TPRH Orgo Passage 1

[Skizye]

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So this question asks how many possible stereoisomers the molecule has. Here's the question/solution:

I reasoned that the epoxide must be syn, so you get 2^2 stereoisomers when the epoxide is into the page (since there are 2 chiral carbons not involved in the epoxide) and 2^2 stereoisomers when the epoxide is out of the page for total of 2(2^2) = 8 stereoisomers. Can you guys explain why this is not the case? Should I just stick with 2^n all the time even when there is something like this?
Thanks in advance!

 

[quicheduty]

Can you post the image again?

 

[Skizye]

 

[Skizye]

Any thoughts on this question? Is the image viewable now?

 

[quicheduty]

View attachment 182002

Sorry about that! Didn't see this.
I think you're totally right. In reality only 8 stereoisomers are possible since epoxide bonds must be cis. But maybe the tricky thing with the question was asking theoretical stereoisomers; theoretically, 2^4 are possible. The 2^n rule is always more of an indicator of max number of stereoisomers, not actual. But I feel like the question could have been more clear.