Question

How many chiral centers are in the given structure? i oooo

Answer 1

A carbon is chiral when all the four substituents of that carbon are different. For example, consider a case of 1-Chloroethanol, the carbon numbered 1 in this molecule is a chiral center because, all of the 4 substituents (-OH, -CH3, -Cl, -H) on this carbon are different, as shown in the image below:

Chiral center

Now, let's come to the question at hand. In this compound, there are 2 carbons at bridge head positions (numbered 1 and 2) which one might think seems to have different substituents. But, they are not chiral, because while substituents marked a and b on both are different groups, substituents marked as c and d are the same groups. So they can not be chiral. This is illustrated in the images given below:

In this image the two carbons which one could mistake for being chiral are marked as 1 and 2.

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Now, let's look at the substituents of carbon 1, first, which are marked as a,b,c and d. Here, groups marked as a and b are different groups, but the groups marked as c and d are same groups (one can verify this by simultaneously go from carbon to carbon and end up at the carbon marked as 2, and one would realize that all the groups up until carbon 2 are similar.)

Same groups

Similarly, in the image given below, the substituents marked a and b on carbon 2 are different, and groups marked c and are same groups.

aOH Same groups

So, the correct choice is the option which says 0 Chiral centers.