Stereo-specific synthesis of hydroanthracene-dicarboximides

Compound 3, N-((1S)-1-cyclohexylethyl)-9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-dicarboximide-1,2,3,4-octahydro, was obtained by ruthenium-assisted hydrogenation of the hydroanthracene-dicarboximide 2 under mild conditions (3 bar H2 and room temperature). In contrast to other related compounds, dicarboximides 2 and 3 were stereo-selectively obtained, confirmed by both solid state (X-ray diffraction) and solution (NMR). This selectivity denoted a hindered rotation around the N–CH axis together with the aromatic hydrogen bond acceptor behaviour of the hydroanthracene skeleton towards a methylene of the cyclohexyl group of the imide moiety. In addition, the nature of the metallic species involved in the hydrogenation process was also investigated.

Graphical abstractOnly one conformer for hydroanthracene-dicarboximides has been isolated due to an hindered rotation around the N–CH axis together with a strong intramolecular CH/π interaction.Figure optionsDownload full-size imageDownload as PowerPoint slide