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

• derived from nucleophilic carbenes. More sophisticated methods, such as the determination of the Huynh electronic parameter, should, however, be better suited to evaluate more precisely the influence of substituents on the donating ability of carbene ligands [22][76][77]. Apart from the asymmetric

• center that may act as a source of chirality. Thus, the novel compounds reported in this study represent a valuable addition to the family of neutral dithiolate ligands derived from stable nucleophilic carbenes, and we are currently investigating their coordination chemistry toward various transition

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• ; nucleophilic carbenes; sulfur transfer reaction; Introduction Imidazole N-oxides constitute a practically valuable class of five-membered aromatic N-heterocycles [1][2][3][4][5]. The subclass of 2-unsubstituted imidazole N-oxides 1 with diverse substituents located at N(1), C(4), and C(5) is of special

• -tetramethylcyclobutane-1,3-dione. Imidazolium salts are of special importance as they are widely used as ionic liquids or precursors of imidazole-based nucleophilic carbenes (imidazol-2-ylidenes). For example, deprotonation of 1,3-diadamantylimidazolium chloride led to the first stable imidazol-2-ylidene (the so-called

• ) at 137.0 and 120.2 ppm, respectively. Unfortunately, attempted syntheses of analogous, symmetric 1,3-dialkoxyimidazolium bromides, derived from diacetyl or 1,2-diphenylethane-1,2-dione, using the same protocol, were unsuccessful. Nucleophilic carbenes are known to undergo conversion into imidazole-2

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• are used as the solvents or are taken in a large excess relative to the CH-reagent. 2.3 Reactions catalyzed by N-heterocyclic carbenes N-heterocyclic nucleophilic carbenes 105 have found use for the oxidative esterification. Scheme 23 shows, in a simplified way, the proposed mechanism of this type of

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

• that the (R)- and the (S)-enantiomer do not have to have the same affinity values. For the phosphane 317 the difference is below 2 kJ/mol, but for phosphane 316 the difference is 21 kJ/mol. A last group of nucleophiles employed in Lewis-base catalysis concerns nucleophilic carbenes (Table 8) [14][15