Drawing 1-bromo-6-chlorodispiro [2.1.2^5.1^3] octane

[Sunwoo Bae]

Homework Statement

The nomenclature for a compound is given: 1-bromo-6-chlorodispiro [2.1.2^5.1^3] octane
Draw the structure of this compound

Relevant Equations

none

I tried drawing the structure, and I do not know which one of the two is the correct compound for the nomenclature.
Which one would be the correct one, and why?

Thank you!

 

[TeethWhitener]

First of all, kudos to you for getting the right ring structure! Polycyclic IUPAC conventions caused me no end of headaches in school.

Actually answering your question is a bit tricky. If you, for instance, plug both formulas into an online IUPAC namer, you get the same name for both compounds. However, if you actually look at models of the two, you see that they are in fact distinct compounds. This means you have to go to the source IUPAC documents for the answer. I found one of relevance here (possibly paywalled):
https://www.degruyter.com/document/doi/10.1351/pac199971030531/html
See section SP-9 in the link above. The numbering always goes to the lower locant. So both compounds are in fact 1-bromo-6-chloro. To distinguish them, per the document above, a cis/trans convention is used (apparently E and Z are only used for double bonds). Alternatively, you can determine the absolute chiral configuration (R vs. S) at the 3 and 5 carbons.