According to Bredt's rule, which of the following cycloalkenes is unlikely to exist?

Question

Quizplus · Accepted Answer

Bredt's rule states that a double bond cannot be placed at the bridgehead of a bridged bicyclic compound if it would create a trans double bond angle of less than 90 degrees. In choice D, the bridgehead carbon has three substituents, which would create a trans double bond angle of less than 90 degrees, violating Bredt's rule. Therefore, choice D is unlikely to exist.

According to Bredt's Rule, Which of the Following Cycloalkenes Is