Ynamides as Precursors of Carbenes and Carbenoids

Carbenes are undoubtedly one of the most useful reactive intermediates in synthetic chemistry, used to access a diverse array of reactions involving C–C, C–X, C–H and X–H bond formation [1, 2]. Carbene-like reactivity, often realized via a metal carbene or metal carbenoid, is commonly accessed by elimination or extrusion of a pre-installed sacrificial functional group. Highly reactive moieties such as diazo groups have been most commonly used to this end, and a sustained number of advances in this area have allowed for widespread reactions where significant control is achieved over reactivity profile and selectivity [1–11]. In addition to the potential operational hazard associated with high energy carbene precursors and the reactants used to prepare them, the effort required to install these sacrificial functional groups can be deleterious to overall synthetic efficiency. Furthermore, these approaches are limited in terms of the carbene environments that they provide access to. To benefit from the full potential of carbene chemistry in enabling efficient synthetic methods, alternative ways to access carbenes are needed [12]. Methods that provide access to carbene reactivity patterns as well as previously inaccessible substitution patterns, or remove the dependency on high energy precursors, or reduce the preparative load are all highly appealing. In addition to enabling more sustainable synthesis, alternative routes into carbene and carbenoid chemistry open up new vistas for synthesis.