[theskiver]

Hi all (I am new),

I have attached the problem to this post (wasn't sure how to display a picture in a post). Any help is greatly appreciated.

[Dynamo22]

So you know the methanol is forming the ester and there is a ring expansion. Can you visualize how the expansion occurs? What do you think the first mechanistic step is in this mechanism?

[zhangcarlin]

think about why the cyclopentane is formed at first

[PhDoc]

I use this and variations of this problem to teach skills in this very subject.

[1] Map all your carbons (1,2,3, etc.)
[2] Don't worry about the rearrangement at first, however keep it in mind.
[3] What's the logical first step?
[4] If the ether is now attached to an unexpected carbon, then what had to exist before the ether bond was made?
[5] How do you relate [4] to [3]?
[6] What's the thermodyamic "payoff" that drives the rearrangement?

[theskiver]

This is what i've come up with so far

[PhDoc]

Very nicely done! The only change I would introduce is the species involved in the deprotonation step. What is the most basic entity (highest pKa) present in abundance?