Synthesis of 1,3-di-1-adamantylimidazol-2-carbonyl from 1,3-di-1-adamantylimidazol-2-ylidene

CO Fixation to Stable Acyclic and Cyclic Alkyl Amino Carbenes: Stable Amino Ketenes with a Small HOMO–LUMO Gap

“…In contrast, although the carbonylation of singlet carbenes is spin‐allowed, there are very few examples of ketene formation using this route 13. In 1994 it was claimed that the imidazol‐2‐ylidene 1 a reacts with carbon monoxide to give the stable diamino ketene 2 a (Scheme ) 14. However, a year later Arduengo et al15 were not able to duplicate these experimental results.…”

Synthesis and Characterization of a Carbene·SO2 Adduct − New Insights into the Structure and Bonding of Thiourea S,S‐Dioxides

“…In 1994, Skrypnik and Lyashchuk reported the isolation of the diamino ketene 4′ 9a,9c and the stable sulfene 5′ (Scheme ) 9b,9c. The existence of 4′ has since been refuted through high level ab initio calculations10 which demonstrated that 4′ would only have the marginal stability of a van‐der‐Waals complex 10.…”

CO Fixation to Stable Acyclic and Cyclic Alkyl Amino Carbenes: Stable Amino Ketenes with a Small HOMO–LUMO Gap

“…[13] In 1994 it was claimed that the imidazol-2-ylidene 1 a reacts with carbon monoxide to give the stable diamino ketene 2 a (Scheme 1). [14] However, a year later Arduengo et al [15] were not able to duplicate these experimental results. They demonstrated computationally that the parent compound 2 b is not even a transition state, and found that there is no stable structure associated with the combination of 1 b and CO, other than "a non-bonded weakly interacting (van der Waals) complex" 3 b (scheme 1).…”