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New Biphenylenophanes and Biphenylophanes – 1,8‐Dimethylbiphenylene by Continuous Vacuum Pyrolysis
Author(s) -
Laufenberg Susanne,
Feuerbacher Nina,
Pischel Ivo,
Börsch Oliver,
Nieger Martin,
Vögtle Fritz
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970915
Subject(s) - chemistry , pyrolysis , pyrolytic carbon , flash vacuum pyrolysis , intermolecular force , sulfur , extrusion , solid state , phase (matter) , organic chemistry , molecule , materials science , metallurgy
The synthesis of 1,8‐disubstituted biphenylenes by pyrolysis of azo compounds has been optimized. By means of a continuously working pyrolysis 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 intermolecular cyclization reaction, subsequent oxidation of the sulfur atoms and pyrolytic extrusion of sulfur dioxide. In an analogous manner, the [2.2]biphenylophane 13 was obtained. The separation of the racemates of the hydrocarbons 12 and 13 could be achieved using a stationary chiral HPLC phase. Compound 12 preferentially adopts a syn conformation in the solid state. The CD spectra of 12 and 13 are compared.