Orgo problem? can you name this?

[Dencology]

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hey guys, can you name this?
see attachment.

 

[yakuza]

hey guys, can you name this?
see attachment.

Whoa whoa whoa, for cycloalkene stuff, number through the double bond first, than lowest # substituents, and substituents are ordered alphabetically.

This guy would be called (3R, 5S)-3-bromo-5-ethyl-1-cyclohexene (I put the 1 there so you can see that I named the double bond as C1)

-the 5S carbon is tricky..but I put the double bond as a higher priority group than the ethyl bc you pretend the double bond is connected to two things.



I really hope I'm not wrong bc this is how I've been always doing it..

 

[yakuza]

And to your question

E/Z needs a double bond, cis/trans doesn't.

This thing could also be called trans

 

[chessxwizard]

I got the same answer. The #5 carbon is tricky, had to assign the double bond #1 priority, the the carbon across from it on the ring as #2.

 

[klutzy1987]

The correct naming is trans (3R 5S) 3bromo-5ethyl-cyclopentene . We always name from the double bond first and then we go to the side that will have lower numbers. In this case either side is going to be 1,3,5 which equals 9. Therefore we then go to the side that has the lower alphabetical substituent. In this case it is Bromo which has a B as opposed to Ethyl which has an E.