The major product obtained in the following conversion is:

1. Step 1: Bromonium Ion Formation

   When the molecule is treated, the alpha-bromo ketone portion or the neighboring groups interact to form a highly reactive three-membered cyclic bromonium ion ring intermediate across the carbon framework, stabilizing the leaving charge:

   $$\text{Regioselective Internal Interaction} \rightarrow \text{3-membered Cyclic Bromonium Ion Intermediate}$$



2. Step 2: Base-Mediated Cleavage / Rearrangement

   The methoxide ion ($$\text{MeO}^\ominus$$) acts as a base/nucleophile to attack the carbonyl or coordinate with the ring system, prompting a ring-opening or Favorskii-type rearrangement of this three-membered intermediate. This directs the framework toward an ester-linked derivative rather than a simple substitution profile.

Conclusion:

Accounting for the initial formation of the key three-membered bromonium ring intermediate, the rearranged framework delivers the ester configuration matching the structural transformation profile.