Consider the following two reactions (source):

enter image description here

I don't quite get why the products shown are the main ones. In reaction 3A., if you rotate the carbon facing us by 120 degrees clockwise, the anisole would be antiperiplanar with the leaving group and should migrate instead of the phenyl group. In reaction 3B., the same rotation should lead to a migration of the phenyl group instead of the anisole group.

Why does phenyl migrate in the erythro isomer and anisole migrate in the threo isomer?

  • $\begingroup$ @Esha Manideep, as a suggestion for future questions: If you intend to substantiate your question by pictures, have a look how to crop and rescale them and eventually insert them here on ChemSE. This will ease visitors of ChemSE to see your question in one glimpse compared to your original post relaying to a page outside ChemSE. $\endgroup$ – Buttonwood Apr 17 '19 at 21:02

Browse other questions tagged or ask your own question.