87779-61-1Relevant articles and documents
Hydrocarbures arylaliphatiques. Partie VII. Orientation dans la reaction de bromation de benzocyclenes bi- et tricycliques superieurs
Gruber, Rene,Cagniant, Denise,Cagniant, Paul
, p. 96 - 104 (2007/10/02)
The bromination of 1,2,3-trimethylbenzene, and bi- and tricyclic fused ring systems (i.e. indan, tetralin, benzosuberan, 2a,3,4,5-tetrahydroacenaphthen and higher homologues) is described in this paper.This work is part of a research project studying the ring size influence of peri-fused semi-aromatic ring system on benzene reactivity.This study was started in a first step on acetylation and was continued on bromination.Forthcoming studies (now underway) concern the kinetic measurement of protodesilylation of univocal silyl derivatives.The synthesis of the starting bromo derivatives used for this latter study is described here.These bromides were used for the attribution via NMR spectroscopy of the electrophile reaction site in the direct bromination of the fused ring unsymmetrical systems (the reactive sites are obvious in symmetrical molecules). Thus, meta substitution is predominant in the case of tetraline and benzosuberan, but ortho substitution is relatively more important in tetralin.In 1,2,3-trimethylbenzene and the fused tricyclic compounds, substitution takes place in an ortho position respective to the substituent or the ring system, the meta position being totally deactivated.In the special case of a five-membered ring, the ortho position this ring is always non reactive.The reactivity differences between these compounds are explained by hyper conjugation and the stabilities of the transition states.
