Elimination of Ethylene from Cyclobutyl Groups Characterised by X-ray Crystallography in a Metal-Organic Framework Matrix

We herein describe a series of breakthroughs in synthetic and structural chemistry. We have developed a novel strategy for the preparation and atomic-level characterisation of aromatic compounds with vinyl functional groups. Such compounds are highly sought after since they make exceptional polymers. Until now, however, deliberate synthetic methods and precise structural details have eluded researchers. We addressed this challenge by using a metal-organic framework as a matrix to isolate the vinyl groups. Cyclobutyl rings serve as synthetic precursors. The expulsion of ethylene from them delivers the desired compounds. This transformation is unprecedented in the literature. The framework is unperturbed by the high temperature required for thermolysis, which itself is a startling observation. We further show how the inherent reactivity of the vinyl groups can be harnessed to deliver addition products in quantitative yields. The two transformations take place in a single-crystal-to-single-crystal manner without changing the overall network structure of the parent framework. This manuscript defines a new strategy for preparing and studying an important class of compound using site-isolation in a framework matrix. It will thus appeal to synthetic chemists, materials scientists and crystallographers. Looking ahead, there are opportunities for the strategy to be extended to related compounds to produce other sought-after targets.