1,2-Asymmetric induction in the ketene Claisen rearrangement of (2S,3E)-5-(isopropylsulfanyl)-3-pentenes

The ketene Claisen rearrangement of chiral (2S,3E)-5-(isopropylsulfanyl)-3-penten-2-amines has been investigated by the semi-empirical AM1 method. The observed efficient direction of the 1,2-asymmetric induction in the ketene Claisen rearrangement has been modelled from comparison of the energies of the four possible transition states arising from two chair-like and two boat-like structures. The resulting trends of relative transition state energy are in reasonable agreement with experimental observations.