What will the final product of this synthetic sequence be?


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> What is the major product formed in the following reaction?
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> [![Question](https://i.stack.imgur.com/HeCGh.png)](https://i.stack.imgur.com/HeCGh.png)
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NBS should do allylic bromination but where will it attack in the larger ring or smaller one ?




Potassium carbonate is not going to give you hydrolysis of a tertiary bromide. It will however close the halohydrin to form an epoxide (**1**). This intermediate undergoes Lewis acid catalyzed rearrangement to form the spiro compound that is choice (D).


[![enter image description here](https://i.stack.imgur.com/6iuKi.png)](https://i.stack.imgur.com/6iuKi.png)


Note that **1** or the carbocation could undergo certain elimination reactions to form (B) and (C). These are probably minor products.


[![enter image description here](https://i.stack.imgur.com/7rmrP.png)](https://i.stack.imgur.com/7rmrP.png)


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