Organic Chemistry: No. of chiral centres in Camphor

[DarkStalker]

Hello. I have a query regarding organic chemistry.

1. http://tinyurl.com/y9nvg2p
See question number 21.



2. Homework Equations : None



3. The first Carbon atom beneath the top-most CH3 group I can tell is a chiral centre, as it has 4 different groups attached to it (C=O, CH2, CH3, C). Apparently the answer is C, i.e 2 chiral centres. I can't locate the second one.

Thanks.

 

[danago]

How about the bottom-most carbon atom?

 

[DarkStalker]

How about the bottom-most carbon atom?

That's the answer, but I couldn't put together a solid reasoning. Normally chiral compounds that we're supposed to identify have, I don't know what to call it, terminal ends? E.g, like the chiral carbon would be bonded to H, OH, CH3, CO2H. That ring confused me. Taking the entire ring as a group, that Carbon is attached to the same group on both the ends.

 

[danago]

You can do a similar kind of analysis even though it is a ring. If you look at the group directly either side of the bottom carbon, they are indeed the same (-CH2), however if you move along and look at the next group, it is a CH2 on the left side and a C=O on the right side i.e. The ring is not symmetrical, so you can kind of think of it as being bonded to 4 different groups.