Title : Fluorous ponytails in catalysis
Fluorous chemistry started in 1994 after publication of the seminal paper by József Rábai and István Horváth in Science. Despite being introduced as a tool for catalysis, it later developed also into powerful instrument of organic chemistry. To return back to its originally intended use in catalysis, careful design (tailoring) of catalysts was needed, be it transition metal complexes with fluorous ponytails or fluorous ponytailed organocatalysts. Principles of the design of fluorophilized catalysts of both types will be presented together with the methods of characterization of both the molecular structure and fluorophilicity of the compounds. The examples will be taken from the work of our group and also from the work of others. In transition metal catalysis we were interested in fluorophilized cyclopentadienyl complexes with metals like titanium, rhodium and iridium and recently also in NHC complexes of the late transition metals. Cyclopentadienyl complexes of several types were prepared and it was shown that the ease of synthesis and also their properties strongly depend on the way of attaching fluorous ponytails to the parent structure. Dynamic behavior of the complexes was often observed showing promise concerning their use in catalysis.
Our recent synthesis of a new type of fluorous tag led us into the underdeveloped area of fluorous organocatalysts since for some purposes relatively expensive transition metals should be avoided. Further expansion of the methodology in terms of solvent use will be also presented. It is known that fluorous componds are well compatible with such environment-friendly solvent like supercritical carbon dioxide. In addition to examples from the work of others, our results of catalysis in supecritical carbon dioxide will be shown.