First Optically Active Heptalenes and their Absolute Configuration

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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 C2 or pseudo‐C2 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.