Friedel-Crafts chemistry. Part 55. Competing indan versus tetralin ring formations during Friedel-Crafts intramolecular cyclialkylations of some selected di-, tri- and tetraphenylated alkanols

Document Type : Novel Research Articles

Abstract

Friedel-Crafts cyclialkylations of six phenylated alkanols 2a-f to new substituted indans and
tetralins mediated by AlCl3/CH3NO2, 85% H2SO4 and/or PPA are described. The results
revealed that competing closures of alkanols 2a-f to structurally isomeric indan and tetralin
derivatives are generally highly dependent on ring strain, carbocation stability and steric
interactions but to a lesser extent on catalyst type. Unusual rearrangements from stable
tertiary to less stable secondary carbocations were noted due to competing interactions. Apart
from stereoisomerism (which is not the aim of this study), determination of the structural
identities of the final products have constituted our main target. In practice, the structural
identities of both starting materials and final products were achieved by elemental, IR, 1H
NMR and MS analyses. Mechanistic interpretations have been given in terms of carbocationic
reactions and rearrangements.

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Assiut University Journal of Multidisciplinary Scientific Research
Volume 47, Issue 2
December 2018
Pages 66-80

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