Bredt’s Rule (Ok) (Not happening)

History and Background Discovered in 1924 by Julius Bredt while investigating the chemistry of naturally occurring bicyclic terpenes He’s German Bredt also was the first to determine the structure of camphor (1893) Camphor contains a bridged ring

What It Says You can’t have a double bond connected to the bridgehead of a bridged ring system UNLESS the ring is big enough Having a double bond as part of the bridgehead would be the equivalent of having a trans double bond on the ring This would create massive angular strain on the ring

What It Says

What It’s Good For Good for predicting the product resulting from elimination reactions of bridged ring systems Bredt’s Rule H H B r H 100% NaOEt EtOH + 110 oC 0%

Exceptions 8-membered rings with double bonds at the bridgehead can be isolated Less than 7, extremely difficult to find said character

Exceptions Anti-Bredt Molecules 7 membered (or less) rings that do have double bonds located at the bridgehead Example: 2-quinuclidonium tetrafluoroborate

Exceptions