1. Synthesis and Physicochemical Investigation of
Hydrofluorocarbons with Extended p-Stacked Arene Units
Markus Etzkorn, Department of Chemistry, UNC Charlotte, 9201 University City Blvd., Charlotte, NC 28223
The synthesis of dienedione 3 has been transferred to a preparative multi-gram level. Due to the thermally induced back-isomerization of 3 any functionalization has to be carried out under very mild conditions, thus limiting the use of dienedione 3 as a starting material. Therefore the two known, thermally stable derivatives – mono-alcohol 7 and diol 8 – are better substrates for further functionalization studies. In particular, their Diels-Alder chemistry has been thoroughly investigated as a potential avenue to (fluorinated) benzannulated species of type 4. The [4+2] cycloaddition of tetrachlorothiophene dioxide (TCTD) to one double bond of 7 and 8, followed by SO2 extrusion, yields adducts 10 and 11, respectively. The concomitant transannular cyclization reaction in diol 8 gives rise to an unusual polycyclic framework 11 and eliminates any further benzannulation toward 4, whereas the monoalcohol derivative 10 retains the other double bond for a second cycloaddition reaction.
Our next goals are the introduction of a second diene equivalent in 10, the introduction of protective groups in 7 and 8 to tailor their respective chemistry and the use of fluorinated Diels-Alder components.