Bredt s rule
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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.

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Bredt’s Rule

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Bredt s rule

Bredt’s Rule

(Ok)

(Not happening)


History and background

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

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 says1

What It Says


What it s good for

H

H

B

r

H

H

H

H

H

100%

What It’s Good For

  • Good for predicting the product resulting from elimination reactions of bridged ring systems

Bredt’s

Rule

NaOEt

EtOH

+

110 oC

0%


Exceptions

Exceptions

  • 8-membered rings with double bonds at the bridgehead can be isolated

    • Less than 7, extremely difficult to find said character


Exceptions1

Exceptions

  • Anti-Bredt Molecules

    • 7 membered (or less) rings that do have double bonds located at the bridgehead

    • Example: 2-quinuclidonium tetrafluoroborate


Exceptions2

Exceptions


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