect by comparing the behavior of two well-known organocatalysts, 1,4

• and Lewis basicity (in acetonitrile at 20 °C): Rate (left) and equilibrium constants (right) for the reactions of amines with benzhydrylium ions [94][95]. NHCs 41, 42, and 43 are moderately active nucleophiles and exceptionally strong Lewis bases (methyl cation affinity, MCA, was calculated for the

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

• substrate model for acyl-transfer reactions. Affinities towards these cationic electrophiles are complemented by data for Lewis-base addition to Michael acceptors as prototypical neutral electrophiles. Keywords: ab initio; cation affinity; Lewis basicity; organocatalysis; proton affinity; Introduction

• a comparatively weak nucleophile as already mentioned above. This also applies to imidazole (12), pyrrolidine (18) and a number of trialkylamines, all of which have MCA values below 550 kJ/mol. In the case of pyridine it is possible to increase the Lewis basicity by introducing electron-donating

• basis of their MCA values. The much smaller Lewis basicity of DABCO (44) compared to that of DMAP (54) has also been cited in experimental studies as the prime reason for the different catalytic profile of these two catalysts [27]. The fact that no covalent adduct could be identified between the trityl

Kinetics and mechanism of vanadium catalysed asymmetric cyanohydrin synthesis in propylene carbonate

• Michael North and
• Marta Omedes-Pujol

Beilstein J. Org. Chem. 2010, 6, 1043–1055, doi:10.3762/bjoc.6.119

• silicon species [82] or the formation of cyanide anions. The most effective catalysts possess both Lewis acidity and Lewis basicity and so can simultaneously activate both the aldehyde and TMSCN [1]. We have recently shown [52] that a Hammett analysis correlating the rate of reaction of meta- and para