Synthesis via Cyclic Dipeptides

The classical work of Inoue et al. [8] is an early example of a highly enantioselec-tive chiral synthesis effected by a fairly simple chiral catalyst, cydo-[(S)-Phe-(S)-His], which is shown in Fig. 6. 

There has been a lot of discussion about the mechanism of the catalytic step. The high ee (90%) of mandelonitrile formation through this cyclic catalyst (acyclic 

Catalyst Conditions Benzaldehyde 2-CI-Benzaldehyde Phenylpropanal 3-Phenoxybenzaldehyde Acetophenone 

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