In order to obtain a better insight into the fine‐structure of dibiphenylene‐ethene, the 1,1′‐difluoro‐, 1,1′‐dichloro, 1,1′‐ and 2,2′‐dimethyl derivatives have been prepared using a variety of methods. The attempted preparation of the pure 1,1′‐dibromo‐derivative failed.
SuwmaryThe conformational behaviour of 1 , 1'-disub-difluoro-isomer (1 ; R = F) showed similar behaviour. This stituted tetrabenzopentafulvalene is strongly substituentbehaviour contrasts sharply with the ease of the cis-transdependent ; in the 2,2'-difluoro-derivative, the energy isomerization of 1, 1'-disubstituted tetrabenzopentafulvalbarriers associated with the cis-trans-isomerization did enes carrying bulky groups, e.g. , (1 ; R = C0,R').
Das aus dem entsprechenden Fluorenon nach üblichen Verfahren erhältliche Fluoren (I) läßt sich direkt (mit K‐tert.‐butoxid in tert.‐Butanol oder mit Triton B in Dioxan oder Aceton) oder über das Bifluorenyl (II) (das auch bei der No.1 m55? CH: CH: Br CH3 I JI 70% Triton B CH3 C(CH3)3‐OH5 C f1; direkten Methode als Nebenprodukt entsteht) zu dem Dibiphenylenäthen (III) kondensieren.
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