Example of a transition state for a chemical reaction:

 

the Claisen rearrangement of chorismate to prephenate

 

 

·   Pericyclic reaction - Claisen rearrangement

 

·   Important for synthesis of aromatic amino acids

 

 

 

Optimized TS structure (1 imaginary frequency, 640i cm-1)

 

Calculating the barrier to reaction