Cycloelimination of Imidazolidin‐2‐ylidene N‐Heterocyclic Carbenes: Mechanism and Insights into the Synthesis of Stable “NHC‐CDI” Amidinates

Abstract

The authors noticed that Figure 1a nd Scheme 2a in their Communication were incorrect. In Figure 1, the formula under the first reaction arrow should read "C 2 H 4 ", as described in the text. In Scheme 2a,the N-substituents in both the NHC and the NHC-CDI should be iPr rather than Me. The last sentence of the paragraph below Scheme 2o npage 5687 should read:" This dramatic difference likely stems from the larger steric bulk of the four aryl substituents in our adducts compared to that of the iPr groups in the NHC and amidinate components of Kuhn'sa dduct." The authors apologize for the oversight.

Combining a ligand photogenerator and a Ru precatalyst: a photoinduced approach to cross-linked ROMP polymer films

“…28,29,37,38 Table 1 compares the efficiency of the two methods in terms of NHC generated aer 5 min irradiation. 39 Clearly, 1 irradiated alone at 254 nm (entry a) shows less activity in comparison with the combination of 1 and ITX at 365 nm (entry b) and 405 nm (entry c). Only 11% IMes was liberated in direct photolysis versus 29% (405 nm) and 67% (365 nm) in the sensitized reaction.…”

Synthesis and properties of heteroaromatic carbenes of the imidazole and triazole series and their fused analogues

“…This compound eliminated ethylene (from the ethylene moiety of the ring), and the resulting carbodiimide (di-p-tolyl substituted) added to a second equivalent of the unreacted carbene, forming the zwitterion 66C (Scheme 66). 301 This reaction resembles the above-described autotransformation reaction (Scheme 63); the only difference is that here the stable tolyl groups in the adduct are not cleaved, and hence the zwitterion 66C is the final product.…”

“…375 The analogous zwitterions 98D2,3 were synthesized from ditolylcarbodiimide at room temperature. 301 This reaction is one step in the more complicated decomposition process involving 1,3-ditolyl-4,5-dihydroimidazol-2-ylidene, which proceeds upon heating at 110 C (Scheme 66).…”

Interaction of an imidazolium-2-amidinate (NHC-CDI) zwitterion with zinc dichloride in dichloromethane: role as ligands and C–Cl activation promoters

“…Accordingly, it has been recently shown that symmetric NHC-CDI adducts can be directly generated by the thermal decomposition of certain N-heterocyclic carbenes. 7 Therefore, it is quite surprising that, although the first NHC-CDI zwitterions were reported in 1999, 8 they have received very little attention until 2015, when some of us reported their ability to support ultra-small Ru nanoparticles. 1a Although devoid of net electrical charge, NHC-CDI have betainetype electronic structure, i. e., they cannot be represented by any classic Lewis formula that cancels charge separation between both fragments.…”