Vorschau

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Abstract

This thesis outlines the three-step transformation of imine cages into hydrocarbon cages utilising the Overberger-Lombardino-reaction as the fundamental step, opening a new synthetic pathway towards hydrocarbon cages. This method makes use of the advantages of dynamic covalent chemistry (DCC) like high yields and easy access of imine cages to form the hydrocarbon cage in overall yields up to 24%. The core building block 1,3,5-tri(methylamine)benzene was condensed with derivatives of isopthaldehyde and terephtaldehyde to give a range of [2+3]- and [4+6]-imine cages. After reduction and nitrosylation the Overberger-Lombardino-reaction followed from which the hydrocarbon cages were obtained. By comparison of the hydrocarbon cage yield it is possible to estimate the influence of steric or electronic effects of functional groups from which both the steric and elektronic effect have an influence on the imine cage transformation. Sterically demanding groups lower the yield of the hydrocarbon cage the closer they are set to the reaction site. The highest yields were obtained when the functional groups were pointing inside the cage cavity. An incompletely converted hydrocarbon cage, with one or two N-nitroso groups remaining, was isolated as a side product when no functional group was located in the cage cavity. The electronic properties of the functional groups had no effect on the formation of these side products. From crystal structure analysis and 2D-NMR spectra the orientation of the N-nitroso group could be determined showing the N-nitroso group to be pointing away from the cage center.