ChemInform Abstract: Amidines. Part 36. Influence of Substitution at the Amidino Carbon Atom on the Sensitivity to Substitution at the Imino Nitrogen Atom. pKa Values of N1-Methyl-N1-phenylacetamidines and N1-Methyl-N1- phenylpropionamidines.

This short review provides an overview on the interaction between 1,3,5-triaminobenzene derivatives and different kinds of electrophiles. Due to the ambident reactivity of these nucleophiles (i.e., at the nitrogen atom of the substituents and at the aromatic carbon atom) different compounds can be obtained. Particular attention is devoted to the detection, isolation, and characterization of covalent intermediates of aromatic substitution, starting from Wheland intermediates until the first detection and characterization of Wheland–Meisenheimer intermediates.1 Introduction2 Reactions between 1,3,5-Triaminobenzene Derivatives and Charged Electrophiles2.1 The Proton as an Electrophile2.2 Arenediazonium Salts as Electrophiles3 Reactions between 1,3,5-Triaminobenzene Derivatives and Neutral Electrophiles3.1 Alkyl Halides as Electrophiles3.2 Acyl Halides and Sulfonyl Chlorides as Electrophiles3.3 Aryl Halides and Heteroaryl Halides as Electrophiles3.4 Polynitroheteroaromatics as Electrophiles4 Conclusion

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Dative behavior of N-heterocyclic carbenes (NHCs) with selenium in Se-NHC compounds

Reviews in Inorganic Chemistry ◽

10.1515/revic-2021-0031 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Munazzah Yaqoob ◽

Mahvish Abbasi ◽

Hira Anwar ◽

Javed Iqbal ◽

Mohammad Asad ◽

...

Keyword(s):

Nitrogen Atom ◽

Carbon Atom ◽

Lone Pair ◽

Heterocyclic Ring ◽

Heterocyclic Carbenes ◽

The Other ◽

Donor Ligands ◽

Important Research ◽

Dative Bond ◽

Back Bonding

Abstract N-heterocyclic carbenes (NHCs) are an eminent class of carbenes having a heterocyclic ring in which a divalent carbon atom is attached directly to a nitrogen atom. In the NHCs, the donation of lone pair is another important research in the dative bonding and not only in NHCs the dative bond plays a functionalized role in the other classes of complex formation like ylidones L → E ← L and carbones L → C ← L. M–NHC bond is L-M sigma-dative bond and NHCs are considered as strong sigma-donor ligands. The clear picture of the M–NHC bond can be better understood by M–NHC pi-interaction. M-L pi interaction is comprised of two steps. One is L → M sigma-donation and M → L π* back bonding. This dative donor nature of NHC and also its behavior in organoselenium is studied through DFT in which it’s optimized structure, bond lengths, molecular vibrations are calculated.

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Synthesis of Monobactams via the Diastereoselective Kinugasa Reaction

Synthesis ◽

10.1055/s-0037-1609304 ◽

2018 ◽

Vol 50 (10) ◽

pp. 1991-2000 ◽

Cited By ~ 2

Author(s):

Kamil Kabala ◽

Barbara Grzeszczyk ◽

Bartłomiej Furman ◽

Marek Chmielewski ◽

Jolanta Solecka ◽

...

Keyword(s):

Biological Activity ◽

Nitrogen Atom ◽

Carbon Atom ◽

Bulky Substituent ◽

Protecting Group ◽

Acetylene Molecule ◽

Cyclic Nitrones ◽

Lactam Ring

The Kinugasa reaction between phthalimidoacetylene and cyclic nitrones derived from l-phenylglycine or l-serine and glyoxylic acid, catalyzed by copper(I) chloride in the presence of triethylamine, is reported. The acetylene molecule approaches the nitrone exclusively anti to the bulky substituent next to the nitrogen atom to provide the cis-substituted β-lactam ring preferentially. The six-membered oxazinone ring can be easily opened, the phthaloyl residue can be transformed into a Boc protecting group, and substituents at the C-4 carbon atom and the nitrogen atom of the β-lactam ring can be easily removed or transformed into groups suitable for further synthesis of a variety of monobactam structures. Selected synthesized compounds were evaluated for their biological activity, showing interesting properties.

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Hyperconjugative aromaticity and protodeauration reactivity of polyaurated indoliums

Nature Communications ◽

10.1038/s41467-019-13663-8 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 4

Author(s):

Kui Xiao ◽

Yu Zhao ◽

Jun Zhu ◽

Liang Zhao

Keyword(s):

Nitrogen Atom ◽

Carbon Atom ◽

Electron Density ◽

Cyclic Structure ◽

Indole Ring

AbstractAromaticity generally describes a cyclic structure composed of sp2-hybridized carbon or hetero atoms with remarkable stability and unique reactivity. The doping of even one sp3-hybridized atom often damages the aromaticity due to the interrupted electron conjugation. Here we demonstrate the occurrence of an extended hyperconjugative aromaticity (EHA) in a metalated indole ring which contains two gem-diaurated tetrahedral carbon atoms. The EHA-involved penta-aurated indolium shows extended electron conjugation because of dual hyperconjugation. Furthermore, the EHA-induced low electron density on the indolyl nitrogen atom enables a facile protodeauration reaction for the labile Au-N bond. In contrast, the degraded tetra-aurated indolium with a single gem-dimetalated carbon atom exhibits poor bond averaging and inertness in the protodeauration reaction. The aromaticity difference in such two polyaurated indoliums is discussed in the geometrical and electronic perspectives. This work highlights the significant effect of metalation on the aromaticity of polymetalated species.

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