作者:François Vermersch、Sima Yazdani、Glen P. Junor、Douglas B. Grotjahn、Rodolphe Jazzar、Guy Bertrand
DOI:10.1002/anie.202111588
日期:2021.12.20
Pyrazol-4-ylidenes, a type of mesoionic carbenes, also named cyclic-bentallenes (CBA), can be more basic than Verkade proazaphosphatrane and even Schwesinger phosphazene P4(tBu). With these results it is demonstrated that carbenes should not be overlooked as neutral purely organic superbases.
Pyrazol-4-ylidenes 是一种中离子卡宾,也称为环 Bentallenes (CBA),比 Verkade proazaphosphatrane 甚至 Schwesinger phosphazene P 4 ( t Bu) 的碱性更强。这些结果表明,作为中性纯有机超强碱不应忽视卡宾。
A Stable Thiazol-2-ylidene and Its Dimer
作者:Anthony J. Arduengo、Jens R. Goerlich、William J. Marshall
DOI:10.1002/jlac.199719970213
日期:1997.2
structure determination are described for a stable thiazol-2-ylidene 2. This thiazol-2-ylidene is the first example of a stable, crystallinecarbene in which the singlet carbene center bears a sulfur substituent. The carbene 2 is the closest stable analog of the important thiamin (vitamin B1) carbene. Although the thiazol-2-ylidene 2 is sufficiently stable to isolate at room temperature in the absence
diffraction (XRD) analysis of a crystalline Breslow intermediate (BI) derivedfrom a thiazolin‐2‐ylidene, that is, the aromatic heterocycle present in vitamin B1, is reported. Key to success was the combined use of pentafluorobenzaldehyde and a thiazolin‐2‐ylidene carrying an enol‐stabilizing dispersion energy donor as N‐substituent. A so‐called primary intermediate (PI) could be isolated in protonated form
A closer look at the reactivity between N-heterocyclic carbenes and fluoroalkenes
作者:Matthew C. Leclerc、Jason G. Da Gama、Bulat M. Gabidullin、R. Tom Baker
DOI:10.1016/j.jfluchem.2017.05.012
日期:2017.11
total of 15 N-heterocyclic carbenes (NHCs) with various electronic and steric environments. The activity of these carbenes towards tetrafluoroethylene (TFE), hexafluoropropene (HFP), trifluoroethylene (HTFE) and vinylidene fluoride (VDF) is assessed in THF and toluene. Attempts were made to correlate the observed reactivity with electronic (Tolman Electronic Parameters) and steric (% buried volume) parameters