Transition metal-catalysed carbene- and nitrene transfer to carbon monoxide and isocyanides

Abstract

In this review the transition metal-catalysed carbene- and nitrene transfer to carbon monoxide and isocyanides will be disclosed. The resulting heteroallene allows for in situ transformation towards numerous functional groups and organic compounds.

Iron‐Catalysed Carbene Transfer to Isocyanides as a Platform for Heterocycle Synthesis

“…From a mechanistic point of view, three distinct pathways for the mechanism of the Hieber anion‐catalysed ketenimine formation (Scheme 5) seem plausible [8] . These three pathways are discussed in more detail below and are based on theoretical studies on general carbene transfer reactions [24] as well as previous theoretical and spectroscopic studies [25–27] on the Hieber anion, in combination with mechanistic insight gathered from the palladium‐catalysed carbene transfer to isocyanides [9c] .…”

“…[23] From a mechanistic point of view, three distinct pathways for the mechanism of the Hieber anion-catalysed ketenimine formation (Scheme 5) seem plausible. [8] These three pathways are discussed in more detail below and are based on theoretical studies on general carbene transfer reactions [24] as well as previous theoretical and spectroscopic studies [25][26][27] on the Hieber anion, in combination with mechanistic insight gathered from the palladium-catalysed carbene transfer to isocyanides. [9c] The first pathway (I) commences with the formation of Feisocyanide complex A, followed by formation of the corresponding Fe-isocyanide/carbene complex B, which after 1,1migratory insertion affords iron-coordinated ketenimine complex C. Subsequent or simultaneous liberation of ketenimine 5 closes the catalytic cycle.…”

“…The coupling of carbenes and isocyanides results in ketenimines, which are valuable building blocks in organic synthesis [7] . To date, only a handful of carbene transfer reactions to isocyanides have been reported, [8] which are predominantly catalysed by noble metals, such as palladium [9] and rhodium [10] . Although iron complexes have been used as catalysts in carbene transfer reactions to various functionalities, [11,12] their use in carbene transfer to isocyanides is unprecedented [13] .…”

A Cobalt Mediated Nitrene Transfer aza-Wittig Cascade Reaction To Access 1,3,4-Oxadiazole Scaffolds

“…However, noble metals are expensive and scarce; therefore, moving toward base metals is essential from a sustainable chemistry perspective. Cobalt is an interesting candidate compared to other base metals, because it does not require complex ligands to promote the nitrene transfer, and it tolerates in situ functionalization of carbodiimides. − …”

“…Our proposed mechanism for the formation of products 15 and 16 is depicted in Scheme . The possible mechanisms of the formation of carbodiimide 12 are described and analyzed in detail in our review . Both products are formed from the in situ generated carbodiimide 12 .…”