Friedel-Crafts chemistry. Part 55. Competing indan versus tetralin ring formations during Friedel-Crafts intramolecular cyclialkylations of some selected di-, tri- and tetraphenylated alkanols | ||||
| Assiut University Journal of Multidisciplinary Scientific Research | ||||
| Volume 47, Issue 2, December 2018, Page 66-80 PDF (190.12 K) | ||||
| Document Type: Novel Research Articles | ||||
| DOI: 10.21608/aunj.2018.221247 | ||||
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| 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. | ||||
| Keywords | ||||
| Friedel-Crafts cyclialkylation; phenylated alkanols; carbocation rearrangement; tri- and tetrasubstituted indans and tetralins | ||||
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