This is my approach towards this problem. First off, a positive charge would appear in the C atom at the end of the chain, and then that carbocation would rearrange into a tertiary carbocation.

But I am not being able to figure out what will be the next step. Can the carbocation extract a hydrogen from the benzene ring to form another five-membered chain as the formation of a five-membered rings is very feasible?

Ring formation

  • 1
    $\begingroup$ Yes, Definitely. The carbocation won't extract proton from Benzene ring, the $\pi$-electron cloud of benzene ring will attack to the carbocation to form the fused five-membered ring and a proton will be lost to rearomatise the system. $\endgroup$ – Soumik Das Apr 10 '19 at 13:18
  • $\begingroup$ You need to review cation rearrangements. $\endgroup$ – user55119 Apr 10 '19 at 13:52
  • $\begingroup$ @SoumikDas so should the benzene ring attack from the carbon opposite to the carbon bearing the -och3 group , as then the carbanion formed would be more stable? $\endgroup$ – Pratham Yadav Apr 10 '19 at 14:40
  • $\begingroup$ Yes there will be electrophilic addition at the para position to form a 5-membered ring. $\endgroup$ – Som V. Tambe Apr 10 '19 at 15:53
  • $\begingroup$ @PrathamYadav Yes, I think so, as attack from the ortho position of $\ce{-OCH3}$will make lot of steric crowding, attack from para position of $\ce{-OCH3}$ should be more favoured.. $\endgroup$ – Soumik Das Apr 10 '19 at 15:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.