First Optically Active Heptalenes and their Absolute Configuration

Abstract

Abstract It is shown that dimethyl 7‐isopropyl‐5, 10‐dimethylheptalene‐1, 2‐dicarboxylate ( 1 ) and dimethyl 5, 6, 8, 10‐tetramethylheptalene‐1, 2‐dicarboxylate ( 2 ) can be resolved via the corresponding mono‐acids and with the aid of optically active primary or secondary amines such as 1‐phenylethylamine or ephedrine into the (−)‐( P )‐ and (+)‐( M )‐enantiomeres, respectively. Characteristic for the ( P )‐chirality of the heptalene π‐skeleton with C 2 or pseudo‐ C 2 symmetry are two (−)‐CE's at the long wavelength region (450–300 nm) followed by at least one intense (+)‐CE at wavelengths about or below 300 nm. The absolute configuration of the heptalenes was correlated with the well‐established absolute configuration of (+)‐( R )‐ and (−)‐( S )‐1‐phenylethanol.