Most likely carbons for nucleophilic attack on a molecule

[blueberryfive]

Homework Statement

I've attached a picture of the molecule. The question: at which molecules (s) would it be likely that there would be a nucleophilic attack?

Homework Equations

The Attempt at a Solution

The answer key says a and c, only. However, I think that b is nucleophilic because the nucleophile can attack the alkene carbon furthest from the bromine, which would shift the alkene up, knocking off the bromine.

 

[Saitama]

Homework Statement

I've attached a picture of the molecule. The question: at which molecules (s) would it be likely that there would be a nucleophilic attack?

Homework Equations

The Attempt at a Solution

The answer key says a and c, only. However, I think that b is nucleophilic because the nucleophile can attack the alkene carbon furthest from the bromine, which would shift the alkene up, knocking off the bromine.

Nucleophilic attack can take place if b is the carbon on the right of the double bond but I don't know if the ring structure makes a difference. Let's see what others have to say on this. :)

 

[chemisttree]

B is an SP2-hybridized bridgehead carbon. A pretty poor nucleophile. The attacking species would need to approach from one of the faces axially to the ring system which is fairly sterically restrictive. Were it simply an open allylic system, your analysis would be correct.