Question

Which of the following is true regarding Bredt's rule ?

• A. A double bond cannot be formed at the bridgehead
• B. Double bonds can only be formed at the bridgehead
• C. Double bonds cannot be formed in the molecules having a bridgehead
• D. None of the above

Answer 1

The correct option is A A double bond cannot be formed at the bridgehead

Bredt's rule:
The possibility of formation of multiple bonds, intermediates (cation and radical), transition states at the bridge head position is negligible because it creates a strain at the already strained position.
Bicyclic molecules having bridge can not have bridge head C as $s{p}^2$ C
It is generally applicable for 8 or less membered rings and is not applicable for fused rings as well as for more than 8 membered rings.