Organic and Inorganic Chemistry

Tetracyanoethylene (TCNE) is well known for reacting with some electron-rich alkynes to lead to 1,1,4,4-tetracyanobutadiene (TCBD) moieties in variable yields. This reaction processes according to a [2+2] cycloaddition followed by a [2+2]retroelectrocyclization. Some of the corresponding products have interesting opto-electronic properties, in particular in non-linear optics. However, this reactivity had never been tested with ynamides, which are electron rich alkynes where a nitrogen is directly linked to the triple bond. We recently demonstrated that ynamides easily react with TCNE at room temperature to give TCBDs in generally high yields (Figure 1). This reaction is very tolerant to many substituents. These new TCBDs are electron super-acceptors: indeed, according to electrochemical studies, they can be reduced around -0.1 and -0.6 V vs. SCE (two distinct reversible reduction waves in cyclic voltametry). We showed that they could dramatically influence the absorption properties of the substrate they are linked to. We also explored the possibility to run the reaction with more complex ynamides. In the presentation, we will present the scope of the reaction with a series of various ynamides. Some original optical and electronic properties will also be discussed.