Click Chemistry in Ultra‐high Vacuum – Tetrazine Coupling with Methyl Enol Ether Covalently Linked to Si(001)

The additive‐free tetrazine/enol ether click reaction was performed in ultra‐high vacuum (UHV) with an enol ether group covalently linked to a silicon surface: Dimethyl 1,2,4,5‐tetrazine‐3,6‐dicarboxylate molecules were coupled to the enol ether group of a functionalized cyclooctyne which was adsorbed on the silicon (001) surface via the strained triple bond of cyclooctyne. The reaction was observed at a substrate temperature of 380 K by means of X‐ray photoelectron spectroscopy (XPS). A moderate energy barrier was deduced for this click reaction in vacuum by means of density functional theory based calculations, in good agreement with the experimental results. This UHV‐compatible click reaction thus opens a new, flexible route for synthesizing covalently bound organic architectures