NEW BIPHENYLENOPHANES AND BIPHENYLOPHANES - 1,8-DIMETHYLBIPHENYLENE BY CONTINUOUS VACUUM PYROLYSIS

The synthesis of 1,8-disubstituted biphenylenes by pyrolysis of azo co mpounds has been optimized. By means of a continously working pyrolysi s apparatus, the cis isomer 2 can be reliably produced on a gram scale . The chiral syn-[2.2]biphenylenophane 12 has been synthesized by an i ntermolecular cyclization reaction, subsequent oxidation of the sulfur atoms and pyrolytic extrusion of sulfur dioxide. In an analogous mann er, the [2.2]biphenylophane 13 was obtained. The separation of the rac emates of the hydrocarbons 12 and 13 could be achieved using a station ary chiral HPLC phase. Compound 12 preferentially adopts a syn conform ation in the solid state. The CD spectra of 12 and 13 are compared.