Naming Organic Compounds #-yl

  • #1
Hi all,

I have a question regarding the nomenclature of organic compounds. What is the significance of -5-yl in

bicyclo[2,1,0]pent-5-ylbicyclo[3,3,0]octane

? In general, what is the significance of the # in -#-yl in compounds?

Additionally, in (E)-1,2-diiodo-1methylcyclohexane, does the E indicate trans, whereas a Z would indicate cis? As in the two iodine atoms are on the first and second carbons, and they are both trans to each other (both axial)?

Thanks guys!
 

Answers and Replies

  • #2
I think I figured this out. So I think the -#-yl (when used with bicyclo subunits) denotes the carbon on the subunit that attaches to the main compound.

In the case presented above, the bicyclo[2,1,0]pentyl is not attached via a bridgehead C but rather one C over, but since the 'cyclopropyl' side is attached to the bicyclo[3,3,0]octane, we need to first go around the larger 'cyclobutyl' portion of the bicyclo[2,1,0]pentyl, thus getting a -5-yl. Note that I am using 'cyclobutyl' and 'cyclopropyl' as rough descriptors of the portions of the bicyclo[2,1,0]pentyl I am trying to reference; I can't think of a better way to accomplish this without an image.

Similarly, if we had 5-methylbicyclo[3,3,0]oct-2-yl-4-methylnonane, this would indicate that there is a methyl on the bridgehead of methylbicyclo[3,3,0]oct-2-yl and the bond to the main nonane chain is on the second carbon (one over from the bridgehead carbon) of the methylbicyclo[3,3,0]oct-2-yl.

Can someone confirm this analysis?
 

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