Polycyclic Molecules with Propeller Chirality—Optical Activity and Absolute Configuration of Some New Systems

Abstract

Abstract The configurations of the trishomobarrelene and trishomobullvalene bridgehead derivatives 1b–1g, 2a–2e and 2g have been correlated with the absolute configuration of 1c as determined by X‐ray crystallography, on the basis of their circular dichroisms, especially those of the carboxylic acids 1b and 2b . All derivatives prepared from the dextrorotatory (+)‐ 1b and (+)‐ 2b resemble dextroverse propellers when looked upon from the substituted side. Attempts to prepare the new chiral trioxa‐[D 3 ]‐trishomocubane 7 in optically active form, have failed so far. It is predicted, however, that (−)‐7 should have the same ( all‐S )‐configuration as the levorotatory parent hydrocarbon (S)‐[D 3 ]‐trishomocubane. In addition, a synthetic approach to two more C 3 ‐symmetric propeller molecules, the hexahydrophenalene 13 and its trishomo derivative 14 is presented.