Claisen and related rearrangements

The mechanism was studied extensively in the chorismate mutase-catalyzed conversion of chorismate 8 to prephanate 9, an important intermediate for amino acid biosynthesis.  

One possible role for the enzyme may be to populate and provide electrostatic stabilization of the reactive chair conformer 19. The outcome of the Claisen rearrangement can be predicted by evaluating three structural features. The alkene geometry of the allyl and the vinyl moieties will determine the outcome of syn- or a t/-diastereoselection, and the stereogenicity at the allylic carbon determines an outcome featuring 1,3-chirality transfer. 

1) Aliphatic Claisen, aromatic Claisen and Saucy-Claisen  

2) Ester enolate Claisen, Ireland-Claisen, Reformatsky-Claisen, Corey-Claisen and Kazmaier-Claisen varients  

7) Thio-Claisen and aza-Claisen examples. Aza-Claisen process can be subdivided into zwitterionic aza-Claisen, amide enolate Claisen, 

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