Aldiminium and 1,2,3-triazolium dithiocarboxylate zwitterions derived from cyclic (alkyl)(amino) and mesoionic carbenes

• Nedra Touj,
• François Mazars,
• Guillermo Zaragoza and
• Lionel Delaude

Beilstein J. Org. Chem. 2023, 19, 1947–1956, doi:10.3762/bjoc.19.145

• cyclic (alkyl)(amino) or mesoionic carbenes (CAACs or MICs) onto carbon disulfide. Nine novel compounds were isolated and fully characterized by 1H and 13C NMR, FTIR, and HRMS techniques. Moreover, the molecular structures of two CAAC·CS2 and two MIC·CS2 betaines were determined by X-ray diffraction

• ][19]. These mesoionic carbenes (MICs), together with their pyrazolin-4-ylidene [20] and 1,2-isoxazol-4-ylidene cousins [21], are the strongest donors among the various types of carbene ligands known thus far [22]. A distinct class of mesoionic or abnormal carbenes based on the 1,2,3-triazole ring

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• to be around 25 kcal mol−1 for model imidazol-2-ylidenes [7]. The ylidic structure confers NHC a nucleophilic character. Bertrand reported a new class of mesoionic carbenes 10 based on a 1,2,3-triazolium scaffold [8][9]. These NHCs, also known as remote or abnormal N-heterocyclic carbenes (aNHCs

• benzimidazolium salts 15 in the presence of CuI (Scheme 8). In a similar manner, Cu(I) complexes 18 of so-called “abnormal” carbenes [9] or mesoionic carbenes [8], such as 1,2,3-triazol-5-ylidenes have been prepared (Scheme 9). These NHC–Cu(I) complexes have been found to be highly efficient catalysts for the [3

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• whether stable meta-metalated calix[4]arenes could be formed, isolated and used. For this, our attention turned to the work of Albrecht and co-workers on mesoionic carbenes (MICs) [18][19][20][21][22], particularly the fact that 1,4-diphenyl-substituted 1,2,3-triazol-5-ylideneruthenium(II), iridium(III

Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

• Diego M. Andrada,
• Nicole Holzmann,
• Thomas Hamadi and
• Gernot Frenking

Beilstein J. Org. Chem. 2015, 11, 2727–2736, doi:10.3762/bjoc.11.294

• calculations and with an energy decomposition analysis. The investigated molecules include N-heterocyclic carbenes (NHCs), the cyclic alkyl(amino)carbene (cAAC), mesoionic carbenes and ylide-stabilized carbenes. The bonding analysis suggests that the carbene centre in cAAC and in diamidocarbene have the

• weakest X→p(π) π-donation while mesoionic carbenes possess the strongest π-donation. Keywords: bonding analysis; N-heterocyclic carbenes; π-donation; Introduction Since the isolation and unambiguous characterization of imidazol-2-ylidene by Arduengo in 1991 [1], the chemistry of stable singlet carbenes

• mesoionic carbenes for which no resonance form without formal charges can be written [73]. Molecules 11 and 12 are NHCs with one nitrogen donor atom where the carbene centre is additionally stabilised by another hetero π-donor. Compounds 13 and 14 are ylide-stabilised carbenes while 15 is a diamidocarbene

Rhodium, iridium and nickel complexes with a 1,3,5-triphenylbenzene tris-MIC ligand. Study of the electronic properties and catalytic activities

• Carmen Mejuto,
• Beatriz Royo,
• Gregorio Guisado-Barrios and
• Eduardo Peris

Beilstein J. Org. Chem. 2015, 11, 2584–2590, doi:10.3762/bjoc.11.278

• addition reaction of arylboronic acids to α,β-unsaturated ketones. Keywords: arylation of unsaturated ketones; mesoionic carbenes; nickel; iridium; rhodium; Introduction Highly symmetrical poly-NHCs are a very interesting type of ligands, because they allow the preparation of a variety of supramolecular

• the addition reaction of arylboronic acids to 2-cyclohexen-1-one, where it showed good activity. The same ligand was also used for the preparation of nanometer-sized cylinder-like structures of Cu, Ag and Au [13]. As mesoionic carbenes (MICs) are known to be stronger electron donors compared to NHCs

Synthesis and structure of trans-bis(1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene)palladium(II) dichloride and diacetate. Suzuki–Miyaura coupling of polybromoarenes with high catalytic turnover efficiencies

• Jeelani Basha Shaik,
• Venkatachalam Ramkumar,
• Babu Varghese and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2013, 9, 698–704, doi:10.3762/bjoc.9.79

• mesoionic carbenes because their structures cannot be represented in neutral canonical form [17][19]. Mesoionic NHCs are stronger sigma donors than the normal NHCs (e.g., imidazolylidenes versus triazolylidenes) [21][22][23]. Hence metal complexes of mesoionic carbene ligands are expected to show high